Kailou Liu

Continuous monocropping and inappropriate fertilization have contributed to nutrient depletion and soil degradation, limiting peanut productivity in subtropical red soil agroecosystems. Although diversified cropping may help alleviate these constraints, the reasons why it improves peanut productivity remain unclear. In this study, we conducted a long-term field experiment in Jiangxi, China, to compare four cropping systems, assess soil nutrients, peanut productivity, and bacterial communities, and further evaluate the role of key taxa through inoculation assays and structural equation modeling. Results showed that diversified cropping improved peanut growth and yield, with the green manure integrated system performing best overall. Diversified cropping also increased soil organic carbon, total nitrogen, and available phosphorus, while reshaping bacterial communities. Several taxa, including Bradyrhizobium, Mycobacterium, Dormibacter, and Ardenticatena, were positively associated with soil nutrients. Inoculation assays further showed that a synthetic consortium assembled from representative strains affiliated with key taxa produced stronger effects on plant growth than a single-strain inoculation. Structural equation modeling identified key taxa as the factor most strongly associated with crop productivity. These findings suggest that higher peanut productivity under diversified cropping was closely associated with concurrent improvements in soil fertility and the enrichment of key taxa.

Double‐season rice fields typically exhibit low soil potassium (K) availability despite abundant straw resources. Whether integrating milk vetch could enhance K retention from straw and improve its uptake by subsequent rice remains unclear. Therefore, we examined how the combined incorporation of straw and milk vetch affects soil K distribution and bioavailability. A field experiment conducted in Jiangxi Province, China, which treatments included single straw incorporation (S) and combined straw plus milk vetch incorporation (S + G). The exchangeable and non‐exchangeable K of bulk soil in S + G were higher by 79.33% and 22.26% than the S treatment. Compared with the S treatment, the S + G also improved the exchangeable and non‐exchangeable K in > 2 mm, 0.25–2 mm, and 0.053–0.25 mm aggregates. Notably, milk vetch strengthened the linkage between exchangeable K and non‐exchangeable K within microaggregates (0.053–0.25 mm). These results demonstrate that integrating straw with milk vetch effectively enhances soil K availability for double‐season rice systems.

Organic amendments have shown profound performance to enhance soil carbon (C) sequestration and crop productivity. However, the synergistic effects of various organic amendments on maintaining/improving pH buffering capacity (pHBC) remain unclear. Here, based on a 42-year ongoing field experiment, we explored the response of pHBC and crop productivity to synergistic incorporation of plant C input (green manure with or without straw) vs. diverse C input (livestock combined with plant C). Mineral fertilization caused pH decline by 0.12-0.39 units, compared with diverse C input. Plant C input showed no significant effect on pHBC, whereas diverse C input, e.g., synergistic incorporation of green and livestock manure, increased soil pHBC by 31-40% compared with control. This primarily attributed to the rise in Ex-Ca2+ and soil organic matter, particularly humic substance compositions. Furthermore, the protonation of organic anions produced from humic acid dissociation also enhanced pHBC. Critically, the mitigation of soil acidification establishes a critical foundation for improving crop yields, average outperforming control and plant C input by 32% and 12%, respectively. These findings highlight that the diverse C input based on soil amendments as agronomically optimal and sustainable strategy to mitigate soil acidification and sustain crop productivity in acid soil area.

Soil pore structure plays a fundamental role in particulate organic matter (POM) dynamics by regulating water and air exchange within the soil matrix. However, the effects of long‐term fertilization on POM distribution, pore characteristics, and their interrelationships may differ between upland and paddy soils. In this study, we examined two long‐term fertilization field experiments conducted in contrasting agroecosystems in Jiangxi, China: a 38‐year upland field and a 43‐year paddy field. Four fertilization regimes were compared: no fertilizer (control), inorganic fertilizer (NPK), double‐rate inorganic fertilizer (2NPK), and inorganic fertilizer combined with pig manure (NPKM). X‐ray computed tomography (CT) was used to quantify soil pore structure and POM, and a random forest model was trained on a manually classified dataset of 1322 POM fragments to operationalize the decomposition degree, distinguishing fresh (e.g., exhibiting low blobness, plateness) from decomposed (e.g., exhibiting high sphericity, compactness) morphologies based on four morphological features. The NPKM treatment significantly increased fresh and decomposed POM volume density by 2.05% (7.51 mm ³ cm ⁻³ ) and 47.7% (2.01 mm ³ cm ⁻³ ) in upland soil, and 253% (15.2 mm ³ cm ⁻³ ) and 103% (1.47 mm ³ cm ⁻³ ) in paddy soil, respectively. NPKM also enhanced air permeability ( K _a ), image‐based porosity, connected porosity, > 300 μm porosity, and surface area density in both soils. POM in upland soil is rapidly aerobically decomposed and physically fragmented within dynamic pore networks, while in paddy soil, it is preserved by anaerobic conditions that suppress microbial activity. Overall, our findings demonstrate that combined organic–inorganic fertilization promotes both POM accumulation and the development of pore structure in upland and paddy soils, with distinct mechanisms operating under different land‐use systems.

