施氮量对冬小麦-夏玉米土壤氮素表观盈亏的影响

Effects of Nitrogen Application Rates on Apparent Surplus and Deficit of Soil Nitrogen in Winter Wheat and Summer Maize Rotation System

通过河北清苑连续6年的田间定位试验,以冬小麦—夏玉米轮作体系作为对象,设置不同的施氮处理(N_0、N_(100)、N_(180)、N_(255)、N_(330)),研究不同施氮量对冬小麦—夏玉米轮作体系的土壤氮素表观盈亏的影响。结果表明:6年土壤表观氮素累积盈亏量随施氮量的增加而增加,N_0和N_(100)处理的土壤氮素累积盈亏量为负值,N_(180)、N_(255)和N_(330)处理的土壤氮素累积盈亏量分别高达382,1 173,2 116kg/hm^2;各处理的氮素表观盈亏量年际间变异较大,而在2种作物上的氮素累积盈亏量差异不大;在冬小麦季和夏玉米季,土壤氮库达到平衡状态的施氮量分别为155,134kg/hm^2;土壤氮素表观盈亏量均与土壤无机氮变化量呈显著负相关,与施氮量呈显著正相关,且随降雨量的增加呈增加趋势;不同生育期的结果表明,在冬小麦—夏玉米生长前期均表现土壤氮素盈余,而后期土壤氮素亏缺。因此合理施用氮肥既要考虑土壤氮素盈亏,也要关注生育期的分配。

The apparent surplus and deficiency of soil N in winter wheat-summer maize rotation were investigated under different N application rates（N_0,N_（100）,N_（180）,N_（255）,N_（330））in consecutive six years in Qingyuan,Hebei.Results showed that the cumulative apparent nitrogen balances changed from the deficit in N_0 and N100 treatments to the surplus in N180,N255 and N330 treatments,which reached up to 382,1 173 and 2 116 kg/hm2,respectively.The large annual variations of the apparent N balances were found,but the differences of the N balances between the two crops were small,which were 155 kg/hm2 and 134 kg/hm2,respectively.Meanwhile,it was observed that the apparent soil N balances were negatively correlated with the changes of soil inorganic N and the precipitation,but positively correlated with N application rates.In addition,the apparent soil N surplus in the earlier stage and deficit in the later stage during the growing seasons of winter wheat and summer maize were observed.These findings above indicated that reasonable N recommendation should be established from two aspects including soil apparent N balance and N allocation within a growing season.