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Biochar can be a good soil amendment to reduce the soil pH, increase crop growth rate, and improve the efficient use of fertilizer. Other than that, silicon fertilizer also would promote photosynthetic ability on plant development that would help to produce high yield. In this work, a series of experiments was conducted to observe the effect of rice husk biochar and silicon fertilizer on the maize growth rate and soil pH. A 45-day pot experiment in the greenhouse with three replicates of 9 experimental treatment combinations of RHB at two rates (5 and 2.5 t.ha-1) with silicon fertilizer at three rates (125%, 100%, 75%), sole biochar (10 t.ha t.ha-1), sole silicon fertilizer (100%) and control (NPK) to observe the best rate and combination to improve growth rate and change in soil chemical in acid soil. The result showed that the co-application of sole biochar and biochar with Silicon significantly improved growth development, increased photosynthesis rate, altered soil pH, and reduced Fe concentration compared to control. The plant height increased 88.35% from T4 (5 t.ha-1 RHB + 100% Si) compared to the control and the conductance was higher in T4 (0.53) followed by T8 (0.438) while T1 (0.071) recorded the lowest conductance. The shoot fresh weight was higher in T4 (127.83 g) followed by T8 (57.14 g). However, the weight increased by 343.7% at T4 followed by T8 (2.5 t.ha-1 RHB + 75% Si) at 98.33%. The highest pH increment of 1.24 units (T1 = 5.53, T4 = 6.77) of soil pH was noted from T4 (5 t.ha-1 RHB + 100% Si) compared to control (NPK), and the highest total Fe in soil was observed from T1 (442.30 mg.kg-1). The current study results showed that T4 (50% RHB + 100% Silicon) was the best treatment over the other rates of RHB and silicon increased plant height, photosynthetic rate, and biomass. [ABSTRACT FROM AUTHOR]

The agricultural industry is constantly searching for new solutions to increase the productivity and nutritional value of crops under various conditions. Microbial inoculants have emerged as an alternative to traditional chemical fertilisers which could enhance crop productivity in acid soils - a major problem in modern agriculture. The aim of this research was to evaluate the effects of Bacillus megaterium and Mesorhizobium sp. on the seed germination of bird’s foot trefoil and orchardgrass under low pH (in vitro), as well as the nutrient composition of plants grown in acid soil. A positive impact of bacterial inoculation on seed germination was observed at pH 5 and 6 for both plant species. The content of macro- and microelements was within the range of optimal values for both plant species. This research provides valuable insights into the potential benefits of using bacterial inoculants to improve the seed germination and nutrient composition of plants grown in acid soils.

Utilizing yield, profitability, and environmental sustainability in terms of soil quality as the goal variables, we created a methodological protocol for a thorough assessment of nutrient management (NM) technologies for feasibility and optimized fenugreek production employing organic sources of nutrients in the acid soil of Northeast India. Five organic nutrient management technologies were tried and tested comprising T1: absolute control; T2: 2.5 t ha−1 vermicompost (VC) + 250 kg ha−1 lime; T3: 5 t ha−1 farmyard manure (FYM) + 250 kg ha−1 lime; T4: 10 t ha−1 FYM + 250 kg ha−1 lime; and T5: 5 t ha−1 VC + 250 kg ha−1 lime with four replications laid out in a randomized block design for two consecutive growing seasons during 2018–2020. Results indicated that across the differential levels of organic amendments (treatments) employed, the addition of maximum doses of VC and FYM, in general, excelled over the other treatments concerning fenugreek seed yield, its yield attributes, soil properties, and better economic returns. Thus, the overall findings elucidated that the addition of higher doses of organic amendments (VC and FYM) can sustainably improve fenugreek productivity, soil properties, and economic returns for fenugreek growers in the acid soil of Northeast India. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in agricultural soils has emerged as a significant concern, particularly due to its potential impact on plant-based food. Soil pH reductions can exacerbate Cd mobility, leading to excessive accumulation in crops. While liming has been demonstrated as an effective method to mitigate Cd accumulation in rice grains in acid soils of southern China, its efficacy in remediating acid soils in northern China remains unclear. In this study, a multi-year field experiment was conducted on farmland impacted by zinc ore smelting at coordinates of 33.92° N 112.46° E to investigate the use of limestone for controlling Cd accumulation in wheat and maize grains. The results indicated that applying 7.5 t ha−1 of limestone significantly raised the soil pH from 4.5 to 6.8 as anticipated. Different rates of limestone application (2.25, 4.45, and 7.50 t ha−1) reduced Cd bioavailability in the soil by 20–54%, and Cd accumulation in wheat grains by 5–38% and maize grains by 21–63%, without yield penalty. The remediation effects were sustained for at least 27 months, highlighting limestone as a promising ameliorant for smelting-affected farmland in northern China. [ABSTRACT FROM AUTHOR]

An assessment of soil characteristics pertaining to their suitability for agricultural use in general is necessary to reverse the declining trend of soil quality and to ensure sustainable agriculture. The aim of this study was to determine the soil resistance (SRI) and degradation indices (SDI) under different agrotechniques and to find out whether management-induced changes are large enough to reduce soil degradation. The study was based on the comparison of physicochemical data of 3 long-term experiments conducted in the western part of Lithuania. Changes in soil properties over the past 20 years (1999–2019) have been determined. The most commonly used measures in Lithuania, such as soil liming, manuring, residue maintenance, and tillage, were selected for the analysis. The analysis carried out showed that the soil, which was fertilized with manure, had a higher value of soil quality parameters compared to natural Retisol: organic matter (by 0.53 percentage points), total nitrogen (by 0.04 percentage points), and the available amounts of phosphorus (by 69 mg/kg) and potassium (by 6.6 mg/kg). The assessment of the relative annual change in SOC content revealed that long-term soil manuring has significant SOC sequestration capability. Among the soil management techniques examined, it appeared that the greatest relative annual change (0.47 g kg−1yr−1) in SOC content was noted in manured soil. The results indicate that the higher degradation, and resistance values were observed in acid soil (pH 4.2), where liming was applied, indicating greater sensitivity to degradation. Based on analyzed indices, the agricultural practices ranked as: manuring > residue management > reduced tillage > liming. The lowest SRI values were obtained for low level of nutrients (from −0.11 to 0.89), organic carbon (from −0.72 to −0.49), and pH (from −0.25 to –0.1), indicating that these properties are more sensitive to applied agricultural practices compared to others. All these findings provide information for promoting better soil management, soil protection, land use planning, and the planning of remedial measures, especially in the most afflicted areas. [ABSTRACT FROM AUTHOR]

