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The overestimation of potassium (K) levels in ammonium acetate extractant has led to a significant concern in calcareous soil (CS). Therefore, a pot experiment was conducted to investigate the response of K application on grain yield and to determine the most suitable extractant along with their critical limits. The study utilized soil collected from both calcareous and non-calcareous soils, which were subjected to ten levels of K in a completely randomized design with three replications. The findings revealed that K application had a positive effect on yield and yield parameters in calcareous soils, up to 13.5%, with a response up to 7.5 mg kg−1. The study also demonstrated that grain and straw K concentrations were 2.5% and 8.9% higher, respectively, in calcareous soils when compared to non-calcareous soils (NCS). The study also tested the effectiveness of different extractants in extracting K from both soils. The available K extracted using various extractants varied, with the highest correlation coefficient (r = 0.87***) found in the barium chloride (BaCl2) extractant. The critical limit of soil-K by Cate-Nelson method was found to be 964.3 kg ha−1 for 0.1 M BaCl2, 0.74% for grain, and 3.55% in straw in CS. In conclusion, K application had a significant effect on yield and yield parameters in calcareous soils, with barium chloride being the most effective extractant for estimating potassium levels. The findings of this study provide valuable insights into the appropriate extractants and critical limits for the accurate evaluation of K levels in calcareous soils. [ABSTRACT FROM AUTHOR]

This study was conducted to optimize the calcimetry method (CM) and back titration method (BTM) for determination of calcium carbonate equivalent (CCE) in calcareous soils. For this purpose, 12 soil samples with wide CCE ranges and various physiochemical properties were selected to investigate the effect of contact time, sample preparation, soil-to-HCl ratio, heating, and HCl concentration on CCE measured by CM and BTM. Afterward, the optimized methods were compared by analysis of 100 calcareous soil samples. Results showed that the sample preparation is a key parameter affecting CCE determination, and the complete crushing of the sample without sieving led to the best results. Improper soil-to-hydrochloric acid (HCl) ratio led to overestimation of CCE. The kinetic experiment results revealed that the CCE dissolution in HCl was fast, and equilibrium was established in less than 5 minutes. The optimized BTM involved weighing 1–10 g of ground soil (depending on CCE content), adding 20 mL of 1 N HCl, heating for 5 minutes on a hotplate, and titrating by 1 N NaOH in the presence of phenolphthalein. The optimized CM involved weighing 1–5 g ground soil and adding 7 mL of 4 N HCl with a contact time of 5 minutes. The BTM and CM were highly correlated (r = 0.991) in the determination of CCE in a wide range of calcareous soils (100 soil samples), and the relevant regression equation can be employed as a transfer function to convert the BTM to CM results. [ABSTRACT FROM AUTHOR]

The modeling and assessment of land suitability is a prerequisite for land development and is one of the necessary needs to prevent land degradation. Maize is considered to be the most important crop, covering significant areas of agricultural lands in widely different regions across the world. However, not all available lands are equally suitable for maize cultivation. The main objective of this study was focused on identifying the potentials as well as the limitations of studied calcareous soils for maize cultivation in north Khuzestan province, Iran. Furthermore, some parametric models and multi-criteria land suitability evaluation methods for physical, chemical, fertility, and climatic factors (MC-LSE) were compared in estimating the maize yield. The required samples were taken from 23 land units by excavating control pedons. The necessary physicochemical parameters were then measured in the laboratory. The land indices were calculated by using different methods. The maize potential production of the investigated area was then obtained based on the climatic conditions. Finally, using land indices and the potential production, the estimated yield for each land unit was calculated and compared with the actual yield data. The obtained results indicated that the main limiting factors for maize yield in the region are high soil CaCO3 content, high salinity, high alkalinity and low organic matter. A comparison of predicted and actual yield indicated that the corrected square root method is accurate enough to assess land suitability and to estimate the maize yield with a high coefficient of determination (0.91) and a low RMSE value. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the impact of zinc (Zn) nutrition on enzymatic activity in soil and plant systems of zinc-deficient soils. Additionally, it aimed to understand the impact of solubilizer (such as Zinc Solubilizing Bacteria) and mobilizer (like AM Fungi) on enzyme activity and zinc nutrition in plants across calcareous and non-calcareous soil environments. A pot experiment was carried out with two different soils with three Zn sources (ZnSO4, ZnO and Zn-EDTA), organic manure (FYM) and microbial inoculants - Zinc Solubilizing Bacteria (ZSB) and Arbuscular Mycorrhizal Fungi (AM F). The DTPA-Zn and plant Zn content increased with applied sources of Zn. The microbial inoculants and FYM enhanced the use efficiency of all sources of Zn compared to unapplied treatments. Regarding soil enzyme activity, FYM and AM fungi played a major role which in turn altered the dehydrogenase (SDHA) and alkaline phosphatase (AlP) activities in both soils. The Zn sources and ZSB addition enhanced the plant enzyme activity. Calcareous soil recorded higher CA, SOD and alkaline phosphatase activities compared to non-calcareous soil the latter registered higher dehydrogenase activity and fruit Zn content. [ABSTRACT FROM AUTHOR]

AbstractPhosphorus (P) deficiency is a frequent problem in calcareous soils of Pakistan because of P-fixation, which poses significant threats to pearl millet productivity. The use of P-solubilizing bacteria (PSB) is regarded as a promising approach for improving P-availability in soil-plant systems. However, it needs optimization of P application into the soil. Therefore, this 2-year field study was conducted to optimize P doses in combination with PSB (Bacillus sp. MN54) inoculation to improve phosphorus use efficiency (PUE), yield, economic returns, and grain quality of pearl millet. Five P doses, i.e. 0 (native soil P only - control), 30, 60, 90, and 120 kg P2O5 ha−1 combined with and without PSB inoculated seeds were used in the study. The application of 90 kg P2O5 ha−1 + seed inoculation with PSB improved the grain yield by 36.8% and 36.0% during 1st and 2nd year, respectively. The same treatment significantly improved the PUE, grain protein, zinc (Zn), and total grain P contents compared to the control treatment. Furthermore, the highest economic returns (1053.3 and 1050.5 $ ha−1) and benefit:cost ratio were observed under 90 kg P2O5 ha−1 + seed inoculation with PSB during both years. In conclusion, application of 90 kg P2O5 ha−1 combined with PSB seed inoculation is a pragmatic option to improve P uptake, grain yield, PUE, grain quality and economic returns of pearl millet grown on calcareous soils. [ABSTRACT FROM AUTHOR]

Background: The poor nutrient recovery of phosphatic (P) fertilizers in calcareous soils is a serious worldwide problem resulting in sub‐optimal P use efficiency. This is mainly attributed to P fixation with calcium (Ca) and magnesium (Mg) ions in the soil solution. As a result, most of the applied P (in the form of fertilizer) becomes insoluble or immobilized in soil due to complex edaphic processes, making it unavailable to plants. Polymer‐coated fertilizers are relatively new approaches to minimizing P‐fixation. However, concerns have been recently raised on the environmental effects of synthetic polymers and microplastic loads in agroecosystems. Aim: Here we developed and investigated the effectiveness of biodegradable polymer‐coating on commercial diammonium phosphate (DAP) fertilizer to improve P availability in the soil, hence making P more accessible for plant uptake. Methods: The polymers were coated on DAP fertilizer granules, and two products based on increasing polymer concentration (namely, C‐1 and C‐2, respectively) were achieved. The coated and uncoated DAP granules were characterized for surface properties to confirm the appropriate coating of polymers using scanning electron microscopy (SEM) and crushing strength by a universal telson machine. The biodegradable polymer‐coated C‐1 and C‐2 fertilizers were tested for P availability compared to commercial DAP using spinach as a test plant. Results: The SEM micrographs indicated a uniform coating of biodegradable polymers on DAP granules. Application of C‐1 increased the plant's fresh and dry biomass (+10.71% and +18.09%) over commercial DAP, respectively. The C‐1 application increased the N, P, and K uptake by +24.9%, +66.7%, and +11% over commercial DAP. In contrast, C‐2 produced less biomass than C‐1 due to relatively less nutrient uptake and different concentrations of ingredients in C‐2. Conclusion: Together, our results showed that the novel biodegradable polymer approach has demonstrated the potential to improve P recovery and agronomic yield in alkaline soils. [ABSTRACT FROM AUTHOR]

To date, the dynamic behavior of slopes in calcareous sand is unclear owing to the marine biological origin of calcareous sand. In this study, the internal deformation and the liquefaction mechanism of calcareous sand slopes were investigated by shaking table tests and numerical simulations. The influence of the presence of initial shear stress due to site inclination on the dynamic response of the slope was considered. Moreover, based on the microscopic particle properties of calcareous sand, the special dynamic response of the calcareous-sand slope during earthquakes was explored through the parallel test with the quartz sand field. The results reveal that calcareous-sand slopes exhibit higher dynamic stability during earthquakes than quartz-sand slopes, which is related to the larger occlusion caused by the irregular shapes and porosities of calcareous sand particles. However, the calcareous-sand slope still demonstrates a horizontal displacement of 0.32 times the slope height under strong earthquakes. Moreover, the settlement of the calcareous-sand slope suddenly increased 60 cm from the slope top, while that of the quartz-sand slope decreased with an increase in the distance from the slope top. The seismic protection strategies involving the use of quartz-sand slopes in the calcareous-sand slopes are inapplicable. [ABSTRACT FROM AUTHOR]

