不同矿化度水源膜下滴灌对棉花土壤盐分分布及生长的影响

Effect of Drip Irrigation with Film Mulching on Soil Salinity Distribution and Cotton Growth under Different Water Source Salinity Levels

利用微咸水膜下灌溉是缓解干旱区农业灌溉资源短缺的有效途径之一,分析不同矿化度水源膜下滴灌对土壤盐分分布及作物生长的影响对于确定灌溉水源矿化度阈值具有重要意义。开展4 a不同梯度矿化度水源膜下滴灌棉花测坑试验,设置6个处理矿化度分别为1 g/L(CK)、2 g/L(A)、3 g/L(B)、4 g/L(C)、5 g/L(D)和6 g/L(E),分析不同梯度矿化度水源膜下滴灌土壤盐分累积及棉花生长特征,确定微咸水膜下滴灌棉花灌溉矿化度阈值。结果表明:2019-2022年,0~100 cm平均土壤电导率以每年0.920 dS/m、0.995 dS/m、1.196 dS/m和1.188 dS/m的速率呈线性增长的趋势。随着灌溉年限增加,不同梯度微咸水膜下滴灌下土壤电导率呈现增加趋势。5 g/L和6 g/L处理土壤盐分累积最大,分别为38.70%和39.19%;灌水12 h后,宽行表层20~40 cm土壤盐分累积最为明显,土壤电导率为0.30~2.1 dS/m;窄行土壤盐分在40~60 cm土层处出现累积,土壤电导率为1.26~1.93 dS/m。矿化度为3 g/L水源膜下滴灌棉花土壤盐分累积量较小,对棉花叶片光合作用指数影响最小,生长指标和产量达到最大,微咸水膜下滴灌棉花适宜的灌溉水源阈值为3 g/L。

Drip irrigation with film mulching by using brackish water is one of the effective ways to alleviate the shortage of agricultural irrigation resources in arid areas.It is important to analyze the effect of this method on soil salinity distribution and crop growth to determine the salinity threshold of irrigation water.In this four-year study,a pit test of drip was conducted for drip-irrigated cotton using water sources with different salinity gradients,including six treatments with salinity levels of 1 g/L(CK),2 g/L(A),3 g/L(B),4 g/L(C),5 g/L(D),and 6 g/L(E).We analyzed soil salinity accumulation and cotton growth characteristics under drip irrigation at different salinity levels,ultimately,we determined the salinity threshold for cotton when using drip irrigation with slightly salty water with film mulching.The results showed that during 2019-2022,the average soil conductivity of 0-10 cm exhibited a linear increase trend,with the annual rates of 0.920 dS/m,0.995 dS/m,1.196 dS/m and 1.188 dS/m.With the increase of irrigation years,soil conductivity under drip irrigation using water with different salinity gradients demonstrated a rising trend.Soil salt accumulation was highest in the 5 g/L and 6 g/L treatments,at 38.70%and 39.19%,respectively;after 12 h irrigation,the soil salt accumulation was the most obvious in the 20-40 cm wide surface layer,and the soil conductivity was 0.30-2.1 dS/m.The soil salinity accumulated in the 40-60 cm soil layer,with soil conductivity between 1.26-1.93 dS/m;the soil salt accumulation of cotton under drip irrigation of film mulcing with salinity of 3 g/L water source showed minimal effect on the photosynthetic index of cotton leaves.The optimal irrigation water source threshold for cotton under drip irrigation with brackish water was determined to be 3 g/L.