Effects of Plastic Film Mulching on Nitrous Oxide Emissions from a Vegetable Field

Abstract

Considering the common cropping system (chili-radish rotation) in Southwest China, the objective of this study is to explore the effect of plastic film mulching on N2O flux, N2O concentrations in the soil profile, soil temperature, and humidity from a vegetable field. The method of the static opaque chamber was used and the experimental period lasted for one year. The results showed that the average flux of N2O was 1000.0 μg·(m2·h)-1 in the conventional treatment and 400.6 μg·(m2·h)-1 in the film mulching treatment during the chili growing period. The N2O flux of the film mulching treatment was significantly lower than that of conventional treatment (P<0.05). However, in the radish growing season, the N2O flux of the film mulching treatment was higher than that of conventional treatment, but the difference between the two treatments was not significant (P>0.05). N2O concentrations in the soil profile of the two treatments both increased with the increase in soil depth. The N2O concentrations showed significant correlations among the different soil profiles of each treatment; meanwhile, there was also a significant correlation between soil N2O concentrations at the same soil depth in different treatments. There was a significant positive correlation between the N2O concentration in different profiles and N2O fluxes in surface soils in the conventional treatment, but the N2O flux under the plastic mulching film treatment was only positively correlated with the N2O concentrations of 30 cm deep soil. The soil moisture and temperature observations showed that the effect of plastic film mulching on soil temperature was more significant in summer and the soil moisture was more prominent in autumn and winter. However, the results of the correlation analysis and principal component analysis showed that N2O emissions were mainly determined by the distribution of nitrogen in the soil and were affected by the change in soil total nitrogen content in the conventional treatment but N2O emissions were more sensitive to the variation in soil inorganic nitrogen in the film mulching treatment.