Phylogenetic study of Arrhenia peltigerina revealed a complex of seven divergent clades. Type specimens of Agaricus peltigerinus and Omphalina cupulatoides fell into separate clades; the latter was recombined as Arrhenia cupulatoides. Four clades were described as new species: Arr. baltica, Arr. fennoscandica, Arr. mohniensis, and Arr. talpoides; the fifth, with only a single specimen, was left formally undescribed. These cryptic species are uncommon—more so in North America than Scandinavia—and collections are often misidentified. Spore measurements separated Arr. baltica from the others by its narrower spores; average measurements help separate some species a bit better than ranges. So far, Arr. peltigerina was found only in North America, Arr. mohniensis and Arr. talpoides in both Europe and North America, and the remainder only in Europe. The host species of Peltigera was Peltigera hymenina for Arr. cupulatoides, Peltigera rufescens for Arr. baltica, and varied for the others. All but one collection came from soil over calcareous bedrock. Small sample size does not permit assigning high confidence to noted interspecific differences; these await confirmation by greater experience from future study. [ABSTRACT FROM AUTHOR]

Aims: Soil microbial and enzymatic activity have important roles in soil health, nutrient cycle and plant growth. Biochar is an excellent biomass for increasing soil water content, but some biochar compounds, due to their high pH, are harmful to the soil. This study aimed to investigate the effect of biochar and sulfur-modified biochar on improving the soil water content and biochemical properties in a millet cropping system. Methods: The field experiment was performed in a completely random design with three replications. Experimental treatments included control, 15 t ha− 1 sunflower biochar (B), and 15 t ha− 1 sulfur-modified biochar (BS). Results: Biochar (B and BS) improved the soil water content by 47% and 35%, respectively, compared to the control. B and BS treatments improved soil biological properties, including microbial biomass carbon, basal respiration, and the activity of catalase, dehydrogenase, urease, and alkaline phosphatase enzymes compared to the control. The application of B and BS treatments decreased soil EC and sodium adsorption ratios compared to the control. The highest (8.26) and lowest (7.83) values of soil pH were related to the B and BS treatments, respectively. Treatment of soil with B and BS enhanced soil dissolved organic carbon (90% and 33%), available nitrogen (74% and 48%), and available phosphorus (60% and 96%) compared to the control. The application of B and BS treatments enhanced plant nutrients (nitrogen, phosphorus, and potassium) and the leaf relative water content by 40% and 14%, respectively. Biochar (B and BS) improved millet yield by 58% and 115%, respectively, compared to the control. Conclusion: Sulfur increased the efficiency of biochar in amending saline and calcareous soil and enhanced millet yield by improving the chemical properties (pH and CEC) of biochar. [ABSTRACT FROM AUTHOR]

Phosphorus (P) use efficiency in alkaline/calcareous soils is only 20% due to precipitation of P2O5 with calcium and magnesium. However, coating Diammonium Phosphate (DAP) with phosphorus solubilizing bacteria (PSB) is more appropriate to increase fertilizer use efficiency. Therefore, with the aim to use inorganic fertilizers more effectively present study was conducted to investigate comparative effect of coated DAP with PSB strains Bacillus subtilis ZE15 (MN003400), Bacillus subtilis ZR3 (MN007185), Bacillus megaterium ZE32 (MN003401) and Bacillus megaterium ZR19 (MN007186) and their extracted metabolites with uncoated DAP under axenic conditions. Gene sequencing was done against various sources of phosphorus to analyze genes responsible for phosphatase activity. Alkaline phosphatase (ALP) gene amplicon of 380bp from all tested strains was showed in 1% w/v gel. Release pattern of P was also improved with coated fertilizer. The results showed that coated phosphatic fertilizer enhanced shoot dry weight by 43 and 46% under bacterial and metabolites coating respectively. Shoot and root length up to 44 and 42% with metabolites coated DAP and 41% with bacterial coated DAP. Physiological attributes also showed significant improvement with coated DAP over conventional. The results supported the application of coated DAP as a useful medium to raise crop yield even at lower application rates i.e., 50 and 75% DAP than non-coated 100% DAP application which advocated this coating technique a promising approach for advancing circular economy and sustainable development in modern agriculture. [ABSTRACT FROM AUTHOR]

AbstractAgronomy biofortification is an important crop management strategy to enhance concentrations of micronutrients in edible portions. The availability of micronutrients for plant uptake is reduced by the high salinity, pH, and lime of soils. Hence, this study aimed to determine the most appropriate time and the best ratio of zinc (Zn) and iron (Fe) consumption during the wheat growth stages in a saline and calcareous soil. The experiment consisted of two factors with four levels; 0, 30, 60, and 120 kg Zn ha−1 as Zn0, Zn1, Zn2, and Zn3 respectively, and 0, 2.5, 5, and 7.5 kg Fe ha−1 as Fe0, Fe1, Fe2, and Fe3 respectively, in a randomized complete block design with four replications. The results showed that the interaction effects of Fe and Zn fertilizers application were significant on the wheat yield indices and concentration of Fe and Zn in wheat shoots and grain. The simultaneous application of 120 kg Zn ha−1 and 5 kg Fe ha−1 caused significant improvement (p < 0.05) in thousand kernel weight (9.1%) and subsequently grain yield (23.4%) compared to the control treatment. The Zn concentration in the wheat shoot during tillering (37.0–58.2 mg Zn kg−1) was higher than the other two growth stages (elongation (29.2–40.8 mg Zn kg−1) and booting (20.0–31.0 mg Zn kg−1)). While the highest Fe concentration in wheat shoots was observed at the stem elongation stage (98.5–268.8 mg Fe kg−1), then the booting stage (91.0–150.8 mg Fe kg−1) and finally the least absorption was at the tillering (80.0–120.0 mg Fe kg−1). Because of the high calcium carbonate, salinity and Zn- deficient soil of the experimental site, the Zn concentration in wheat grain was obtained in a range of 3 to 19 mg kg−1. The results clarified that the fertilizer application of 30 kg Zn ha−1 and 2.5 kg Fe ha−1 can be proportionally and simultaneously increased the concentration of Fe and Zn in wheat grain by 100%. Therefore, the soil application of 30 kg Zn and 2.5 kg Fe per hectare proposed for improvement in quantitative (619 kg ha−1 increase in wheat grain yield) and qualities (100% increase in grain Zn and Fe concentration and 8% increase in thousand kernel weight) indices of wheat yield in calcareous and saline soils. [ABSTRACT FROM AUTHOR]

Soils play an important role in the balance of carbon on the global scale. The study of the carbon cycle in Calcareous soils has received less attention, while Calcareous soils cover a third of the world's soils and most croplands of Iran. The aim of this study was to investigate soil organic carbon fractions and the relationship of soil organic carbon (SOC) with soil properties in 30 wheat farms of Calcisols of Alborz, Iran. To study the effects of soil geochemical properties, the data were subjected to cluster analysis to select samples with similar texture and low salinity. We applied a densimetric method using sodium iodide (NaI) to isolate light fraction (LF < 1.6 g/cm3), occluded fraction (OF < 1.8 g/cm3), and mineral-associated organic matter (MAOM > 1.8 g/cm3) of selected soils. Results showed that SOC decreased up to 61% throughout the soil profile. Mineral-associated organic matter had the highest proportion (more than 75%) of SOC in agricultural soils. The mean value of C/N reduced in mineral-associated organic matter compared to that of bulk soil, which indicates nitrogen concentration in this fraction. The study of soil properties suggested that calcium carbonate equivalent (CCE) could explain SOC content in calcareous soils, while extracted metals (iron, magnesium, and calcium) had a significant relationship with the organic carbon content of heavy fraction. [ABSTRACT FROM AUTHOR]

The impact of drip irrigation with saline-sodic water on the nutrient status and productivity of fodder beet (Beta vulgaris) was evaluated in rainy and dry Mediterranean cropping seasons. Two field experiments were conducted during two growing seasons (winter and summer) in calcareous soil (31% CaCO3) of Sais area, Northwestern Morocco. The rainfall was 337 mm for winter and 53 mm for summer. Four salinity levels of irrigation water (ECi) were investigated: control (1ds m−1), 4, 6, and 10 ds m−1. The ECi levels were prepared by adding sodium chloride (NaCl, laboratory grade, 99.5%) to water. The results showed that the soil salinity (ECs) was related to the growing season and the irrigation water salinity (ECi). The depressive effect of salinity on the whole plant dry biomass (−25% as average) was observed only in the summer crop cycle at different ECi ≥ 4 ds m−1 compared to control. The plant NaCl uptake for both seasons could be predicted by a linear model: Y (kg ha−1 of NaCl) = 36.3 ECi + 23.6 Q − 101.3 (adjusted R2 = 0.88) where Q = total dry biomass (t ha−1). Saline-sodic irrigation water reduced the contents of boron, calcium, and magnesium in the plants. The exchangeable sodium percentage (ESP) in the soil exceeded 41% at ECi ≥ 4 ds m−1 for both seasons. The study demonstrated that fodder beet escapes the negative impact of salt stress in the rainy season. However, the high ESP recorded at harvest did not reveal the efficacy of fodder beet in NaCl removal from the soil. [ABSTRACT FROM AUTHOR]

