含盐土壤不同作物根系分布对水盐分布的影响

Effect of root distribution of different crops in salt-containing soil on soil water and salt

以相同含盐水平农田种植的紫花苜蓿与玉米为研究对象,研究根系分布变化对水盐分布的影响,为盐渍化土壤紫花苜蓿合理化种植提供参考.结果表明:整个生育期0~100 cm苜蓿平均土壤含水率显著低于玉米,深层60~100 cm土壤平均含水率比玉米低1.98%,其有效利用深层水分.土壤平均储盐量随时间上下波动逐渐减小,二者盐分分布规律不同,苜蓿8月前后浅层土壤盐分均匀分布,玉米主要体现在8月后期.苜蓿脱盐率显著高于玉米,生长后期苜蓿深层根系占比增大,根系分布密集土层,脱盐效果明显.苜蓿细根根长密度与HCO_3^-呈正相关关系,HCO_3^-随根长密度增大而增大,土壤中HCO_3^-可减缓K^++Na^+,Cl^-增加,使作物土壤达到降盐效果.

After farmlands adjusted the planting structure, the root distribution of different crops affec- ted water salt and vertical distribution. Alfalfa and maize planted in the same saline soil were taken as the research objects. The relationship between soil water, salt and root distribution was studied to pro- vide a reference for rationalized cuhivation of alfalfa in saline soil. The resuhs show that the average soil moisture content of alfalfa at 0 - 100 cm is significantly lower than that of maize in the whole growth period, and the average soil moisture content of alfalfa at the depth of 60 - 100 cm is 1.98% lower than that of maize, which effectively uses deep water. The average salt accumulation in the soil decreases gradually with time, and their salt distribution is different. The salt content of alfalfa in the shallow soil is evenly distributed around August, but that of maize appears mainly in late August. The salt removal rate of alfalfa is significantly higher than that of maize. The proportion of alfalfa deep root system in the late growth stage increases, and the soil layer is densely distributed in the roots, its de- salination is obvious. The root length density of alfalfa fine roots is positively COlTelated with HCO3^- , and HCOf increases with the increase of root length density. HCO3^- in soil can reduce the increase of K ＋ ＋ Na ＋ and Cl^- , which causes the desalination of the crop soil.