马铃薯—大白菜双季栽培体系中大白菜氮肥施用量对其产量、氮肥利用、硝酸盐累积的影响

Effects of Chinese Cabbage Nitrogen Application Rate on Chinese Cabbage Yields,Nitrogen Utilization,Nitrate Accumulation(Soil & Cabbage)of Potato—Chinese Cabbage Double Cropping System

在内蒙古河套灌区建立的马铃薯—大白菜双季栽培体系下通过大白菜茬口5水平氮肥施用量田间试验,研究了不同施氮量对大白菜产量、氮肥利用率、大白菜硝酸盐含量、土壤硝态氮累积的影响。结果表明:双季栽培体系下,大白菜产量,体系净收益随施氮量的增加而增加,但当复种茬口施氮量≥120kg·hm-2时,大白菜产量、体系净收益不再随施氮量的增加而显著增加;总施氮量225～405kg·hm-2范围内双季栽培体系氮素累积、氮肥利用率比传统马铃薯单季露地栽培显著提高;大白菜硝酸盐含量、收获后0～160cm土壤硝态氮累积量随复种茬口施氮量的增加而增加,当复种茬口施氮量≥120kg·hm-2时,大白菜硝酸盐达到高度累积,0～160cm土壤硝态氮累积量≥162kg·hm-2,在秋浇水时加剧了地下水污染的风险。合理控制氮肥施用量是降低地下水污染风险、降低大白菜硝酸盐含量和提高经济净收益的有效平衡途径。

The effects of Chinese cabbage N application rate on Chinese cabbage yields,nitrogen utilization,nitrate contents,and nitrate nitrogen accumulation in soil were studied under potato-Chinese cabbage double cropping system in Hetao irrigated area of Inner Mongolia with 5 N application rates at Chinese cabbage planting season.The results showed that the yields and the double cropping net economic returns were the highest with the Chinese cabbage N application rate of 120 kg·hm-2;the double cropping system N accumulation and N recovery ratio were enhanced at the total N application rate from 225 kg·hm-2 to 405 kg·hm-2,compared with that of the conventional mono potato production in the open field at the N application rate of 225 kg·hm-2;the nitrate contents in Chinese cabbage and the nitrate accumulations within 0-160 cm soil profiles were increased with the increscent N applied rates.At the Chinese cabbage N application rate was≥120 kg·hm-2,the nitrate contents in Chinese cabbage reached a high level,and the nitrate accumulations within 0-160 cm soil profiles were≥162 kg·hm-2,hence the risk of nitrate contamination in underground water was increased for autumn irrigation.Reasonable N application rate had an effective effects on reducing nitrate contamination in groundwater,reducing nitrate content in Chinese cabbage,and increasing net economic return.