滴灌条件下施氮量对黄瓜-番茄种植体系中土体NO3--N淋洗的影响

为了解不同氮肥用量对土壤NO3--N淋洗的风险程度, 合理指导温棚蔬菜施肥和灌溉,2005～2006年在宁夏引黄灌区滴灌条件下,以轮作体系下的温棚黄瓜-番茄为研究对象,采用田间土壤溶液定位提取、田间试验与室内分析相结合的方法,设化肥施氮量150 kg/hm2(低氮)、300 kg/hm2(中氮)、450 kg/hm2(高氮1)、600 kg/hm2(高氮2)及有机肥和不施肥(CK)处理,研究滴灌条件下施氮量对土体中NO3--N淋洗的影响.结果表明:无论是低、中或高氮处理下,黄瓜-番茄轮作周期中,滴灌施肥对0～30 cm土壤溶液NO3--N含量变化的影响明显;在高氮处理下,由于番茄季较强的滴灌量,土体中NO3--N不断向下淋洗至90 cm土层;与CK处理相比,单施有机肥会造成的土壤NO3--N向深层淋洗.因此,提出每茬蔬菜推荐施氮量控制在300 kg/hm2左右为宜,在冬春茬后期4～6月份减少滴灌次数是减少土体NO3--N向下淋洗的措施.

Effect of N rate on soil nitrate leaching in cucumber-tomato rotation system under drip irrigation condition

The objective of this study was to evaluate NO3^- -N leaching with different N rate, and to give a scientific fertilization and irrigation suggestion for greenhouse vegetables. An method with field experiment, soil solution collecting and chemical analysis was conducted to study the effects of N rate on NO3^- -N leaching under cucumber- tomato rotation system of drip irrigation with greenhouse in Yellow River irrigated area in Ningxia from 2005 to 2006. N rate 150, 300, 450, 600 kg/hm^2 was defined by low N rate, middle N rate, high N rate 1 and high N rate 2, respectively. The results showed that drip irrigation or N rate affected significantly NO3^- -N content of 030 cm soil solution under low, middle or high N rate in cucumber- tomato rotation system. Especially in high N rate, NO3^- -N of topsoil solution would leach to 90 cm soil depth because of high drip irrigation in tomato season. Organic manure application may cause NO3^- -N leaching to deep soil depth compared to treatment CK. Therefore, it is recommended to keep the application of nitrogen less than about 300 kg/hm^2 each vegetable season and to decrease irrigation times in winter-spring tomato season, so as to decrease NO3^- -N leaching.