Search Results (104)

Foxtail millet (Setaria italica L.), a typical dryland crop, has a high nutrient uptake capacity, which can lead to rapid soil nutrient depletion. Establishing soil conservation strategies compatible with the high yield traits of hybrid millet is crucial. Although organic fertilization and deep tillage are proven measures for maintaining soil productivity, their effects on dryland crops like millet remain understudied. This study investigated Zhangzagu 10 under five treatments: rotary tillage without fertilization (RT), rotary tillage with compound fertilizer (RTC), rotary tillage with organic fertilizer (RTO), deep tillage with organic fertilizer at 20–30 cm (DT1O), and deep tillage with organic fertilizer at 30–40 cm (DT2O). Soil physicochemical properties were measured at seven sampling periods and four tillage layer depths in a two-year field experiment. Compared to RT, RTO increased organic carbon and total nitrogen in mechanically stable macro-aggregates (0–20 cm) by up to 141.2% and 135.14%, respectively. Corresponding increases in water-stable aggregates reached 105.9% for organic carbon and 193.33% for total nitrogen. RTO also enhanced the pH buffering capacity of the topsoil while reducing soil bulk density and solid volume fraction in the surface layer during the late growth stages of foxtail millet. Combining organic fertilization with deep tillage (DT1O and DT2O) further optimized subsoil (20–40 cm) structure, increasing macro-aggregate content and stability, with effects intensifying at greater tillage depths. The integration of organic fertilization and deep tillage synergistically improved soil structure and nutrient distribution, offering a sustainable approach for dryland foxtail millet production. Full article

This study evaluates the impact of applying biochar alongside nitrogen fertilizer on soil aggregates and aggregate-associated carbon through a two-year experiment under irrigated conditions in North Xinjiang. In 2021, a randomized block design established 36 experimental plots. The experiment employed a factorial design with three levels of nitrogen fertilizer and four levels of biochar. Measurements of soil aggregates and aggregate-associated organic carbon were taken in 2022. This study’s objectives were to quantify biochar’s effect on soil aggregation and stability and to determine the distribution of SOC across different aggregate sizes. The results indicated that macroaggregates (>2 mm and 0.25–2 mm) were most common (N2B1, N2B2, and N2B3), making up 75.57–78.46% of all aggregates. In treatments with reduced nitrogen and biochar (N2B1, N2B2, and N2B3), soil aggregate refractory organic carbon content was significantly higher compared to other treatments. Generally, applying reduced nitrogen with moderate biochar (N2B2) significantly increased soil organic carbon and refractory organic carbon levels, aiding carbon fixation and improving soil carbon storage. Thus, biochar application effectively enhances carbon storage in agricultural soils, offering valuable insights for improving soil fertility in irrigated regions of northern Xinjiang. Full article

De-sealing, or depaving, is increasingly adopted to restore soil permeability and support green infrastructure, yet its potential to recover soil functions remains insufficiently understood. This study reports one year of soil monitoring following the de-sealing of a brownfield site in Milan (Italy). It compares the evolution of pedoclimatic parameters in sealed and de-sealed soils and assesses the suitability of recycled aggregates (RAs) from demolition waste as a soil-forming material. Buried sensors continuously recorded pedoclimatic parameters, temperature, water content, and oxygen concentration, while periodic sampling was carried out to analyse soil chemical properties, bacterial community composition, and the quality of percolation water (heavy metal content). De-sealing immediately improved pedoclimatic conditions, enhancing soil aeration, water regulation, and heat exchange capacity. No significant variation was detected in soil chemical properties, apart from pH fluctuations linked to the leaching of alkaline ions from concrete-based RAs. The presence of RAs caused no adverse effects on either soil or percolation water. Bacterial community composition was strongly associated with soil organic carbon, C:N ratio, and soil water content, without showing clear temporal trends. Overall, the study demonstrates that de-sealing rapidly triggers soil functional recovery and that, when properly characterised for composition and contamination risk, RAs pose no evident threat to the surrounding environment. Full article

