Abstract:【Objective】Soil erosion is a major factor causing soil degradation and crop productivity reduction in the northeast black soil region. However, the in situ systematic and quantitative assessment of the effects of erosion on soil quality and crop productivity remains unclear. 【Method】A long-term field experiment on erosion-productivity relation was set up at Heshan Farm, Heilongjiang Province in 2005 based on comprehensive effects of erosion and tillage on soil profile. The experiment was a two-factor completely randomized block design with simulated erosion depth (8 levels of 0, 10, 20, 30, 40, 50, 60, and 70 cm) and fertilization (no fertilization and fertilization), totaling 16 treatments with 3 replications per treatment. In 2022, a series of soil physicochemical properties [bulk density (BD), soil water content (SWC), clay content, pH, soil organic C (SOC), alkali-hydrolyzed N (AN), Olsen-P (AP) and available K (AK)] and biological properties [microbial biomass C and N (MBC, MBN), catalase, urease, ?-glucosidase, cellulase activity] in 0-20 cm soil layer and corn yield were measured after 18 years of the setup. 【Result】1) Soil clay content, SOC, AN, AP, MBC and cellulase activities decreased significantly with the increase of simulated erosion depth, while soil BD and AK increased significantly. Also, fertilization significantly decreased soil BD, pH, AK, and catalase activity, but increased clay content, SOC, AN, AP, and the activities of urease, ?-glucosidase, and cellulase. Interestingly, fertilization weakened the correlation between soil urease activity, BD and other physicochemical properties. 2) Simulated erosion resulted in significant reductions in soil quality and corn yield, the decrease mainly occurred before the erosion depth of 40 cm. Soil quality index decreased by 28.1% for the unfertilized treatment and 26.7% for the fertilized treatment, and yield loss was 45.8% for the unfertilized treatment and 11.7% for the fertilized treatment at 40 cm of erosion depth. Additionally, fertilization increased the soil quality index by 7.0% and corn yield by 3.0 fold. 3) The main factors affecting soil quality under simulated erosion were cellulase activity, MBC and AN for the unfertilized treatment, and cellulase activity, MBC, AP for the fertilized treatment. Also, the main factors affecting corn yield under long-term simulated erosion were AN for the unfertilized treatment and AP for the fertilized treatment. 【Conclusion】These results quantified the degree of soil erosion on soil quality and productivity and clarified the major factors affecting soil quality and productivity in black soil, and can serve as reference for the restoration of degraded black soil.

Abstract:【Objective】 Rapeseed (Brassica napus L.), one of the most important oilseed crops in China, is sensitive to magnesium (Mg) deficiency. The Yangtze River Basin is the main planting area for winter oilseed rape in China, and the climatic characteristics of the region with simultaneous rain and heat, high-intensity planting patterns and long-term unbalanced fertilization have led to serious depletion of soil magnesium. It provides a theoretical basis for the rational application of Mg fertilizers in rapeseed cultivation to investigate the impact of different Mg fertilizers on seed yield and quality of rapeseed in China’s main winter oilseed rape production areas. 【Method】 Between 2019 and 2020, 56 field trials were conducted in the main rapeseed-growing regions in China. The trials followed a one-way experimental design, with three distinct Mg fertilizer treatments: no Mg fertilizer (CK), magnesium sulfate at the rate of 45 kg·hm–2(Calculated as MgO, the same as below) (MgSO4·H2O, referred to as MgSO4), and magnesium chloride, also at the rate of 45 kg·hm–2 (MgCl2,referred to as MgCl2). The response of rapeseed to the two Mg fertilizers was evaluated by analyzing the rapeseed yield, yield components, oil, protein, sulfide content and fatty acid fractions. 