Search Results (684)

To evaluate the optimal substitution ratio of organic fertilizer for chemical nitrogen fertilizer and its underlying mechanisms, a pot experiment was conducted in the rhizosphere soil of oat (Avena sativa) on the Qinghai–Tibet Plateau. Five treatments were established: CK (control), T1 (chemical fertilizer alone), T2 (100% organic fertilizer substitution for chemical nitrogen fertilizer), T3 (30% organic fertilizer substitution for chemical nitrogen fertilizer), and T4 (60% organic fertilizer substitution for chemical nitrogen fertilizer). We analyzed soil carbon fractions, microbial community structure, carbon-cycling enzyme activities, and yield responses and applied partial least squares–structural equation modeling (PLS-SEM) to identify key regulatory pathways. The results showed that 30% organic substitution (T3) was associated with optimized soil carbon pools, improved microbial community composition, and enhanced carbon-cycling enzyme activities, while reducing the abundance of potentially harmful fungi. Structural equation modeling indicated that β-glucosidase activity and the relative abundance of Proteobacteria were the primary drivers of yield, together explaining 76% of its variation. The ecosystem multifunctionality index (EMF) was significantly and positively correlated with yield. In summary, under the conditions of this experiment, 30% organic fertilizer substitution achieved a favorable balance between soil ecological functions and crop yield, providing a valuable reference for sustainable nutrient management in oat production in high-altitude cold regions. Full article

Arid and semi-arid soils represent extreme habitats where microbial life is constrained by high temperature, low water availability, salinity, and nutrient limitation, yet these ecosystems harbor unique bacterial communities that sustain key ecological processes. To explore the diversity and functional potential of prokaryotic assemblages in Algerian drylands, we compared soils from three contrasting sites: The Oasis of Djanet (RM1), the hyper-arid Tassili of Djanet desert (RM2), and the semi-arid El Ouricia forest in Sétif (RM3). Physicochemical analyses revealed strong environmental gradients: RM2 exhibited the highest pH (8.66), electrical conductivity (11.7 dS/m), and sand fraction (56%), whereas RM3 displayed the greatest moisture (10.9%), organic matter (7.6%), and calcium carbonate (20.7%) content, with RM1 generally showing intermediate levels. High-throughput 16S rRNA gene sequencing generated >60,000 effective reads per sample with sufficient coverage (>0.99). Alpha diversity indices indicated the highest bacterial richness and diversity in RM2 (Chao1 = 3144, Shannon = 10.0), while RM3 showed lower evenness and the dominance of a few taxa. Across sites, 66 phyla and 551 genera were detected, dominated by Actinobacteriota (38–45%) and Chloroflexi (13–44%), with Proteobacteria declining from RM1 (17.5%) to RM3 (3.3%). Venn analysis revealed limited overlap, with only 58 operational taxonomic units shared among all sites, suggesting highly habitat-specific communities. Predictive functional profiling (PICRUSt2, Tax4Fun, FAPROTAX) indicated metabolism as the dominant functional category (≈50% of KEGG Level-1), with carbohydrate and amino acid metabolism forming the metabolic backbone. Notably, transport functions (ABC transporters), lipid metabolism, and amino acid degradation pathways were enriched in RM2–RM3, consistent with adaptation to osmotic stress, nutrient limitation, and energy conservation under aridity. Collectively, these findings demonstrate that Algerian arid and semi-arid soils host diverse, site-specific bacterial communities whose functional repertoires are strongly shaped by soil chemistry and climate, highlighting their ecological and biotechnological potential. Full article

