Variation of soil organic matter depends on light-fraction organic matter under long-term monocropping of different crops

• Published in: Plant, soil and environment Vol. 67; no. 10; pp. 588 - 599
• Main Authors: Zhang, Futao, Qiao, Yunfa, Han, Xiaozeng, Zhang, Bin
• Format: Journal Article
• Language: English
• Published: Prague Czech Academy of Agricultural Sciences (CAAS) 01-01-2021; Czech Academy of Agricultural Sciences
• Subjects: Bulk density; carbon turnover; Carbonyl compounds; Carbonyls; chemical stability; Clay minerals; Continuous cropping; Corn; crop species; Crops; farmland; mollisol; Organic matter; Organic soils; Principal components analysis; Soil organic matter; Soils; Soybeans
• ISSN: 1214-1178; 1805-9368
• DOI: 10.17221/350/2021-PSE

Cultivating crops influences soil organic matter (SOM), but the effect of different crops remains unclear, particularly under long-term monocropping. The objective of this study was to identify how different crops influence the content and chemical structures of SOM under long-term monocropping. Here, soils were sampled (0–20 cm) under 27-year soybean and maize monocropping and separated into different physical fractions. The content and chemical structures of SOM in all fractions were determined. SOM contents were higher under soybean than maize in bulk soil and macroaggregates and their light-fractions instead of microaggregates and silt and clay. The difference in SOM chemical structure was observed in aggregates and density fractions rather than bulk soils and supported by the result of principal component analysis. The proportion of O-alkyl C in macro- and microaggregates and all free light fractions and that of aromatic C in mineral-associated fractions were higher, while that of carbonyl C was lower under maize than soybean. These results demonstrated that different crops monocropping influences the content and chemical structures of SOM, and the variations were mainly in the light-fraction SOM and highlight a higher sensitivity of physical fractions than bulk soil to different crops.