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• The potential of microorganisms in olive trees in southern Brazil is still a gap. • Beneficial microorganisms can improve seedling growth and resistance to stress. • Each species of microorganism had its beneficial potential affected by pH. • The inoculant species can be adjusted according to the soil condition. The benefits of plant growth-promoting microorganisms to increase productivity have been demonstrated in various crops. Little is known about their potential in olive orchards in southern Brazil, whose naturally acidic soils are intensively limed for olive production. The present study investigated the effect of four inoculations (no inoculation, inoculation of the bacterium Azospirillum brasilense , inoculation of the fungus Trichoderma harzianum and inoculation of the fungus Trichoderma virens) at different levels of soil liming on the development of olive seedlings. The results showed that the microorganisms T. virens, T harzianum, and A. brasilense, but especially T. virens , when applied to the soil, promoted increased growth in height, diameter, and total dry mass yield of young olive trees, especially in conditions of lower soil acidity, with increases of 92, 34 and 33 % respectively, compared to the soil without inoculation. Less acidic environments, more favorable for olive tree development, enhanced the positive effect of these microorganisms. The microorganisms also mitigated the effects in potentially more stressful conditions, as observed by the higher concentration of photosynthesizing pigments, the reduction in hydrogen peroxide content, and the reduction in antioxidant enzyme activities in leaves and roots, in soil pH below that recommended for olive cultivation. [ABSTRACT FROM AUTHOR]

Continuous monitoring of soil quality is vital to understand the effects and to identify best management practices for sustainable agroecosystems. This study focuses on evaluating the soil quality and crop yield sustainability in a long-term maize-wheat cropping system experiment spanning 47 years. Physical, chemical, and biological soil quality indicators were assessed at two soil depths (0–0.15 m and 0.15–0.30 m) under eleven fertilizer and amendment regimes i.e., 50 % NPK, 100 % NPK, 150 % NPK, 100 % NPK + Zn, 100 % NPK+ hand weeding, 100 % NP, 100 % N, 100 % NPK + farmyard manure (FYM), 100 % NPK(S), 100 % NPK + lime and control, laid out in a completely randomized block design. Principal component analysis (PCA) was employed to select a minimum data set (MDS) of indicators for soil quality assessment, followed by weighted additive approach to calculate the soil quality index (SQI). Results showed that balanced dose of NPK fertilizers, in combination with FYM or lime, enhanced average wheat grain yield by 39.9 and 29.4 % over sole 100 % NPK fertilizers, respectively. Treatment 100 % NPK + FYM recorded a significant improvement in aggregate stability, available nutrients, microbial biomass over control and 100 % NPK. The highest value of SQI (0–0.15 m) was recorded in 100 % NPK + FYM (0.99), followed by 100 % NPK + lime (0.86) and lowest in 100 % N (0.41). Omission of NPK, PK, K and S from fertilizer regime caused a decline of respective 33, 39, 22 and 6 % in the SQI, whereas, all the treatments recorded a decline in SQI in sub-surface layer. The average contribution of MDS towards the SQI of 0–0.15 and 0.15–0.30 m depth was labile carbon (LC) (30 %) > microbial biomass N (MBN) (28 %) > mean weight diameter (MWD) (17 %) > pH (16 %) > available K (6 %) and LC (33 %) > N mineralization (24 %) > MWD (22 %) > pH (21 %), respectively. The SQI positively correlated with average grain yield and SYI, highlighting the importance of soil quality for sustainable crop production. This research underscores the significance of continuous soil quality monitoring and use of balanced fertilization, organic manure and lime in maintaining soil health and crop productivity in agroecosystems. • Balanced NPK fertilizers with FYM or lime increased the wheat yield by 39.9 and 29.4 %, respectively. • Continuous urea application rendered the soil unproductive. • Labile carbon was the major contributor towards the soil quality index. • Soil quality index correlated positively with grain yield and sustainable yield index. [ABSTRACT FROM AUTHOR]