This study evaluated the effects of applying fecal sludge-based co-compost (CC) integrated with chemical fertilizers on soil nutrient status, organic carbon (OC) storage, and economic returns in paddy soils. Ten integrated nutrient management (INM) treatments were tested, i.e., BRRI recommended dose of fertilizer (RDF), CC 5.0 t ha⁻¹, RDF + CC 2.0 t ha⁻¹, RDF + CC 1.5 t ha⁻¹, RDF + CC 1.0 t ha⁻¹, RDF + CC 0.5 t ha⁻¹, 75% RDF + CC 2.0 t ha⁻¹, 75% RDF + CC 1.5 t ha⁻¹, 75% RDF + CC 1.0 t ha⁻¹, and 75% RDF + CC 0.5 t ha⁻¹. Two rice varieties were cultivated over two consecutive seasons—winter rice (boro) and monsoon rice (aman)—in the experimental field. Soil samples (0–15 cm) were collected before and after the seasons and fractionated into labile particulate organic matter (>53 µm) and stable mineral-associated organic matter (<53 µm). Bulk soils and CC were analyzed for OC, nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and heavy metals, while the fractions were analyzed for OC and N. Across both seasons, 75% RDF combined with 2.0 t ha⁻¹ or 1.5 t ha⁻¹ of CC consistently showed the highest OC, total N, and soil C stock, with moderate P, K, and S levels. Sole RDF produced the lowest OC and N. Among fractions, stable OC was the highest in the 75% RDF + 2.0 t ha⁻¹ CC treatment, statistically similar to 75% RDF + 1.5 t ha⁻¹ CC, and the lowest under RDF alone. Economically, sole RDF yielded the highest profit, while full RDF + CC achieved competitive returns. Reduced RDF + CC treatments (75% RDF + 1.5 or 2.0 t ha⁻¹ CC) offered slightly lower returns but improved soil sustainability indicators. Overall, applying 75% RDF + 1.5 t ha⁻¹ CC provided the most cost-effective balance of nutrient enrichment, soil C stock, and profitability. This CC-based INM approach reduces chemical fertilizer dependency, enhances soil health, and promotes sustainable waste management, supporting environmentally resilient rice production. Full article

To reveal the driving mechanisms of oxidative carbon components in urban forest soils in highly urbanized areas, this study collected 126 soil samples from the 0–30 cm layer of typical urban forests in Shenzhen, China. Soil organic carbon (SOC) was classified into four fractions based on oxidation stability: highly oxidizable organic carbon (VAC), moderately oxidizable organic carbon (AC), poorly oxidizable organic carbon (PAC), and inert oxidizable organic carbon (IAC). Integrating multi-source data on climate, topography, vegetation, soil, and urbanization, we adopted a synergistic multi-model approach to screen key drivers, identify nonlinear thresholds, and quantify pathway contributions, thereby systematically exploring the dominant characteristics and driving mechanisms of soil carbon components under urbanization. The results showed that (1) urban forest soils in Shenzhen were dominated by reactive carbon, with VAC accounting for the highest proportion of SOC, and the proportion of reactive organic carbon was significantly higher than that of recalcitrant organic carbon; (2) SOC and total nitrogen (TN) were the core driving factors of carbon fractions, and the number of regulatory factors increased with the enhancement of carbon fraction oxidation stability; (3) soil factors directly affected carbon fractions, while urbanization indirectly acted on inert carbon by altering vegetation characteristics. Based on the research results, urban soil and forest managers can implement zonal management for carbon fractions with different oxidation stabilities, which is expected to effectively enhance the carbon sink capacity and stability of urban forest soil carbon pools, providing practical support for ecological sustainable development. Full article

The effects of soil organic carbon fractions and tea enzyme activities on the antioxidant quality of tea leaves were determined. The experiment set up single biogas slurry application and co-application of biochar and biogas slurry (50%, 100%, 150%, 200% slurry substitution for nitrogen fertilizer, 350 °C pig manure biochar at 1% and 2% application rates and 500 °C rice straw biochar at 1% and 2% application rates). The results showed that, compared with the control (CK), the combined application of biochar and biogas slurry had a synergistic effect, with the most significant effect observed when 350 °C pig manure was combined with biogas slurry at a ratio of 2%. This treatment resulted in peak levels of readily oxidizable organic carbon (ROC) and dissolved organic carbon (DOC) in the soil, significantly increasing by 8.43 g/kg and 0.23 mg/kg, respectively, compared to the CK, and significantly enhancing the activity of key carbon cycle enzymes such as β-glucosidase (S-β-GC). These improvements in soil biochemical properties directly translated into improved tea quality: the tea leaves treated under this treatment had the highest content of tea polyphenols and amino acids, and the ABTS and DPPH free radical scavenging rates increased by 3.25% and 5.97%, respectively, compared to the CK, while the malondialdehyde (MDA) content was the lowest. Mantel test and multivariate regression analysis further confirmed that particulate organic carbon (POC) and dissolved organic carbon (DOC) were the main carbon components driving the accumulation of tea polyphenols, while catalase (CAT) and other enzymes were key co-regulatory enzymes. The optimal application ratio of biochar and biogas slurry not only improved tea leaf quality but also resulted in increased SOC content within the study period, providing preliminary evidence for promoting SOC accumulation in the short term. Full article

