施氮对不同质地滴灌棉田土壤硝态氮分布及棉花产量的影响

为了探究施氮对不同质地滴灌棉田硝态氮分布及产量的影响,采用温室土柱模拟的方法,研究了滴灌条件下不同质地土壤硝态氮分布迁移特征,分析了施氮对NO_3-N和棉花产量的影响。结果表明,在灌水量一定的条件下,在砂土、壤土中施氮量分别为256.00、287.34 kg/hm~2时,相应的氮素积累量最大,皮棉产量最高,土壤硝态氮主要集中分布在30~40 cm土层,有利于棉花根系的吸收,且分别比不施氮增产43.87%和44.92%。一定施氮量下,壤土硝态氮分布的均匀性优于砂土,并且根层20~40 cm土层硝态氮量高于砂土,且比砂土平均增产6.16%。砂土、壤土中硝态氮量在各生育期总体呈现"降-增-降"的变化趋势,并且收获前期施纯氮340 kg/hm~2处理60cm土层砂土硝态氮量的第二个峰值较壤土提高15.98%,在生育期末端砂土在深层的氮素积累高于壤土,存在继续向下淋失的风险。

Effect of Soil Texture on the Distribution of Nitrate Nitrogen in the Soil Profile and Its Influence on Drip-irrigated Cotton Production

The methods of column simulation in greenhouse was used to study the effect of soil texture on the distribution of NO3-N in the 0～60 cm soil and cotton yield under drip irrigation.The results showed that when irrigation amounts were the same,N application rates of 256.00 kg/hm2 to sand soil and 287.34 kg/hm2 to loam resulted in the greatest cotton production.Compared with the unfertilized control (CK),these fertilizer amounts increased cotton yield by 43.87％ in the sand soil and by 44.92％ in the loam.Soil NO3-N was mainly distributed in the 30～40 cm depth under these N application rates.This was conducive to the absorption of N by the cotton root system,thus allowing soil N absorption efficiency to be properly regulated and production to be increased.The results also showed that when fertilizer rates were the same,soil NO3-N was distributed more uniformly in the loam soil than in the sandy soil.Soil NO3-N was mainly distributed in the 20～40 cm soil depth of the loam soil.This improved the N utilization rate and increased cotton yield by an average of 6.16％ compared with the sand soil.Soil NO3-N content in both the sand soil and loam soil changed with the curve of "decrease-increase-decrease" across the growing season.At the second peak,soil NO3-N content in the 60 cm depth with N application rate of 340 kg/hm2 was 15.98％ greater in the sand soil than in the loam soil.At the end of the growth period,the sand soil had greater N content than the loam soil and therefore had greater risk for N loss due to leaching.