Soil erosion in vineyards is a major environmental problem, particularly in hilly Mediterranean environments. Our study evaluated the effectiveness of permanent grass cover (PG), continuous tillage (CT), and green manure (GM) in reducing soil erosion. Furthermore, a new software tool (ISUMmate_1.1.xlsm), based on the improved stock unearthing method (ISUM), was developed and tested to quantify soil mobilization between successive transects along vineyard inter-row. The field trial was carried out over a three-year period in a Tuscany (Italy) vineyard. The results showed that PG significantly improved aggregate stability and soil organic carbon (SOC) content, while exhibiting the lowest erosion rates. In contrast, GM showed the highest erosion rates as a result of soil disturbance associated with cultivation operations and the occurrence of unexpected intense rainfalls. ISUMmate_1.1 has proven to be a reliable tool for monitoring both water- and tillage-induced erosion, providing valuable information for sustainable vineyard management. Full article

The progressive replacement of conventional plastic films with biodegradable alternatives in agricultural systems has led to the accumulation of diverse plastic residues in soils, exerting documented impacts on microbial-mediated ecological processes. However, systematic investigations into how these residues influence organic carbon (C) turnover and inter-aggregate C flows remain critically lacking. This study investigated the effects of diverse plastic film residues on organic C decomposition dynamics and aggregate-associated C sequestration through a 60-day soil incubation experiment. Two representative plastic film types—conventional polyethylene (PE) and biodegradable polylactic acid + polybutylene adipate-co-terephthalate (PAT)—were incorporated into agricultural soil under contrasting organic matter input regimes: with maize straw addition (St) and without any straw addition. The results demonstrated that, in the absence of maize straw, both PE and PAT residues enhanced native soil organic C (SOC) mineralization. Notably, PAT elevated the cumulative CO₂ emission by 7.4% (P < 0.05) relative to the control. PE slightly reduced the final SOC content but increased the proportion of soil gates (Mi) and silt plus clay (S + C) toward Ma. Conversely, PAT exerted a negligible effect on final SOC content but reduced Ma by 40.9% (P < 0.05) and increased Mi by 33.4% (P < 0.05), driving C redistribution from Ma to Mi. In contrast, with the addition of maize straw, both St + PE and St + PAT treatments reduced organic C mineralization and diminished the increases in SOC content. Specifically, St + PAT decreased the cumulative CO₂ emission by 1.9% (P < 0.05) and lowered the SOC content by 7.1% (P < 0.05) compared to straw addition alone (St). Both St + PE and St + PAT also lowered Ma formation; notably, St + PAT significantly reduced Ma by 33.6% and diminished C flow from Mi and S + C into Ma. In conclusion, biodegradable film residues may impede SOC sequestration and macroaggregate-associated C storage by stimulating the mineralization of native SOC and suppressing organic matter decomposition after crop residue input in soil. These findings provide novel insights into the mechanisms governing SOC turnover and C stabilization via soil aggregation in the context of accumulating plastic wastes. Full article