Soil salinity is a major challenge in agriculture, particularly in calcareous soils with high calcium carbonate levels. Biochar, produced from biomass pyrolysis, is being considered as a potential solution for mitigating salinity effects. A greenhouse pot experiment was conducted using calcareous soil from a saline field to investigate the effects of sugarcane biochar applied at different rates (0.0%, 2.0%, and 5.0%) on soil properties and wheat (Triticum aestivum L.) growth. Results showed that both Low Rate (2.0% biochar) and High Rate (5.0% biochar) treatments significantly improved soil pH, reduced electrical conductivity (EC), and increased soil organic matter (SOM) content. Plant growth indicators such as plant height, stem diameter, and leaf chlorophyll content also showed significant improvement with biochar application. High Rate had more pronounced effects compared to Low Rate. The analysis confirmed the significant effects of biochar on soil properties and plant growth, indicating its potential as a beneficial soil amendment. Sugarcane biochar has the potential to mitigate salinity stress and enhance crop productivity in calcareous soils. Further research is needed to explore the long-term effects of sugarcane biochar application and its interactions with other soil management practices in different crop systems. These findings highlight the promising role of biochar as a sustainable approach for mitigating salinity stress in agriculture and improving soil quality for crop production. The study's findings highlight the potential industrial applications of sugarcane biochar in addressing soil salinity issues prevalent in calcareous soils, particularly in agriculture. The research underscores the positive impact of biochar on soil attributes, plant growth, and nutrient availability. With its ability to improve soil pH, reduce salinity, increase soil organic matter, and enhance plant growth, sugarcane biochar emerges as a promising soil amendment for agricultural use. This presents an opportunity for industries involved in sustainable agriculture, soil management, and crop enhancement to explore the integration of biochar into their practices. Additionally, the study emphasizes the need for further research and field trials to optimize biochar application rates, assess economic feasibility, and ensure environmental sustainability. The insights gained from this study offer a pathway for industrial stakeholders to explore biochar's role in enhancing soil quality, promoting plant growth, and ensuring sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

The standard method to determine soil salinity is by measuring the electrical conductivity (EC) of a saturated soil paste extract (ECe). Models that convert EC of soil:water suspensions (EC(soil:water)) to ECe are soil specific and are not universal models. This study aimed to develop models to convert EC(1:1; 1:2; 1:5) to ECe for the calcareous soil of Malta. Moreover, the effect that soil texture, carbonate and organic matter content might have on these models was investigated. Using 114 soil samples with contrasting textural, carbonate and organic matter characteristics, the general models followed the equation ECe = 10(a(logEC(soil:water))+b) with good correlation coefficients (r2 = 0.91–0.93, p <.001). Models specific to fine and medium textured soil, soils with carbonate content between 35% and 50%, and soils with organic matter content between 2.5% and 4.2% showed a higher correlation coefficient (mean r2 = 0.96). Validation of the models using 22 independent soil samples showed that the general models are reliable (RMSE = 0.93, 0.87, 0.97 dS m−1; NSE = 0.96, 0.97 and 0.95 for 1:1, 1:2 and 1:5, respectively). Except for the models developed from coarse textured soil, all the parameter-specific models were reliable. This study suggests that the general models could be used for soils of Malta having contrasting characteristics except for those with high sand content. [ABSTRACT FROM AUTHOR]

Background and aims: Cover cropping is a strategy to increase soil phosphorus (P) use efficiency in agroecosystems. We investigated adaptations on P acquisition strategies of nine cover crops grown in a calcareous and a non-calcareous chernozem with low available P. Methods: Through a 108-day pot experiment using a calcareous and a decalcified chernozem, we evaluated black oat (Avena strigosa Schreb.), white lupin (Lupinus albus L.), narrow-leaf lupin (Lupinus angustifolius L.), phacelia (Phacelia tanacetifolia Benth.), berseem clover (Trifolium alexandrinum L.), buckwheat (Fagopyrum esculentum Moench), linseed (Linum usitatissimum L.), ramtil (Guizotia abyssinica [Lf] Cass.) and white mustard (Sinapis alba L.) for their dry biomass production, tissue P concentration and uptake, and effects on soil pH, phosphatase activity, mycorrhiza infection rate and soil P fractions. Results: Cover crops differed in several parameters between the two soils. Dry biomass varied from 3.3 (white lupin) to 41.6 g pot-1 (mustard). Tissue P concentrations ranged from 0.046% (mustard) to 0.24% (clover). Species affected pH of both soils, ranging from − 0.66 to + 0.24. Acid phosphatase activity was higher in the decalcified soil, while alkaline phosphatases were higher in the calcareous soil. Root mycorrhizal infection rates ranged from 0 to > 50%. Most plants explored soil labile P exclusively, with organic P mineralization being more relevant in the calcareous soil. Conclusion: We confirm that cover crops favoured distinct strategies to access the predominant soil labile P forms in each soil. Mycorrhizal species were particularly efficient in the decalcified soil, while species with high phosphatase secretion accessed higher Po, especially in the calcareous soil. [ABSTRACT FROM AUTHOR]

In the Mediterranean Region, calcareous soils are generally considered to be of low fertility. The use of large amounts of chemicals and irrigation to compensate for low productivity reduces the producer’s net profit and degrades physical and chemical properties of the soils. As a result, the selection of adaptable genotypes is important in agriculturally limited lands. Grapevine is one of the leading crops in the Mediterranean Basin due to its high tolerance to abiotic conditions. However, the fact that the grapevine grows in extreme soils does not mean that such crop does not respond to a good nutritional program, especially to the natural amendments. In this research, natural organic and inorganic soil amendments were tested on “Prima” grape cultivar grown in calcareous soils of the Mediterranean Basin, with the aim of developing environmentally friendly and cost-effective nutrition recommendations. Basaltic pumice (P), cereal straw (S), commercial dried compost (DC), grapevine pruning residue (PR), and farm cattle manure (FM) were used alone or in different combinations. The combination of P+PR+FM produced the best results for yield, cluster weight, and berry weight. However, it also resulted in the highest acidity and the lowest ripening index (total soluble solids/acidity). The highest ripening index values were obtained from S+FM and PR+FM applications. The treatments did not have different effects on total sugars, organic acids, and malvidin-3 glucoside anthocyanin, a relatively abundant component in V. vinifera grapes. However, P+PR+FM resulted in significantly higher levels of ascorbate peroxidase and total amino acids. The highest total anthocyanins were shown by DC, P+DC, and P+PR+FM. The results of the work demonstrated that the uses of different mixtures of natural and readily available materials have positive and diverse effects on grape quantity and quality in Mediterranean calcareous soils where vine is widely cultivated. [ABSTRACT FROM AUTHOR]

Soil cadmium (Cd) contamination poses a serious threat to ecosystems, and the application of phosphorus fertilizers can reduce Cd toxicity. However, the specific effects of different phosphorus fertilizers on the subcellular distribution and chemical morphology of Cd in eggplant grown in calcareous Cd-contaminated soil remain unclear. This study examined the impact of various types and levels of phosphate fertilizers on the subcellular distribution and chemical morphology of cadmium in eggplant seedlings using a two-factor analysis. The investigation was conducted via a pot experiment utilizing a two-factor analysis. The application of 0.35 g kg−1 dicalcium phosphate significantly decreased the Cd content in the subcellular distribution and induced notable alterations in the chemical morphology of Cd in eggplant roots. Specifically, the ethanol-extracted Cd state decreased by 65.45%, and the sodium chloride-extracted Cd state decreased by 64.65%. Conversely, Cd extracted by deionized water, acetic acid, hydrochloric acid, and the residue state increased by 6.20%, 4.01%, 20.87%, and 17.85%, respectively. The application of 0.35 g kg−1 dicalcium phosphate resulted in the most significant reduction in Cd content in eggplant and modification of subcellular Cd distribution and chemical morphology in roots. [ABSTRACT FROM AUTHOR]

Context: Arsenic (As) is a noxious metalloid for plants, animals and humans. Elevated levels of As in soils may cause it to accumulate to above-permissible levels in wheat grains, posing a threat to human health. Moreover, vulnerable population groups in developing countries have inadequate dietary zinc (Zn) linked to cereal-based diets. Aims: The present study evaluated the effect of soil Zn application on accumulation of As and Zn in grains of two Zn-biofortified wheat (Triticum aestivum L.) cultivars (Akbar-2019 and Zincol-2016). Methods: Wheat plants were grown on an alkaline calcareous soil spiked with three levels of As (0, 5 and 25 mg kg−1). Before sowing, two rates of Zn (0 and 8 mg kg−1) were also applied to the soil. Key results: Arsenic spiking in soil decreased plant dry matter yield, chlorophyll pigments, and phosphorus (P) and Zn accumulation, and increased As accumulation in wheat. By contrast, soil Zn application enhanced crop yield and increased P and Zn accumulation, with a simultaneous decrease in As accumulation in both cultivars. Compared with the Zn control, soil Zn application decreased grain As concentration by 26%, 30% and 32% for plants grown in soil spiked with 0, 5 and 25 mg As kg−1, respectively. Conclusions: Applying Zn to As-spiked soil mitigates the harmful effects of As by increasing Zn and decreasing As concentrations in wheat, resulting in improved grain quality for human consumption. Implications: Zinc application to crop plants should be recommended for addressing the health implications associated with As-contaminated crops and human Zn deficiency. Wheat grown on soils contaminated by arsenic (As) may accumulate toxic levels of As in grains, allowing As to enter the human food chain. The study evaluated the effect of soil zinc (Zn) application on grain As and grain accumulation of Zn in two Zn-biofortified wheat cultivars grown on As-contaminated soil. Soil Zn application decreased grain As accumulation to below the permissible limit of 0.15 mg As kg−1 and simultaneously increased grain Zn accumulation. [ABSTRACT FROM AUTHOR]

