滴灌条件下排水暗管间距对土壤盐分淋洗的影响

在滴灌淋洗条件下设计暗管排水试验,研究暗管不同埋设间距(15、20、25 m)对土壤剖面盐分分布及脱盐淋洗效果的影响。结果表明:滴灌淋洗期间,0~70 cm土层含盐量显著降低,与CK相比,试验地不同地段土壤平均含盐量减少10 g/kg以上。从暗管上方至相邻暗管中点位置处不同剖面土壤平均脱盐率逐渐减小,15、20、25 m间距小区在0~100 cm埋深土壤中点位置处最大脱盐率分别为84.01%、77.75%、73.98%,土壤整体脱盐率介于51.82%~60.43%之间。吸水管埋管间距越小,小区暗管排水阶段排水流量越大,排水矿化度、电导率也越大,但成本会略高。15 m间距相比20、25 m间距小区每公顷多投入的成本和平均脱盐率差值分别为8 430、12 570元和4.78%、8.61%;15 m间距暗管处理在水平距离暗管0、5、7.5 m处土壤脱盐率最大值分别为86.47%、85.15%、84.01%,且排水期间排水流量、矿化度、电导率最大,分别为2 m~3/h、189.15 g/L和35.9 mS/cm;土壤盐分淋洗效果优于20、25 m间距小区,淋洗相同盐分含量土壤所需灌水量也低于20、25 m间距;2次灌水后0~70 cm土层盐分整体已降至10 g/kg以下,作物生长条件大为改善,适宜作为指导新疆盐渍土改良滴管条件下暗管间距布设参数的依据。

Effects of Drainage Pipe Spacing on Soil Salinity Leaching under Drip Irrigation Condition

In order to explore the water saving and efficient alkali-saline land pattern, the underground pipe drainage experiment was designed under the condition of drip irrigation to seek the effects of different buried spacings in the width of 15m, 20m and 25m on salt distribution in soil profile and the desalination and leaching. The results showed that soil salinity in 0~70cm soil layer was decreased significantly during the drip irrigation, and compared with CK the average salinity of soils was decreased by more than 10g/kg. Different spacing widths of 15m, 20m and 25m below 100cm soil layer indicated different maximum soil desalination rates, which were 86.47%, 84.79% and 81.35%, respectively, and the total desalination rate of soil was between 51.82% and 60.43%. The smaller the spacing of the buried pipe was, the larger the drainage flow in the drainage and drainage salinity and conductivity were, and thus the cost would be slightly higher. However, compared with 20m and 25m, the actual investment was increase by 8430 yuan/hm2 and 12570 yuan/hm2 in the spacing of 15m and the overall soil desalination rate was increased by 1%. When 15m spacing drainage pipes in the horizontal distances of 0m, 5m and 7.5m, the maximum soil desalting rate was 86.47%, 85.15% and 84.01%, respectively, and drainage flow, salinity and conductivity during drainage were 2m3/h, 189.15g/L and 35.9mS/cm, respectively. Besides, soil salinity leaching curve fitting effect was better than 20m and 25m spacing area, and overall level of soil layer below 70cm was fallen to below 10g/kg and crop growth conditions were greatly improved, which was suitable as a parameter for the layout of the underground pipe drainage pipe of Xinjiang saline soil. These results revealed that the drip evolution mode had great importance for the underground pipe drainage salinity, laied the foundation for the following long-term research, ultimately achieved improvement goals, and met the conditions for the growth of the crops.