农作制度对黑河中游沙质土壤硝态氮积累及作物产量的影响

Effects of Farming Systems on Soil Nitrate Accumulation and Crop Yield in Sandy Soil Field in the Middle Reaches of Heihe River Basin,China

为研究沙地农田不同土壤耕作、覆盖方式和轮作对作物产量、土壤硝态氮含量及积累的影响,在黑河中游边缘绿洲典型沙地进行农田定位试验。试验结果表明,在沙地农田生态系统,相对传统的三耕两耱的耕作方式,减少秋耕对玉米和大豆产量没有显著影响;相对于地膜覆盖处理,麦秆覆盖处理使玉米减产11.3%～18.8%,使大豆产量增加6%;不同处理0～40cm土壤硝态氮积累量存在显著差异,作物收获后传统耕作处理土壤硝态氮的平均积累量比少耕处理低8.5%～22.7%,覆膜处理比覆麦秆处理低7.0%～8.8%,玉米连作处理比玉米-大豆轮作处理高54.9%。分析结果表明,减少秋耕、麦秆代替地膜覆盖均有利于土壤硝态氮在作物根系集中层的积累,玉米大豆轮作对土壤硝态氮积累和淋失的影响仍需进一步研究;该试验研究的继续深入将对维持绿洲农田环境的健康和提高沙地农田生态系统生产力提供重要的理论依据。

Field experiment was conducted to determine the effects of minimum tillage,straw mulching and crop rotation on grain yield,nitrate accumulation in the profile of a sandy soil in the marginal oasis of Heihe River basin for two consecutive years（from 2007 to 2008）.Results showed that the average grain yield of crops under conventional tillage treatment was not significantly decreased than those under minimum tillage treatment.The average maize yield for straw mulching treatment was 11.3%～18.8% lower than that for plastic film mulching treatment,while the average grain yield of soybean was 6% higher.There was a significant difference in nitrate accumulation in the 0～40 cm soil layer between different treatments.For instance,the average nitrate accumulation in 0～40 cm soil layer was 8.5%～22.7%,7.0%～8.8% lower under conventional tillage and film mulching treatment compared that under minimum tillage and straw mulching treatment,respectively.Average nitrate accumulation in 0～40 cm soil layer was 54.9% higher under continuous maize cropping treatment compared with that under maize-soybean rotation cropping treatment.These data showed that minimum tillage and straw mulching had positive affect in increase nitrate accumulation in rhizosphere of soil.However,the effect of maize soybean rotation on nitrate leaching in sandy soil was very preliminary.Further investigations about effects of cropping systems on soil nitrate accumulation and crop yield was necessary,which could contribute to protecting soil and ground-water from potential nitrate pollution,and provide some theoretical bases for keeping high productivity of the oasis agro-ecosystem in this region.