【Result】 The results revealed that the application of both MgSO4 and MgCl2 significantly increased rapeseed yield by 14.1% and 11.8%, respectively. The increase was primarily attributed to an increase in pod number per plant and seeds per pod. MgSO4 and MgCl2 increased the pod number per plant by 10.2% and 8.2%, and the seeds per pod by 3.9% and 2.4%, respectively. Analyzing the relationship between soil Mg content, sulfur content and yield increase resulting from Mg application indicated that the increase in seed yield was mainly associated with soil Mg content but not soil sulfur. The addition of MgSO4 and MgCl2 resulted in an 11.8% and 8.7% increase in seed Mg content (relative to no Mg application treatment), respectively. However, Mg accumulation was similar in both Mg application treatments. Additionally, the application of Mg fertilizer significantly improved rapeseed quality by increasing oil, oleic acid, and linoleic acid content by 5.5% and 4.8%, 8.3% and 7.7%, 7.8% and 11.4% for MgSO4 and MgCl2, respectively. Meanwhile, stearic acid, palmitic acid, and erucic acid contents were decreased by 4.60% and 26.1%, 7.5% and 13.9%, and 33.2% and 24.1% for MgSO4 and MgCl2, respectively. Although the application of MgSO4 resulted in a significant increase in sulfide, it remained below the national limits for edible rape oil and feed cake meal for double-low oilseed rape. 【Conclusion】 In the main winter oilseed rape production areas in China, the application of MgSO4 and MgCl2 can significantly increase rapeseed yield, with MgSO4 having a slightly greater effect compared to MgCl2. Magnesium application also increases the Mg content and improves the oil quality of rapeseed by increasing the content of oleic acid and linoleic acid while reducing stearic acid and palmitic acid contents. These synergistic improvements contribute to both yield and quality enhancement.

Abstract:【Objectives】This study aimed to provide a scientific basis for optimizing appropriate film mulching practices to improve productivity and protect the environment in dryland farming.【Methods】A complete random two-factor field experiment was conducted in Pengyang, Ningxia Province to investigate the coupled effects of mulching (started in 2012) with different straw-derived carbon inputs on the soil aggregate characteristics, organic carbon content, and maize yield. Specifically, the mulching method was the main factor and the straw return form was the sub-factor. Six treatments were established as follows: straw return with film mulching (PS), biochar return with film mulching (PC), no-return with film mulching, straw return without mulching (TS), biochar return without mulching (TC), and no return without mulching.【Results】The results indicated that each straw and biochar return treatment significantly (P < 0.05) improved the soil aggregate distribution and stability of each particle size, and the aggregate content > 0.25 mm increased significantly (P < 0.05) by 47.32% on average. Compared with the no-mulching treatment, the mean weight diameter and geometric mean diameter of the soil particles increased by 9.19% and 4.15%, respectively, under the double ridge-furrow mulching treatments. The organic carbon content of the 0-60 cm soil layer increased significantly (P < 0.05) under each straw and biochar return treatment compared with the no-return treatments, where the contents were 2.60% and 2.73% higher under PC and TC than PS and TS, respectively. The aggregate organic carbon contents under each treatment increased as the aggregate particle size increased. Also, the straw and biochar return treatments significantly increased the organic carbon content of aggregates, whereas the contents decreased under double ridge-furrow mulching treatments. Structural equation modeling showed that the straw return form, mulching method, and soil organic carbon content could significantly promote yield increases, while the straw and biochar return treatments significantly increased (P < 0.05) the corn yield in film-mulched fields by 14.6% on average. However, the yield increase did not differ significantly between the straw return treatments and biochar return treatments.【Conclusion】In conclusion, double ridge-furrow mulching and straw carbon input treatments significantly improved the soil stability, soil organic carbon content, crop yield, and the coupled effect of the double ridge-furrow mulching and biochar return had a positive effect on improving the farmland soil quality and fertility.