Soil acidity is one of the most important constraints to maize production in Angola, where both yellow and white maize is essential for food and feed requirements. In this study, four yellow acid soil tolerant donor lines from the International Maize and Wheat Improvement Centre (CIMMYT)—Colombia were crossed with ten yellow elite lines adapted to the mid-altitude climatic conditions developed by CIMMYT—Zimbabwe, in order to identify donor lines, which can be potential sources of acid tolerance genes in breeding programs in Angola and within the mid-altitude climatic zones. The two groups of parents were crossed using a line by tester mating design, yielding 36 crosses with sufficient seed, which were evaluated alongside six acid tolerant commercial hybrids, during the 2014–16 cropping seasons at nine sites, representing acid and non-acid soils in Angola and Zimbabwe. A significant (p < 0.05) line and line × tester effect for grain yield performance was observed across acid and non-acid conditions. Acid tolerance donor lines CY3 and CY1 showed the highest positive GCA effects for grain yield. In addition, crosses involving these two donor lines had the best yielding ability and stability under both acid and non-acid conditions. For instance, the crosses CH142464 (ZY2 × CY3) and, CH142447 (ZY2 × CY1) were the best combinations for grain yield performance under both acid and non-acid soil conditions, and were stable compared to the commercial check hybrids. Crosses involving the acid tolerant donor lines mostly flowered earlier than the commercial checks. Overall, the data showed the potential of tropically-adapted exotic yellow maize acid tolerance donor lines in improving productivity of sub-tropical maize under both low-pH and well-managed soil conditions. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acid tropical soils may become more productive when treated with agricultural lime, but optimal lime rates have yet to be determined in many tropical regions. In these regions, lime rates can be estimated with lime requirement models based on widely available soil data. We reviewed seven of these models and introduced a new model (LiTAS). We evaluated the models' ability to predict the amount of lime needed to reach a target change in soil chemical properties with data from four soil incubation studies covering 31 soil types. Two foundational models, one targeting acidity saturation and the other targeting base saturation, were more accurate than the five models that were derived from them, while the LiTAS model was the most accurate. The models were used to estimate lime requirements for 303 African soil samples. We found large differences in the estimated lime rates depending on the target soil chemical property of the model. Therefore, an important first step in formulating liming recommendations is to clearly identify the soil property of interest and the target value that needs to be reached. While the LiTAS model can be useful for strategic research, more information on acidity-related problems other than aluminum toxicity is needed to comprehensively assess the benefits of liming.

Soil acidity poses a challenge to crop production by limiting the availability of nutrients for plants. The aim of this study was to assess the efficacy of a natural waste-based fertilizer composed of Mytilus chilensis seashells, coffee bean wastes, banana peels, and wood ashes on lettuce growth and physiological quality. The seashells were used with organic matter (W-OM), without organic matter (Wo-OM), and a mixture of equal parts of W-OM and Wo-OM (50:50). The coffee bean wastes, banana peels, and wood ashes were used as ingredients. The soil pH, chlorophyll index in the lettuce leaves, and nitrogen level (in the soil and leaf) were measured for a period of 66 days. Vitamin C content in the harvested leaves was measured. The W-OM fertilizer allowed for an increase the soil pH from less than 6.5 to 7.0±0.5. The nitrogen provided by the coffee bean waste was partially available to the plant root, which decreased the chlorophyll index in the lettuce leaves. The studied fertilizer (W-OM, Wo-OM, and 50:50) allowed to increase of vitamin C content in the lettuce leaves. In conclusion, the natural waste-based fertilizer showed a promising effect in alleviating soil acidity and enhancing the nutritional quality of lettuce plants. [ABSTRACT FROM AUTHOR]

In order to clarify the ameliorating effect of organic fertilizer and lime on acidic soil in south China, a field trial was conducted to study the effects of single and combined application of organic fertilizer and lime on the acidification properties, rice growth and yield of acidic soil in double cropping rice areas. The experiment included five treatments：no fertilization(CK), single application of controlled release fertilizer(CF), controlled release fertilizer+application of lime(LM), controlled release fertilizer+application of organic fertilizer (OF), and controlled release fertilizer + lime combined with organic fertilizer(CLO). Except for CK, the nutrients in each treatment remained consistent, and the materials were all applied to the soil before rice transplantation. The results showed that the combination treatment had the best improvement effect on soil pH, increasing by 0.42 units, while the OF and LM treatments were 0.27 and 0.37, respectively. The organic matter content in the soil treated with OF was the highest, reaching 44.46 g · kg-1, followed by the combined application of CLO, reaching 37.76 g · kg-1, CLO treatments significantly reduced soil exchangeable acid content by 71.4%. There is a significant negative correlation between soil pH and exchangeable aluminum and hydrogen. The absolute slopes of the regression equations for exchangeable hydrogen and exchangeable aluminum with pH are 1.356 8 and 0.156 0, respectively. The total amount of exchangeable base ions in the soil treated with a single application of lime reached 7.52 cmol·kg-1, significantly higher than other treatments, followed by the combined application of CLO, reaching 6.92 cmol·kg-1 . The combination application treatment can increase the chlorophyll content in rice leaves during the filling period, resulting in the best yield increase effect. The comprehensive research results indicate that the combination of organic fertilizer and lime improves acidified soil more than a single application, which can provide data support for subsequent acidified farmland management. [ABSTRACT FROM AUTHOR]