Approaches to the classification of thermophilous fringe and tall-herb vegetation in Central Europe vary in many respects. In this study, we provide new vegetation-plot data from South Moravia (Czech Republic), develop a new classification based on differences in overall species composition and compare it with recently used classifications. A dataset of 169 relevés fulfilling the condition of at least 50% cover of tall herbs or lower broad-leaved herbs characteristic of fringe vegetation was classified into six informal vegetation types, four of which may be considered equivalent to phytosociological associations. The most mesophilous and species-rich type Potentilla alba-Laserpitium latifolium is distributed on deep loamy soils developed over the Carpathian flysh, mainly in the White Carpathians. Potentilla argentea-Geranium sanguineum is the most heliophilous type, including acidophilous species and occurring on siliceous rock outcrops along the eastern margin of the Bohemian Massif. Type Vincetoxicum hirundinaria-Origanum vulgare is confined to hard base-rich rocks and occurs mainly in the limestone areas of the Moravian Karst and the Pavlov Hills. Type Geranium sanguineum-Peucedanum cervaria occurs mainly on deep calcareous soils developed over loess and Tertiary claystones in the central part of the South Moravian forest-steppe. The floristic classification of the thermophilous fringe and tall-herb vegetation in South Moravia yielded ecologically and geographically well characterized units that simultaneously differ from dry grasslands by the dominance of herbs, mainly tall herbs. It may serve as a model for future revisions of the national syntaxonomic classification scheme of fringe and tall-herb vegetation in the Czech Republic. [ABSTRACT FROM AUTHOR]

Background: In Sicilian calcareous soils, red wines often display unripeness and bitterness features. To enhance wine quality, we employed the 'sur lies élevage' technique, involving prolonged contact of dead yeast cells with the wine to favor the extraction of yeast cellular components through cell lysis. The 7 month treatment utilized two types of Chardonnay lies: fresh and previously matured. To overcome challenges in retrieving lies from red winemaking, we have recovered the lies from a white winemaking. Additionally, the lies underwent a preliminary passage on a red wine to minimize color adsorption on yeast cell walls. Results: The sur lies treatment effectively reduced astringency, bitterness, and brown pigment in wines, with partial removal of red color. It successfully eliminated quercetin aglycone and induced remarkable changes in the aromatic profile, showing increased ethyl esters and relative fatty acids. Sensory evaluations revealed sur lies‐treated wines had fruitier and more complex characteristics compared to untreated wines. Matured lies had a greater impact on enhancing fruitiness than fresh lies. Conclusions: The treatments mitigated the unripeness and bitterness of studied wines. Sur lies treatment improved the aromatic profile, leading to fruitier and more complex notes, enhancing overall sensory quality. Matured lies showed greater efficacy in elevating fruitiness than fresh lies. These findings highlight the value of the sur lies technique in enhancing the quality and sensory attributes of Nero d'Avola and Syrah wines from Sicilian calcareous soils. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The relatively small Frankeniaceae family is represented by halophyte plants, growing in arid and semi-arid climates in saline, alkaline or calcareous soils. Due to their living conditions, they usually produce a large diversity of compounds, which often exhibit bioactivities. Some species of this genus have long been used as traditional herbal medicines to treat dysentery, diarrhea, gonorrhea, vaginal leucorrhea, respiratory diseases and wounds. To date, several studies on either phytochemical or pharmacological aspects, or both, have revealed that this genus is a rich source of diverse and novel bioactive chemicals, including phenolics, flavonoids, alkaloids and fatty acids. This review describes all the reported chemical profiles of Frankenia species, as well as the corresponding biological properties, when available. The aim of this review is to show the potential of these plants for various applications, especially therapeutic ones. [ABSTRACT FROM AUTHOR]

This study investigates the distribution, morphology, and properties of these soils, focusing on areas such as littoral plains, high hilly areas, and rift depression valleys. Black soils occur in the eastern Mediterranean with a limited distribution, and some of them meet the requirements for black soils according to the INBS (International Network of Black Soils), while others do not. Black soils can be categorized into three types based on their genesis and evolution: calcareous black soils (mainly raw rocky rendzina), hydromorphic black soils, and black soil on basalt. While black soils were found in various bioclimatic stages and parent materials, their presence was notably limited in certain areas, contrary to prior indications. A soil morphology analysis revealed distinct color variations and depths, influenced by the accumulation of organic matter for hydromorphic and calcareous black soils and basaltic parent material for black soils on basalt. A particle size analysis indicated texture variations from clay to loam, with no clear indication of illuviation. A chemical analysis showed alkaline pH levels, except in basalt-derived soils, which exhibited a slight acidity. Hydromorphic black soil is the most important in terms of expansion and agricultural use and is only found in limestone marl deposits and lakes in depressions emerging from Dead Sea rifts under conditions of saturation or poor drainage. These soils have a thick, dark moly horizon and a high organic matter content. [ABSTRACT FROM AUTHOR]

Irrigation of calcareous soil with saline–sodic water can modify the composition of the soil solution and exchange complexes in agricultural land of arid and semi-arid regions with low water resources. The objective of this study was to monitor (medium-term) potential changes in a calcareous clay soil irrigated with two types of sodic waters without cropping. Irrigation water with two high sodium adsorption ratios (SAR = 20 and 40) and electrical conductivity (EC < 3 dS m−1) was prepared using NaCl and NaHCO3 salts. The sodic irrigation waters were applied (June–October) in three periods (1, 2, and 4; one period = five irrigations) to bare non-saline soil with drip irrigation during two growing seasons; no irrigation action was taken in the winter–spring rainy season (period 3). Sampling (0–30 cm) was made after each period to determine the changes in soil pH, EC, water-soluble Na+, Ca2+, Mg2+, K+, Cl−, and HCO3−. Relative to the control, irrigation with both sodic waters increased soil pH, EC, and water-soluble Na+ and decreased or did not change water-soluble cations (Ca2+, Mg2+). The Cl− concentration increased rapidly with NaCl-type water application, but it was leached away quickly by winter–spring rains. The HCO3− concentration increased with NaHCO3-type water application, yet it leached out slowly in the rainy period. The movement of HCO3− ions in the upper soil profile (0–30 cm) was significantly slower compared to Cl− ions. Dissolution of slightly soluble soil CaCO3 by irrigation increased the solution concentration of Ca2+ and its mobility, yet the kinetics of processes depended on water type and irrigation period. The released Ca2+ interacted with other cations in the soil, causing further significant positive physicochemical changes in the soil solution and exchange capacity (comparable with control soil) at the end of the irrigation period. The CaCO3 content in the soil would be a long-term guarantee of the Ca2+ resource in soils, even if the amount of water-soluble Ca2+ may decrease for the short-term period during irrigation. The results should be considered for rational irrigation management (with various water qualities) in semi-arid and arid regions. [ABSTRACT FROM AUTHOR]

Background: Vegetable pea is one of the relevant vegetable crops grown in the cool season all over the India. Sulphur deficiency is becoming more prevalent in Bihar due to the less use of boron and sulphur-containing fertilizer in calcareous soils and the consequent decrease in sulphur and boron nutrients. On the other hand, organic matter-rich manures, are utilized in very small quantities which is a source of a macro-and micronutrients, including sulphur and boron. As a consequence, soils have become deficient in sulphur and boron, which is detrimental to crop production. In the absence of these sulphur and boron in the soil, different legume crops such as vegetable pea suffer from reduced growth, yield and nodule formation. Methods: In this field investigation during 2020-2022, experiments were conducted in Factorial Randomized Block Design using fifteen different combinations of Boron and Sulphur doses in Azad Pea-3 variety of vegetable pea in three replications and different pod and seed yield attributing traits were studied. Result: Among the different treatments, it has been inferred that treatment combination 40 kg S ha-1 + 2 kg B ha-1 exhibited superiority over rest of the treatment combinations with respect to pod and seed yield attributes of vegetable pea. [ABSTRACT FROM AUTHOR]

The article discusses the importance of increasing Nutrient Use Efficiency (NUE) in agriculture to address challenges such as food production, land and water shortage, climate change, and environmental threats. NUE is influenced by various factors including plant nutrient acquisition, plant-microbe interactions, root functioning, and fertilizer management strategies. The article also highlights research presented at the XIX International Plant Nutrition Colloquium, covering topics such as nutrient bioavailability, plant growth-promoting microorganisms, climate change effects on plant nutrition, and field practices to improve nutrient use efficiency. Additionally, the article explores the impact of nutrient deficiencies on human health and the role of mineral nutrition in fruit quality. [Extracted from the article]

Background and aims: Proteaceae are a prominent plant family in south-western Australia. Most Proteaceae are 'calcifuge', occurring exclusively on old phosphorus (P)-impoverished acidic soils, with a few 'soil-indifferent' species also found on young P-richer calcareous soils. Calcium (Ca)-enhanced P toxicity explains the calcifuge habit of Proteaceae. However, previous research has so far been focused exclusively on the roles of Ca and P in determining Proteaceae distribution, and consequently there is little knowledge on how other soil-based strategies influence this distribution. We aimed to study the effects of young calcareous soils on four soil-grown Proteaceae and assess differences between calcifuge and soil-indifferent Proteaceae to better understand their natural distribution. Methods: Two calcifuge and two soil-indifferent Proteaceae from south-western Australia were grown in six contrasting soils, including young calcareous, and old acidic soils. Results: When grown in calcareous soils all species showed root growth inhibition, micronutrient deficiency, Ca-enhanced P toxicity, and negative impacts on physiology. Calcifuge species were more sensitive to calcareous soils than soil-indifferent ones, although this varied between genera. Soil-indifferent species tended to produce more cluster roots, release more carboxylates per root mass, and allocate less Ca to their leaves, compared with calcifuges; they also had smaller seeds and were less sensitive to Ca-enhanced P toxicity. Conclusion: We surmise that a combination of these traits allows soil-indifferent species to tolerate calcareous soils. This study provides insight into how Proteaceae respond to young calcareous soils and how this influences their distribution. [ABSTRACT FROM AUTHOR]