Soils represent the largest reservoir of organic carbon (OC) in terrestrial ecosystems, storing approximately 1500 Gt C. Forest and grassland ecosystems contribute 39% and 34% to global terrestrial carbon stocks, with soils holding about 44% and 89% of forest and grassland carbon, respectively. Land-use changes, such as the conversions between forest and grassland ecosystems, can strongly influence soil carbon accumulation, though the direction and magnitude remain uncertain. Comparative data from paired-plot studies of forest and grassland soils are still limited. In this study, we conducted pairwise comparisons of total OC and total nitrogen (TN) stocks in mature forest and climax grassland soils along a climatic and pedogenic gradient encompassing Retisols, Luvisols, and Chernozems. Relationships between OC and TN stocks (0–10 cm) and soil physicochemical properties—OC and TN contents, bulk density, pH, clay content, and humus fractional composition, as well as biological indicators—the abundance of culturable fungi and bacteria, microbial biomass carbon, potential metabolic activity, and activities of laccase and dehydrogenase, were evaluated. Strong positive correlations were found between OC and TN stocks and OC and TN contents (r = 0.62–0.99), pH (r = 0.79–0.81), clay content (r = 0.70–0.87), and the fraction of humic acids bound with calcium (r = 0.73). OC stocks also correlated strongly with dehydrogenase activity (r = 0.85–0.95). At 0–10 cm depth, OC stocks were higher in grassland soils than in forest soils by factors of 1.6–1.7 in Retisols and 1.4–1.5 in Chernozems. Similarly, TN stocks were 1.6–2.0 times greater in grasslands across all soil types. Community-level physiological profiling revealed higher potential metabolic activity in forest soils compared with grasslands, with the strongest differences in Retisols and Luvisols, while contrasts were attenuated in Chernozems. Overall, the results highlight the fundamental role of organo-mineral interactions and calcium binding in OC stabilization, as well as the likely involvement of dehydrogenase activity in the biogenic formation of calcium carbonates that contribute to this process. Full article

Biochar and beneficial microorganisms (BM) is considered promising soil amendment for saline-alkali amelioration and soil carbon storage.However, the effects of biochar combined with BM addition soil organic carbon (SOC) accumulation and microbial characteristics are less known in coastal saline-alkali soil. Herein, we investigated the SOC content and fractions, soil carbon enzyme activities, and microbial community composition in coastal saline-alkali soil, following three levels of biochar and BM addition. Compared to the control treatment, biochar and BM application effectively reduced soil salinity by 37.58–66.53% and increased soil NH₄⁺ by 9.49–121.16% and NO₃⁻ by 43.56–254.28%, respectively. Biochar integrated with BM addition significantly increased the content of SOC, soil mineral-associated organic carbon (MAOC), soil particulate organic carbon (POC), and carbon pool management index (CPMI) by 37.76–108.02%, 15.43–140.44%, 13.73–64.55%, and 81.11–154.61%, respectively, compared with CK treatment. Additionally, biochar and BM significantly enhanced the activities of soil carbon cycle enzymes, including α-1,4-glucosidase (14.54–124.45%), β-1,4-glucosidase (12.71–133.98%), and cellulose hydrolase (6.07–19.17%). Biochar and BM addition also improved the bacterial diversity and altered the microbial composition at the phylum level. The co-addition of biochar and BM improved SOC by decreasing soil salinity and, enhancing soil nutrient availability, soil carbon cycle enzymes, and microbial activity. Furthermore, the combination of 4% biochar and BM exhibited the highest MAOC/POC ratio, demonstrating the most significant impacts on enhancing SOC stability in coastal saline-alkali soil. This study highlighted that the combined use of biochar and BM could serve as a promising approach to fortify soil carbon pool content and stability in saline-alkali land. Full article

