河套灌区不同覆膜方式膜下滴灌土壤盐分运移研究

A Study on Soil Salinity Movement of Drip Irrigation Under Different Film Mulching Treatment in Hetao Irrigation District

随着灌溉面积的增加和引黄水量的减少,河套灌区土壤盐渍化和水资源紧缺的问题日益突出,为保持农田水土环境的良性发展,以内蒙古河套灌区曙光试验站为研究对象,开展不同覆膜方式膜下滴灌土壤水盐运移规律研究。试验设置全膜覆盖(PQ)和半膜覆盖(PB)2个处理,采用5TE土壤水盐监测探头测定剖面土壤含水率和电导率。结果表明:膜下滴灌过程中剖面土壤盐分发生再分布,滴头下方30cm附近形成主要脱盐区,盐分逐渐向湿润区外缘积聚。半膜覆盖处理土壤盐分在膜间表层聚集,全膜覆盖处理保水抑蒸效果明显,起到了较好的压盐效果。表层土壤电导率值具有距滴头水平位移50cm>20cm>0cm的特点,膜间电导率值波动较大。不同水平位置处土壤电导率曲线变化规律相同,随土层深度增加振幅变小。全生育期内0—70cm深度土层不同覆盖方式均起到了一定的脱盐效果,半膜覆盖2个生长季内盐分变化(SA)分别为4.71mg/hm^2和9.24mg/hm^2,全膜覆盖处理SA分别为12.22mg/hm^2和21.55mg/hm^2。全膜覆盖处理可以有效抑制土壤水分蒸发,减弱盐分随水向上运动趋势,创造适宜作物生长的淡盐环境。可为河套灌区膜下滴灌种植模式下田间水盐管理提供理论依据。

In recent years, with the increase of irrigation area and the decrease of water quota from the Yellow River, several agro-ecological issues, such as water scarcity and soil salinization, are becoming more and more severe. It is important to maintain a farmland ecological environment and soil health. In order to explore soil salinity movement of mulched drip irrigation under different plastic film mulch modes in arid areas, a two-year consecutive experiment was carried out in the Shuguang experimental station located in Hetao Irrigation Area. We designed two treatments, including flat tillage with full film mulching （PQ） and flat tillage with half film mulching （PB）. Soil moisture and salinity was checked by 5TE sensor. The results indicated that soil salinity was redistributed after drip irrigation. The main desalination area was formed with 30 cm under the dripper, and salt accumulated towards the outer side of the humid area. Soil salinity of the partial film mulching treatment was likely to build up on the surface of the un-filmed soil by evaporation. However, full film mulching treatment could effectively decrease soil salt due to the effects of soil moisture. Under mulched drip irrigation, salt content of different horizontal position from drip irrigation zone showed the same trends of electrical conductivity curve variation, and the variation decreased with the increasing soil depth. Soil electrical conductivity of the surface layer followed the order of 50 cm〉20 cm〉0 cm with the distance from the driooer, and soil conductivity value fluctuated greatly in the soil without film mulching.During the whole growing stages, different film mulching treatment all played a certain desahing effect on the 0--70 cm soil layer, the desalination capacity of partial film mulching treatment was much less than that of the full film mulching treatment. Soil salt content （SA） of the half film mulching treatment in the two growing seasons was 4.71 mg/hm2 and 9.24 mg/hm2 , respectively, and SA of the full film mulching treatment was 12.22 mg/hm2 and 21. 55 mg/hm2, respectively. Full film mulching treatment efficiently restrained soil water evaporation, resulted in decreased upward movement of soil salt, and created suitable environment for the growth of crops. The results will provide a theoretical basis for water and salt management under mulched drip irrigation in Hetao irrigaiton district.