Slow-release fertilizers (SRFs) play an essential and necessary role in sustainable agriculture. Using slow-release and environment friendly fertilizers can increase the growth of plants and reduce the loss of nutrients. Considering the deficiency of iron (Fe) and zinc (Zn) in calcareous soils, a slow-release fertilizer was prepared based on the polymeric nanocomposite, which contains NPK, Fe, and Zn. Its potential was evaluated on tomato plant growth by conducting an experiment in a factorial completely randomized design with three replications. Two levels of salinity (2 and 5 ds m−1, two types of soil texture) clay loam and sandy loam) and five levels of fertilizers were examined in the experiment. To this, the graphene oxide-chitosan coated-humic acid@Fe3O4 nanoparticles (Fe3O4@HA@GO-Cs), and the graphene oxide-chitosan coated-ammonium zinc phosphate (AZP@GO-Cs) were used as Fe and Zn sources, respectively. Then, the optimal Fe and Zn fertilizers in the presence of urea, phosphorus, and potassium slow- release fertilizers (SRF) were investigated under greenhouse conditions. The results indicated that the best improvement in growth and nutrient uptake in plants was achieved by using the SRF. Notably, in the shoots of tomato plants, the nitrogen, phosphorus, potassium, Fe, and Zn concentration increased by 44, 66, 46, 75, and 74% compared to the control. The use of nanofertilizer can be an effective, biocompatible, and economical option to provide Fe and Zn demand in plants. [ABSTRACT FROM AUTHOR]

The access of vinasse leachates to water bodies and groundwater exacerbates environmental problems, especially eutrophication. Therefore, a column experiment was performed to examine the effect of adding zeolite (ZL), bone char (BC), and wood chips biochar (WCB) in the presence of vinasse on carbon dioxide (CO2) emission, leaching dissolved organic carbon (DOC) and ammonium (NH4+) in calcareous sandy soil, as well as studying the kinetics of leaching dissolved organic carbon and ammonium. This column experiment contains four treatments: soil alone (CK), soil + zeolite (SZL), soil + bone char (SBC), and soil + wood chips biochar (SWCB). These amendments were applied to the soil at a level of 4%. Vinasse was added to all treatments at a level of 13 mL per column. The leached total cumulative DOC and total cumulative soluble ammonium amounts decreased significantly with applying ZL, BC, and WCB compared with the soil alone. The effectiveness of these amendments in lowering the total cumulative DOC leaching is in the order of SBC > SWCB > SZL > CK. However, the effectiveness of these amendments in decreasing the total cumulative NH4+ leaching is in the order of SZL > SWCB > SBC > CK. The rate constant (k) of DOC leaching decreased significantly with the application of bone char compared to soil alone treatment. In the presence of vinasse, the apparent half-life of leached DOC from the soil was 8.1, 12.9, 36.7, and 15.5 days for soil CK, SZL, SBC, and SWCB treatments, respectively. Half-life values of leached soluble ammonium from the soil in the presence of vinasse addition were 10.1, 39.5, 28.5, and 37.9 days for CK, SZL, SBC, and SWCB treatments, respectively. Amending soil with BC increased significantly the phosphorus availability, however, applying ZL and BC caused a significant increase in the available potassium in calcareous sandy soil compared to the control treatment. According to these results, it is recommended not to add vinasse alone to sandy soils, but it is preferred to be co-applied with BC amendment at the level of 4% better than ZL and WCB. This would decrease leaching DOC and ammonium to the water table and groundwater as well as enhance nutrient retention in the soil, which in turn, plays a vital role in reducing the harmful effect of vinasse and improving soil fertility. [ABSTRACT FROM AUTHOR]

This study was carried out to examine the interaction of enzyme activities, microbial biomass carbon, and CO2 respiration with heavy metals under different land uses in terms of quality and sustainability of the soil. There is a statistically significant positive correlation between dehydrogenase enzyme activity and Mn, Pb, Cd, and Co, while it was negative between Cr. There was a positive correlation between catalase enzyme activity and Mn and Pb and between urease and Co. The higher interaction of dehydrogenase activity with heavy metals, which is included in the endo enzyme group, has been explained as a much stronger effect of heavy metals on living microorganisms and endoenzymes than extracellular enzymes stabilized on clay minerals and organic matter. The high clay content of the soil is thought to reduce some of the negative effects of heavy metals on enzymes. The results of this study may be good indicators of enzyme activities, especially dehydrogenase, catalase, and urease, for soil health and quality, chemical degradation and restoration processes, and ecosystem functioning in soils contaminated or to be contaminated with heavy metals. It shows that the activities of these enzymes are very sensitive and can decrease rapidly in case of high concentrations of heavy metals. [ABSTRACT FROM AUTHOR]

Potassium (K) equilibration, release and fixation in the cadmium (Cd) contaminated soils may be affected by organic amendments application. The effect of 1.5% corn, cotton and wheat residues and their produced biochars and 150 mg kg–1 Cd application on different soil K forms, K release to 0.01 M CaCl2 and 1% wood vinegar and K fixation of a coarse-textured calcareous soil was studied. Plant residues and their produced biochars increased soluble K content by 24–69 and 22–99 mg kg–1, respectively. The exchangeable K content was also increased 57–191 mg kg–1 after organic amendments application. Contamination of the soil with Cd increased the soluble K content by 11–23 mg kg–1. Cadmium application also increased exchangeable K and decreased non-exchangeable K of the biochar-treated soils. Exchange of Cd with exchangeable K and Ca and non-exchangeable K and subsequently exchange of soluble Ca with non-exchangeable K may be the main mechanisms for changes in K fractionations. CaCl2 and wood vinegar extracted 500 and 502 mg K kg–1, respectively, with non-significant difference. The main mechanism of K release with both solutions is the exchange reaction of non-exchangeable K with soluble Ca (originated from CaCl2 or dissolution of CaCO3 by wood vinegar) and it seems that acidic wood vinegar is not able to dissolve K-bearing minerals (micas and feldspars). Potassium released from the soil increased 32–338 mg kg–1 in the uncontaminated soil samples and 58–408 mg kg–1 in the Cd-contaminated soil samples after organic compounds application. Potassium fixation in soils treated with CaCl2 and wood vinegar was 124 and 113 mg kg–1, respectively and decreased with organic amendments application. Organic acids in wood vinegar may enter to the interlayers of clay minerals or adsorbed on the mineral edge and decrease layer collapse and K fixation. Generally, it is concluded that contamination of soil by Cd and remediation of soil with organic compounds application may increase the K availability of K-depleted calcareous soils via K addition to soil and release of native non-exchangeable K. In addition, an increase in soil soluble K by 21–230% may increase the risk of K leaching, soil salinity and cations equilibration of soil solution in long-term periods and this should be considered in K fertility management strategies of K-depleted soils. [ABSTRACT FROM AUTHOR]

Background: Over the years, the excessive P fertilizer application to crop fields resulted in the build up of insoluble phosphorus pool in soil known as legacy phosphorus. This represents a vast and largely untapped resource in soil. The current study was conducted to evaluate the potential of some P activators (Phosphorus solubilising bacteria, phytase, humic acid, farmyard manure) on increasing the plant availability of legacy P in calcareous soil. Methods: A field experiment was conducted with maize hybrid COH(M) 6. The P activators were combined and applied along with the different doses of P fertilizer (100%, 75% and 50% soil test dose of single super phosphate). Result: Farmyard Manure (FYM) application with Humic acid (HA) showed the increased Olsen P under 100% and 75% of P application. The phosphorus activation response of FYM+HA applied plots showed a higher value than other treatments. The maize yield and P uptake obtained with FYM and HA were statistically comparable at 100% and 75% soil test dose of P. The findings have illustrated that even the reduced amount of P fertilizer application can support the crop growth due to the release of legacy P if they are applied along with P-activators such as FYM and HA. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is one of the 17 essential plant nutrients, and it is critical for plant metabolism, photosynthesis, and growth. P fertilizers are also critical for crop production and global food security. Type and application method of P fertilizer may lead to increased P accumulation and crop production in the Ganges delta soils. The aim of the present study is to increase the P use efficiency (PUE) by two different P application methods for maize cultivation. The experiment comprised a factorial combination of two methods (broadcasting and furrow placement) and three rates of P fertilizer (36, 48, and 60 kg P/ha). Considering P application methods, furrow placement gave 8.66–27.92% yield benefit over broadcasting method. Maize yield, PUE by crop plant, partial factor productivity, economic efficiency, and P concentration in leaf were remarkably higher in furrow placement than conventional broadcasting method of P application. The furrow placement exhibited higher yield at lower rate of P application (36 and 48 kg P/ha), while no significant changes were observed for grain yield between two methods for high P rate (60 kg/ha). Thus, it is concluded that furrow placement of P application at 36 and 48 kg/ha would give the best grain yield of maize in the Ganges delta floodplain soils. [ABSTRACT FROM AUTHOR]