The degradation of soil structure in paddy fields is critical, and the application of organic amendments is an effective way to enhance soil structure and function. However, the mechanisms by which different organic amendments influence soil aggregate-associated humus carbon and nutrients remain unclear. Considering this, four treatments were employed in a randomized complete block design with three replications: (1) chemical fertilizer (CK); (2) chemical fertilizer plus organic amendment (MC); (3) chemical fertilizer plus organic amendment containing Bacillus subtilis (FT); and (4) Chemical fertilizer plus organic amendment containing polyacrylamide (PM). The results showed that all soil improvement measures significantly increased the proportion of macroaggregates (>2 mm and 2–0.25 mm), primarily the 2–0.25 mm fraction (34.53–48.46%), and the mean weight diameter (MWD), compared to CK. Soil organic carbon (SOC), humic acid carbon (HAC), fulvic acid carbon (FAC), humin carbon (HUC), total nitrogen (TN), and total phosphorus (TP) were predominantly concentrated within the macroaggregates. Relative to CK, the PM increased the HUC content in large aggregates (>2 mm) and significantly enhanced HAC by 19.53% within the same fraction, while the FT significantly boosted FAC by 31.78% in the >2 mm fraction. Furthermore, MC, FT, and PM treatments significantly enhanced SOC, TN, and TP contents within large macroaggregates compared to CK, with PM generally showing the highest SOC and TN levels, and FT being the highest in terms of TP in large aggregates (though differences among treatments were non-significant). Correlation analysis revealed that only in large aggregates did SOC show significant positive correlations with humus carbon fractions (except HAC), as well as with TN and TP. The amendments, particularly PM, effectively enhanced nutrient and humus carbon accumulation within large aggregates and improved aggregate stability. Notably, PM strengthened the direct pathways for the formation of SOC and humus carbon. In summary, the combined application of chemical fertilizer and organic amendments, containing polyacrylamide positively influenced aggregate stability and nutrient accumulation in paddy soil. Full article

Soil organic carbon (OC) storage in crop rotation systems benefits soil productivity and global climate change. However, the regulatory mechanisms and pathways by which soil OC storage is affected under medium-term crop rotation at the aggregate level are not fully understood. Herein, fifteen soil samples from five cropping systems (abandoned farmland, continuous cropping of tobacco, tobacco–pea rotation, continuous cropping of dasheen, and dasheen–ryegrass rotation for over 10 years) were collected from soil at 0 to 20 cm depths in Miyi County, Sichuan Province, China. The soil aggregates and aggregate-associated OC, enzyme activities, and microbial biomass were evaluated. The effects of medium-term crop rotation on soil aggregate-associated OC content and biochemical properties varied between crop types. Specifically, tobacco–pea rotation significantly decreased the proportion of macro-aggregates (0.25–2 mm); the contents of OC, Ca-OC, aliphatic C, alcohols, and phenols; enzyme activities; and fungal biomass in the aggregate fractions, compared with those associated with the continuous cropping of tobacco. In contrast, dasheen–ryegrass rotation significantly increased the recalcitrant OC content, β-glucosidase and polyphenol oxidase activities, microbial biomass in mega-aggregates (>2 mm) and macro-aggregates, and the recalcitrant OC content and enzyme activity in microaggregates (0.053–0.25 mm) and slit clay (<0.053 mm), relative to those in the continuous cropping of dasheen. Moreover, for the continuous-cropping soils, the OC contents were positively correlated with POD activity but negatively correlated with other enzymes. For the rotational soils, the OC content was positively related to the Fe/Al-OC, aromatic-C, aliphatic-C, and microbial biomass contents but negatively related to the carbohydrate content. The increased OC content was driven by the microbial biomass in the aggregate fractions, and medium-term crop rotation changed the negative effect of microorganisms on the OC content into a positive effect at the aggregate level. Overall, medium-term crop rotation enhances OC storage by improving soil structural stability and microbial community dynamics. Full article

Increasing soil organic carbon (SOC) storage is essential for improving soil fertility and mitigating climate change. The priming effect, which is regulated by physical, chemical and microbial interactions, plays a pivotal role in SOC turnover. However, the fate of both native and newly added carbon under different tillage regimes remains unclear. To address this gap, a ¹³C-glucose labelling incubation experiment was conducted to assess SOC mineralization and priming effects under long-term tillage practices, including subsoiling with straw mulching (ST), no tillage with straw mulching (NT), and conventional tillage with straw removal (CT). The results demonstrated that conservation tillage (NT and ST) significantly reduced total SOC mineralization and glucose-derived CO₂ release compared to CT. Notably, the priming effect under CT was 19.5% and 24.7% higher than under NT and ST, respectively. In the early incubation stage, positive priming was primarily driven by microbial co-metabolism, while during days 1–31, microbial stoichiometric decomposition dominated the process. In addition, NT and ST treatments significantly increased the proportion of >250 μm aggregates and their associated carbon and nitrogen contents, thereby enhancing aggregate stability and physical protection of SOC. The priming effect observed under conservation tillage was strongly negatively related to aggregate stability and aggregate associated carbon content, whereas it was positively related to the β-glucosidase/Peroxidase ratio (BG/PER) and the subtraction value between carbon/nitrogen (R_C:N) and the carbon–nitrogen imbalance of the available resources (TER_C:N). Overall, our findings highlight that conservation tillage enhances SOC stability not only by improving soil physical structure but also by alleviating microbial stoichiometric constraints, offering a synergistic pathway for carbon retention and climate-resilient soil management. Full article

