腐殖酸对耕地棕壤固钾与释钾作用的影响研究

EFFECT OF HUMIC ACIDS ON FIXATION AND RELEASE OF POTASSIUM IN CULTIVATED BROWN SOIL

通过室内等温培养试验,研究了施用富里酸和胡敏酸对耕地棕壤钾素释放和固定作用的影响。结果表明,施用腐殖酸可以促进土壤钾素的释放,并有随腐殖酸用量提高而增高的趋势。其中,施用富里酸4%,在25℃条件下培养21d,土壤的钾素释放量增加了6.25%,而在相同条件下,施用胡敏酸土壤钾素的释放量仅增加了2.26%;施用腐殖酸可以降低土壤对外源钾的固定量,在施用外源钾400mgkg-1土条件下,与对照比较各处理的固钾量差异均达到了极显著水平。外源钾施用方式对腐殖酸降低土壤固钾作用的影响不同,腐殖酸与土壤恒温培养7d以后施用钾素的固钾量低于钾素与腐殖酸同时施用处理的。腐殖酸对土壤钾素释放和固定的影响是通过对含钾矿物的溶解和层间堵塞以及对钾素的吸附作用实现的。

Laboratory incubation experiments in constant temperature were implemented to study influence of humic-acid and fulvic-acid on fixation and release of potassium in cultivated brown soil. The results indicate that application of humic acids accelerated potassium release from the soil, showing a tendency of the rate of K release increasing with the rate of humic acid addition. After incubating at 25℃for 21days, K release increased by 6.25% in the soil treated with 40 g kg -1 fulvic-acid, but only by 2.26% in the soil treated with humic-acid. Application of humic acids may reduce the rate of the soil fixing extraneous K. After application of 400 mg kg -1 K, the soils treated with humic acids differed significant from the soil in the control in K fixation. But the effect of humic acids reducing K fixation rate was affected by how K was applied. In the treatments where humic acids-treated soils were incubated in constant temperature for 7days before application of potassium, the K fixation rates were lower than that in the treatment of applying potassium and humic acids at the same time. The effect of humic acids on fixation and release of potassium in soil was accomplished by dissolving K-bearing minerals or blocking interlayers and adsorbing K.