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

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

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。

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.