Soil organic carbon (SOC) sequestration plays a vital role in sustaining soil productivity and mitigating climate change. Although biochar and charcoal-based fertilizers are known to enhance SOC sequestration, current understanding is predominantly derived from studies applying high doses. With the goal of elucidating the mechanisms through which long-term, low-dose biochar application influences SOC composition and stability, this study evaluated the long-term impacts of biochar and carbon-based fertilizers on SOC content, chemical structure, and microbial residual carbon assessed via amino sugar biomarkers. The following features are demonstrated by this study: (1) The application of biochar and carbon-based fertilizers significantly increased the contents of active organic carbon components (DOC, MBC, POC) and stable carbon components (MAOC, humic carbon) in the plow layer soil. Notably, the C50 treatment reduced the easily oxidizable organic carbon (EOC) content by 19.25% compared to the control. (2) Long-term application increased the relative abundance of aromatic functional groups in SOC, enhanced SOC decomposition resistance (as reflected by the F-index). Compared with NPK, the BBF treatment increased the F-index by 21.28% and 25.00% in the 0–20 cm and 20–40 cm soil layers. (3) The BBF treatment significantly increased both soil amino sugar content and the contribution of microbial residual carbon to SOC. Specifically, it elevated the levels of GluN, GalN, and MurN by 9.24% to 33.31% across soil layers. Fungal residual carbon constituted the dominant fraction across all treatments. In summary, the content and stability of SOC are enhanced by biochar and biochar-based fertilizers through synergistic mechanisms that involve altering its chemical composition and stimulating the accumulation of fungal residual carbon. Full article

Using cover crops (CCs) following annual crops, together with sustainable nitrogen (N) management, significantly enhances soil carbon (C) storage. However, carbon accumulation in tropical soils is strongly influenced by the respective crop sequences. This study evaluated soil C stocks and fractions in a system incorporating maize–soybean rotation and successive CCs. A randomized block design with split plots was implemented, where main plots consisted of different CCs and the subplots of treatments with and without N fertilization of maize. Chemical fractions of soil organic matter (SOM) were analyzed at depths from 0 to 40 cm, and C stocks down to 100 cm. The SOM fractions responded to N topdressing of maize, varying with soil depth. Soil C stocks during the maize phase were significantly higher than during soybean cultivation (p < 0.05), likely reflecting greater residue inputs from species with elevated C:N ratios. Legume crops following maize intensified C accumulation, emphasizing the importance of N inputs for soil C dynamics. Soil C losses were lowest in the treatments with Raphanus sativus without and Crotalaria juncea with N fertilization. These findings highlight the relevance of combining CCs and N management to optimize C sequestration in tropical agroecosystems. Full article

Post-industrial heaps are a major environmental problem. They require remediation and reclamation, in which natural succession plays a key role in ecosystem development. This study aimed to assess the effect of heaps formed from materials of different origins on the nutrient content of silver birch (Betula pendula Roth), a pioneer species in this process. We analyzed nutrient contents in biomass fractions (fine and coarse roots, stemwood, bark, coarse and fine branches, leaves) and in soils sampled from 0 to 10, 10 to 20, 20 to 40, and 40 to 80 cm. Basic soil properties and the contents of N, P, K, Ca, Mg, S, Fe, Mn, Cu, and Zn in both soil and biomass were determined. The soils were poor in total organic carbon and differed in pH, texture, and nutrient status. Leaves and roots contained the highest nutrient contents, whereas stemwood contained the lowest. Statistical analyses revealed significant differences in all studied elements between heaps. Among macronutrients, N, P, and Mg were most abundant, followed by K, Ca, and S. Among micronutrients, Mn dominated, followed by Fe, Zn, and Cu. Findings underscore that silver birch growing on contaminated post-industrial heaps cannot be considered a hyperaccumulator of trace elements. Full article