This study explored the effects of soil acidification on degradation of Chinese hickory forest under field experimental conditions. Responses of plant nutrient absorption and non-targeted metabolomics based on LC-MS were analyzed to understand the mechanisms of Chinese hickory plant to acid resistance and susceptibility. In this field experiment, Chinese hickory plants were treated with CK (T1, control), nitrogen application (urea) (T2), and aluminum application (aluminum sulfate) (T3). Results showed that Al is the key toxic factor of acidification of soils planted with Chinese hickory. T2 and T3 treatments significantly inhibited absorption of nutrient elements (N, P, K, Ca, Mg, Cu, B and Zn) by Chinese hickory (except N in T2). The metabolomics data analysis showed that there were differences in plant metabolites between the experimental group (T2 and T3) and the control (T1), including p-coumaroyl quinic acid, chlorogenic acid, catechin, (+) germacrene A, myricetin 3-galactoside, and neoglucobrassicin. These metabolites may be the main regulators of Chinese hickory to soil acid stress or related to the effect of soil acidification on Chinese hickory resistance. KEGG metabolic pathway enrichment analysis showed that these differential metabolites were mainly enriched in four metabolic pathways: Flavonoid biosynthesis, Phenylpropanoid biosynthesis, Tyrosine metabolism, Stilbenoid, diarylheptanoid, and gingerol biosynthesis. This study provides a reference for metabolomics studies in Chinese hickory. [ABSTRACT FROM AUTHOR]

Changes in soil resulting from agricultural practices can lead to acidification and the accumulation of toxic elements, such as Al3+. In acidic soils, aluminium solubility decreases nutrient availability, causing biochemical and morphophysiological changes that impede plant growth. This study aimed to determine how native species respond to the effects of Al3+ and its impact on their persistence in the environment. Soil samples were collected in areas with and without Al3+ in a natural regeneration zone. Leaves of three herbaceous species prevalent in the rainy season underwent biochemical analysis. The results revealed that Al3+ influenced enzymatic activity in Ayenia erecta, reducing superoxide dismutase and increasing ascorbate peroxidase and catalase. Pavonia varians exhibited an accumulation of H2O2 and a reduction in ascorbate peroxidase, while Sida galheirensis demonstrated an accumulation of sucrose and a reduction in proline levels in areas affected by Al3+, without changes in enzymatic activity or the accumulation of reactive oxygen species. The presence of 0.31 cmolc/dm³ of Al3+ was insufficient to induce lipid peroxidation in the studied species. Overall, the species responded differently to aluminium, impacting oxidative stress and potentially influencing their survival in the environment. These results provide insights into conservation practices and sustainable management in arid areas. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Oil Crop Sciences is the property of Oil Crops Research Institute of Chinese Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims: Biochar has been used as an amendment to improve soil fertility and increase crop yield. A pot trial and incubation experiment were conducted to evaluate the effects of combined biochar and phosphate fertilizer applications on changes in soil physiochemical properties, photosynthetic parameters, and plant growth of Brassica napus L. in acidic soil. Methods: Biochar (B) was applied at rates (B0: 0%, B1: 2%, and B2: 4% w/w) to the soil, while phosphorus (P) as KH2PO4 was added at P0: 0 mg kg–1 soil, P1: 100 mg kg–1 soil, and P2: 150 mg kg–1 soil. Non‐amended soil served as the control (Ck). Results: The study found that the maximum photochemical quantum yield of photosystem II (Fv/Fm) and non‐photochemical quenching were affected by biochar and P fertilizer treatments. The Fv/Fm was significantly lower in the Ck while the highest in B2P1. Compared to the Ck treatment, the electron transport rate and photosynthetic rate were significantly increased under the application of biochar with P fertilizer. Additionally, malondialdehyde content declined by 68.9% when biochar was added with P fertilizer treatments. Furthermore, the plant P content and plant growth parameters were significantly increased. Biochar with and without P fertilizer treatments increased soil pH significantly, compared to the application of P fertilizer alone. Water‐soluble P decreased with incubation time, while Al‐P decreased significantly by 69.9% and 76.4% under B1 and B2 treatments, respectively, compared to CK. Conclusion: The findings revealed a positive effect of the combined application of biochar with phosphate fertilizer on the growth of oilseed rape in acidic soil. [ABSTRACT FROM AUTHOR]

This study aims to understand the characteristics and distribution patterns of soil phosphorus (P) forms in the tropical high‐P orchards under cover cropping and to explore the biotic and abiotic factors driving the changes in P forms. The study collected three kinds of soil (clean tillage [CK, control], Stylosanthes guianensis cover [SC, legume], and Cynodon dactylon (L.) Pers. cover [CC, grass]) from a mango orchard and determined P forms in the water‐stable aggregates and bulk soil, analyzed the environmental factors and the structure of the bacterial‐fungal community. Compared to CK, SC and CC have a significant positive influence on the forms and distribution of soil P, increase the content of organic P (Org‐P) and certain inorganic P forms (Al‐P and Fe‐P), and enhance the content of P within macroaggregates (>0.25 mm), thereby maintaining total P (TP) and Olsen‐P in the top 30 cm of soil, particularly for the SC treatment. SC and CC also improved acid phosphatase (ACP), and water‐stable aggregates while decreasing bulk density (BD) and exchangeable aluminium (Ale) in the topsoil (0–15 cm). Redundant and Pearson analysis revealed these factors significantly affected soil P availability. Moreover, SC and CC increased the relative abundance of Nitrospira, Candidatus‐Udaeobacter, Pseudolabrys, and ADurb.Bin063–1 in the topsoil (0–15 cm), and decreased the relative abundance of Occallatibacter. Redundant and Pearson analysis indicated that these bacterial communities are likely associated with the availability of P. Overall, cover cropping promoted the transformation and distribution of P forms by altering the physical, chemical, and biological environment of the soil, which was beneficial for the sustainable P management in tropical high‐P soils. This research offers practical insights into the use of cover crops as a tool for enhancing soil health and sustainable P management in tropical high‐P orchards. [ABSTRACT FROM AUTHOR]

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0–300 μM Al under sand culture revealed that 150 μM Al as critical and 200 μM Al as tolerable limit. Increase in Al from 0 to 300 μM reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 μM and 100 μM) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 μM) as compared to control. TRL, RSA, RDW and RV at higher Al (300 μM) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 μM) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 μM Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 μM Al and 250 μM Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR.