Soil acidity is the most limiting factor for agricultural yield and sustainability in acid soils. Liming is the management practice recommended for reducing soil acidity and increasing the availability of macronutrients, but it can also lead to reduction in the availability of cationic micronutrients when applied at high rates. The aim of this study was to evaluate the effect of application of high rates of limestone, incorporated in the 0–0.40 m soil layer, on nutrient availability and their relation to cumulative grain yield in an annual crop production system. Three experiments were set up in 2017 with six liming rates (0, 3, 6, 9, 12, and 15 Mg ha−1), with incorporation in the 0–0.40 m layer. Soil and leaf samples were collected for determination of macro- and micronutrient concentration in the leaves. Regression and linear correlation analyses were used to evaluate the effect of the application rates on the availability of nutrients and on cumulative yield in soybean, maize, dry bean (common bean) wheat crops over three crop years. The micronutrient that showed the greatest reduction in level in the soil through liming was Fe, in contrast with Zn, which was not affected. The concentrations of micronutrients in soybean and common bean leaves were more sensitive to the effect of deep liming than the levels in the soil, and reductions were observed in the concentrations of B, Fe, Mn, and Zn; however, they remained at suitable levels according to regional standards. Thus, even with the reductions in the availability of the micronutrients brought about by incorporation of higher doses of limestone (≥ 9 Mg ha−1), the cumulative grain yields showed an increase in accordance with liming rates, with the optimal dosage from 8.77 to 12.6 Mg ha−1, depending on the site. The main factors that had positive correlation with yield were soil pH and the macronutrients concentration in the leaves, which generally increased along with the liming rates. • Micronutrients availability to plants reduces with increasing limestone doses incorporated at 0.40 m. • The concentrations of macronutrients in the leaves increased with increasing limestone rates incorporated at 0.40 m. • There is a positive correlation with grain yield and soil pH and macronutrient concentration in leaves. • Accumulated grain yield increases with increasing limestone rates incorporated at 0.40 m. [ABSTRACT FROM AUTHOR]

Plant functional traits can serve as indicators of plant resource-use strategies in response to environmental changes. Plants growing in acidified soil exhibit conservative traits and limit growth, but there is still little known about changes in above- and belowground functional traits and their coordination under alleviation of soil acidification. Here, we conducted a pot experiment on raising soil pH by liming in Chinese fir (Cunninghamia lanceolata) saplings in southern China. The experiment involved in two degrees of acidified soil (Mild, pH = 4.3; Severe, pH = 3.6) and three liming treatments: Control (CK, 0), low liming treatment (L, 1000 kg CaO hm−2) and high liming treatment (H, 4000 kg CaO hm−2). We measured 22 above- and belowground functional traits of Chinese fir including allocation, morphological, photosynthetic, and chemical traits to assess their response to liming. The results show that liming enhanced aboveground mass fraction and total leaf area (TLA), and reduced construction cost (lower C concentration). However, specific leaf area (SLA), nutrient concentrations of N and P, and photosynthetic rate (Pn) remained unchanged. These results suggest that aboveground components exhibited acquisitive strategies in response to liming with greater TLA and lower construction cost. Moreover, liming reduced root mass fraction (RMF), increased specific root length (SRL), specific root area (SRA), and root N and Ca nutrient concentrations. These results suggest that belowground components also exhibited acquisitive strategies through constructing longer and thinner roots with greater metabolic rates. Our findings show that liming shifts above- and belowground resource-use strategies of Chinese fir from conservative to acquisitive. These changes in functional traits support the ability of Chinese fir to grow rapidly in response to alleviation of soil acidification. Our research not only contributes to a deeper understanding of plant adaptation mechanisms in the face of environment changes but also provides valuable insights for improving carbon sequestration of plantations in subtropical China. • 22 functional traits of Chinese fir were measured to assess their response to liming. • Liming elevated total leaf area and reduced leaf construction cost. • Liming elevated specific root length, specific root area and root N concentration. • Liming shifts resource-use strategies of Chinese fir towards acquisitive. [ABSTRACT FROM AUTHOR]

