大田蔬菜地春季硝态氮淋溶特征研究

春季,对上海浦东新区大田蔬菜地试验田按照不同施肥(常规、减量、无肥)处理水平、不同土壤深度(30 cm、50 cm、70 cm、120 cm),利用现场采样与室内实验结合的方法,对硝态氮淋溶进行了研究。实验结果表明,降雨量和氮肥施用对土壤硝态氮淋失有显著性影响。施肥试验区施肥后各土层硝态氮浓度均很高,4月份淋溶浓度普遍高于3月份。常规施肥区不同深度的硝态氮含量明显高于不施肥区,减量施肥区含量则介于二者之间。施肥区部分氮素硝态氮随降雨在土壤中不断向下淋溶,尤其在施肥初期较多的氮素由土壤表层不断淋失到土壤深层,在接近地下水位120 cm的剖面处产生渗漏液的硝态氮浓度超过国家限量标准(20mg L-1)。

NO3--N Leaching Character from Vegetable Land in Springtime

NO~-_3-N leaching was in vestigated according to different fertilization(general,decreased,non-fertilizing) and different depth(30cm,50cm,70cm,120cm) on Yide farm in Pudong New District,Shanghai.Both sampling on the location and indoor experiment was conducted. It was shownd that there was significant influence of rainfall and nitrogenous fertilizer on the concentration of NO~-_3-N.The concentration of NO~-_3-N was high in different depth on the fertilized farmland and its concentration in April was higher than in March.The concentration of NO~-_3 on general fertilization was clearly higher than that of non-fertilizing,and the concentration of the reduced fertilization was between general fertilization and non-fertilization.The nitrogen element of fertilizer was ceaselessly leached in soil after rainfall,especially much NO~-_3-N was leached to deep soil layer in early stages of the fertilization.The leaching concentration of NO_3~——N exceeded to national standard(20mg L~(-1)) in 120cm section plane,which location is shallow groundwater.