A lahar-laden soil is described as marginal soil due to its poor physicochemical and biological properties and is hypothesised to have low biodiversity of soil microbes that would help support plant growth. Thus, the study aimed to assess the presence of soil microorganisms in lahar-laden soils in Sta. Rita, Pampanga, with their ability as beneficial microbes for crop production. Vigna radiata was used as the trap crop and grown for a maximum of 35 days in a microcosm experiment where all variables were similar except for the location of the sampling site. Through the sequence analysis of the 16S rRNA gene, five representative isolates revealed close resemblance to the genus Bradyrhizobium and Rhizobium, while the others were classified as non-rhizobial endophytes, namely, Pseudomonas, Agrobacterium, and Leifsonia. These results indicate that the lahar-laden soils in the sampling site harbour some agronomically-important genera of microorganisms. Surprisingly, this is the first time that the species Leifsonia xyli was identified and isolated in acidic lahar-laden soil. In contrast, it is hypothesised that the presence of L.xyli in this study might be attributed to the acidic soil pH, leading to the suppression of rhizobia in root nodules.

The marginal Himalayan ecosystems have great potential for biochar application for conserving soil moisture, ameliorating soil acidity, improving soil fertility, and thus, contributing to sustainable intensification. Thus, the efficacy of biochar was tested along with nutrient management practices (NMP) on the performance of maize (Zea mays L.)‐French bean (Phaseolus vulgaris L.) as the emerging cropping system in an acid soil under rainfed hill ecosystem. The rainy season maize was grown with three levels of biochar (0, 2.5, and 5 Mg ha−1, applied only once in the first year), and four NMP (100% recommended dose of fertilizer [RDF] [80:60:40 N:P2O5:K2O kg ha−1], 75% RDF, 75% RDF + 4 Mg ha−1 farm yard manure [FYM], and 50% RDF) under minimum tillage. After harvesting of maize, French bean was grown under no‐till with four NMP (100% RDF [50:60:40 N:P2O5:K2O kg ha1], 75% RDF, 75% RDF + 4 Mg ha−1 FYM, and 50% RDF). The soil properties after 3 years viz., soil moisture, soil organic carbon (SOC), pH, and available N, P, and K status were significantly improved under 5 Mg ha−1 biochar than no biochar. Among the NMP, 75% RDF + FYM and 100% RDF had higher soil moisture, water infiltration, pH, SOC concentrations, and available N, P, and K status than others. The interaction effect of 5 Mg ha−1 biochar and 75% RDF + 4 Mg ha−1 FYM registered the highest SOC content (15.7 g kg−1). Available N was the highest in soil under 75% RDF + 4 Mg ha−1 FYM whereas, available P in soil under 100% RDF. Application of 5 Mg ha−1 biochar produced significantly the highest mean grain yield of maize and succeeding French bean. The combined application of 100% RDF and biochar 5 Mg ha−1 produced the highest maize equivalent yield. Thus, 5 Mg ha−1 biochar and application of recommended fertilizers are suggested for sustaining soil fertility and sustainable intensification of rainfed hill agriculture under acidic soil. [ABSTRACT FROM AUTHOR]

Abiotic stress is a major cause of the declining crop yield worldwide, especially in tropical agricultural areas. Meeting the global food demand has become a serious challenge, especially in tropical areas, because of soil acidity, Al and Fe toxicity, drought and heat stress, and climate change. In this article, we reviewed several research and review papers from Google Scholar to list the different solutions available for the mitigation of abiotic stress, especially in tropical regions where several major crops, such as maize, sorghum, wheat, rice, soybean, and millet, are affected by abiotic stress and fertilizer input. In particular, Sub-Saharan Africa (SSA) has been affected by the low use of fertilizers owing to their high cost. Therefore, soil and plant researchers and farmers have developed many techniques to mitigate the effects of stress and improve the crop yield based on the agroecological zone and crop type. Nutrient management using chemical fertilizers alone or in combination with organic crops is a strategy recommended to cope with abiotic stress and increase the crop yield, particularly in developing countries. Notably, integrated soil fertility management has been effective in semi-arid areas under drought and heat stress and in subhumid and humid areas with high soil acidity and Fe toxicity in Africa. Recent advances in the molecular physiology of various crops considered a staple food in SSA have facilitated the breeding of transgenic tolerant plants with high yield. However, the feasibility and implementation of this technique in the African continent and most tropical developing countries are major issues that can be solved via adequate subsidies and support to farmers. This review can aid in the development of novel strategies to decrease hunger and food insecurity in SSA. [ABSTRACT FROM AUTHOR]

Tropical soils are often deeply weathered and vulnerable to degradation having low pH and unfavorable Al/Fe levels, which can constrain crop production. This study aims to examine nitrogen-enriched novel biochar co-composts prepared from rice straw, maize stover, and gram residue in various mixing ratios of the biochar and their feedstock materials for the amelioration of acidic tropical soil. Three pristine biochar and six co-composts were prepared, characterized, and evaluated for improving the chemical and biological quality of the soil against a conventional lime treatment. The pH, cation exchange capacity (CEC), calcium carbonate equivalence (CCE) and nitrogen content of co-composts varied between 7.78–8.86, 25.3–30.5 cmol (p+) kg−1, 25.5–30.5%, and 0.81–1.05%, respectively. The co-compost prepared from gram residue biochar mixed with maize stover at a 1:7 dry-weight ratio showed the highest rise in soil pH and CEC, giving an identical performance with the lime treatment and significantly better effect (p <.05) than the unamended control. Agglomerates of calcite and dolomite in biochar co-composts, and surface functional groups contributed to pH neutralization and increased CEC of the amended soil. The co-composts also significantly (p <.05) increased the dehydrogenase (1.87 µg TPF g−1 soil h−1), β-glucosidase (90 µg PNP g−1 soil h−1), and leucine amino peptidase (3.22 µmol MUC g−1 soil h−1) enzyme activities in the soil, thereby improving the soil's biological quality. The results of this study are encouraging for small-scale farmers in tropical developing countries to sustainably reutilize crop residues via biochar-based co-composting technology. [ABSTRACT FROM AUTHOR]

