不同滴灌施肥策略对棉花氮素吸收和氮肥利用率的影响

EFFECTS OF FERTIGATION STRATEGY ON NITROGEN UPTAKE BY COTTON AND USE EFFICIENCY OF N FERTILIZER

在温室条件下应用15N标记尿素进行了不同滴灌施肥策略对棉花氮素吸收和氮肥利用率影响的盆栽试验。根据滴灌灌水施肥时段的分配,设置四种不同氮肥滴灌施肥策略。研究结果表明,不同滴灌施肥策略显著影响棉花的干物质重和氮素吸收量,棉花的氮素吸收量明显受到根系生长的影响,整株氮素吸收量与根干物质重之间呈显著的正相关关系。在一次灌溉过程中先滴1/2时间的肥液,然后再滴1/2时间清水的施肥策略可显著促进棉花根系的生长,增加棉花的氮素吸收量,减少氮肥在土壤中的残留,提高氮肥利用率。因此,在膜下滴灌条件下采用合适的施肥策略有助于提高肥料的利用效率。

Effects of fertigation strategy on nitrogen （N） uptake by cotton and N use efficiency （NUE） were investigated through a pot experiment under greenhouse conditions. According to timing of irrigation and fertilization, four fertigation treatments were designed, nitrogen applied 1 ） in the beginning of the irrigation cycle （N-W）, 2） at the end （W-N）, 3 ） in the middle （W-N-W）, and 4）throughout the irrigation cycle （N-N））in a completely randomized layout, each with four replications. Cotton was grown in plastic containers,84 L in volume,filled with a clay loam soil and fertilized at a rate of N 6.44 g per pot as 15N-labeled urea. Treatment N-W was significantly higher than Treatment N-N in total dry matter（DM）and N content, but did not differ much from Treatment W-N and Treatment W-N-W. Plants in Treatments W-N and N-W were found to have a significantly higher content of nitrogen derived from fertilizer（ NDFF） than those in Treatments W-N-W and N-N. Fertigation strategy had a consistent effect on total NUE：Treatment N-W was the highest in total NUE, and followed by Treatments W-N and W-N-W, which were quite similar to each other, and Treatment N-N was the lowest. After harvesting, the residue of fertilizer N in soil was highest in Treatment W-N, and the lowest in Treatment N-W, but did not vary much between Treatment N-N and Treatment W-N-W. The difference between the four treatments in total ^15N recovery was not statistically significant. From the aspect of nitrate leaching losses from the root zone, Treatments N-N and W-N may lead to an increase in soil residual nitrates and hence a higher risk of nitrate leaching. In contrast, Treatment N-W tends to reduce potential leaching loss of nitrate from the root zone. In this study, the fertigation strategy, Treatment N-W（ nitrogen applied in the beginning of the irrigation cycle）increased DM accumulation, N uptake and NUE of cotton. Therefore, NUE could be enhanced by optimizing fertilization strategies with drip irrigation.