基于秸秆还田条件下的黄灌区稻旱轮作土壤硝态氮淋失特征研究

宁夏引黄灌区农田面源污染较为严重,区内大部分排水沟水质为劣Ⅴ类,其主要污染物硝态氮与铵态氮。设置常规施肥(CK)、常规施肥条件下施用4500kg/hm~2(T1,半量还田)和9000 kg/hm~2(T2,全量还田)秸秆3个处理。利用树脂芯法吸附10、20、30、60、90cm土层的硝态氮流失量。2009—2013年的试验结果表明:秸秆还田能够减少土壤30cm土层的硝态氮淋失。与对照硝态氮淋失量(15.76 kg/hm~2)相比,T1(13.76 kg/hm~2)与T2(13.74 kg/hm~2)均达到显著差异(P0.05),淋失量分别减少12.71%和12.84%,T1与T2没有达到显著差异。秸秆还田对土壤硝态氮淋失的影响效应主要体现在30cm土层处,10、20、60与90cm土层处的处理与对照都没有达到显著差异。秸秆还田提高了30cm土层的土壤有机质与土壤总氮,与对照(13.78 g/kg)相比,T1与T2土壤有机质分别提高0.89 g/kg和1.24 g/kg;试验结束后,对照、T1和T2的总氮是达到0.64、0.66和0.69 g/kg,与对照相比,处理分别提高了2.76%和6.83%。秸秆还田有助于作物增产,T1与T2的水稻平均增产9.24%和10.37%,小麦增产10.11%和11.51%。

Effect of straw application to soil nitrate leaching of paddy-upland rotation in the Yellow River irrigation area

The Yellow River irrigation area within Ningxia was a region severely polluted by non-point sources, where surface water quality in most drainage ditches was classified as Inferior Category V, and the primary pollutants were nitrate and ammonium. In this region a 5-year straw application and nitrate leaching experiment had been conducted, which consisted of 3 treatments: traditional fertilizing without rice straw amendment(CK), traditional fertilizing with 4500 kg/hm² rice straw returning application (T1, semi), and traditional fertilizing with 9000 kg/hm² rice straw amendment (T2, total). Nitrate nitrogen leaching losses within 10, 20, 30, 60, 90 cm soil layers were measured by the resin core method. Results indicated straw application could reduce soil nitrate leaching losses within the 30 cm layer. From the nitrate nitrogen loss of CK (15.76 kg/hm²), the loss of T1 (13.76 kg/hm²) and T2 (13.74 kg/hm²) all showed significant differences (P < 0.05), soil nitrate leaching losses were decreased by 12.71% and 12.84%, respectively. However no significant differences (P > 0.05) was detected between T1 and T2. The effects of straw application were only observed in plowing layer (30 cm depth soil layer), no significant difference was detected between experimental treatments and control (CK) in deeper layers (60 and 90 cm) and in topsoil (10 and 20 cm). Straw application could increase soil organic matter (SOM) and total nitrogen (TN) content: SOM of T1 and T2 were increased by 0.89 g/kg and 1.24 g/kg compared to CK (13.78 g/kg). TN of CK, T1 and T2 were 0.64, 0.66 and 0.69 respectively, at 0-30 cm layer, which were increased by 2.76% and 6.83%. Straw application could also increase crop yield,rice production of T1 and T2 were increased by 9.24% and 10.37%, and winter wheat yield were increased by 10.11% and 11.51%, respectively.