[Display omitted] • In soil, adsorption of FA is limited by the binding to external surfaces of nano-aggregates. • The overall adsorption of FA is pH independent and has a relatively low affinity. • In acid soils, FA prefers direct interaction with soil oxide particles, releasing phosphate. • NOM-oxide interaction can be reduced by soil liming, decreasing the solubility of oxyanions. • A dual-phase model is developed to describe the release of PO 4 upon FA addition. For more insight into the interaction of natural organic matter (NOM) with metal (hydr)oxides and oxyanions, the adsorption of added fulvic acid (FA) and the corresponding release of phosphate (PO 4) were studied for a series of agricultural soils (∼0 – 25 cm), strongly varying in soil properties. Interpretation of the data with surface complexation modeling using the NOM-CD model applied in a dual-phase mode shows that the adsorption of added FA, in contrast to PO 4 , is restricted to the external surfaces of nano-aggregates. The adsorption is relatively weak and pH-independent, due to its competition with the native NOM of the organo-mineral phase. At low pH, the functional groups of both added FA and native NOM shift in the interface towards the soil oxide surfaces, making both a good competitor for adsorbed phosphate, resulting in a higher amount of phosphate being released. With an increase in pH, the competition becomes weaker. As a result, more phosphate is bound and less is released when FA is added. Our surface complexation modeling points to the existence of organo-mineral nano-aggregates with sizes of >∼10 – 270 nm, which depends on the total reactive surface area of the soil. Our findings imply that organic amendments containing FA equilibrate with only a portion of the total reactive surface area. In acidic soils, the addition of such organic amendments will be more effective in solubilizing phosphate, which is beneficial from a plant nutrition perspective, but simultaneously it may also contribute more to environmental eutrophication. [ABSTRACT FROM AUTHOR]

[Display omitted] • 5 RDs neutralise 500 up to 10 000 mmol H+/kg, variation in mineralogy and target pH. • Automatic titration (pH stat) estimates pH-dependent dissolution rates and slopes. • Novel soil-RD suspension estimates fast/slow pools of acid neutralising capacity. • Low and high doses (12 Mg/ha, 340 Mg/ha) for validation in 2 year soil-RD mesocosm. • Mechanistic model using pH stat and soil-RD suspension predicts mesocosm soil pH. The ongoing acidification of soil poses a significant threat to the proper functioning of various ecosystems worldwide. Silicate rock dusts (RD) are increasingly amended to acid soils to restore their pH, but the acid neutralising capacity (ANC) and dissolution rate of these products are highly variable and lack proper assessment protocols. It is expected that pH-dependent RD ANCs and dissolution rates dictate the pH increase in soils depending on the initial pH and pH buffer power of the soil. This study addressed these questions by comparing and validating three accelerated weathering tests for their capacity to predict the gradual liming effects in a two-year outdoor mesocosm. Five commercial RDs (two basalts, phonolite, foidite, and trachy-andesite) were tested in four acidified forest soils varying in initial pH, in texture and associated pH buffer power. First, RD dissolution was measured in aqueous batch renewal systems during one year at various starting pH (3.5, 4.5, and 5.5) and constant temperatures (20 °C, 37 °C, and 65 °C). These showed that the ANCs of RDs exhibit a fast fraction (half-life < 1 day) followed by a slower fraction. Second, titration tests of RDs at fixed solution pH, i.e., pH stat , performed between pH 3.5 and 4.5 revealed surface normalised dissolution rates that decreased factors 10–100 per unit pH increase, the slope depending on the RD's mineralogy. Indeed, the rate ranking of observed surface area normalised dissolution rates confirmed that of literature-based values, weighed by the XRD-derived mineralogical fractions. Third, lime-calibrated agitated soil-RD suspension tests were conducted for two months, illustrating the dependency of RD ANC on soil context, and yielding ANCs that were factor 2–5 times larger than in the batch renewal test because of pH buffering effects of soil particulates. Finally, an outdoor soil mesocosm on the four acid soils amended with RDs at 12 Mg/ha and 340 Mg/ha was established and soil pH was monitored for 2 years. The observed pH trends corresponded well for both the low dose (R2 a = 0.67) and the high dose (R2 a = 0.93) with model predictions made using the pH- and temperature-dependent RD dissolution rates (pH stat test) and the soil pH buffer power and RD slow ANC-fraction (soil-RD suspension test). This model predicts half-lives of RD dissolution ranging between <1 month to >100 years depending on the starting pH of the soil, its pH buffer power, the RD mineralogy (XRD based) and its specific surface area. This study shows that the dissolution and ANC of RD can be most pragmatically predicted with a series of lime-calibrated soil-RD suspension tests of maximally two months. [ABSTRACT FROM AUTHOR]

