氮肥施用量对水浇地覆膜马铃薯土壤矿质氮含量及马铃薯产量的影响

Effects of nitrogen fertilizer rates on content of soil mineral nitrogen and potato tuber yield under film mulching

【目的】针对马铃薯生产中存在的氮肥过量施用问题,探索氮素在土壤中的残留情况和马铃薯最佳施氮量,为科学施用氮肥提供参考.【方法】通过田间试验,研究不同氮肥水平（0,75,150,225,300,375Nkg/hm2）对水浇地覆膜马铃薯‘青薯9号’各生育期土壤0~20cm和20~40cm土层矿质氮（铵态氮＋硝态氮）含量及马铃薯产量的影响.【结果】随施氮量的增加,土壤铵态氮含量变化较小,但0~20cm和20~40cm土层硝态氮的含量随施氮量增加显著增加,不同氮肥用量T2、T3、T4、T5和T6处理的0~20cm土层中硝态氮含量至收获期时高达57.53,88.53,149.86,185.10mg/kg和240.42mg/kg,比播前增加了40~200mg/kg;20~40cm土层硝态氮含量至收获期时分别为63.90,88.11,156.70,192.13mg/kg和244.51mg/kg,比播前增加了30~200mg/kg;过量施氮（T5和T6）和氮肥施用不足（T1、T2和T3）均降低了马铃薯的块茎产量.【结论】试验条件下,马铃薯的经济最佳施氮量和最高产量施氮量分别为180.99kg/hm2和231.07kg/hm2.不同氮水平主要通过影响‘青薯9号’的平均单株薯质量而影响块茎产量.

【Objective】Aimed at the problem of excessive applying nitrogen fertilizer,this study explores the residual of nitrogen element in the soil and optimum nitrogen application rate.【Method】A field experiment was carried out in Dingxi County of Gansu Province to determine the reasonable N fertilizer rates and effects on content of soil mineral nitrogen（NH4＋-N,NO3--N）and potato tuber yield under filmmulching culture conditions.Six N fertilizer rates（0,75,150,225,300 and 375Nkg N/hm2）were laid out in a randomized complete block design with four replications.【Result】The content of ammonium nitrogen（NH4＋-N）in soil was relatively stable,but the content of nitrate nitrogen（NO3--N）increased significantly with the increase of N fertilizer rates.NO3--N content in 0~20cm soil layer of T2,T3,T4,T5 and T6at the harvest period reached to the higher levels of 57.53,88.53,149.86,185.10 and 240.43mg/kg,which in 20~40cm soil layer were 63.90 mg/kg,88.11 mg/kg,156.70 mg/kg,192.13 mg/kg and 244.51 mg/kg,much higher than that in the same soil layers before the sowing period.Both N deficiency and excessive application of N fertilizer led to decline in potato tuber yield.【Conclusion】Under the condition of this experiment,the N rates for highest yield and largest economic benefit are 180.99kg/hm2 and 231.07kg/hm2 respectively.The yield component factor analysis result showed that the average fresh-weight was the major factors affecting the potato tuber yield under the different N rates.