Lime application combined with complementary sustainable management practices increases crop yields, but liming is only modestly applied in Serbia. This study investigated the influence of liming (1000 kg/ha) combined with the common application of mineral fertilizers on maize yield and the chemical properties of pseudogley soil. The experiment was conducted near Kraljevo, Western Serbia, on the maize hybrid ZP 606 sown in a two-year monoculture. The experiment had three treatments: fertilizer, fertilizer + lime, and a control treatment. The soil is acid, poor in humus, and contains an increased content of mobile aluminum. There was a significant increase in yield under the fertilizer and lime + fertilizer treatments, compared to the control. The yield of maize in the limed treatment was 4.4–9% higher than in the fertilizer treatment. The positive effects of liming on soil are related to an increase in pH, base saturation, and available phosphorus, and a decrease in available aluminum. In the fertilizer treatment, there was a small decrease in pH and base saturation, whereas the amount of aluminum remained high, indicating that the further application of fertilizers without lime can increase aluminum content and foster its toxicity. The long-term sustainability of maize production in Serbia should include liming as a regular management practice on pseudogley soil, with the utilization of smaller doses of lime because of the potential CO2 effects. To improve soil health, food, and environmental security, and to incorporate new crops, developing a framework promoting liming as a sustainable management practice is of high importance. [ABSTRACT FROM AUTHOR]

Environmental pollution caused by increasing levels of heavy metals (HM) is a pressing problem throughout the world. Phytoremediation is considered a prospective remediation approach for HM-contaminated soil, but more research is required to enhance remediation efficiency. Biochar is a promising bio-residue material that can be used for the sustainable remediation of heavy metal-contaminated soil. In this study, a pot experiment was conducted to investigate the effects of biochar from different bio-substrates (digestate, waste of biodiesel production from rapeseed, corn stalk) on HM (Cr, Cd, Cu, Ni, Pb, and Zn) accumulation in buckwheat and white mustard cultivated in sewage sludge-contaminated soil. The total amount of HM in soil, plant above- and below-ground biomass, leachate, and bioconcentration and translocation factors were studied to explore the mechanism of how the different bio-substrates' biochar affects HM accumulation in selected plants. It was observed that rapeseed biochar showed the greatest significant effect in reducing the HM content in soil, plant biomass, and lysimetric water. Meanwhile, the incorporation of digestate biochar significantly increased the HM content in all the soil-plant systems and affected the HM leaching from the soil. The concentration of HM in the leachate decreased from 2.5 to 10 times. It was determined that phytostabilization is the core process of HM accumulation in buckwheat, in contrast to mustard, where the mechanism is phytoextraction. This study confirmed that biochar addition enhances the phytoremediation efficiency in soil, which can potentially improve the development of ecofriendly in-situ bioremediation technology for HM-contaminated sites. [ABSTRACT FROM AUTHOR]

The purpose of the study was to assess the influence of humic substance on the transformation of phosphorus in acid soil, so an experiment was conducted in a lab setting using the same soil (Typic Rhodustalf) collected from the land where the field experiment is expected (Agricultural and Horticultural Research Station, Tarikere taluk, Karnataka India). Humic substance employed in treatment application was extracted from farm yard manure. The study proven that, in contrast to P fertilizers applied without humic substance, application of humic substance at higher doses along with P fertilizers increased the available P status, saloid-P and organic-P fraction over the course of the incubation period, particularly when rock phosphate combined with humic substance @ 60 mg kg−1. However, compared to P fertilizers without humic substance treatments, significant decrease in in Al-P, Fe-P, reductant soluble P, occluded P and Ca-P was found in Rock phosphate + humic substance @ 60 mg kg−1 with lower P fixation (35.31%) and Rock phosphate + humic substance @ 40 mg kg−1 with P fixation of 37.32%, while the absolute control treatment (60.34%) had the maximum P fixation capacity. [ABSTRACT FROM AUTHOR]

The focus of this study was to explore how various fertilizers influence the movement of cadmium in soil treated with biochar. The research utilized a strong acid sandy loam soil from Chanthaburi Province, naturally rich in organic matter with moderate cation exchange capacity and low nitrogen, potassium, phosphorus, sulfate, salinity and chloride levels. The soil was purposely contaminated with 50 mg kg-1 of cadmium and treated with biochar derived from water hyacinth through pyrolysis at 450°C for an hour. This biochar displayed moderate alkalinity, high organic matter, phosphorus, potassium, and cation exchange capacity, but low nitrogen content. Analytical techniques like Scanning Electron Microscopy and Fourier-Transform Infrared Spectroscopy were employed to study the surface characteristics of the biochar. The cadmium adding soil was blended with 10% biochar and various chemical fertilizers at a 0.04% ratio. Diethylenetriamine pentaacetate (DTPA) extraction was used to assess the bioavailability of cadmium to plants in the soil, while sequential extraction was conducted to identify the different forms of cadmium present in the soil. The study revealed distinct effects of different fertilizers on cadmium mobility. Fertilizers like 46-0-0 and 0-3-0 caused a transformation of cadmium from stable to less stable forms, increasing the bioavailability of cadmium to plants. Conversely, fertilizers such as 15-15-15, 0-0-50, 0-0-60, and 0-52-34 shifted cadmium from less stable to more stable forms, resulting in decreased cadmium extracted by DTPA. Other fertilizers showed no significant impact on cadmium mobility in the soil. A stepwise linear regression analysis highlighted that nitrogen content, potassium content, and electrical conductivity were influential factors affecting cadmium mobility.

