Seasonal changes in labile organic matter, mineral nitrogen, and N2O emission in a loamy sand Orthic Luvisol cultivated under three management practices
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Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, P.O. Box 201, 20-290 Lublin 27, Poland
Agrophysical Research Institute, 14 Grazhdansky Prospekt, St. Petersburg, 195220, Russia
Int. Agrophys. 2007, 21(2): 127–132
Valid evaluation of soil quality requires better understanding of short- and long-term responses of key biochemical and microbiological soil properties to seasonal changes and types of management practice. In our study we evaluated the effects of growing of winter wheat on seasonal changes in the state of a loamy sand Orthic Luvisol cultivated under the conventional, monoculture and organic management practices. The extent of seasonal changes in soil organic matter (SOM) was more pronounced in terms of its labile forms - particulate organic matter (POM) and microbial biomass carbon (MBC) than of its total content. The management practices contributed to the formation of an equilibrium state of SOM, mainly towards the end of the growing season. Seasonal variations in the total amount of NO3--N showed weak correlations to those of N2O emission (r=0.31-0.49, p<0.50) from the soil for all the management practices. However, we observed stronger correlations between the seasonal changes in N2O emission and MBC content, whereas the organic management practice, compared to the monoculture and conventional practice, had the strongest influence on these relationships (r=0.89, p<0.01), probably as a result of higher content of microbial biomass N. Moreover, differences in N2O emission induced by the management practices alone were also highly correlated to changes in the MBC content in April and July (r=0.71, p<0.05).