Abstract:【Objective】 Based on the current situation and severity of soil and water loss, it is vital to investigate the nature and extent of surface structure degradation of slope farmland and long-duration rainfall characteristics in the red soil region of southern China.【Method】 The method of long-term rainfall simulation were adopted to test the effects of topsoil structure and rainfall intensity on rainfall redistribution, runoff and sediment yield. In this paper, three rainfall intensities, 30 mm·h-1, 60 mm·h-1 and 90 mm·h-1, respectively, and three cultivation depths, 10 cm, 20 cm and 30 cm, respectively, were set to study the effects of tillage lager depth and rainfall intensity on surface flow, subsurface flow, soil loss rate and erosion pattern.【Result】 The results showed that:(1) The topsoil structure significantly changed the redistribution process of runoff. Higher tillage layer depth can mitigate the effects of rainfall intensity, reduce the surface flow coefficient, and increase subsurface flow. Under the condition of 60 mm·h-1 and 90 mm·h-1 rainfall intensity, the average surface flow coefficient decreased in the sequence of 70.5% (TLD10 cm), 62.9% (TLD20 cm), and 56.8% (TLD30 cm), and the average subsurface flow ratio increased in the sequence of 7.1% (TLD10 cm), 12.3% (TLD20 cm), and 18.1% (TLD30 cm). (2) The soil loss rate was enhanced with the increase in rainfall intensity but decreased with the depth of the tillage layer. Under 60 mm·h-1 rainfall intensity, the peak soil loss rate of 10 cm, 20 cm and 30 cm tillage depth were 35.1, 25.6 and 20.5 g·m-2 min-1, respectively. For 90 mm·h-1 rainfall intensity, these values were 68.7, 55.8 and 48.4 g·m-2 min-1, respectively. (3) Rainfall intensity and topsoil structure significantly affect the final slope erosion forms. With the increase of tillage layer depth, the erosion degree decreased significantly. Under the condition of 30 mm·h-1 rainfall intensity, the surface of the soil was relatively intact, and the soil erosion type was splash erosion. Also, under the condition of 60 mm·h-1 rainfall intensity, the soil erosion was all sheet flow erosion, under 10 cm and 20 cm tillage depth, spot erosion appeared in the lower part of the slope, and the soil erosion degree was lower for sheet flow erosion at 30 cm tillage depth. For the 90 mm·h-1 rainfall intensity, rill erosion appeared on the slope while at 10 cm tillage depth, rill erosion was well developed. In addition, at 20 cm tillage layer depth, rill erosion development was significant while at 30 cm tillage depth, slope erosion was mainly sheet flow erosion.【Conclusion】 The top soil structure can significantly change the relationship between rainfall and runoff. Higher tillage layer depth can reduce surface erosion, promote the deep infiltration of soil moisture, and increase the soils deep-water holding capacity. Also, this research can serve as a reference for the rational layout of topsoil structure, improvement of rainfall utilization rate and enhancement of soil erosion resistance in the southern red soil area.

Abstract:ObjectiveIn order to comprehensively study the effect of desulfurized gypsum in improving saline-alkali soils, this paper statistically analyzed the change characteristics of soil pH value, exchangeable sodium percentage (ESP), soil electrical conductivity (EC), and crop yield after applying 0~60 t·hm-2 desulfurized gypsum in the northwest, north, northeast, and coastal areas of China through literature search. To achieve this, a comprehensive improvement evaluation model of saline-alkali soil was used in which the desulfurized gypsum amount was designed as an independent variable based on the grey relational analysis and entropy weight method.MethodSoil pH value and ESP are often used to evaluate the alkalization property of saline-alkali soil while EC is used to evaluate the salinization property of saline-alkali soil. This paper used the data of literature to explore the relative change rates of soil pH, ESP, and EC in 0~20 cm soil layer with and without desulfurized gypsum within 1 year after the crop harvest in order to quantitatively reveal its improvement effect. Grey relational analysis and entropy weight method were used to synthesize three soil indexes to evaluate the improvement effect of desulfurized gypsum on saline-alkali soil. Due to the few literature data on light saline-alkali soil and moderate saline-alkali soil, the application of desulphurized gypsum in severe saline-alkali soil was mostly studied. This paper combined light saline-alkali soil and moderate saline-alkali soil into light and moderate saline-alkali soil for analysis.ResultApplication of desulfurized gypsum reduced soil pH and ESP and increased crop yield, but increased EC. As the application rate of desulfurized gypsum increased, the decrease rate of pH and ESP and the increase rate of crop yield increased first and then decreased whereas the increase rate of EC showed an increasing trend. When the amount of desulfurized gypsum applied to moderate saline-alkali soil and severe saline-alkali soil exceeded 30 t·hm-2, the increase rate of crop yield(Oil sunflower, alfalfa, corn, rice, wheat, Lycium barbarum, and sweet sorghum) showed a decreasing trend. To further analyze the effect of desulfurized gypsum on the improved saline-alkali soil, an entropy weight grey correlation evaluation model was established, and the application of desulfurized gypsum was optimized.ConclusionThrough the study on the improvement effect of desulfurized gypsum applied in the range of 0~60 t·hm-2 in saline-alkali soil, using statistical analysis and mathematical modeling, it was concluded that the amount of 18~22 t·hm-2 desulfurized gypsum in light and moderate saline-alkali soil; the amount of 23~29 t·hm-2 desulfurized gypsum in severe saline-alkali soil could achieve good soil improvement effect and increase crop yield. The research results provide a reference for improving saline-alkali soil with desulfurized gypsum.

