不同灌溉量膜下微咸水滴灌土壤盐分分布与积累特征

于2010年在新疆石河子大学节水灌溉实验站进行膜下微咸水滴灌试验。灌溉水矿化度为3.32 g L-1,三个灌溉定额处理(Q36:3 150 m3 hm-2、Q48:4 200 m3 hm-2、Q60:5 250 m3 hm-2),并分析了土壤盐分分布及其积累特征。在灌溉周期内土壤盐分运移特征为:根区土壤盐分基本表现趋势为湿润体形成阶段降低,再分布阶段聚集;根底土壤盐分表现趋势为湿润体形成阶段增加,再分布阶段降低。秋后土壤盐分剖面与盐量平衡结果显示:Q36、Q48处理中灌溉输入土壤的盐分基本上存于120 cm土壤以内,Q60处理在120 cm以下土壤盐分显著增加。灌前灌后土壤水分入渗剖面显示,三个处理滴灌后36 h土壤水分湿润深度分别达到80、90、120 cm。滴头部位水分携带盐分向深层迁移,在滴灌中起着深层淋溶作用,这对于减缓上层土壤盐分积累具有积极意义。

Saltdistribution and accumulation in soils different in rate of under-mulch drip irrigation with brackish water

Under-mulch drip irrigation is an important irrigation method in irrigation agriculture of Xinjiang. However, soil salt accumulation induced by its slow deep leaching and brackish irrigation water is an urgent problem in development of sustainable agriculture.To explore characteristics of the salt distribution and accumulation in soils as affected by rate of under-mulch drip irrigation with brackish water, a field experiment was carried out in the Water-saving Irrigation Experiment Station of the Shihezi University. The experiment was designed to have three irrigation rate treatments, Treatment Q36: 3 150 m3 hm-2, Q48: 4 200 m3 hm-2 and Q60: 5 250 m3 hm-2, and used water 3.32 g L-1 in salinity. Analysis of soil samples taken before and after the irrigation indicated that the soil salinity in the root area demonstrated a basical declining trend at the forming stage of a wetted soil volume, and accumulation at the redistribution phase of soil water, while that in the soil under the root displayed an opposite way, rising in the former phase and falling in the latter. Analysis of salt distribution and balance in the soil profiles after harvest show that in Treatments Q36 and Q48, the input of salt with the irrigation stayed mainly in the 0~120 cm soil layer column, while in Treatment Q60, soil salinity increased significantly in the soil below 120 cm. Irrigation contributed about 21 percent of the increase. It was found that after 36 hours of irrigation, the wet front got into 80, 90 and 120 cm deep in Treatments Q36, Q48 and Q60, respectively. The water from the dripper infiltrated deep into the soil, bringing down salt into deep layers of the soil profile, which contributes positively to mitigating the problem of salt accumulation in the surface soil.