阴山北麓节水灌溉马铃薯田氮素平衡研究

Nitrogen balance of water-saving irrigated potato in Northern Yin Mountains

阴山北麓是内蒙古马铃薯主产区,由于近年来灌溉与水肥一体化技术的推广,大量化学氮肥施用到马铃薯田,导致氮素在土壤中的累积,从而造成潜在的环境风险。为了探究这一问题,通过实地调查、取样,结合前人研究结果,对阴山北麓灌溉马铃薯田氮素投入、输入输出的数量特征、平衡状况、土壤残留情况、灌溉水中硝酸盐含量等进行了系统的研究分析,并且对该地区氮肥施用优化管理进行评估。结果表明:阴山北麓灌溉马铃薯田有机肥和化学氮肥施用总氮量为114.6～1 029.5 kg/hm2,平均为440.7 kg/hm^2;阴山北麓地区灌溉马铃薯田氮素总输入为158.5～1 076.1 kg/hm^2,平均为496.4 kg/hm^2;总输出为134.4～335.7 kg/hm^2,平均为247.4 kg/hm^2。所以,阴山北麓地区灌溉马铃薯田氮素处于大量盈余的状态,盈余量18.6～742.9 kg/hm^2,平均为249.5 kg/hm^2;氮素的盈余导致大量的活性氮残留在土壤中(平均为227.0 kg/hm^2),最终引起地下水硝酸盐含量的上升,从最小的5.0 mg/L变化到74.0 mg/L,平均为22.4mg/L。阴山北麓灌溉马铃薯田氮肥的投入量远远超过了马铃薯对氮素的需求量,处于盈余状态,致使氮素淋失风险增高,亟须进行氮素优化管理,否则将导致地下水硝酸盐超标,影响农牧民的生产生活。

The Northern Yin Mountain is the main productive area of potato in Inner Mongolia. Recently, large amounts of chemical N fertilizers were applied to potato fields with the extension of tertigation in the local area. The applied N in excess of potato requirement probably leads to potential environmental risk. In the current study, through on-site investigation, sampling and combining previous resuhs, the N input and output, N residuals and N balance of potato fields in the Northern Yin Mountain were analyzed and N optimum management on a regional scale was evaluated. The results indicated that the total applied N rate as chemical and organic fertilizer ranged between 114.6 and 1 029.5 kg/hm^2, with an average of 440.7 kg/hm^2 in irrigated potato fields. The total nitrogen input was 158.5-1 076.1 kg/hm^2, with an average of 496.4 kg/hm^2 and total N output was 134.4-335.7 kg/hm^2, with an average of 249.5 kg/hm^2. Thus, the N in irrigated potato fields occurred in surplus. The amount of N surplus changed fi＇om 18.6 to 742.9 kg/hm^2, with an average of 249.5 kg/hm^2, which caused high N residual in the soil （227.0 kg/hm^2）. The nitrate content of groundwater achieved 5-74 mg/L, with an average of 22.4 mg/L. It is concluded, in Northern Yin Mountain, that the N input in irrigated potato fields greatly exceeds potato demand and maintains a surplus. Technologies and methods tor eflective N tertilizer managenlent are urgently needed in this area. Otherwise, environmental risks will rise, which influence local production and the livelihoods of farmers and herdsmen.