Abstract:【Objective】There are about 0.66 million hectares of coastal saline-sodic soil in Jiangsu that have not been developed and used as arable land for agriculture. This is because the saline-sodic soil has a higher concentration of salt that requires urgent ameliorating. 【Method】This study used waste phosphogypsum (PG), a kind of by-product from the phosphate industry, to conduct an amelioration experiment of saline-sodic soil in the field. Eight treatments were employed in the field experiment: no fertilizer and PG, fertilizer but no PG, and compound fertilizer + different amounts of PG. 【Result】Results showed that pH was decreased by 0.07～0.40 pH units in the depth of 0～20 cm topsoil treated with PG compared to the control. Soil bicarbonate and sodium ions decreased by 15.81%～43.53% and 17.25%～89.83%, respectively. The concentration of potassium ion, calcium ion, and organic matter in the amended soil treated with PG was increased by 8.17%～384.90%, 59.51%～1977.72%, and 4.51%～19.50%, respectively. Also, the amounts of total N and P in the wheat leaves in the PG treatment were increased by 7.85%～26.21% and 5.02%～35.97%, respectively, and the wheat grain yield increased by 11.41%～45.26%. Overall, PG can be used to ameliorate costal saline-sodic soil with better effectiveness. Mechanistically, the increase in calcium ions occurred as PG exchanged with sodium ions adsorbed in soil, and the sodium ions were leached underground during irrigation and rain to decrease the soil pH. Also, some acid-containing groups in PG were able to neutralize the bicarbonate ions to decrease the soil pH. PG increased the N uptake in wheat leaves and the yield of wheat grain due to the increased P from PG which induced a proportionate uptake of nutrients by the plant. Comprehensively, the best performance was the treatments of 30% compound fertilizer (1050 kg`hm-2)＋ PG (1125 kg`hm-2) and 30% compound fertilizer (1050 kg`hm-2)＋ PG (2250 kg`hm-2).【Conclusion】The positive effect of PG should not be considered proportional to the amount applied, because trace hazardous elements in PG could accumulate in the soil which will result in environmental risks and grain safety issues. Thus, proper care should be taken when using high doses of PG for soil amendment.

Abstract:【Objective】China depends heavily on agricultural potassium fertilizer imported from abroad. Thus, it is important to improve potassium utilization efficiency by changing the existing forms of potassium.【Method】In this paper, a two-year field trial (in 2020 and 2021) was set up using Virginia-type peanut Huayu 22 to investigate the effects of inorganic potassium (free ionic state) and sorbitol chelated potassium on peanut yield, dry matter accumulation, potassium accumulation, and bacterial community structure in peanut rhizosphere soil by a completely randomized block design. Under the premise of conventional fertilization, peanut spraying experiments were carried out at different growth stages and with five treatments: CK, water control; IK, inorganic potassium; MK, sorbitol mixed inorganic potassium; SK, sorbitol chelated potassium (self-made); and LK, commercially available chelated potassium (Canada).【Result】The results showed that foliar topdressing potassium fertilizer on leaves could significantly increase the peanut yield. Compared with the treatment of IK or LK treatments, the two-year average yield of SK treatments increased by 18.9% and 14.97%, respectively. The yield components of 100-seed weight, 100-pod weight, and full fruit rate were all significantly improved. Also, the dry matter accumulation and potassium accumulation of peanut plants treated with sorbitol-chelated potassium were significantly increased. Compared with CK, IK, and LK treatments, the total dry matter of peanut plants treated with SK increased by 19.5%, 19.1%, and 15.7% in the stage of the full pod, and increased by 22.8%, 27.4%, and 11.7% at the mature stage, respectively. Potassium accumulation in peanut kernels increased by 30.6%, 49.8% and, 44.8% in the stage of full pod, and increased by 30.8%, 59.1%, and 10.8% at the mature stage, respectively. The above results showed that self-made sorbitol-chelated potassium could promote the absorption and distribution of potassium nutrients in plants. Furthermore, the microbial diversity and richness of peanut rhizosphere soil increased under SK treatment compared with the other treatments. Compared with CK, MK, and LK treatments, the Sobs index of microbial communities in SK treatment increased by 10.7%, 12.5%, and 10.7%, respectively. The species significantly enriched in SK treatment were p-Verrucomicrobiota_g-Roseimicrobium and p-Planctomycetota_c-vadinHA49. The correlation analysis showed that the increase in production was significantly related to the absorption and distribution of potassium and the changes in rhizosphere microorganisms.【Conclusion】In summary, compared with inorganic potassium form, sorbitol-chelated potassium could promote the absorption and accumulation of potassium in peanuts at the same potassium application level, which is comprehensively reflected in production. The research results could provide theoretical and practical references for improving potassium efficiency.

