利用3年(2008-2011年)的野外对比试验与长期实地监测数据,分析喀拉米吉绿洲滴灌沙枣(Elaeagnus angustifolia)防护林地的土壤盐分及动态情况。结果表明:(1)林地在滴灌与不滴灌条件下,土壤盐分含量差异显著(p〈0.05)。在不同灌水量条件(单株单次灌水18,30,48L)下的林地土壤盐分含量与分布特征不相同,其中单株单次灌水48L处理与对照相比,土壤盐分含量差异达极显著水平(p〈0.01);3种不同灌水量处理(18,30,48L)分别使30cm以上土层、50cm以上土层、整个根系土层的盐度值低于1.4mS/cm;(2)在沙枣生育期内,土壤盐分呈现逐渐上升的趋势,且通过了显著性水平;不同深度(20,40,60cm)的土壤盐分上升趋势有差异,其中40cm深处土壤盐分上升趋势最显著,20cm与60cm深处趋势水平差异不大;(3)在1个灌溉周期内(20d),林地土壤盐分动态表现为集中-均匀-集中的过程。停水后第2天,上层土壤盐分含量明显下降,滴灌将盐分压于30cm以下,并集中于40-60cm土层;停水后第4~8天,整个观测范围内的剖面土壤盐分明显下降,原聚集于中土层的盐分基本消失,从而使停水后第4~8天土壤盐分淋洗效果最显著;停水后第12天,剖面高盐分土层又重新出现,然后随着时间的延续高盐分土层愈加明显。因此,随着1个灌溉周期的结束,高含盐量土层的位置逐渐上移,其范围逐步扩大;(4)本试验中,在种植的第2~3年,水分供给不足是沙枣成活率低、生长量低的主要原因,而影响沙枣第1年成活率的是土壤次生盐渍化(盐分高达5~9mS/cm)。滴灌洗盐只是局部,建议滴灌防护林1年采取1次大水漫灌。
Based on three years of field test from 2008 to 2010, distribution characteristics of salinity in Elaeagnus angustifolia shelterbelts was checked in Kalami oasis in the lower reaches of Tarim river. The main results are as follow: (1)There was significant difference in salinity between shelterbelt with drip irrigation and without any irrigation. There was different salinity and salinity distribution characteristics under different irrigation amount treatments (18, 30, 48 L for per plant each time). The treatments of 18, 30, 48 L made the high salinity layer respectively under 30 em underground, 50 cm underground, and the whole scope of roots. (2)During the growth period of Elaeagnus angustifolia, there was a increasing trend in salinity and the test value(Zc) was significant. There was difference in trend level in different soil depth, among them the Zc was the largest in 40 cm, and there was almost no difference between that in 20 cm and 60 cm. (3)Within a irri- gation cycle(20 days), since 2 days after the irrigation the leaching depth by drip irrigation increased with time, leaching effects was significantly compared to the contrast(p~0.01), but with the ending of a irriga- tion cycle, the position of soil layer with high salinity gradually moved up, the scope of soil with high salinity gradually increased. On the 16th day after irrigation, the salinity of 70 cm above soil exceeded 2 mS/cm, and on the 20th day after irrigation, the salinity of 70 cm above soil exceeded 2.5 mS/cm. (4)Scare water was the main reason to the poor survival rate of the 2-year and 3-year shelterbelts, and heavy salinity was the main reason to the poor survival rate of the 1-year shelterbelt. Accordingly, there was only partial impact of drip irrigation on salinity in shelterbelt. It is proposed taking a flooding irrigation at least once a year.