Thoracican barnacles are a diverse group of marine organisms for which the availability of genome assemblies is currently limited. In this study, we sequenced the genomes of two neolepadoid species (Ashinkailepas kermadecensis, Imbricaverruca yamaguchii) from hydrothermal vents, in addition to two intertidal species. Genome sizes ranged from 481 to 1054 Mb, with repetitive sequence contents of 21.2% to 50.7%. Concordance rates of orthologs and heterozygosity rates were between 82.4% and 91.7% and between 1.0% and 2.1%, respectively, indicating high genetic diversity and heterozygosity. Based on phylogenomic analyses, we revised the nomenclature of cement genes encoding cement proteins that are not homologous to any known proteins. The major cement gene, CP100A, was found in all thoracican species, including vent‐associated neolepadoids, and was hypothesised to be essential for thoracican settlement. Duplicated genes, CP100B and CP100C, were found only in balanids, suggesting potential functional redundancy or acquisition of new functions associated with the calcareous base. An ancestor of CP52 genes was duplicated dynamically among lepadids, pollicipedids with multiple copies on a single scaffold, and balanids with multiple sequential repeats of the conserved regions, but no CP52 genes were found in neolepadoids, providing insights into cement gene evolution among thoracican lineages. This study enhances our understanding of the adhesion mechanisms of thoracicans in underwater environments. The newly sequenced genomes provide opportunities for studying their evolution and ecology, shedding light on their adaptation to diverse marine environments, and contributing to our knowledge of barnacle biology with valuable genomic resources for further studies in this field. [ABSTRACT FROM AUTHOR]

Management of nitrogen (N) fertilizer is a critical factor that can improve maize (Zea mays L.) production. On the other hand, high volatilization losses of N also pollute the air. A field experiment was established using a silt clay soil to examine the effect of sulfur-coated urea and sulfur from gypsum on ammonia (NH3) emission, N use efficiency (NUE), and the productivity of maize crop under alkaline calcareous soil. The experimental design was a randomized complete block (RCBD) with seven treatments in three replicates: control with no N, urea150 alone (150 kg N ha−1), urea200 alone (200 kg N ha−1), urea150 + S (60 kg ha−1 S from gypsum), urea200 + S, SCU150 (sulfur-coated urea) and SCU200. The results showed that the urea150 + S and urea200 + S significantly reduced the total NH3 by (58 and 42%) as compared with the sole application urea200. The NH3 emission reduced further in the treatment with SCU150 and SCU200 by 74 and 65%, respectively, compared to the treatment with urea200. The maize plant biomass, grain yield, and total N uptake enhanced by 5–14%, 4–17%, and 7–13, respectively, in the treatments with urea150 + s and urea200 + S, relative to the treatment with urea200 alone. Biomass, grain yield, and total N uptake further increased significantly by 22–30%, 25–28%, and 26–31%, respectively, in the treatments with SCU150 and SCU200, relative to the treatment with urea200 alone. The applications of SCU150 enhanced the nitrogen use efficiency (NUE) by (72%) and SCU200 by (62%) respectively, compared with the sole application of urea200 alone. In conclusion, applying S-coated urea at a lower rate of 150 kg N ha−1 compared with a higher rate of 200 kg N ha−1 may be an effective way to reduce N fertilizer application rate and mitigate NH3 emission, improve NUE, and increase maize yield. More investigations are suggested under different soil textures and climatic conditions to declare S-coated urea at 150 kg N ha−1 as the best application rate for maize to enhance maize growth and yield. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity (Kψ) is one of the most important soil properties that influences water and chemical movement within the soil and is a vital factor in various management practices, like drainage, irrigation, erosion control, and flood protection. Therefore, it is an essential component in soil monitoring and managerial practices. The importance of Kψ in soil-water relationship, difficulties for its measurement in the field, and its high variability led us to evaluate the potential of stepwise multiple linear regression (SMLR), and multilayer perceptron (MLPNNs) and radial-basis function (RBFNNs) neural networks approaches to predict Kψ at tensions of 15, 10, 5, and 0 cm (K15, K10, K5, and K0, respectively) using easily measurable attributes in calcareous soils. A total of 102 intact (by stainless steel rings) and composite (using spade from 0–20 cm depth) soil samples were collected from different land uses of Fars Province, Iran. The common physico-chemical attributes were determined by the common standard laboratory approaches. Additionally, the mentioned hydraulic attributes were measured using a tension-disc infiltrometer (with a 10 cm radius) in situ. Results revealed that the most of studied soil structure-related parameters (soil organic matter, soluble sodium, sodium adsorption ratio, mean weight diameter of aggregates, pH, and bulk density) are more correlated with K5 and K0 than particle-size distribution-related parameters (sand, silt, and standard deviation and geometric mean diameter of particles size). For K15 and K10, the opposite results were obtained. The applied approaches predicted K15, K10, K5, and K0 with determination coefficient of validation data (R2val) of 0.52 to 0.63 for SMLR; 0.71 to 0.82 for MLPNNs; and 0.58 to 0.78 for RBFNNs. In general, the capability of the applied methods for predicting Kψ at all the applied tensions was ranked as MLPNNs > RBFNNs > SMLR. Although the SMLR method provided easy to use pedotransfer functions for predicting Kψ in calcareous soils, the present study suggests using the MLPNNs approach due to its high capability for generating accurate predictions. [ABSTRACT FROM AUTHOR]

A pot experiment was carried out for investigating the possibility of partial or entire replacement of mineral nitrogen fertilizers with organic and biofertilizers, aiming to improve the efficiency of nitrogen fertilization for barley plant grown on sandy calcareous soil collected from Agriculture Research Station in Nubariya. Mineral nitrogen fertilizer was added at the rates 30, 60, 90 and 120 mg N kg soil-1. Phosphorus and potassium were added at the recommended rates of 15 mg P and 30 mg K kg soil-1, respectively. Organic fertilizers were added from different sources "compost, chicken manure and pigeon dung" at a rate of 30 mg kg N soil-1 based on their nitrogen content. Biofertilization was achieved through the addition of 5g pot-1 serialin or/and 5g pot-1 phosphorene; mixed thoroughly with soil. Upon the observed data, the highest dry matter yield was obtained when "compost + serialin " were applied to the soil in combination with mineral-N at addition level of "90 mg N kg soil-1". The highest nitrogen uptake was obtained when the soil was treated with "chicken manure + serialin" combined with mineral-N at addition level of 60 mg N kg soil-1. The highest phosphorus uptake was obtained when soil treated with "chicken manure + phosphorine "combined with mineral-N at level of 60 mg N kg soil-1. The highest potassium uptake was obtained when soil was treated with "chicken manure + serialin" combined with mineral-N at level of 90 mg N kg soil-1. The highest yield of straw and grains as well as protein content were obtained when soil was treated with "chicken manure + serialin" combined with mineral-N at level of 60 mg N kg soil-1. [ABSTRACT FROM AUTHOR]

Phosphorus (P) use efficiency is crucial for sustainable wheat production, particularly on alkaline calcareous soils. This study investigates the relative importance of two factors; P acquisition efficiency (PAE) and P utilization efficiency (PUtE), in determining P use efficiency (PUE) in wheat. A field trial with ten wheat genotypes was conducted under two P levels (no P application and P application at 110 kg P2O5 ha-1). Results revealed significant genetic variability in PUE, PAE, and PUtE among wheat genotypes under varying P availabilities. Genotypes MK-4 and MK-8 exhibited superior PUE, making them ideal candidates for soils with differing P levels. PAE played a more substantial role in influencing PUE, with PUtE contributing less to the variability. The findings underscore the importance of improving PAE, particularly for wheat genotypes grown in P-deficient conditions. Moreover, selecting genotypes with lower grain P concentration can enhance PUtE, contributing to improved PUE. These insights can improve breeding efforts and crop management practices to enhance P use efficiency in wheat, ultimately reducing production costs and fertilizer demand, especially in P-limited alkaline calcareous soils. [ABSTRACT FROM AUTHOR]

The distribution of calcareous nannofossil species in the upper part of Gurpi Formation and lower part of Pabdeh Formation has been investigated in the Karta section (northwest of Izeh in Zagros Basin, Iran, Eastern Tethys) to provide a biostratigraphic framework from Maastrichtian to Thanetian interval. In this study, 31 genera and 52 species of calcareous nannofossils have been identified and based on the recognized bioevents and the resulting biozones, the studied interval spans from the top of the nannofossil zone UC19TP to the base of the NP7 zone and covers ~10.8 Myr. In this study, the Gurpi Formation spans from the upperUC19TP to NP4 zones, while the lowest part of Pabdeh Formation covers NP5, NP6 and NP7 zones. The studied sequence is continuous and encompasses Cretaceous-Paleogene (K/Pg), Danian/Selandian and Selandian/Thanetian boundaries. The K/Pg boundary is characterized by nannofossil assemblage recognized worldwide, such as the occurrence of Biantholithus, Cruciplacolithus, Braarudosphaera, Praeprinsius, and calcareous blooms of Thoracosphaera spp. A decrease in the abundance of nannofossils is observed in the upper part of the Maastrichtian to the lower part of the Danian; poor to moderate preservation of nannofossils and low diversified nannofossil assemblages cover most of the studied samples. Here, as a result of species poor to moderate preservation, we observe patterns of stepwise extinctions upward in the top of CC25 zone, that culminate with the last occurrence of eight species, just prior to the base of the UC20bTP. We interpret these patterns to be mainly the result of diagenetic alteration. Our dataset provides a record over a long-lasting interval of stepwise extinctions toward the K/Pg boundary that was likely caused by the diagenetically-enhanced Signor-Lipps effect. [ABSTRACT FROM AUTHOR]

