Effects of organic matter incorporation on nitrous oxide emissions from rice-wheat rotation ecosystems in China

Abstract

Organic matter addition is thought to be an important regulator of nitrous oxide (N 2 O) emissions from croplands. Contradictory effects, however, were reported in previous studies. To investigate the effects of crop residue management on N 2 O emissions from rice-wheat rotation ecosystems, we conducted field experiments at three sites (Suzhou, Wuxi and Jiangdu) in the Yangtze River Delta, using static chamber and gas chromatography methods. Our data show that N 2 O emissions throughout the rice season from plots treated with wheat straw application at a high rate (WS) prior to rice transplanting (1.1-2.0 kg N ha −1 ) were significantly lower (P<0.05) than those from the control plots without organic matter addition or added with wheat straw at a moderate rate (1.6-2.9 kg N ha −1 ). Furthermore, the WS treatments had a residual inhibitory effect on N 2 O emissions in the following non-rice season, which consistently resulted in significantly lower emissions (P<0.05) compared to the control treatments (2.2-3.1 vs. 3.9-5.6 kg N ha −1 ). In comparison to the control treatments, the WS treatments reduced both the seasonal and annual direct emission factors of the applied nitrogen (EF d ) by 50-68% (mean: 57%). The addition of compost (aerobically composted rice or wheat straw harvested in the last rotation) reduced the seasonal and annual EF d s by 29-32%. Over the entire rice-wheat rotation cycle, annual N 2 O emissions from the fertilized fields at the three sites ranged from 3.3±0.3 to 16.8±0.6 kg N ha −1 , with a coefficient of variation (CV) of 61%. Similarly, the EF d s during the rice-wheat rotation cycle ranged from 0.4% to 2.5%, with a CV of 67%. These high spatial variations might have been related to: variations in soil properties, such as texture and soil organic carbon; management practices, such as straw treatments (i.e., compost versus fresh straw) and weather conditions, such as precipitation and rainfall distribution. Our results indicate that the incorporation of fresh Plant Soil (2010) 327:315-330 wheat straw at a high rate during the rice season is an effective management practice for the mitigation of N 2 O emissions in rice-wheat rotation systems. Whether this practice is also effective in reducing the overall global warming potential of net N 2 O, CH 4 and CO 2 emissions needs to be seen through further studies.

Changes in soil quality following poplar short-rotation forestry under different cutting cycles

“…The increase of SOC under SRF may result in positive changes of soil structure, water retention, nutrient availability, biological diversity and C sequestration, since it is well known to affect directly or indirectly the overall soil quality parameters (Schjønning et al, 2004). Here, SOC showed a pattern similar to the soil N concentration as reported in other studies (Franzluebbers and Stuedemann, 2009;Yao et al, 2010). Such similarity between SOC and N patterns was previously explained by carbon inputs from plant production and outputs through microbial decomposition (Gill et al, 1999).…”

Effects of Irrigation Regime and Nitrogen Fertilizer Management on CH4, N2O and CO2 Emissions from Saline–Alkaline Paddy Fields in Northeast China

“…In the current research, the reaction substrate concentration was increased through urea application, promoting the emission of N 2 O [55,56]. As more N fertilizer was used, more cumulative N 2 O emissions were detected at each rice-growing stage.…”

Diurnal pattern of nitrous oxide emissions from soils under different vertical moisture distribution conditions

“…Fisher's least significant difference (LSD) tests were performed to detect the difference in N2O fluxes between SW and SUW treatments at certain observation times. For all the statistical analyses, p > = 0.10, 0.05 < p < 0.10, and p < 0.05 levels were considered to be nonsignificant, slightly significant, and significant, respectively (Yao et al, 2010).…”