Abstract:【Objective】The combined application of crop straw with chemical fertilizers and chicken manure can change soil microbial community structure and the interaction between microorganisms. However, whether there is a correlation between these changes and wheat yield remains unclear.【Method】A 7-year field experiment was used as the research platform, and this included five management strategies: (1) N0S0: no fertilizer or crop straw returning, (2) N0S: crop straw returning, (3) NS0: traditional chemical fertilization, (4) NS: crop straw returning with chemical fertilizer, and (5) NSM: crop straw returning with chemical fertilizer and the nitrogen was substituted 20% by chicken manure. The effects of different management strategies on microbial community composition in bacterial-fungal co-occurrence networks and the correlation between key microorganisms and wheat yield were studied.【Result】The results showed that compared with N0S0 treatment, the grain yield of wheat under NS0, NS and NSM treatments increased by 539.20%, 611.56% and 676.56%, respectively, while there was no significant change under N0S treatment. The bacterial and fungal community compositions were divided into three significantly different groups: N0S0 and N0S, NS0, and NS and NSM, respectively, indicating that the microbial community composition was significantly different with or without chemical fertilizer application. Under both chemical fertilizer applications, there was a significant difference in whether organic materials were applied. Ranked from high to low importance, we found that available phosphorus, electrical conductivity, microbial biomass nitrogen, soil organic carbon, readily oxidizable organic carbon, and particulate organic carbon were the main soil physicochemical properties that caused the changes in bacterial community composition under different treatments. Also, electrical conductivity, microbial biomass nitrogen, readily oxidizable organic carbon, particulate organic carbon, available phosphorus, and soil organic carbon were the main soil physicochemical properties that caused the changes in fungal community composition under different treatments. In the bacterial-fungal co-occurrence network, two key modules (module 1 and module 4) were significantly correlated with wheat yield changes. NS+NSM treatments increased the relative abundance of beneficial microorganisms in module 4, including Nocardioides, Cellulomonas, Pir4_lineage, Chrysosporium,Acaulium, and Schizothecium, which were positively correlated with wheat yield. These beneficial microorganisms could degrade cellulose and lignin, promote nutrient conversion and recycling, or inhibit the growth of the potential pathogen. NS+NSM treatments also significantly reduced the relative abundance of plant pathogenic fungi in module 1, including Stachybotrys,Achroiostachys, and Fusicolla, which were negatively correlated with wheat yield and were detrimental to soil health and crop growth.【Conclusion】Therefore, crop straw returning with chemical fertilizer and crop straw returning with chemical fertilizer and chicken manure were beneficial to the increase of key beneficial microorganisms and the decrease of pathogenic fungi. The function and the relative abundance of key microorganisms had effects on wheat yield.