Reasonable nitrogen fertilizer management and cultivation methods can enhance the nitrogen supply and carbon sequestration capabilities of soil, which is beneficial for meeting the growth requirements of crops and alleviating environmental issues. However, the existing research on optimizing nitrogen use efficiency and soil carbon sequestration in organic systems remains limited. Therefore, a field trial was conducted to elucidate the impacts of different cultivation patterns and nitrogen application rates on soil carbon and nitrogen pools, especially on how these factors affect the components of soil organic carbon. The treatments included conventional cultivation with low nitrogen treatment (CFN12), conventional cultivation with high nitrogen treatment (CFN18), organic cultivation with low nitrogen treatment (OFN12), and organic cultivation with high nitrogen treatment (OFN18). The results demonstrated that, relative to CFN18, OFN12 significantly increased the accumulation amounts of organic carbon and nitrogen in paddy soil. This was evident under multiple classifications of organic carbon, while it showed no advantage in the accumulation of mineral nitrogen. Notably, the organic cultivation mode increased the activities of enzymes involved in the carbon–nitrogen cycle in the cultivated layer and optimized the structure of humus, which gave the proportion of aggregates with a particle size greater than 0.5 mm more advantages. Correlation analysis demonstrated that the pertinent indices associated with soil carbon and nitrogen pools exhibited a highly significant positive correlation in the topsoil layer, accompanied by pronounced synergistic interactions among them. The PCA comprehensive scoring results indicate that OFN12 has the highest total score, indicating that it is beneficial for the improvement of soil fertility. This study offers practical insights for improving soil health, boosting plant growth, and enhancing climate mitigation through soil carbon storage, contributing to more sustainable agricultural practices. Full article

Soil nitrogen (N) is critical for crop yield. Although previous studies have shown that straw return enhances soil mineral N availability, the response of soil aggregate microbes to straw return and its impact on soil mineral N availability remains unclear. We conducted a 13-year experiment to explore how soil N mineralization potential, fungi, and bacteria within soil aggregates responded to straw return. Our findings indicated that straw return significantly increased mineral N concentrations in soil macroaggregates, with no statistically significant effect observed on microaggregate composition. We observed increased microbial community α-diversity, enhanced co-occurrence network stability, and an increase in functional groups associated with N (nitrate respiration, denitrification, nitrite denitrification) and carbon (saprotrophs, saprotroph–symbiotrophs, patho-saprotrophs) cycling within the aggregates. Additionally, microorganisms in macroaggregates were influenced by total N, while those in microaggregates were affected by soil total organic carbon and C–N ratio. A sensitivity network analysis identified specific microorganisms responding to straw return. Within macroaggregates, microbial community shifts explained 42.88% of mineral N variation, with bacterial and fungal β-diversity contributing 27.82% and 12.58%, respectively. Moreover, straw return upregulated N-cycling genes (N ammonification: sub, ureC, and chiA; nitrification: amoA-AOB; denitrification: nirK, nirS, nosZ, norB, and narG; and N fixation: nifH) in macroaggregates. Partial least squares path modeling revealed that N availability in macroaggregates was mainly driven by ammonification, with bacterial β-diversity explaining 23.22% and fungal β-diversity 15.16% of the variation. Our study reveals that macroaggregates, which play a crucial role in soil N supply, are highly sensitive to tillage practices. This finding provides a practical approach to reducing reliance on synthetic N fertilizers by promoting microbial-mediated N cycling, while sustaining high crop yields in intensive agricultural systems. Full article

