喷灌冬小麦农田土壤NO_3^--N分布特征及作物吸氮规律

Effects of sprinkler irrigation on soil nitrate-N distribution and nitrogen uptake of winter wheat under the field conditions

以传统地面灌溉(畦灌)为对照,2002~2003和2003~2004两个生产年度田间试验分析喷灌对冬小麦农田土壤NO3--N分布和作物吸氮的影响。试验结果表明:喷灌与地面灌溉相比,土壤NO3--N含量峰值迁移较浅,土壤NO3--N主要分布在冬小麦主要根系分布层0~40 cm土层内。与喷灌相比,在冬小麦根系层下部,地面灌溉土壤NO3--N存在不同程度的累积。试验期间地面灌溉土壤NO3--N累积淋失量分别为8.68 kg/hm2和7.70 kg/hm2,喷灌条件下没有明显的土壤NO3--N淋失,最大累积淋失量只有地面灌溉条件下的3%。2003和2004年喷灌冬小麦地上部分吸氮量分别为235.7 kg/hm2和161.7 kg/hm2,分别比地面灌溉高7.0 kg/hm2和34.7kg/hm2。与地面灌溉相比,喷灌有利于冬小麦后期吸收氮素,喷灌不同生育期冬小麦吸氮量年际之间的差异都小于地面灌溉。

The effects of sprinkler irrigation on soil nitrate-N distribution and nitrogen uptake of wi＇nter wheat were analyzed through two-year field experiments. The control treatment was traditional surface irrigation（border irrigation）. The experimental results indicate that the peak of soil nitrate-N transports shallowly and distributes mainly within upper 40 cm soil layers where most roots of winter wheat distribute under＇sprinkler irrigation compared with under surface irrigation. In the sublayer of root zone of winter wheat, soil nitrate-N cumulates under surface irrigation in various degrees compared with under sprinkler irrigation. The accumulation of soil nitrate-N leached are 8.68 kg/hm^2 and 7.70 kg/hm^2 under surface irrigation in 2003 and 2004, respectively. The accumulation of soil nitrate-N leached under sprinkler irrigation is very small, about less than 3 % of surface ＇irrigation conditions. The amount of nitrogen uptake by winter wheat under sprinkler irrigation is 235. 7 kg/hm^2 and 161.7 kg/hm^2 in two years, 7.0 kg/hm^2 and 34.7 kg/hm^2 higher than that under surface irrigation, respectively. Sprinkler irrigation has the promoting effects on nitrogen uptake by winter wheat in the later period. The difference of nitrogen uptake by winter wheat during different growing periods between each year under sprinkler irrigation is all smaller than that under surface irrigation.