Acidification improvement is the core measure for the sustainable utilization of red soil cultivated land resources. In addition to organic fertilizers, adding alkaline materials for acidification improvement to increase crop yields has always been one of the main measures in agriculture. Red sandstone powder contains a lot of alkaline substances. Therefore, it is urgent to make efficient use of these red sandstone powders. This study evaluated the effects of red sandstone powder on crop yield and soil physicochemical properties to elucidate its potential as a soil amendment for red soils. A field experiment was conducted using six treatments: control (CK), chemical fertilizer alone (F), and chemical fertilizer combined with increasing rates of red sandstone powder (R0.5, R1, R2, and R3). Impacts on radish and peanut yields, soil pH, organic matter, available nitrogen, phosphorus, potassium, and particle size distribution were assessed. Compared to CK, both chemical fertilizer and red sandstone treatments significantly increased yields ( p < 0.05), with higher sandstone application rates corresponding to greater yield improvements. Under R3, radish and peanut yields increased by 46.97 × 10 ³ kg·hm ⁻² and 5.43 × 10 ³ kg·hm ⁻² compared to CK, respectively, representing 40.1% and 106.78% increases over F. Chemical fertilizer alone reduced soil pH by 0.28–0.29 units; red sandstone application effectively mitigated acidification. In R3, pH increased by 1.59 units (radish) and 0.23 units (peanut) compared to F. Notably, chemical fertilizer decreased available phosphorus, whereas red sandstone significantly elevated it by 102.38 mg·kg ⁻¹ and 91.26 mg·kg ⁻¹ for radish and peanut, respectively, under R2. Red sandstone altered soil texture, increasing sand content by 11.36% (radish) and 8.05% (peanut), while decreasing clay content by 11.69% and 7.04%, respectively, with minimal silt changes. Red sandstone powder enhances soil structure, counteracts acidification from chemical fertilizers, and improves phosphorus availability, ultimately enhancing yield. R2–R3 rates strike a balance between yield optimization and sustainable soil management. This work provides a basis for using red sandstone and reduced chemical fertilizer reliance.

Oyster shell powder enhances soil quality by mitigating acidification and improving fertility, boosting crop yields. However, its efficacy in immobilizing cadmium (Cd) in paddy soils remains uncertain. We performed a field experiment from 2014 to 2018 and assessed four treatments of oyster shell powder: 0 kg/ha (L0), 750 kg/ha (L750), 1,500 kg/ha (L1500), and 2,250 kg/ha (L2250). From 2014 to 2018, grain yield among all treatments was assessed at maturity, and Cd of grain, soil pH, and available Cd content were measured. Our results revealed that oyster shell powder significantly increased rice yields compared to L0, with L750, L1500, and L2250 treatments enhancing yields by 0.53–3.07% (average value of 1.80%), 3.20–7.61% (average value of 5.41%), and 4.19–10.96% (average value of 7.58%), respectively. Simultaneously, the Cd concentration in rice grains decreased by 3.57–5.51%, 7.14–16.34%, and 9.91–19.84% for L750, L1500, and L2250, respectively, with L2250 demonstrating the most effective Cd reduction. Additionally, soil pH increased by 0.12–0.39, 0.20–0.60, and 0.38–0.79 units, while soil bioavailable Cd decreased by 5.71–13.04%, 10.39–15.46%, and 14.73–18.84% for L750, L1500, and L2250, respectively. Further analysis indicated that over five years of continuous application, a 0.1-unit increase in soil pH correlated with a reduction of 0.42–0.82 mg/kg in Cd levels in rice grains, while a 0.1 mg/kg reduction in bioavailable Cd in the soil corresponded to a 0.07–0.16 mg/kg decrease in Cd in rice grains. In conclusion, five years of continuous application of oyster shell powder effectively mitigated soil acidification and reduced Cd bioavailability, increasing rice yields and diminishing Cd accumulation in rice grains. Higher application rates of oyster shell powder (up to 2,250 kg/ha) resulted in more pronounced acid control, Cd immobilization, and yield enhancements.