Cadmium (Cd) contamination in agricultural soils has emerged as a significant concern, particularly due to its potential impact on plant-based food. Soil pH reductions can exacerbate Cd mobility, leading to excessive accumulation in crops. While liming has been demonstrated as an effective method to mitigate Cd accumulation in rice grains in acid soils of southern China, its efficacy in remediating acid soils in northern China remains unclear. In this study, a multi-year field experiment was conducted on farmland impacted by zinc ore smelting at coordinates of 33.92° N 112.46° E to investigate the use of limestone for controlling Cd accumulation in wheat and maize grains. The results indicated that applying 7.5 t ha−1 of limestone significantly raised the soil pH from 4.5 to 6.8 as anticipated. Different rates of limestone application (2.25, 4.45, and 7.50 t ha−1) reduced Cd bioavailability in the soil by 20–54%, and Cd accumulation in wheat grains by 5–38% and maize grains by 21–63%, without yield penalty. The remediation effects were sustained for at least 27 months, highlighting limestone as a promising ameliorant for smelting-affected farmland in northern China.

Biomineralization in plant roots refers to the process of cell-induced self-assembly to form nanostructures on the root surface. Silicon (Si) is the second most abundant element in soils, and beneficial to plant growth. Meanwhile, silicon is shown to participate in the process of biomineralization, which is useful for improving mechanical strength and alleviating biotic and abiotic stress, for example silicic acid polymerizes to form amorphous silica (SiO2–nH2O) in the process of growing to resist fungi and environmental stress. This process alters physical and chemical properties of cell wall. However, the mechanistic basis of this process remains unclear. Aluminum toxicity is a major constraint affecting plant performance in acid soil. This paper summarizes recent research advances in the field of plant biomineralization and describes the effects of silicon biomineralization on plant aluminum tolerance and its adaptive significance, using aluminum toxicity as a case study.

A field experiment was conducted at the instructional farm of Uttar Banga Krishi Viswavidyalaya, Cooch Behar, West Bengal, India during early Pre-kharif seasons of 2020 and 2021 to evaluate the comparative performance of green gram (Vigna radiata L. Wilczek) under single super phosphate (SSP) and nano-phosphorus. Experiments consisted of T1: 100% phosphorus through SSP, T2: 75% through SSP +1 ml L−1 of nano-phosphorus at 15 days after sowing (DAS), T3: 50% through SSP +1 ml L−1 of nano-phosphorus at 15 DAS, T4: 25% through SSP +1 ml L−1 of nano-phosphorus at 15 DAS, T5: 100% through nano-phosphorus (1 ml L−1 at 15 and 30 DAS), T6: 100% through nano-phosphorus (2 ml L−1 at 15 DAS), and T7: control (no phosphorus). Results of the experiment revealed that whenever nano-phosphorus was applied either in combination or in alone performed better in terms of growth and yield of green gram over single use of molecular phosphatic fertilizer. Pooled data over the years revealed that application of 2 ml L−1 of nano-phosphorus at 15 DAS (T6) recorded significantly tallest plant, larger root volume, greater leaf area, maximum dry matter, longest pod, and highest number of pod plant−1 which ultimately helped in producing 33.13% more grain yield and contributing 50.28% higher profit over 100% phosphorus through SSP. It can be concluded that farmers of the Eastern sub-Himalayan region can grow green gram profitably during summer season with the foliar application nano-phosphorus 2 ml L−1 along with 20 kg nitrogen and 40 kg potassium ha−1. [ABSTRACT FROM AUTHOR]

Electrochemical experiments, slow strain rate tensile testing (SSRT), and scanning electron microscopy were used to investigate the effect of various applied potentials on the stress corrosion cracking (SCC) of X80 pipeline steel in acidic soil containing sulfate-reducing bacteria (SRB). The results demonstrated that when the anodic potential was applied, X80 steel exhibited sensitivity to SCC, which was attributed to anodic dissolution. The SCC sensitivity initially decreased, but then increased with a negative shift in the applied potential. At −1200 mV, SCC was the most sensitive, which corresponded to the substantial cathodic polarisation and toxic impact of SRB, which increased the risk of hydrogen embrittlement. At −850 mV, the SCC sensitivity was the lowest because cathodic polarisation suppressed anodic dissolution. The experimental results can contribute to the prevention and management of SCC in operational pipelines. [ABSTRACT FROM AUTHOR]

An incubation experiment was conducted in laboratory conditions for 60 days to observe the impact of different Magnesium fertilizers on soil chemical properties, i.e. pH, available nitrogen, phosphorus, potassium, and DTPA extractable micronutrient cations. A complete factorial complete randomized block design (FCRD)with two replications and six levels was selected as the experimental layout. The levels included were (L0) Absolute control (L1) soil + Mg @ 10 kg ha-1, (L2) soil + Mg @ 20 kg ha-1, (L3) soil + 30 kg ha-1, (L4) soil + 40 kg ha-1, (L5) soil + 50 kg ha-1. Findings revealed that applying magnesium fertilizers to soil significantly (p ≤ 0.05) affects soil parameters. The impacts of magnesium fertilization on soil pH altered with sources and incubation period. The application of CaMg(CO3)2 @ 50 kg ha-1 recorded significantly (p ≤ 0.05) higher soil pH (5.67) as compared to MgCO3 @ 50 kg ha-1 that increased the pH up to 5.57 due to the impact of carbonate ion whereas MgSO4.7H2O decreased the soil up to 4.80 because of dissolution of SO42- ions to the soil solution. Applying CaMg(CO3)2 significantly (p ≤ 0.05) influenced soil available N, P, K, Fe, Mn, and Cu content which is due to the decrease in acidity, which indirectly enhanced the nutrient availability. The positive effects persisted throughout the experimental duration, indicating the potential long-term benefits of magnesium fertilization in acid soil management. This study contributes to the current body of knowledge by providing novel insights into applying magnesium fertilizers as an effective strategy for addressing soil acidity and improving nutrient availability in acid soil. [ABSTRACT FROM AUTHOR]

Coordinated evolution and mutual adaptation of soybean–rhizobium–soil (SRS) are crucial for soybean distribution, but the genetic mechanism involved had remained unclear. In a recent study, Li et al. identified a natural variant of the GmRj2/Rfg1 gene that affected the ability of soybean to adapt to distinct soil types by controlling soybean–rhizobium interaction, thus unravelling the mystery of SRS compatibility. [ABSTRACT FROM AUTHOR]

