Abstract
Field experiments were conducted in rice-wheat rotation under conventional management to determine the effects of straw return ((half straw return, HS) and (total straw return, TS)) on crop yield, N uptake, soil properties and soil NO3−–N leaching. We found that straw return significantly increased crop yield and N uptake. TS significantly increased soil SOM at depths of 20 cm and 30 cm. Straw return had significantly increased soil NO3−–N leaching at a depth of 10 cm, whereas significantly decreased soil NO3−–N leaching at depths of 30 cm and 90 cm in the rice season. In wheat season, HS and TS performed better than conventional fertilization management without straw return in reducing soil NO3−–N leaching at depth of 90 cm. Soil NO3−–N leaching was significantly decreased through enhancing total N uptake, improving soil aggregation and decreasing soil NO3−–N concentration. Our results indicated that total straw return has the potential to increase crop yield, improve soil aggregation and decrease soil NO3−–N concentration, thus increasing total N uptake and reducing soil NO3−–N leaching in the rice-wheat rotation system of Ningxia Yellow river irrigation district. In the future, the long-term observation of crop yield and nitrate nitrogen leaching are necessary to identify the environmentally friendly straw return practices for rice-wheat rotation.
Highlights
Synthetic nitrogen (N) fertilizer has enabled the doubling of world food production in the past four decades[1]
We hypothesized that straw return will increase crop yields and reduce soil NO3−–N leaching in rich-wheat rotation, and this response will promoted with increasing amounts of straw return
Straw return significantly increased the crop yield compared with the CM treatment for the HS and TS treatments (Table 2)
Summary
Synthetic nitrogen (N) fertilizer has enabled the doubling of world food production in the past four decades[1]. Annual N loss in Qingtongxia area of Yellow River was 41.1 thousand tons, which is 1.52 times higher than that from the interzone point source pollution[17] Both total N and ammonium N contents were increasing significantly with the increase of fertilizer application rates, especially since 1990s in Ningxia segment of the Yellow River[18,19]. Return of straw with N fertilizer will has a widespread prospect in agricultural field management to increase productivity and reduce soil NO3−–N leaching in Ningxia area[25,26]. Our objectives were (1) to examine the effects of straw return on rice-wheat rotation system crop yields as well as soil NO3−–N leaching; and (2) to identify the environmental friendly straw return management practices for rice-wheat system in Ningxia region
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