Co-incorporating rice straw and Chinese milk vetch (CMV) residues can enhance soil organic carbon (SOC) sequestration and productivity. However, limited information exists regarding its effects on SOC and nitrogen (N) pools as well as the sustainability of rice production in the middle and lower reaches of the Yangtze River Basin. A 3-year field experiment was conducted to assess the effects of co-incorporating rice and CMV residues into paddy soils with chemical-N reduction on SOC and total N (TN) sequestration, SOC and N fractions, grain yields and the sustainable yield index (SYI) in Ma’anshan City, Anhui Province. The treatments included winter fallow–rice rotation without or with both rice straw incorporation and fertilization, as the control (CK and WF-IF, respectively), and rice-CMV rotation with the co-incorporation of rice and CMV residues under 100%, 80%, and 70% recommended N fertilization (CMV-IF, CMV-MIF and CMV-LIF, respectively). Compared with the CK, the CMV-IF significantly increased the rice grain yield and the SYI by 82.1% and 90.4%, respectively. The SOC and TN stocks under CMV-IF were significantly enhanced by 6.3% and 26.4%, respectively, relative to the CK. The CMV-IF exhibited the highest soil active organic C (AOC) and active total N (ATN) contents, followed by CMV-MIF, CMV-LIF, WF-IF, and CK. Microbial biomass C and microbial biomass N were the primary components of soil AOC and ATN, respectively, and linked more explicitly to the SYI than other soil C and N parameters. Therefore, the co-incorporation of rice and CMV residues, coupled with 70~80% recommended N fertilization, might represent an environmentally friendly field management practice for rice production in the middle and lower reaches of the Yangtze River Basin. Full article

The interaction between organic and inorganic nutrients, bacterial communities, and soil fertility has been well documented over time. Conventional agricultural systems heavily utilize both inorganic and organic fertilizers, each exerting distinct effects on soil microbial dynamics and plant growth. The objective of our experiments was to identify the most effective fertilization strategy for improving the biological quality of a microbiologically impoverished and low-productivity soil. To this end, four fertilization strategies were evaluated: (i) organic fertilizers characterized by a high content of organic carbon (Fertil 4-5-7—variant 1); (ii) organic fertilizers with 12% organic nitrogen from proteins (Bio Ostara N—variant 2) (iii) combined inorganic–organic fertilizers (P35 Bio—variant 3) and (iv) mineral (inorganic) fertilizers (BioAktiv—variant V4). This study aimed to assess the short-term effects of fertilizers with varying chemical compositions on the density of cultivable heterotrophic bacteria and their associated dehydrogenase (DH) activity in a petrocalcic chernozem soil containing pedogenic carbonates. Soil sampling was conducted according to a randomized block design, comprising four replicates per treatment (control plus four fertilizer types). The enumeration of cultivable bacteria was performed using Nutrient Agar and A2R Agar media, whereas dehydrogenase activity (DHA) was quantified based on the reduction of 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) to 1,3,5-triphenyl-tetrazolium formazan (TPF) by bacterial dehydrogenase enzymes. Marked differences were observed in both parameters between the plots amended with inorganic fertilizers and those treated with organic fertilizers, as well as among the organic fertilizer treatments of varying composition. The most pronounced increases in both bacterial density and dehydrogenase activity (DHA) were recorded in the plots receiving the fertilizer with a high organic nitrogen content. In this treatment, the maximum bacterial population density reached 6.25 log₁₀ CFU g⁻¹ dry soil after approximately two months (May), followed by a significant decline starting in July. In contrast, DHA exhibited a more rapid response, reaching its peak in April (42.75 µg TPF g⁻¹ soil), indicating an earlier DHA activation of microbial metabolism. This temporal lag between the two parameters suggests that enzymatic activity responded more swiftly to the nutrient inputs than did microbial biomass proliferation. For the other two organic fertilizer variants, bacterial population dynamics were broadly similar, with peak densities recorded in June, ranging from 5.98 log₁₀ CFU g⁻¹ soil (V3) to 6.03 log₁₀ CFU g⁻¹ soil (V1). A comparable trend was observed in DHA: in V3, maximum DHA was attained in June (30 µg TPF g⁻¹ soil), after which it remained relatively stable, whereas in V1, it peaked in June (24.05 µg TPF g⁻¹ soil) and subsequently declined slightly toward the end of the experimental period. Overall, the temporal dynamics of bacterial density and DHA demonstrated a strong dependence on the quality and biodegradability of the organic matter supplied by each fertilizer. Both parameters were consistently lower under inorganic fertilization compared with organic treatments, suggesting that the observed increases in microbial density and activity were primarily mediated by the enhanced availability of organic substrates. The relationship between the density of culturable heterotrophic bacteria and dehydrogenase (DH) activity was strongly positive (r = 0.79), indicating a close functional linkage between bacterial density and oxidative enzyme activity. This connection suggests that the culturable fraction of the heterotrophic microbial community plays a key role in the early stages of organic matter mineralization derived from the applied fertilizers, particularly in the decomposition of easily degradable substrates. Full article

