滴灌氮肥用量对设施菜地硝态氮含量及环境质量的影响

Nitrate nitrogen contents and quality of greenhouse soil applied with different N rates under drip irrigation

【目的】滴灌施肥较传统施肥更为精准的将肥水输送至作物的根区,减少肥料的用量,降低土壤水分和养分深层渗漏带来的环境风险。本试验研究滴灌管理下不同氮肥(N)用量对设施菜地供氮能力及环境质量的影响,以期获得滴灌水肥一体化管理条件下最佳施氮用量。【方法】采用日光温室冬春茬黄瓜-秋冬茬番茄轮作,共设计4个化肥氮用量梯度(N_0、N_1、N_2、N_3,对应冬春茬黄瓜季施氮0、300、600、900 kg/hm^2;秋冬茬番茄季施氮0、225、450、675 kg/hm2)3年定位研究比较不同氮用量下0-100 cm土体硝态氮、电导率(EC_(5:1))、pH动态变化计算了各施氮水平下设施蔬菜生产的氮素表观平衡、氮肥利用率和经济效益。【结果】随着种植年限的延长,N_2和N_3处理0-100 cm土体硝态氮和盐分积累显著土壤硝态氮含量分别由2008年黄瓜季季平均14.4~31.1和14.9~41.0 mg/kg增至2010年番茄季季均76.4~119.8和129.0~184.5 mg/kg,分别增加了1.9~5.1和3.5~7.7倍;两处理EC。分别由2008年黄瓜季季平均379.6~514.3和407.0~476.7S/cm增至2010年番茄季季平均663.0~1212.4和710.0~1359.6μS/cm分别增加了0.3~1.8和0.5~2.0倍。与N_2和N_3处理相比,N_1处理节氮50%~66.7%,经过三年的种植0-100cm土层季均硝态氮含量和EC_(5:1)分别下降了35.5%~67.4%和6.0%~25.2%,pH增加0.06~0.18,氮肥利用率显著增加9.0~13.8个百分点而种植蔬菜的经济效益未有显著下降。【结论】温室滴灌冬春茬黄瓜一秋冬茬番茄经济施氮量分别为N 300和225kg/hm^2,既能保证3年5季蔬菜根层(0-60 cm)土层硝态氮处于相对适宜水平,具有较好的经济和环境效益。

[Objectives]Drip irrigation could effectively inhibit nutrient leakage as water and nutrients can be accurately sent to close the crop root zone.In this paper,the soil mineral N contents and environmental qualities were detected under different N rates and drip irrigation,to provide a base for efficient N management in vegetable production.[Methods]A three-years＇ feild experiment was conducted with winter-spring cucumber and autumnwinter tomato double cropping system in a greenhouse.Four N rates were applied as 0,300,600,900 kg/hm^2 for cucumber and 0,225,450,675 kg/hm2 for tomato under drip irrigation（correspondingly recorded as N_0,N_1,N_2,N_3）.The mineral nitrogen contents,salinity（EC_（5：1）） and acidity（pH） of 0- 100 cm soil depth were investigated,and the economic and environmental efficiencies of N were calculated.[Results]As the elongation of the cropping year,the NO_3-N contents under N_2 and N_3 treatments in 0-100 cm soil profile were significantly increased from 14.4-31.1 and 14.9-41.0 mg/kg in cucumber season in 2008,respectively,to 76.4-119.8 and129.0- 184.5 mg/kg in tomato season in 2010,respectively,increased by 0.3- 1.8 and 0.5-2.0 times respectively.The electrical conductivity（EC_（5：1）） of 0-100 cm soil profile under N_2 and N_3 was significantly increased from 379.6-514.3 and 407.0-476.7 μS/cm,respectively,to 663.0-1212.4 and 710.0-1359.6μS/cm of tomato season in 2010,respectively,increased by 0.3-1.8 and 0.5-2.0 times.The N rates in N_1 was33.3%-50%of N_2 and N_3.Compared with N_2 and N_3,the NO_3^--N content and EC_（5：1） of N_1 decreased by 35.5%-67.4%and 6.0%-25.2%after three years cultivation,and the pH and NUE increased by 0.06-0.18 unit and9.0-13.8 percentage points.[Conclusions]Under this condition,the proper N rate for winter-spring cucumber and autumn-winter tomato was recommend as N 300 and 225 kg/hm^2.In most crop seasons（5 seasons）,the NO_3^--N contents in 0-60 cm depth were in the proper range for cucumber and tomato growth,and no significant accumulation of NO_3^--N was observed below 60 cm in the soil under this recommended N rate.