Abstract:Counter tillage is a common soil and water conservation tillage practice, which can influence the soil erosion process by increasing storage and infiltration capacity on sloping farmland. However, studies about the effects of counter tillage on nutrient losses during soil erosion processes on sloping farmland are still limited. 【 Objective】 Therefore, this study aimed to reveal the characteristics of nutrient loss on sloping farmland. 【 Method】 In this study, the rainfall simulation was conducted with a rainfall intensity of 90 mm·hh–1, five slope gradients (3°, 5°, 10°, 15°, 20°) and two types of slope treatments (counter tillage and flat slope) on runoff plots with projection length 4.5 m and projection width 1.5 m to explore the effects of counter tillage on the characteristics of soil erosion and nitrogen and phosphorus nutrient losses on sloping farmland of different slope gradient. 【 Result】 The results showed that: (1) When the slope gradient was less than 20°, counter tillage significantly reduced the amount of runoff and sediment on the sloping farmland and the amount of runoff and sediment reduced by a maximum of 95% and 99% respectively. When the slope gradient increased to 20°, a break in the ridge occurred on the counter tillage and the control effect on the runoff and sediment was gradually weakened. Also, the amount of runoff and sediment was close to or greater than that of the flat slope. (2) The effect of counter tillage on the concentration of nutrient loss was small, but it had a significant effect on the nutrient losses. When the slope gradient was less than 20°, the counter tillage had a better effect on controlling the nutrient losses on the sloping farmland. However, when the slope gradient increased to 20°, the effect of counter tillage on controlling nutrient losses was weakened. Additionally, TN losses were always greater than TP losses in runoff; except for the 10° slope gradient on CT, while TP losses were greater than TN in sediment. (3) The nutrient losses were mainly determined by the amount of runoff and sediment, while the nutrient loss rate and runoff rate or sediment production rate satisfied a linear positive correlation. In addition, the reduction benefits of nutrient losses on counter tillage in runoff and sediment can reach 45% to 100% and 59% to 100%, respectively. 【 Conclusion】 Our results show that counter tillage is an effective tillage practice to control soil erosion and nutrient losses.

Abstract:【Objective】The combined application of crop straw with chemical fertilizers and manure is an effective measure to improve soil quality, but its effect on wheat yield and its mechanism in the different textures of fluvo-aquic soils are still unclear. 【Method】Here, we examined shifts in soil quality and wheat grain yield when three soil textures (sandy, loam and clay) were subjected to different management strategies and through a 7-year field experiment at the Fengqiu Agro-Ecological Experimental Station of the Chinese Academy of Sciences. Five different treatments were used: no fertilizer or crop straw returning(N0S0), crop straw returning(N0S), traditional chemical fertilization(NS0), crop straw returning with chemical fertilizer(NS), and crop straw returning with chemical fertilizer and the nitrogen was substituted 20% by chicken manure(NSM). 【Result】The results showed that compared with the N0S0 treatment, the grain yield under the NS treatment was increased by 611.56%, 440.00%, and 403.55% while under the NSM treatment, it was increased by 676.56%, 546.67% and 492.86%, respectively. In sandy, loam, and clay soils, compared with the N0S0 treatment, the soil quality index(SQI) under the N0S and NS0 treatments was significantly increased, with that under the NS treatment being more significant. In sandy soil, the SQI of the NSM treatment was better than that of the NS treatment, but in loam and clay soils, the SQI of the NSM and NS treatments showed no significant differences. Random forest analysis indicated that in sandy soil, grain yield was significantly affected by pH, alkali-hydrolyzable nitrogen(AHN), dissolved organic nitrogen(DON), available phosphorus(AP), soil organic carbon(SOC), and available potassium(AK), in loam soil, it was significantly affected by AP, pH, AK, AHN, microbial biomass carbon(MBC), and SOC, while in clay soil, grain yield was significantly affected by AP, DON, AHN, and pH. The partial least squares path model(PLS-PM) showed that in sandy, loam, and clay soils, the soil properties significantly affecting grain yield were significantly regulated by management strategies, and all of these properties had significant effects on SQI, and SQI had direct significant effects on grain yield. The key soil properties affecting grain yield could be used as indicators to monitor the changes in soil quality and grain yield to select management strategies. In addition, in loam soil, SQI also indirectly affected the grain yield by affecting wheat yield components. 【Conclusion】The combined application of crop straw with chemical fertilizers and chicken manure improved soil quality and directly or indirectly affected grain yield through different action modes in the different textures of fluvo-aquic soils.