The addition of organic materials in arid and semi-arid regions not only improves the physicochemical and biological characteristics of the soil but also increases plant growth. In this study, the effect of individual and combined application of humic acid (HA) (150 mg kg−1 soil), wood vinegar (WV) (75-fold dilution), and biochars (corn straw biochar (CSB) and cotton residue biochar (CRB) each at 2% wt.) on the soil Zn chemical fractions and its uptake by Sour Orange (Citrus aurantium L.) seedlings were investigated in a calcareous soil. The results showed the CRB was more effective in increasing the Zn concentration in fractions with high bioavailability (soluble+exchangeable (WsEx) and organic (OM) forms) than the CSB. This may be due to its higher organic carbon content (74%) and electrical conductivity (3.52 dS m−1) than those for the CSB. There was no significant difference between HA and WV in terms of the effect on soil Zn chemical fractions. The CRB+WV and CRB+HA were the best treatments for enhancing the soil Zn bioavailability. The greatest increase in the shoot dry matter yield (2.5-fold) and Zn uptake (29%) was associated with the combined treatment of CRB+HA compared to the control. Furthermore, the shoot dry matter yield of Sour Orange seedlings had a significant and positive correlation with the Zn-WsEx fraction and Zn uptake. It could be concluded that among the treatments, the combined application of CRB+HA was the best in enhancing soil Zn bioavailability, Zn uptake and shoot dry matter yield of Sour Orange seedlings in the calcareous soil. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are a genus of obligatory root biotrophs that can develop mutualistic symbioses with most terrestrial plants. This study aimed to investigate the impact of three different isolates of AMF (Acaulospora spinosa [M1], Glomus ambisporum [M2], and Scutellospora heterogama [M3]) isolated from native environments and three carriers (biochar, alginate, and polyacrylate) on wheat (Triticum aestivum L.) grown in a saline calcareous soil in conditions of water deficit. In a pot experiment, reduced amounts of water were applied at intervals of 4, 8, and 12 days, while in a field experiment, the intervals were 1, 2, and 3 weeks (W1, W2, and W3). By analyzing the chlorophyll index and dry weight data from the pot experiment, it was revealed that two AMF isolates (M1 and M2), along with two carriers (biochar and alginate), showed promising results in stimulating wheat growth. Based on these findings, a field validation experiment was conducted to further evaluate the effects of these isolates and carriers. The wheat plants subjected to water deficit stress exhibited improved vegetation characteristics, grain yield, nutrient uptake, and colonization percentage when treated with the AMF isolate M2 formulated on biochar. For instance, under W2 conditions without any mycorrhiza or carrier, the grain yield was recorded at 6,600 kg ha-1. However, with the inoculation of M2-biochar at the same W2 level, the yield significantly increased to 9110 kg ha-1. The study concluded that AMF formulated on biochar outperformed other carriers, leading to enhanced wheat growth under water stress conditions. [ABSTRACT FROM AUTHOR]

Soil fertility in Pakistan is hindered by insufficient and unstable organic matter, leading to stagnation and a decline in overall agricultural productivity. Methodology A pot study was conducted in 2018-19 comprised of four treatments including T1 = Recommended NPK fertilizer, T2 = NPK+FYM, T3 = NPK + Poultry manure, and T4 = NPK + Plant residue based on Complete Randomized Design (CRD) and was replicated thrice. Result The results exhibited significant differences in peas’ growth, yield, and nutrient use efficiency across the organic amendments. Among them, the higher plant height (70.63 cm), pod length (9.37 cm), and pod yield (158.63 g pot-1 ) was observed in T3 followed by T2. Regarding nutrient concentration and uptake, both T2 and T3 treatments elevated leaf tissue levels of N (4.76% and 5.03%), P (1.01% and 0.98%), and K (2.27% and 2.31%). These values were statistically comparable, accompanied by higher but non-significant P uptake (0.61 and 0.67 g pot-1) and K uptake (1.13 and 1.21 g pot-1) for the respective treatments. Further, higher nitrogen, phosphorus, and potassium use efficiency (49.4, 5.20, and 42.0%) were recorded in T3 followed by T2. Together with that significantly positive correlation between soil properties and pod yield was found which reflects the nutrient-supplying power of soil under organic amendments. Conclusion Consequently, it is suggested that the joint utilization of organic additives of any source and chemical fertilizer is necessary for increasing yield and nutrient use efficiency over sole chemical fertilizer application in calcareous soils. [ABSTRACT FROM AUTHOR]

Original Walkley-Black (OWB) method has been extensively used for measuring Soil Organic Carbon (SOC), mainly because of its convenience. However, the reliability of this method is still under speculation. In recent years, Permanganate Oxidizable Carbon (POXC) has been suggested to be more useful than the total SOC. In the present study, SOC contents of the 20 non-calcareous soil samples (0-20 cm) were determined by the OWB method and its modified versions (WB with external heating and WB using colorimetric determination) to understand their relationships with easy-to-find Soil Organic Matter (SOM) determined by the method of Loss-On-Ignition (LOI) at two temperatures (400 and 550°C). The POXC was also determined in the sampled soils and applicable relationships were specified between these methods. Eight of the 20 soils were selected to determine the accuracy of different WB methods using total organic carbon by CHN elemental analysis. Results showed strong power relationships between LOI and OWB methods. The WB method with external heating exhibited the highest recovery (95.3%) among the tested methods. This could be attributed to the finer soil particles used in the proposed method (less than 0.15 mm) than what has been used in the conventional method (less than 0.5 mm). The POXC method showed a high correlation with OWB method and, on average, accounted for only 4.1% of the Total Organic Carbon (TOC). This would likely reduce the value of POXC as an independent parameter to derive the labile fraction of SOC. [ABSTRACT FROM AUTHOR]

The complexity of retrieving paleoenvironmental variability from hemipelagic sedimentary archives in the marginal seas has been exacerbated by intricate interactions between sedimentary sources and climatic fluctuations, modulated by sea-level shifts and oceanic currents. These challenges are particularly pronounced in the northern South China Sea (SCS). This study introduces new data, incorporating Sr Nd isotopic, clay minerals, grain-size, and calcareous nannofossil proxies, to assess the sedimentary provenance and paleoenvironmental changes in the northwestern SCS since the Last Glacial Maximum. The sedimentary provenance highlights the primary source from the northern SCS, particularly the Red River drainage system, with potential contributions from the Indochina drainage systems. The combined analysis of multiple proxies suggests that sedimentary processes and biotic activity in the examined core were mainly influenced by sea-level fluctuations, concerning global ice dynamics. Variations of grain sizes and kaolinite / (illite + chlorite) (K/(I + C)) ratio largely correspond to the terrestrial flux variation from northern SCS associated with sea-level changes during glacial-interglacial cycles. Furthermore, the smectite / (illite + chlorite) (S/(I + C)) ratio in this study appears to have been primarily influenced by the activity of the Kuroshio current in the northern SCS. The possible interference of intensified northeastward warm currents during relatively warm intervals caused the depletion of the S/(I +C) ratio and was responsible for the depletion of soluble calcareous nannofossils. Additionally, this study deduces that sedimentary processes and biotic activity in the northern SCS, in response to mainly sea-level changes and surface currents, were largely controlled by global ice dynamics and solar radiation. This study also underscores the need for further interdisciplinary research, combining various proxies, to enhance our understanding of paleoenvironmental assessments in hemipelagic sediments in marginal seas. • The study contributes a multiproxy analysis to assess marine sedimentary processes. • Sedimentary processes were mainly influenced by sea-level fluctuations. • The Kuroshio activity might significantly influence the clay mineral distribution. • This study suggests the polar-ice controlling of the paleoenvironment in the northern SCS. [ABSTRACT FROM AUTHOR]

This study evaluated the feasibility and efficiency of stabilizing washed recycled sand (RS) derived from construction and demolition wastes when treated by soybean-based enzyme-induced carbonate precipitation (EICP), cured at a low temperature of 4 °C. Two types of RS were studied, being fine recycled sand (FRS) and coarse recycled sand (CRS). Urease extracted from soybeans was used to catalyze the urea hydrolysis reaction, which led to the precipitation of calcium carbonate, which acts as a soil binder. Such a low-temperature curing condition was found to effectively minimize surface clogging at the same treatment cycles when compared to room-temperature curing due to a comparatively low urease activity. The excess amount of CaCO 3 precipitated on the surface was found to block the effective EICP solution from flowing through the sample and did not contribute to strength improvement. The unconfined compressive strength (UCS) results on CRS depicted a slight strength reduction at low-temperature curing, but the improvement in bio-clogging indicated the potential of involving extra treatment cycles which could further develop the strength. SEM, EDS and XRD analyses further established the existence of the biocement gel triggered by soybean-extracted urease cured at low temperatures within the both CRS and FRS particles. As such, soybean-based EICP solution was found to be an effective green binder for washed RS in terms of the noticeable stabilizing effect, hence was found to be a suitable as a geotechnical fill material for ground improvement works. • Washed recycled sand could be stabilised by soybean based EICP. • The increased soybean powder concentration usually implies a higher value of urease activity; however, it results in surface bio-clogging that disrupts strength development. • The drop in curing temperature delays the overall reaction of EICP by reducing the urease activity, as reflected in the decreased UCS. • Low temperature helps ease the surface bio-clogging, indicating the potential of applying extra EICP treatment to further improving the strength. [ABSTRACT FROM AUTHOR]

