氮肥施用量对设施番茄氮素利用及土壤NO3--N累积的影响

在宁夏引黄灌区滴灌条件下,以温棚番茄为研究对象,采用田间试验与室内分析的方法,研究不同施氮量对番茄产量、氮素利用率及土壤NO3--N残留的影响,并对土壤-番茄体系的氮平衡进行了表观评估。试验结果表明:2004年秋冬茬番茄,施用氮肥显著增加了当茬番茄果实、植株产量(增产幅度19.9%～29.6%)及地上部总吸氮量(204～232.6kg/hm2)。2005年冬春茬番茄,与空白处理产量相比(106kg/hm2)只有N200处理的果实增产达显著水平(120kg/hm2)。两季番茄的氮肥利用率都随氮肥施用量的增加而明显降低(3.3%～10.9%)。2004年秋冬茬番茄收获后,表层0～30cm的NO3--N大量累积(200～650kg/hm2),其累积量随施氮量增加呈增加的趋势,经过2005年冬春茬番茄种植后,上茬0～30cm土层NO3--N向下有淋失的趋势,淋失层次主要在90cm以上的土体(250～380kg/hm2)。综合考虑番茄果实产量、氮肥利用率及土壤NO3--N残留等因素,秋冬茬番茄推荐氮肥用量在100～200kg/hm2和适量的磷钾肥配施为当茬氮肥优化管理处理。而冬春茬番茄氮肥推荐在200～400kg/hm2范围可以满足当茬番茄对氮肥的需求。

Nitrogen fertilizer effects on N recovery and residual soil NO3--N for greenhouse-grown tomato

A greenhouse experiment for double-cropping tomato was carried out with drip irrigation in the Yellow River irrigation area of Ningxia to determine the effects of N fertilizer rate on tomato yield,apparent N recovery and soil NO-3-N accumulation,and to analyze N balance in the tomato crop-soil system.Both yields(fruits stems)and the aboveground N uptake increased significantly(204-232.6 kg/hm2)with N application for autumn-winter tomato in 2004,but only the treatment at N200 showed higher fruit yields(120 kg/hm2)for winter-spring tomato in 2005,as compared with the control treatment(106 kg/hm2).The apparent N recovery by tomato plants decreased(3.3%-10.9%)with increasing N rate for both seasons.The residual NO-3-N in the topsoil(0-30 cm)was high(200-650 kg/hm2)after autumn-winter tomato harvest in 2004,especially increased with increasing N rate.The NO-3-N in the top 30 cm layer tended to move downward to the above 90 cm layer(250-380 kg/hm2)after winter-spring tomato harvest in 2005.The fertilizer N rates for getting high tomato fruit yield and N recovery,but low residual soil NO-3-N should be optimized at a range of 100-200 kg N/hm2 for the autumn-winter tomato and 200-400 kg N/hm2 for the winter-spring tomato,respectively.