长期施用有机肥小麦玉米轮作土壤系统氮盈余及损失量估算

Long-term effect of organic fertilizer on soil system nitrogen surplus and nitrogen loss in winter wheat-summer maize rotation system

以连续10年长期定位试验数据为依据,研究不同有机肥(以纯N计)0、120、240、360、600 kg/hm^(2)处理在冬小麦-夏玉米轮作土壤系统的氮素吸收利用和土壤氮库变化,利用氮素平衡法估算氮损失量,计算氮素利用率、残留率和损失率,探讨利用氮素平衡法计算氮效率作为有机肥合理施用的评价指标。结果表明:(1)随着试验年限的增加,有机肥氮0、120、240 kg/hm^(2)处理的氮盈余逐年增加,然后趋于稳定状态;有机肥氮360、600 kg/hm^(2)处理每年都存在超过有机肥氮投入量一半的氮盈余。(2)施用有机肥处理土壤氮库逐年增加,且施氮量越大增量越大;10年后各有机肥氮处理土壤氮库趋于稳定。(3)10年后,有机肥氮120 kg/hm^(2)处理氮素利用率在75%左右;有机肥氮240、360和600 kg/hm^(2)处理氮素利用率分别维持在60%、45%和30%左右;各有机肥氮处理的氮素残留率在10%~15%之间;有机肥氮120 kg/hm^(2)处理氮素损失率为10%左右,有机肥氮240 kg/hm^(2)处理氮素损失率为30%左右,360和600 kg/hm^(2)处理氮素损失率为45%和60%左右。在华北地区冬小麦夏玉米一年两熟条件下,长期施用有机肥10年后,土壤系统趋于稳定状态,每季作物施用有机肥氮240 kg/hm^(2),周年氮素盈余为250 kg/hm^(2)左右,氮素表观残留量为80 kg/hm^(2)左右,氮素损失量为180 kg/hm^(2)左右,相应的氮素平衡法计算的氮素利用率、残留率、损失率分别为60%、10%、30%左右。利用氮素平衡法计算氮效率可以作为评价有机肥合理施用的指标。

Based on a 10-year long-term experiment,nitrogen uptake and utilization and changes of soil nitrogen pool in wheat-maize rotation system with 0,120,240,360 and 600 kg/hm^(2) of organic nitrogen treatments were studied to analyze and evaluate the effects of long-term application of organic fertilizer on nitrogen absorption and utilization,soil residual rate and loss rate and to explore the use of nitrogen balance to estimate nitrogen efficiency as an evaluation index for application of organic fertilizer.The results showed:(1)With the extension of the time,the nitrogen surplus of treatments with 0,120,240 kg/hm^(2) organic nitrogen increased year by year,and then reached a relatively stable state;the nitrogen surplus of treatments with 360 and 600 kg/hm^(2) organic nitrogen exceeded 50%of the corresponding nitrogen application amount each year.(2)The content of soil nitrogen increased year by year,and the greater the amount of nitrogen applied,the greater the increment is 10 years later,the soil nitrogen content of different organic fertilizer treatments tended to be stable.(3)10 years later,the nitrogen use efficiency of treatment with 120 kg/hm^(2) organic nitrogen was about 75%;the nitrogen use efficiency of treatment with 240,360 and 600 kg/hm^(2) organic nitrogen was maintained at about 60%,45%and 30%,respectively;the residual rate of nitrogen was between 10%and 15%;the nitrogen loss rate of treatment with 120 kg/hm^(2) organic nitrogen was about 10%,and that of treatment with 240 kg/hm^(2) organic nitrogen was 30%.The nitrogen loss rates of the treatments with 360 and 600 kg/hm^(2) organic nitrogen were about 45%and 60%,respectively.The soil system was basically stable after 10 years of long-term organic fertilization in winter wheat-summer maize rotation system.When 240 kg/hm^(2) organic nitrogen was applied each rotation,the annual nitrogen surplus was about 250 kg/hm^(2),the residual nitrogen in soil was about 80 kg/hm^(2),and the nitrogen losses was about 180 kg/hm^(2).The corresponding nitrogen use efficiency,residual rate and loss rate were about 60%,10%and 30%,respectively.Using nitrogen balance to estimate nitrogen efficiency can be used as an index to evaluate the application of organic fertilizer.