中文摘要：

通过田间小区试验和微区试验相结合研究滴灌条件下不同灌溉水盐度、灌水量和施氮量对棉田土壤中氮肥去向的影响。试验设置3种灌溉水盐度（电导率,EC）：0.35、4.61和8.04 d S m^-1（分别以S0.35、S4.61和S8.04表示）;2个灌水量：405和540 mm;同时设置2个施氮水平：240、360 kg hm^-2（360 kg hm-2为当地棉田推荐氮肥用量）。结果表明：S0.35和S4.61灌溉处理的棉花氮素吸收量和产量无显著差异,分别较S8.04灌溉处理高出27.46%和33.65%、21.29%和21.63%。灌溉水盐度主要通过影响棉花单株结铃数来影响棉花产量。增加施氮量和灌水量,棉花氮素吸收量和产量均有所增加。15N同位素标记试验结果表明：植物15N回收率在34.20%~62.51%之间,随灌溉水盐度的增加,植物15N回收率呈现先增加后减小的趋势,S0.35、S4.61处理较S8.04处理分别高出30.70%和41.77%;增加灌水量和施氮量可显著提高植物15N回收率。土壤15N残留率随灌溉水盐度的增加而增加,S4.61和S8.04处理的土壤15N残留率较S0.35处理分别高出3.48%和23.22%。施氮量由240 kg hm^-2增加至360 kg hm^-2,土壤15N残留率增加9.51%。各处理15N淋洗损失率在0.35%~3.59%之间,低施氮量下,S0.35和S4.61处理的15N淋洗损失率无显著差异,S8.04处理的15N淋洗损失率分别较S0.35、S4.61处理高出1.87倍和0.84倍;高施氮量下,15N淋洗损失率随灌溉水盐度的增加而显著增加。增加灌水量和施氮量,15N淋洗损失率均显著增加。

英文摘要：

Freshwater scarcity is a serious long-term hindrance to the agricultural production in arid and semi-arid regions. While the supply of brackish water is quite plenty, therefore the use of brackish water or saline water for irrigation has received considerable attention in those regions. A field experiment was carried out to study the effect of drip irrigation with saline or brackish water in cotton （ Gossypium hirsutum L. ） fields on fate of nitrogen in the soil relative to salinity of the water, irrigation rate, and N application rate. 15^N-labeled urea was applied in the experiment field or plots to trace N movement in the soil. The experiment was designed to have three treatments （S0.35, S4.61 , and S8.04 ） in salinity of irrigation water （0.35, 4.61, and 8. 14 dS m ^-1 , respectively）, two levels in irrigation rate （405 mm and 540 mm）, and two levels in N application rate （240 and 360 kg hm^-2, 360 kg hm^-2 is a common rate used by local farmers）. The experi- ment shows that both cotton yield and N uptake were significantly lower in Treatment S8.14 than those in Treatment S0.35 and S4.61, and there was no significant difference in either cotton yield or N uptake between Treatment S0.35 and Treatment S4.61. Salinity of the water affected mainly the number of cotton bolls and hence yields of the crop. Cotton yield and N uptake in- creased with irrigation rate and N application rate. Results of 15^N tracing show that the plant 15^N recovery rate ranged from 34.20% to 62.51% , and followed a curve that rose first and then declined with rising salinity of the water. Plant 15^N recovery rate in Treatment S4.61was 30. 70% higher than that in Treatment S0.35and 41.77% higher than that in TreatmentS8.04. Higher irrigation rate or N application rate significantly increased plant 15^N recovery rate, however, higher salinity of the irrigation water decreased that. Treatment S4.61 and Treatment S8.04 was 4.03 % and 23.88% higher, respectively, than Treatment S0.35 in soil tSN residue rate. Increase in