Background: To determine the effectiveness of controlled slow-dissolving NPK fertilizers with NPK 19-16-18 to improve soil nutrients on rice (Oryza sativa L.). Methods: The field experiment was on saline-affected acid sulfate soil in Hau Giang province, Viet Nam, in the Winter-Spring rice crop 2018-2019. The experiment consisted of 2 treatments, corresponding to 2 formulas and 2 types of fertilizers, including new generation fertilizer application with the formula 50N-40P205 -30K20 kg/ha; and conventional fertilizers of 126N-88 P205-23K20. Each formula with 3 replications and each repetition is 1,000 m². Result: The NPK-CFR fertilizers and urea humate help improve proper soil nutrients and total micro-organisms. In which; (i) when compared to the farmer's control field, the rice growth and yield were comparable and did not differ significantly (5.68 tons/ha in the farmer's control field and 5.85 tons/ha in the experimental field). (ii) However, when compared to the farmer's field, the amount of fertilizer in the experimental field is reduced by more than 50%. Besides, the economic efficiency of NPK-CFR and Urea humate is higher than in farmers' fields, from 1 to 8.6%. The total profit is higher than farmers' fields. The NPK-CFR fertilizers and urea humate can be used to replace traditional fertilizers. [ABSTRACT FROM AUTHOR]

Aluminum toxicity, nutrient imbalance, and reduced microbial activity are the most limiting factors for optimum agronomic productivity in acid soils. A field study was conducted to investigate the impact of micronutrient and liming on soil properties and productivity of groundnut‐rapeseed system in an acidic Inceptisol. The impact of six micronutrient (control or no micronutrient, Zn at 5 kg ha−1, B at 1 kg ha−1, Mo at 0.5 kg ha−1, Zn + Mo, and Zn + B + Mo) and two soil amendment (furrow liming at 500 kg ha−1 and no lime addition) treatments were first tested in groundnut and theirs residual effects were assessed on soil properties of succeeding rapeseed crop. Results indicated that liming significantly improved soil pH, soil organic carbon (SOC), available N, P and K, and diethylene triamine penta acetate (DTPA)‐extractable micronutrients, soil microbial biomass C and dehydrogenase activity as compared to no‐lime. After harvesting groundnut, Mo + Zn + B treated plots maintained the highest SOC content, whereas sole B and Mo treatment had the highest SOC content after harvesting rapeseed. Further, Mo + Zn + B treated plots showed higher contents of soil DTPA‐extractable micronutrients as compared to others. The highest groundnut equivalent yield (GEY) of the cropping system (pooled data of 2 years) was obtained with Mo + Zn + B (2.12 Mg ha−1) but remained at par with Zn + Mo (2.02 Mg ha−1). Multivariate principal component analysis indicated that available P was the most prominent soil nutrient with a strong effect on GEY. The results indicated that integrated application of Zn + B + Mo along with liming improves soil properties and agronomic productivity of groundnut‐rapeseed cropping system. [ABSTRACT FROM AUTHOR]

Main conclusion: The 4-coumarate:coenzyme A ligase 4CL4 is involved in enhancing rice P acquisition and use in acid soil by enlarging root growth and boosting functional rhizosphere microbe recruitment. Rice (Oryza sativa L.) cannot easily acquire phosphorus (P) from acid soil, where root growth is inhibited and soil P is fixed. The combination of roots and rhizosphere microbiota is critical for plant P acquisition and soil P mobilization, but the associated molecular mechanism in rice is unclear. 4CL4/RAL1 encodes a 4-coumarate:coenzyme A ligase related to lignin biosynthesis in rice, and its dysfunction results in a small rice root system. In this study, soil culture and hydroponic experiments were conducted to examine the role of RAL1 in regulating rice P acquisition, fertilizer P use, and rhizosphere microbes in acid soil. Disruption of RAL1 markedly decreased root growth. Mutant rice plants exhibited decreased shoot growth, shoot P accumulation, and fertilizer P use efficiency when grown in soil—but not under hydroponic conditions, where all P is soluble and available for plants. Mutant ral1 and wild-type rice rhizospheres had distinct bacterial and fungal community structures, and wild-type rice recruited some genotype-specific microbial taxa associated with P solubilization. Our results highlight the function of 4CL4/RAL1 in enhancing rice P acquisition and use in acid soil, namely by enlarging root growth and boosting functional rhizosphere microbe recruitment. These findings can inform breeding strategies to improve P use efficiency through host genetic manipulation of root growth and rhizosphere microbiota. [ABSTRACT FROM AUTHOR]

Background and Aims: Suitable N source supply is critical to improve plant growth and N uptake, but the importance of nitrate (NO3−) for rice (Oryza sativa L.) and microbiota is often neglected in acidic paddy soils where ammonium (NH4+) is dominant. This study aimed to explore the differential effects of NH4+ and NO3− on rice growth, fertilizer nitrogen recovery efficiency (FNRE), and rhizosphere bacterial community in acid soil. Methods: Two rice varieties, Kasalath (Al-sensitive indica) and Koshihikari (Al-tolerant japonica), were exposed to different N sources with or without lime in an acid soil. Results: Liming and NO3− application solely improved the growth and FNRE of the Al-sensitive rice, namely, by increasing soil pH and alleviating Al toxicity. Compared with liming and rice variety, N source had a more pronounced influence on rhizobacterial community composition. Of the two sources, NO3− had a stronger effect on the rhizobacterial community than NH4+. Remarkably, rice plants fed with NH4+ specifically recruited Desulfosporosinus and Desulfitobacterium associated with ferric NH4+ oxidation in the rhizosphere, whereas those exposed to NO3− recruited Alicyclobacillus with NO3−-reducing iron oxidation ability. Three keystone taxa were identified in a rhizobacterial co-occurrence network analysis: Alicyclobacillus, which was positively associated with rice growth and FNRE, and Acidobacteriales and WPS-2, both with negative associations. Conclusion: Compared with NH4+, NO3− enhances the growth and FNRE of Al-sensitive rice and exerts dominant effects on the rhizobacterial community, which indicates the importance of NO3− for rice and has instructive implications for N management in acid soil. [ABSTRACT FROM AUTHOR]

