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通过测定与调查铁尾矿区营建沙棘-桑树人工混交林的土壤理化性质、养分含量及分布,评价人工混交林对铁尾矿区土壤改良的作用。与新尾矿区土壤相比,沙棘-桑树混交林下尾矿土壤容重与毛管孔隙度分别减小5.85%、5.04个百分点,空气孔隙度和自然含水量分别增加了10.97、1.35个百分点,混交林下尾矿土壤0～40 cm土层的平均相对含水量比新尾矿土壤增加12.90个百分点,表明混交林植物根系的生长促使原来致密的尾矿砂土的物理性质得到有效改善。混交林对尾矿碱性土壤的改良作用明显,且桑树的改良作用优于沙棘。混交林下尾矿土壤中的有机质含量增加,为对照新尾矿土壤的7.22倍,有机质含量随土层加深而递减,且均有一定的表聚性,主要分布在0～20 cm土层;但混交林下尾矿土壤中的有机质含量仍然较低,仅是该区域对照山地天然灌丛土壤的17.15%。混交林下尾矿土壤速效态大量元素的含量依次为速效P>速效K>碱解N,全量为K>P>N,其中沙棘根系周围土壤中的全N、全P、全K含量高于桑树,而桑树根系周围土壤中的全Ca和全Mg平均含量略高于沙棘。依据上述结果认为,沙棘-桑树人工混交林可有效改良铁尾矿土壤的理化性质,增加土壤养分含量。
Soil physical and chemical properties, nutrient contents and distribution of Hippophae rhamnoides mixed with mulberry plantation in the iron-tailing area were measured and investigated to evaluate the effect of mixed plantation on soil improvement in the iron tailings area. Compared with the soil in the new tailing area, the soil bulk density and capillary porosity of the tailings in the seabuckthorn-mulberry mixed forest decreased by 5.85% and 5.04% respectively, while the air porosity and natural water content increased by 10.97 and 1.35 percentage points respectively. The average relative water content of 0-40 cm soil layer in lower tailing soil increased by 12.90 percentage points compared with that of new tailings soil, indicating that the growth of root system in mixed plantation improved the physical properties of original dense tailings sand soil effectively. Mixed forest on the improvement of alkaline soil tailings significantly, and the improvement of mulberry better than sea buckthorn. The content of organic matter in the tailing soil increased 7.22 times than that of the new tailings soil. The content of organic matter decreased with the deepening of the soil layer, and both had some surface aggregation, which mainly distributed in 0 ~ 20 cm soil layer. However, the content of organic matter in the tailings soil under mixed forest was still low, only 17.15% of the native shrub soil in the control mountainous area. The content of soil available N, P and K in the tailings of mixed forest was: available P> available K> alkali N, and the total K> P> N. The content of total N, total P and total K in the soil around the root of Hippophae rhamnoides L. was higher than Mulberry, while the average content of total Ca and total Mg in the soil around the root of mulberry was slightly higher than that of seabuckthorn. Based on the above results, it is considered that the artificial mixed forest of seabuckthorn and mulberry can effectively improve the physical and chemical properties of soil and increase the nutrient content of soil.