The intensification of agricultural production has significantly reduced land availability, necessitating continuous cropping cycles that degrade soil quality and inhibit crop growth. While the short-term use of soil amendments has shown significant potential for mitigating these challenges, few studies have explored their long-term effects on acidified soils and heavy metal accumulation. Between 2013 and 2018, a field experiment was conducted in the peanut (Arachis hypogaea L)-growing region of Jinxian County, Jiangxi Province, to investigate the long-term effects of oyster shell powder applied to upland red soil. Before the experiment, the soil properties were as follows: pH, 4.54, total soil cadmium (Cd) content, 0.49 mg kg^-¹; and available Cd content, 0.25 mg kg^-¹. The experiment included three treatments combining chemical fertilizers with oyster shell powder at application rates of 750, 1500, and 2250 kg ha^-¹ (L750, L1500, L2250) and a control with only chemical fertilizer (L0). From 2013 to 2018, peanut yield among all treatments was assessed at maturity. Soil pH was then measured using a pH meter with a 2.5:1 water-to-soil ratio. Exchangeable hydrogen and aluminum were determined using the potassium chloride exchange-neutralization titration method. Meanwhile, available Cd content was extracted using 0.1 M CaCl₂ and measured with a flame atomic absorption spectrophotometer. While all treatments showed an annual decline in peanut yield from 2013 to 2018, but oyster shell applications significantly reduced the rate of crop yield decline. Compared to L0, the yields of L750, L1500, and L2250 treatments increased by 5.55%-19.42%, 8.64%-28.74%, and 15.43%-37.01%, respectively. Soil pH values in the L750, L1500, and L2250 treatments were higher than the L0 treatment by 0.03-0.31, 0.16-0.48, and 0.28-0.65 units, respectively. Their exchangeable hydrogen contents decreased by 10.17%-24.24%, 16.67%-27.94%, and 23.40%-29.44%. In addition, exchangeable aluminum contents decreased by 5.05%-26.09%, 23.23%-46.27%, and 39.73%-66.97%. In contrast, soil available Cd contents in the L750, L1500, and L2250 treatments were lower than the L0 treatment by 7.96%-19.29%, 9.56%-30.71%, and 13.94%-34.65%, respectively. Correlation analysis revealed that soil pH was positively associated with peanut yield and negatively correlated with exchangeable hydrogen, exchangeable aluminum, and available Cd. For every 0.1 unit increase in soil pH, peanut yields increased by 119.62-389.82 kg ha^-¹, while available Cd decreased by 0.06-0.12 mg kg^-¹. Therefore, these findings demonstrate the efficacy of continuous oyster shell powder application in controlling soil acidification and reducing Cd levels in upland red soil.

This study investigates the effects of various treatments on soil pH, SOC, and crop yield in red soil with a pH of 4.25 through a two-year field experiment, using a rapeseed and sesame cropping system. The treatments included the control (CK); lime (CaO) (L); fully fermented pig manure (M); a calcium–magnesium–phosphate fertilizer (P); lime and fully fermented pig manure (LM); lime and the calcium–magnesium–phosphate fertilizer (LP); fully fermented pig manure and the calcium–magnesium–phosphate fertilizer (MP); and lime, fully fermented pig manure, and the calcium–magnesium–phosphate fertilizer (LMP). Then, the changes in yield, soil pH, and SOC were analyzed. The results showed that, among all treatments, the LMP treatment produced the highest yields for both rapeseed (93.62%) and sesame (45.10%); they increased by 93.62% and 45.10% compared with that for CK. Furthermore, these treatments with lime application increased the soil pH. During the rapeseed season, compared with CK, the soil pH values increased by 0.87, 0.75, 0.90, 1.03, 1.24, 1.18, and 1.45 units in the L, M, P, LM, LP, MP, and LMP treatments, respectively. Moreover, they increased by 0.66, 0.34, 0.51, 0.95, 0.82, 0.72, and 1.03 units, respectively, in the sesame season. Similarly, in terms of yield, the highest pH was observed in the LMP treatment for both the rapeseed and sesame seasons. In contrast to soil pH, the effects of these treatments on SOC were less pronounced. Furthermore, the relationship between soil pH and crop yields was significant (R², p < 0.05). In addition, fitted equations indicated a higher yield response (5.17%) in rapeseed compared with that in sesame (2.32%), while soil pH increased by 0.1 unit. Therefore, the combined application of lime, composted pig manure, and calcium–magnesium–phosphate is an effective strategy to reduce soil acidification and improve crop yield in highly acidified red soils, with the increase in soil pH having a more substantial impact on crop yield than the increase in SOC.

Physical protection of carbon (C) in soil aggregates is an important mechanism affecting soil organic carbon (SOC) stocks but there is little information on the turnover dynamics of aggregates in dryland red soils after different long‐term fertilizer application practices. Different aggregate size classes in zero fertilizer (CK), chemical fertilizer (CF) and chemical fertilizer combined with manure (MCF) treatments were examined. The RothC model was used to simulate C inputs based on SOC dynamics, the carbon, aggregation and structure turnover (CAST) model was used to evaluate soil structure and C sequestration at different aggregate size classes with time. MCF treatment significantly ( p < .05) increased total macroaggregate C, and fractions of macroaggregate C compared with the other two treatments because C inputs and C sequestration rate increased significantly ( p < .05) according to RothC model simulation. The CAST model performed well in simulating the changes in soil structure and organic C stocks in different aggregate size classes with time. The simulation results indicate that particulate organic matter (POM) is the primary source of aggregate turnover, that free silt‐clay particles have a more rapid turnover than the silt‐clay particles in other (larger) aggregates, and that the disruption criterion for aggregate distribution in CAST model parameters followed the sequence MCF > CF > CK in the low pH and low SOC red soil. Overall, the CAST model is a good tool for simulation of aggregate dynamics in red soil under different fertilizer application treatments.