Soil organic carbon fractions and pool management indices are critical for the ecosystem function of bamboo forests; however, their response to varying degrees of expansion of Chimonobambusa utilis (EDCU) and altitudinal gradients remains poorly understood in high-altitude karst regions. In this study, 225 samples (three replicate soil samples, each with five duplicate samples) were collected from 45 typical soil sites in the Jinfo high-altitude karst mountains, China. This study investigated the effects of three EDCUs (low, moderate, and high expansion) and five altitudinal gradients (1300–1500 m, 1500–1700 m, 1700–900 m, 1900–2100 m, and 2100–2300 m) on root elemental composition, soil properties, soil organic fractions, and pool management indices. The results revealed that root total C, N, R_C:P, and R_N:P decreased with increasing altitude, whereas root total C, N, P, and R_C:N also increased significantly with increasing EDCU. Compared with those at low and moderate EDCU, the POC:SOC (34.12%), HFOC (32.73 g kg⁻¹), and HFOC:SOC (37.07%) ratios were highest at high EDCU along the altitudinal gradient of 1700–1900 m. Meanwhile, the L (2.38), LI (2.01), and CMI (174.55) ratios reached their highest values at moderate expansion degrees of Chimonobambusa utilis within the altitudinal gradient of 1900–2100 m. Moreover, redundancy discriminant analysis (RDA) and structural equation modeling (SEM) revealed that the soil carbon pool management index was significantly positively associated with soil properties through direct pathways and negatively correlated with root elemental composition through indirect pathways. In general, the quality of the carbon pool in Chimonobambusa utilis is optimal within the moderate expansion degrees of Chimonobambusa utilis within the altitudinal gradient of 1900–2100 m. The findings of this study establish a theoretical basis for the expansion of Chimonobambusa utilis in high-altitude karst regions and provide scientific evidence to support the increase in the carbon sequestration capacity of bamboo forest ecosystems in these mountainous areas. Full article

Understanding how straw incorporation affects soil stoichiometry and biochemical processes is essential for improving soil fertility in dryland wheat systems on the Loess Plateau. We quantified effects of four wheat straw return rates [0 (W0), 3500 (W1), 7000 (W2), and 14,000 kg ha⁻¹ (W3)] on C-N-P stoichiometry, microbial biomass, active carbon fractions, and enzyme activities in a randomized block experiment in Dingxi, Gansu. Composite soil samples from 0–10, 10–20, and 20–30 cm were analyzed for soil organic carbon (SOC); total nitrogen (TN); total phosphorus (TP); microbial biomass C, N, and P; dissolved, particulate, and readily oxidizable organic C; and sucrase, urease, alkaline phosphatase, and catalase activities. Increasing straw input significantly increased SOC, TN, and TP across all depths, with W3 increasing them by up to 42, 33, and 24% relative to W0, respectively. Under W3, microbial biomass C and N more than doubled, and labile C fractions and enzyme activities increased by 35–80% compared with W0. Straw return also modified soil and microbial C:N:P stoichiometry, decreasing microbial C:N and C:N:P and increasing N:P, suggesting alleviated N limitation. Overall, moderate-to-high straw incorporation improved soil fertility and functioning, supporting straw return as a sustainable management practice for Loess Plateau drylands. Full article

Exogenous carbon addition is widely regarded as an effective soil management strategy for rapidly increasing soil organic carbon, improving soil structure and function. However, a systematic comparison of the effects of diverse organic amendments on key soil attributes and processes is needed to inform their targeted application. We evaluated the impacts of seven organic amendments (biochar, organic fertilizer, corn straw, soybean straw, rapeseed straw, green manure, and carbon material) on a purple soil (Luvic Xerosols) in a pot experiment. The results showed that organic fertilizer and carbon material performed best in enhancing soil nutrient availability and promoting soil organic carbon content. Straw amendments promoted the formation of macro-aggregates. Green manure and straws enhanced carbon transformation-related β-glucosidase and cellobiohydrolase activities. Random Forest and structural equation modeling indicated that the organic amendments enhanced maize carbon sequestration capacity and biomass by improving aggregate stability and regulating the fungal community and by increasing nutrients and enhancing active carbon fractions. Green manure and organic fertilizer demonstrated the most significant agronomic effects. These findings provide guidelines for targeted organic amendment selection in purple soil regions. Full article