不同前茬与施氮量对半干旱黄土高原夏玉米产量和土壤有机碳库的影响

Effects of previous crop stubbles and nitrogen applied amount on summer maize yield and soil organic carbon pool at a semiarid loess site of China

研究了不同前茬(冬油菜茬、冬小麦茬)与不同施氮量(N0,0 kg·hm^(-2);N120,120 kg·hm^(-2);N240,240 kg·hm^(-2))对半干旱黄土高原夏玉米产量和土壤有机碳库的影响。结果表明:施氮显著增加了夏玉米产量,与不施氮比较,冬油菜茬和冬小麦茬分别增产9.76%~24.88%和12.56%~22.50%,且冬油菜茬的产量高于冬小麦茬6.40%~11.05%。同一茬口不同处理间夏玉米田土壤总有机碳(TOC)含量为N_(240)>N_(120)>N_0,N_0、N_(120)和N_(240)处理下冬油菜茬土壤TOC含量分别高于冬小麦茬1.07~1.70、1.07~1.93 g·kg^(^(-1))和0.77~1.60 g·kg^(^(-1))。两种前茬下,夏玉米出苗至成熟土壤易氧化有机碳(EOOC)和颗粒有机碳(POC)含量均随着施氮量的增加而增加,冬油菜茬土壤EOOC和POC含量分别高于冬小麦茬0.09~4.91 mg·kg^(^(-1))和0.05~0.27 g·kg^(^(-1))。施氮对土壤EOOC和POC的贡献率分别为0.34%~3.45%和10.14%~51.41%。综上分析,施氮有利于增加半干旱黄土高原夏玉米产量,并能促进土壤有机碳库的积累。在本试验区同等肥力土壤条件下,复播夏玉米以冬油菜茬为优,且施氮量以240 kg·hm^(-2)为宜。

In order to identify the effects of different previous crop stubbles and nitrogen applied amount on summer maize yield and soil organic carbon pool at a semiarid loess site of China,a field experiment was conducted with three nitrogen fertilizer application rates: 0 kg·hm^(-2)( N_0),120 kg·hm^(-2)( N_(120)),240 kg·hm^(-2)( N240) under previous winter rape and winter wheat crops stubbles respectively at Zhenyuan,Gansu province,China. The results showed that,the summer maize yield was increased by 9.76% ~ 24.88% and 12.56% ~ 22.50% under previous winter rape and winter wheat crops stubbles compared with no control N0( CK) respectively. Especially,the yield of summer maize in condition of previous winter rape crop was 6.40% ~ 11.05% higher than that under winter wheat crop. Under different nitrogen supply levels within each of crop stubbles,the orders of successively decreasing in content of total soil organic carbon( TOC) was N_(240)>N_(120)>N_0,and the content of total soil organic carbon under winter rape crop was 1.07 ~ 1.70,1.07 ~ 1.93 g·kg^(^(-1)) and 0.77 ~ 1.60 g·kg^(^(-1)) higher than that under winter wheat crop. The contents of easily oxidized organic carbon( EOOC) and particu1 ate organic carbon( POC) increased with the nitrogen amount under both previous winter rape and winter wheat crops. However,the contents of EOOC and POC under winter rape crop was 0.09 ~ 4.91 mg·kg^(^(-1)) and 0.05 ~ 0.27 g·kg^(^(-1)) higher than that under winterwheat crop respectively. The contribution of nitrogen application to contents of EOOC and POC was 0.34% ~ 3.45%and 10.14% ~ 51.41% respectively. Therefore,manure application with nitrogen fertilizers to soil was both beneficial to yield of summer maize increase and organic carbon pools upgrade in soil at a semiarid loess site of China.And multiple cropping summer maize should be adopted in the field with winter rape stubble; the optimal nitrogen fertilizer fertilization for summer maize was 240 kg·hm^(-2) nitrogen( N_(240)) for the experimental area.