Liming materials are widely applied to alleviate soil acidification and increase rice yield in acidic soils, but their effects on nitrogen (N) use efficiency are still unclear. Here, we conducted a field-, pot-, and micro-plot experiment to investigate how the application of slaked lime (i.e., Ca(OH) 2) affects the fate of chemical fertilizer-N and straw-N in a double rice cropping system. In the field experiment, liming increased grain yield and N uptake by an average of 9.0% and 10.6%, respectively. In contrast, CaCl 2 application did not affect rice yield and N uptake, suggesting that the effects of lime application were not related to the addition of Ca2+. Results from a 15N tracer experiment (i.e., 15N-labeled urea and straw) indicated that liming reduced N uptake from fertilizer (−5.7%), but increased N uptake from straw (+31.3%). Liming also reduced soil retention of both urea- and straw-N and increased their loss rates. Taken together, our results indicate that although liming increases rice yield and N uptake, it lowers the use efficiency of fertilizer N and facilitates N losses. In addition, our results emphasize the need for long-term studies on the impact of liming on soil N dynamics in paddy soils. • Liming of an acidic rice paddy soil increased both rice yield and N uptake. • Addition of Ca2+ did not affect rice yield and N uptake. • Liming reduced N uptake from fertilizer but increased that from straw. • Liming reduced soil retention of both urea- and straw-N and increased their loss rates. [ABSTRACT FROM AUTHOR]

The solubility of cadmium (Cd) in soil and its transfer to plants are influenced by soil pH. While increasing soil pH reduces Cd solubility and accumulation in rice plants grown in acidic soils, its effect on Cd accumulation in vegetables remains inconclusive. Here, we investigated the impact of soil pH on Cd accumulation in dicotyledonous vegetables and elucidated the underlying molecular mechanisms. Soils collected from various locations were supplemented with varying quantities of lime to achieve soil pH values of around 5.0, 6.0, 7.0, and 8.0. Raising soil pH from around 5.0 to 8.0 markedly decreased extractable Cd. However, increasing soil pH tended to promote shoot Cd accumulation in dicotyledonous vegetable species including lettuce, pakchoi, and Chinese cabbage, and the model dicotyledonous plant Arabidopsis thaliana. Conversely, soil pH increase resulted in a monotonic decrease in rice Cd accumulation. In our hydroponic experiments, we discovered that iron (Fe) deficiency substantially increased Cd uptake and accumulation in dicotyledonous plants but not in rice. Increasing soil pH reduced soil Fe availability and induced the Fe transporter gene IRT1 expression in dicotyledonous vegetables roots, which led to an increase in IRT1-mediated Cd uptake and subsequently increased Cd accumulation as soil pH increases. A comprehensive model incorporating extractable Cd and root IRT1 expression better explained Cd accumulation in vegetable shoots. The application of 50 mg/kg of Fe fertilizer in neutral or alkaline soils resulted in a significant reduction in Cd accumulation by 34–58% in dicotyledonous vegetables. These findings reveal that increasing soil pH has two opposite effects, decreasing soil Cd availability while promoting Cd uptake through IRT1 upregulation, reconciling the inconsistency in its effect on Cd accumulation in dicotyledonous plants. Our findings provide important insights for understanding the factors affecting Cd uptake in plants and offer a practical solution to mitigate Cd contamination in vegetables. [Display omitted] • Elevating soil pH increases Cd accumulation in lettuce, pakchoi, and cabbage. • Fe-deficiency increases IRT1-mediated Cd uptake by dicotyledonous vegetables. • Fe-transporter gene IRT1 is responsible for Cd uptake in dicotyledonous vegetables. • Applying Fe fertilizer can decrease Cd accumulation in dicotyledonous vegetables. [ABSTRACT FROM AUTHOR]