Soil salinization is closely related to land degradation and is presumed to exert a significant effect on the preservation of soil organic carbon (SOC). However, the salinization-induced changes in SOC accumulation over the application gradient of amendments remain unclear. To evaluate the potential for salinization elimination and C sequestration, incubation experiments with four straw addition levels and six aluminum sulfate (Al³⁺) gradients were conducted in a soda saline–alkali soil, followed by the analysis of partial least squares path models (PLS-PM). The results showed that combined applications significantly reduced soil salinity and sodicity. The C sequestration performance under coapplications was greater than that under individual applications. The SOC and heavy fraction OC (HFOC) contents under the coapplication of 1.6% Al³⁺ and 10% straw were greater than those under the individual applications of either 1.6% Al³⁺ or 10% straw by 231.08% and 149.86%, and 9.70% and 18.78%, respectively. Coapplications significantly increased macroaggregates and aggregate-associated SOC levels. PLS-PM demonstrated that Na⁺, Ca²⁺ and HCO₃⁻ were important environmental factors associated with C sequestration. Overall, our results suggest that Al³⁺ and straw enhanced C sequestration by regulating salt ions and increasing soil aggregates and that 10% straw combined with 1.6% Al³⁺ had a greater effect on soda saline–alkali soil. Our study is highly important for the utilization of saline–alkali land and C sequestration in western Jilin Province. Full article

Soil organic carbon (SOC) plays a vital role in maintaining soil fertility and ecosystem sustainability, with crop residues serving as a key carbon input. However, how different maize residue components influence SOC stabilization across aggregate sizes and fertility levels remains poorly understood. This study investigated the effects of maize roots, stems, and leaves on SOC dynamics and aggregate-associated carbon under low- and high-fertility Brown Earth soils through a 360-day laboratory incubation. Results revealed that residue incorporation induced an initial increase in SOC, followed by a gradual decline due to microbial mineralization, yet maintained net carbon retention. In low-fertility soil, leaf residues led to the highest SOC content (12.08 g kg⁻¹), whereas root residues were most effective under high-fertility conditions (18.93 g kg⁻¹). Residue addition enhanced macroaggregate (>0.25 mm) formation while reducing microaggregate fractions, with differential patterns of SOC distribution across aggregate sizes. SOC initially accumulated in 0.25–2 mm aggregates but gradually shifted to >2 mm and <0.053 mm fractions over time. Root residues favored stabilization in high-fertility soils via mineral association, while stem and leaf residues promoted aggregate-level carbon protection in low-fertility soils. These findings highlight the interactive roles of residue type and soil fertility in regulating SOC sequestration pathways. Full article

Soil aggregate stability and carbon–nitrogen content are critical indicators for assessing the vegetation restoration effects. Salix cupularis plays a vital role in rehabilitating desertified alpine meadows on the eastern Qinghai–Tibet Plateau. However, research remains limited about how afforestation influences the soil aggregate stability and associated carbon and nitrogen dynamics. In this study, sandy land (0 years) served as the control, and the spatial time replacement method was used to examine changes in the soil water-stable aggregate composition, stability, organic carbon (OC) and total nitrogen (TN) contents, and density at a 0–60 cm depth after 5 and 10 years of afforestation restoration (Salix cupularis). Ecological restoration significantly enhanced the proportion of macroaggregates (>0.25 mm) in the topsoil (0–20 cm), and improved aggregate stability. After 10 years of restoration, macroaggregates increased by 45.04% and 51.32%, respectively. The average weight diameter and geometric mean diameter of the aggregates increased by 51.32% and 59.53%, respectively. Following restoration, there was a gradual increase in the OC and TN contents in the soil, with the highest increase observed in the 0–10 cm layer (266.67% and 391.67%). The OC and TN of the aggregates also displayed a similar trend. Correlation analysis results indicated a significant positive relationship between the soil OC and TN contents and density, OC content in aggregates of various diameters, and the stability of these aggregates. The Pearson’s correlation coefficient for OC in aggregates > 1 mm was the highest. Compared with 5 years, 10 years of recovery were more conducive to the formation of macroaggregates, enhancement in aggregate stability, and the accumulation of OC and TN. Therefore, vegetation restoration on the Zoige Plateau can significantly enhance the soil water-stable aggregate composition and stability and can also increase the soil and OC and TN contents and density, thereby enhancing the soil ecological quality. This study provides fundamental data and theoretical support for rehabilitating desertified grasslands on the eastern Qinghai–Tibet Plateau. Full article

