不同施肥模式对菜地氮素径流损失与表观平衡的影响

Effects of Different Fertilization Modes on Nitrogen Loss by Surface Runoff and the Apparent Nitrogen Balance in the Vegetable Fields of Taihu Lake Region,China

采用田间小区定位试验(2014—2015年)研究了自然降雨条件下农户习惯性施肥、减量施肥及减量施肥配施生物炭等不同施肥模式对太湖流域蔬菜地氮素径流流失、蔬菜产量及氮素表观平衡的影响。结果表明:甘蓝种植季内菜地径流水量达1 729.20m^3/hm^2,且与降雨量呈显著线性正相关关系。农户习惯性施肥(T1)处理条件下,菜地TN径流流失量达47.66kg/hm^2。减量施肥(T2)和减量施肥配施生物炭(T3)处理显著减少了氮素径流流失量,分别达13.95%和23.68%。与T2相比,配施生物炭(T3)可显著降低菜地氮素径流流失量达11.31%。菜地径流氮素以NO_3^-—N损失为主,各处理条件下,其流失量占TN的比例达81.11%~85.94%。菜地氮素平衡盈余量达158.24kg/hm^2,且随着氮素输入量的减少,氮素盈余量显著降低。T2、T3处理条件下,盈余量显著降低29.03%~39.81%。同时,T2、T3处理显著降低甘蓝叶球产量达16.12%~19.11%,而球形指数则显著增加6.17%~7.41%,氮素偏生产力也显著提高24.39%~28.98%。与T2相比,配施生物炭(T3)处理可小幅提高甘蓝产量及氮肥偏生产力,但处理间差异不显著。

Under natural rainfall conditions,a field plot experiment（2014—2015）was conducted to study the effects of different fertilization modes（i.e.conventional fertiliser application,T1;reduced fertiliser application,T2;optimized fertiliser application,reduced fertiliser application and wheat straw biochar application,T3）on nitrogen（N）loss by surface runoff,the apparent N balance,and vegetable yield in the vegetable field of cabbage（Brassica Oleracea L.）in Taihu Lake Basin,China.The results showed that total volume of surface runoff reached up to 1 729.20 m3/hm^2 during the vegetable growing season,which showed a significant positive linear correlation with rainfall capacity.In T1 treatment,total nitrogen（TN）loss by surface runoff reached up to 47.66 kg/hm^2 during the vegetable growing season.Compared with T1,T2 and T3 significantly reduced TN losses by 13.95% and 23.68%,respectively.Compared with T2,TN loss decreased significantly by 11.31%,after application of wheat straw biochar（T3）.The lost N was mainly nitrate nitrogen（NO_3^-—N）,which accounted for 81.11%~85.94% of TN loss.Meanwhile,N surplus amount in the vegetable field of cabbage reached up to 158.24 kg/hm^2 under T1 treatment.With decreasing N application in the vegetable field,N surplus significantly decreased.Compared with T1,N surplus decreased significantly by 29.03%~39.81%.Furthermore,T2,T3 significantly reduced cabbage head yield by 16.12% ~19.11%,but the sphericity index increased significantly by 6.17% ~7.41%,and the partial factor productivity of nitrogen（PFPN）for cabbage head increased significantly by 24.39%~28.98%.And,compared with T2 treatment,after application of wheat straw biochar（T3）in the vegetable field,cabbage head yield and PFPN increased slightly,but no significant difference was found.