西辽河流域不同土地利用结构硝酸盐氮输出通量模拟

采用土槽模型渗流试验方法,结合土地利用结构现场调查资料研究了西辽河流域不同土地利用结构耕层土壤NO3--N淋溶输出通量的时空变化规律.结果表明,不同土地利用结构NO3--N淋溶输出通量的空间分布规律为农田〔50.23kg/(hm2.a)〕>沙荒地〔12.77kg/(hm2.a)〕>林地〔8.68 kg/(hm2.a)〕>草地〔4.17 kg/(hm2.a)〕,农田和沙荒地对NO3--N输出起源作用,林地和草地起汇作用;西辽河流域沙土区耕层土壤NO3--N输出总量为13.86×104 t/a,不同土地利用结构的NO3--N输出比例为农田(95.31%)>沙荒地(4.69%),农田是西辽河流域氮素营养管理的重点结构;NO3--N输出量夏季(65%)>秋季(25%)>春季(8%)>冬季(2%),夏季是流域氮素营养管理的重点时段;NO3--N淋溶输出通量与土壤硝态氮含量呈极显著正相关. 

Nitrate-Nitrogen Output Flux Simulation from Different Sandy Soils in Western Liaohe River Basin

The temporal and spatial variations of nitrate-nitrogen output flux in the Western Liao River basin were studied through local investigation on land use structure and water leakage experiments in a soil sink.The results indicated that: 1) The output flux of nitrate-nitrogen decreased in the order farmland(50.23 kg/(hm2·a) > sandy wasteland(12.77 kg/(hm2·a) > forest land(8.68 kg/(hm2·a) > grassland(4.17 kg/(hm2·a).2) Farmlands and sandy wastelands play the role of source in nitrate-nitrogen output,while grasslands were the output collection place.3) The total annual amount of nitrate-nitrogen output from the Western Liao River basin was 0.1386 million tons.4) The ratio of output flux in different land use structures was arranged in the following order: farmland(95.31%) > sandy wasteland(4.69%).5) Farmlands were the focus of nitrogen-nutrition management in the Western Liao River basin.6) Over a year,nitrate-nitrogen output decreased in the order of summer(65%) > autumn(25%) > spring(8%) > winter(2%),with summer being the most important season for nitrogen-nutrition management.6) There was a positive linear correlation between the output flux and nitrate-nitrogen content of the soil.