竖井对新疆盐碱地新开垦枣田土壤盐分的影响

为研究竖井排水工程对极端干旱区新开垦盐碱地水盐运移的影响,本文在新疆和田地区墨玉县新开垦枣树种植灌区布设2口井深30 m、直径250 mm、间距500 m的竖井进行田间试验,测定不同距井距离下各土层深度土壤含盐量,以两年田间实测资料为依据分析滴灌条件下竖井排盐效果。结果表明:在距离竖井0~250 m的土层深度0~100 cm内,果实成熟期相比于萌芽期在2016年、2017年土壤总盐分别减少52.11%、56.58%,两年累计减少59.34%,萌芽期、果实成熟期分别减少9.34%、14.42%;2016年、2017年在距离竖井100 m范围内平均脱盐率分别为66.41%、70.09%,1m土体脱盐率分别为51.28%、56.06%;生育期间在距离竖井0~100 m、土层深度0~100 cm内高效均匀脱盐,非生育期间在距井0~100 m范围内土壤表层0~20 cm内返盐显著,而2017年萌芽期比2016年萌芽期在距井0~100 m范围内土层0~100 cm脱盐率为15.77%,竖井工程明显降低年际间返盐程度并导致年内间土壤全剖面显著脱盐,试验期间竖井脱盐效果随运行时间增加有所增强,但基本保持稳定。因此,竖井排水降盐效果最优的范围在距井100m内,竖井对新疆新开垦林果种植灌区的盐碱化程度有明显改良作用。

Comparative investigation on soil salinity leaching under subsurface drainage and ditch drainage in Xinjiang arid region

This study was carried out to explore the effects of leaching salinity under subsurface drainage and mulched drip irrigation on saline and alkaline land from the year 2012 to 2014 in Xinjiang Region of China.Three sampled points were both set up in the subsurface drainage and ditch drainage areas.Soil samples were obtained at varied depths.Through observing the underground water table under each sampled point and measuring the electrical conductivity(EC)of the soil extracts,the following results were obtained:(1)after draining,the underground water table ranged from 1.6 m to 2.2 m in the ditch drainage area,and ranged from 1.5 m to 2.2 m in the subsurface drainage area.Thus,both irrigations could control underground water table below 1.5 m which is deeper than the main water-absorbing layers of crop root systems;(2)for subsurface drainage,the closer to the pipe,the better to leach salinity;decreased from the initial 13.54-22.95 g/kg to 8.20-11.47 g/kg;(3)compared with the amounts in 2012,soil total salt at each sampling point at depths of 0-200 cm in subsurface drainage area decreased by 42.99%,36.84%and 24.41%respectively in 2014;and in ditch drainage area decreased by 46.85%,38.12%and 30.80%respectively in 2014.The results showed both ditch and subsurface drainage could leach salinity effectively.