Long-term wastewater irrigation leads to the loss of calcium carbonate (CaCO 3) in the tillage layer of calcareous land, which irreversibly damages the soil's ability to retain cadmium (Cd). In this study, we selected calcareous agricultural soil irrigated with wastewater for over 50 years to examine the recalcification effects of sugar beet factory lime (SBFL) at doses of 0%, 2.5%, 5%, and 10%. We found that SBFL promoted Cd transformation in the soil from active exchangeable species to more stable carbonate-bonded and residual species, which the X-ray diffraction patterns also confirmed results that CdSO 4 reduced while CdS and CaCdCO 3 increased. Correspondingly, the soil bioavailable Cd concentration was significantly reduced by 65.6–84.7%. The Cd concentrations in maize roots and shoots were significantly reduced by 11.7–50.6% and 13.0−70.0%, respectively, thereby promoting maize growth. Nevertheless, SBFL also increased the proportion of plant-unavailable phosphorus (P) in Ca 8 –P and Ca 10 –P by 4.3–13.0% and 10.7−25.9%, respectively, reducing the plant-available P (Olsen P) content by 5.2–22.1%. Consequently, soil P-acquiring associated enzyme (alkaline phosphatase) activity and microbial (Proteobacteria , Bacteroidota , and Actinobacteria) community abundance significantly increased. Our findings showed that adding SBFL to wastewater-irrigated calcareous soil stabilized Cd, but exacerbated P limitation. Therefore, it is necessary to alleviate P limitations in the practice of recalcifying degraded calcareous land. [Display omitted] • Sugar beet factory lime (SBFL) significantly reduced soil bioavailable Cd content. • Soil Cd species transformed from an active form to a more stable mineral form. • Cd content in the roots and shoots of maize was significantly reduced. • Plant-available P content was significantly reduced under the SBFL treatments. [ABSTRACT FROM AUTHOR]

The performance of biochar (BC) in reducing the transport of antibiotics under field conditions has not been sufficiently explored. In repacked sloping boxes of a calcareous soil, the effects of different BC treatments on the discharge of three relatively weakly sorbing antibiotics (sulfadiazine, sulfamethazine, and florfenicol) via runoff and drainage were monitored for three natural rain events. Surface application of 1 % BC (1 %BC-SA) led to the most effective reduction in runoff discharge of the two sulfonamide antibiotics, which can be partly ascribed to the enhanced water infiltration. The construction of 5 % BC amended permeable reactive wall (5 %BC-PRW) at the lower end of soil box was more effective than the 1 %BC-SA treatment in reducing the leaching of the most weakly sorbing antibiotic (florfenicol), which can be mainly ascribed to the much higher plant available and drainable water contents in the 5 %BC-PRW soil than in the unamended soil. The results of this study highlight the importance of BC's ability to regulate flow pattern by modifying soil hydraulic properties, which can make a significant contribution to the achieved reduction in the transport of antibiotics offsite or to groundwater. [Display omitted] • Biochar effects on antibiotic discharge via runoff and drainage were monitored. • 1 % biochar surface application could effectively reduce the runoff. • 5 % biochar amended permeable reactive wall could effectively decrease the drainage. • All biochar treatments reduced antibiotic discharge upon heavy rainfall. • Biochar effects on soil hydrology and antibiotic sorption are both important. [ABSTRACT FROM AUTHOR]

Water and iron are crucial elements for soybean growth and development, particularly in calcareous soils and arid climatic conditions. The aim of this study was to improve iron and water use efficiency and enhance soybean resilience to water scarcity and iron deficiency. So, the effect of 16 treatments; 4 deficit irrigation water regimes (25, 50, 75 and 100 % crop water requirements (CWR)) combined to 4 foliar iron gradual concentrations (F0=0, F1=1, F2=3 and F3=5 g/L of FeSO 4) applied at 3–4 leaves, at the beginning of flowering and at the end of flowering; was investigated in this split plot experiment with 4 replicates. Our results showed that supplying iron and water to plants can improve chlorophyll florescence a, chlorophyll content, stomatal conductance, yield, iron uptake, and protein content. Determining the optimal combination of deficit irrigation treatment and gradual iron sulfate concentrations for soybean is an alternative to save water and improve growth parameters. In our manuscript, we can conclude that 75 % CWR × F2 is the best combination of the two factors that led to the same biological yield as 100 % CWR. Consequently, we can say that applying F2 as a foliar iron concentration led to an economy of 25 % of the soybean crop water requirement by ensuring an adequate supply of soluble iron, facilitating root uptake, promoting protein synthesis, enhancing chlorophyll formation, and supporting overall nutrient uptake and metabolism. • Supplying water and iron to soybeans can improve chlorophyll florescence a and chlorophyll content. • Deficit irrigation and gradual iron sulfate treatments in soybeans saves water and boosts growth. • Applying F2=3 g/L as foliar iron concentration saves 25 % of soybean crop water requirements (CWR). • 75 % CWR*F2 is the best combination that led to the same biological yield as 100 % CWR. • Adequate supply of water and iron facilitates root nutrient uptake and promotes protein synthesis. [ABSTRACT FROM AUTHOR]

The migration and transformation mechanisms of arsenic (As) in soil environments necessitate an understanding of its influencing processes. Here, we investigate the subsurface biogeochemical transformation of As and iron (Fe) through amended in the top 20 cm with iron oxidizing bacteria (FeOB) and organic fertilizer (OF). Our comprehensive 400-day field study, conducted in a calcareous soil profile sectioned into 20 cm increments, involved analysis by sequential extraction and assessment of microbial properties. The results reveal that the introduction of additional OF increased the release ratio of As/Fe from the non-specific adsorption fraction (136.47 %) at the subsoil depth (40–60 cm), underscoring the importance of sampling at various depths and time points to accurately elucidate the form, instability, and migration of As within the profile. Examination of bacterial interaction networks indicated a disrupted initial niche in the bottom layer, resulting in a novel cooperative symbiosis. While the addition of FeOB did not lead to the dominance of specific bacterial species, it did enhance the relative abundance of As-tolerant Acidobacteria and Gemmatimonadetes in both surface (39.2 % and 38.76 %) and deeper soils (44.29 % and 23.73 %) compared to the control. Consequently, the amendment of FeOB in conjunction with OF facilitated the formation of poorly amorphous Fe (hydr)oxides in the soil, achieved through abiotic and biotic sequestration processes. Throughout the long-term remediation process, the migration coefficient of bioavailable As within the soil profile decreased, indicating that these practices did not exacerbate As mobilization. This study carries significant implications for enhancing biogeochemical cycling in As-contaminated Sierozem soils and exploring potential bioremediation strategies. The long-term exposure of sewage irrigation has potential adverse effects on the local ecosystem, causing serious environmental problems. Microorganisms play a vital role in the migration and transformation of arsenic in calcareous soil in arid areas, which highlights the necessity of understanding its dynamics. The vertical distribution, microbial community and fate of arsenic in calcareous farmland soil profile in northwest China were studied through field experiments. The results of this work have certain significance for the remediation of arsenic-contaminated soil in arid areas, and provide new insights for the migration, transformation and remediation of arsenic in this kind of soil. [Display omitted] • Vertical distribution of As and bacterial communities were studied. • Addition of FeOB and OF for remediation. • FeOB promoted the formation of amorphous iron oxides. • As bioavailability increase sharply in the deeper layers of treatment. • Acidobacteria and Gemmatimonadetes abundance increased by adding the bacteria. [ABSTRACT FROM AUTHOR]

Organic amendment substitutes mineral fertilizers has been proven to increase the organic matter content of soils, which in turn may induce phosphorus (P) mobilization by triggering the redox reaction. However, under flooded conditions according to local agricultural practices, as one of the factors restricting the decomposition of organic matter, the role ammonium plays in P transformation and leaching from soils with different organic matter remains unclear. To address the knowledge gap, the calcareous soils were collected from a long-term field trial (>13 years) containing two treatments with equal P inputs: a long-term mineral fertilization and a long-term organic amendment. Both long-term mineral fertilized soil and long-term organic amended soil were split into ammonium applications or no ammonium applications. A series of column devices were deployed to create flooded conditions and monitor the P leaching from the collected soils. The K - edge X-ray absorption near-edge structure and sequential extraction method were employed jointly to detect soil P fractions and speciation, and the P sorption/desorption characteristics of soil were evaluated by Langmuir fitting. The results showed a reduction of cumulative leached P from soils by 33.2%–43.3% after ammonium addition, regardless of previous long-term mineral fertilization or organic amendment history. A significant enhancement of soil labile P pool (indicated by the H 2 O–P fraction and NaHCO 3 –P fraction) after ammonium addition results in the reduction in soil P leaching. The reduced P sorption capacity coupled with the transformation from hydroxyapatite to β -tricalcium phosphate indicated that the phosphate retention is attributed to the precipitation formation rather than phosphate sorption by soil. The present study highlights that the ammonium addition could affect the phosphate precipitation transformation. This may be attributed to the effect of ammonium addition on the calcium and magnesium ion content and molar ratio in this soil, thereby regulating the form of soil phosphate precipitation. The mechanisms revealed in this study can support developing optimized agricultural management practices to alleviate soil P loss. [Display omitted] • Ammonium addition reduces phosphorus leaching in flooded alkaline calcareous soils. • The calcareous soil phosphorus sorption capacity reduced after ammonium addition. • The transformation from hydroxyapatite to β -tricalcium phosphate were found in soil. • The Ca and Mg content and molar ratio may play an important role in phosphate form. [ABSTRACT FROM AUTHOR]