The sustainability of agroecosystems depends on the maintenance of soil organic matter (SOM) and soil aggregate stability, which are key components of soil health. The long-term effects of conservation management systems, such as the adoption of no till (NT) associated with cover crops, on soil quality are still unclear. The aim of this study was to evaluate the long-term effects of NT systems combined with cropping systems ecologically intensified by the presence of legumes on the carbon management index (CMI) and the state of soil aggregation, as sensitive tools to assess the quality of soil management systems. NT combined with autumn and spring legume cover crops increased the proportion of soil aggregates > 2 mm, resulting in higher weighted average diameters and higher aggregation index values in comparison to conventional tillage (CT), which favored the soil microaggregate proportion. The soil C content was favored by NT only in the surface layer, while the use of legume cover crops increased the C stock by 23% compared to the system without legume cover crops in the 0–20 cm layer. In the topsoil under NT, the stocks of particulate organic matter (POM) and mineral-associated organic matter (MAOM) were 100% and 37% greater than in CT, respectively. A greater CMI was observed under NT compared to CT in systems with no legumes (18%), with one legume (52%), and with two legumes (72%) as cover crops. These results highlight no till’s positive impact on soil health, further enhanced by the legume-based ecological intensification of cropping systems. Full article

Intensive agricultural management affects the physical, chemical, and biological properties of soil, potentially contributing to a decrease in soil carbon storage. In this study, the effects of soil management intensity on soil organic carbon (SOC) content and its labile fractions, i.e., water-soluble organic carbon (OC-sol) and permanganate oxidizable carbon (POXC), were evaluated in a volcanic-ash-derived soil (Andisol) with a very high soil organic matter (SOM) content (>20%). These indicators were associated with water-stable aggregates (WSAs) and biological indicators, namely, earthworm density, cellulase activity, and autoclaved-citrate-extractable (ACE) proteins, related to the decomposition of SOM and its physical protection. The conditions evaluated were secondary native forest (SF), naturalized grassland (NG), no-till (NT), and conventional tillage (CT), considering the last item to be representative of a higher agriculture management intensity. Soil samples were collected by horizon. The SF and NG soil showed higher contents of SOC, OC-sol, and POXC. When comparing the evaluated annual cropping systems, NT showed higher values than CT (p < 0.05) in the first horizon (Hz1), while similar values were found at deeper horizons. The highest cellulase activity, ACE protein levels, and earthworm densities were found in NG and SF. NT also showed significantly higher levels of the aforementioned factors than CT (p < 0.05). A positive and significant relationship was found between the SOC content and WSA (R² = 0.76; p < 0.05) in the whole profile and between POXC and WSA for Hz1 (R² = 0.67; p < 0.05). Soil C storage was affected by the intensity of agricultural management, mainly because of the effect of tillage on structural stability, considering that biological activity synthesizes compounds such as enzymes and proteins that react and adhere to the mineral fraction affecting aggregate stability. The C content stored in the soil is consequently a key indicator with which to regulate SOM and protect SOC. Full article