The effects of the integrated adoption of several recommended sustainable agricultural practices (SAP) on maize grain yield and the quantitative and qualitative characteristics of soil organic carbon (SOC) were studied in 2 years, spring maize monoculture field plot experiment. The recommended agricultural practices included conservation tillage, combined application of organic manure and chemical fertilizers, and crop residue return. Compared with the conventional agricultural practices (CAP), the maize grain yield increased in the SAP treatment, and the difference between the two treatments was statistically significant (P<0.05) in the second season of the experiment (2010). The content of soil total organic carbon (TOC) and organic C fractions (that is, water soluble organic C, easily oxidizable organic C, particulate organic C, humus C and black C) were higher in the SAP than in the CAP treatment, although the differences between the two treatments were not significant. The relative intensities of O-alkyl C and carbonyl C and the aliphatic C / aromatic C ratio were higher, while the relative intensities of alkyl C and aromatic C and the ratios of alkyl C / O-alkyl C and hydrophobic C / hydrophilic C were lower in solid-state 13C CPMAS NMR spectra of HF-treated soils in the SAP than in the CAP treatment. The recommended sustainable agricultural practices were beneficial for the increase of maize grain yield and the improvement of the quantity and quality of SOC during a short-term period.
Key words: Soil organic carbon, organic carbon fraction, agricultural practice, spring maize, 13C CPMAS NMR.
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