Wei Han

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³ C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (AI); in sandy loam, alkyl C increased, elevating alkyl C to O-alkyl C (A/OA) and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fine POC (fPOC). In loam, the AI and HI of SOC showed significant positive path relationships with EOC, DOC and POC (coarse POC [cPOC] and fPOC), while the accumulation of both cPOC and fPOC contributed to MAOC formation. In sandy loam, HI was mainly positively associated with EOC and cPOC, while MAOC was primarily related to EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

The long‐term benefits of organic amendments on soil health are recognized, yet the mechanistic pathways by which integrated fertilization sustains crop productivity in brown soils remain poorly quantified. We addressed this using a unique 46‐year field experiment with six treatments: an unfertilized control (CK), chemical fertilizer alone (NPK), low‐ and high‐rate organic fertilizer alone (M1, M2), and their combinations with NPK (NPKM1, NPKM2). To capture the integrated soil quality, a soil quality index (SQI) was established based on key physicochemical and microbial properties. We found that combined organic–inorganic fertilization (NPKM) achieved the highest maize yield and SQI. Crucially, structural equation modeling unraveled the causal mechanisms: (1) Available phosphorus (AP) directly enhanced SQI and microbial biomass carbon (MBC), which boosted yield, overriding its concurrent direct negative effect. (2) Reduced soil bulk density suppressed fungal richness, thereby improving SQI and yield. Furthermore, long‐term organic amendments drove a beneficial restructuring of the microbial community, selectively enriching beneficial genera (e.g., Bacillus ) while suppressing pathogenic fungi such as Epicoccum . Our findings establish a systemic perspective that integrated soil health rather than single‐factor optimization governs long‐term productivity, providing a mechanistic basis for sustainable brown soil management.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.

Manure is widely applied in greenhouses to enhance soil organic carbon (SOC) and improve fertility. However, how SOC fractions and their chemical stability change under different soil textures and long-term manure inputs remains unclear. We investigated greenhouse soils with 2–50 years of manure application in loam and sandy loam. SOC, easily oxidizable carbon (EOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) were quantified. The molecular structures of SOC were analyzed via ¹³C NMR spectroscopy. Results showed that SOC in loam stabilized after about 20 years of manure application, whereas sandy loam reached equilibrium within 2 years. In loam, aromatic C and carbonyl C in SOC increased, raising the aromaticity index (ARM); in sandy loam, alkyl C increased, elevating A/OA and the hydrophobicity index (HI). Loam contained higher SOC, EOC, POC, and MAOC contents than sandy loam, with SOC positively correlated with EOC, POC, and MAOC, whereas in sandy loam SOC was positively correlated only with EOC and MAOC, and negatively with fPOC. In loam, ARM and HI promoted SOC accumulation by stimulating EOC and POC, which enhanced MAOC formation. In sandy loam, HI mainly promoted SOC through increasing EOC, which enhanced MAOC formation. In loam, MAOC formation was mainly associated with POC, whereas in sandy loam it was driven by EOC. Overall, in greenhouses, long-term stability of SOC depends on the transformation of labile carbon into stable fractions, with fine-textured soils exhibiting greater sequestration efficiency due to higher structural stability and greater MAOC accumulation.