The Lijiang River Basin covers great variation in altitude, soil and vegetation types. In order to study the characteristics of its soil nutrients and enzymes activities, we determined soil nutrient contents and activities of several extracellular enzymes (amylase, sucrose, urease, protease and catalase) of the surface soils (0-20 cm) of typical vegetation types［natural forest, bamboo (Phyllostachys edulis) forest, Pinus massoniana forest, orchard and rice paddy field］with calcareous soils and acid soils in the Lijiang River Basin. The results were as follows: (1) The soils at high altitude had greater total nitrogen (TN), total phosphorus (TP), available phosphorus (AP) contents as well as amylase, sucrose, urease and protease activities, whereas the catalase activity was to the contrary. (2) Compared with the acid soils, the calcareous soils had higher contents of total phosphorus (TP) and available phosphorus (AP). Among the acid soils, vegetation types had greater impact on soil nitrogen and phosphorus contents. In general, anthropogenic vegetation resulted in decrease of nitrogen content and increases of phosphorus content; while the nutrients in the calcareous soils had relatively little variation among different vegetation types. (3) Compared with the natural forest soils, soils from the anthropogenic vegetation had lower nitrogen related enzyme activities; whereas the carbon related enzyme activities was less impacted. The enzymatic stoichiometry revealed that soils of natural forests were nitrogen limited whereas those of anthropogenic vegetation was carbon limited. (4) The results of canonical correspondence analysis (CCA) showed that soil physiochemical properties in the first and second axes explained 86.56% of the variation of soil enzyme activities with the contribution order of TN>pH>NH4+>AP>TP>NO3-, with the first three as the main impacts. All the above results indicate that acid soils in the Lijiang River Basin have great ecological sensitivities; vegetation changes easily result in nutrient imbalance, therefore, in order to improve the sustainable utility of landscape resources of the Lijiang River Basin, special attention should be paid to the conservation of soil nutrients and prevention of the loss of soil organic matter. This study provides theoretical base for the scientific conservation and development of local ecosystem.

The study evaluated the effects of lime and dolomite application (2 and 4 t ha−1) in combination with NPK fertilizer (1 t ha−1) or borax (50 kg ha−1) on micronutrient concentrations in the raspberry leaves and fruits grown in the soil with a strongly acid reaction. Changes in the content of micronutrients (Fe, Mn, Cu, Zn, and B) and Al in the soil and raspberry leaves and fruits were monitored during a two-year period. Calcification reduced the content of micronutrients and Al in the soil, as well as their content in the plant. Applied doses of lime or dolomite of 4 t ha−1 almost completely neutralized the high to toxic content of mobile Al in the soil, but the values in the leaves although reduced were still high. In all applied treatments, high and very high concentrations of available forms of Fe and Mn in the soil and/or leaves and fruits were significantly reduced. However, the Mn concentrations in the soil, leaves, and raspberry fruits were very high. Calcification did not reduce the available Cu in the soil, while this effect was observed in raspberry leaves and fruits where the Cu concentrations were within optimal values. After calcification, the Zn and B concentrations decreased in the soil and plant, but they mostly remained within the optimal values. The results indicate that due to the very high concentrations of Al and Mn in the soil and plant after lime application, additional doses of lime materials in more than one season are required.

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Acid soils (0-20 cm) from five different locations namely Jibanpur, Kamalpur, Washabarie, Hansqua (from the state of West Bengal) and Padu (Meghalaya) were collected to evaluate the efficiency of organic acids in dissolving phosphorus which was conducted in the laboratory. The extracted P by different organic acids varied from soil to soil and least was in the soil of Padu followed by Jibanpur. These two soils are collected from bare land having low P content. Citric acid is most effective in releasing inorganic P in these soils. On the other hand, the other three soils, were known to have fertilized regularly over 100 years under tea plantation and thus bearing high amount of total P, extracted higher amount P with oxalic acid at comparable level of acid addition. The time-depended P release data were fitted to different models and the data were better model by Elovich and Power functional equations based on the values of the coefficient of determination (r2) and the standard errors of the estimates (S.E). The dissolution and complexation of the Fe3+/Al3+or Ca2+compounds that bind most P in soils may be the possible mechanisms for its release by low molecular weight organic acids according to the well fitted Elovich and Power function models in kinetic experiment. [ABSTRACT FROM AUTHOR]

Sweet potato is one of the major crops grown for food, animal feed and industrial products. The yield obtained in the Northeast of Thailand is far below its genetic potential due to soil degradation, erosion, acidification, loss of organic matter, waterlogging and salinization causing nutrient deficiency. The objectives of this research are to investigate yield components, accumulation of nutrients and food nutrition of different sweet potato species under acidic sandy soil. The experiment with four replications was laid out in a farmer's field at Phu Wiang and Nong Ruea District, Khon Kaen Province, where young smart farmers are interested to grow sweet potato. Trials were planted for 2 years using four species of sweet potato: (A) Honey Sweet, (B) Okinawan Orange, (C) Okinawan Purple and (D) Purple Sweet Lord. All plots were treated with a basal application of 1.56 t ha-1 of cow and poultry manure with 0.03 t ha-1 of chemical fertilizer formula (N12-P4-K4). An addition of 0.15 t ha-1 of chemical fertilizer formula (N12-P4-K20) was made at 15 and 30 days after growing. The results show that Okinawan Orange and Purple Sweet Lord were higher growth in Phu Wiang district than Nong Ruea district. If the cost and unit price are the same, Okinawan Orange will give farmers a higher return than Purple Sweet Lord. Regarding the leaf residues of Okinawan Orange and Purple Sweet Lord are suitable to be used for fish farming, because they contain the highest protein and carbohydrates. [ABSTRACT FROM AUTHOR]