土壤物理因素影响钾素转化和扩散的初步研究

A Preliminary Study on the Influence of Some Soil Physical Factors on Potassium Transformation and Diffusion in Soils

选用浙江省嘉兴市的青紫泥田、黄斑田、黄化青紫泥田和半砂田等四种具有代表性的水稻土为供试土样,初步研究了温度和土壤水分等物理因素对这四种水稻土钾素转化和扩散的影响.结果表明:多次冻融、干湿交替处理分别提高土壤速效钾含量7～49％和25～52％,尤其是结构良好的黄斑田和黄化青紫泥田,其速效钾提高更为明显.随着温度增加,土壤速效钾水平显著提高,至600℃高温时,速效钾提高8.2～8.8倍.在还原条件下(Eh=-99～-224mV),土壤速效钾水平有下降的趋势,其下降幅度为4～15％.随着土壤含水量增加,水溶性钾在土壤中的扩散强度有明显提高,0.3巴含水量与0.8巴含水量相比,钾扩散系数提高4.3倍.因此建议:在大田施用钾肥的同时,还应注意配合干耕晒垡及冬季深翻等合理的水分管理和农作管理措施,以提高钾肥增产的经济效益.

Four kinds of representative paddy soils in the suburb of Jiaxing City of Zhejiang province were used to study the effect of some soil physical factors such as temperature, soil water content, etc. on potassium transformation and diffusion in soils. Experimental results showed that,1 ) Through several times freezing-thawing and drying-wetting alternations, available K in four soils increased by about 7-49% and 25-52% respectively in comparison with their air-dry ones. The effects of the two treatments mentioned above were especially in the soil which had good structure and permeability.2 ) With the increase of temperature, available K in soil rose markedly. Comparing 600℃ with the room temperature treatment, available K in the air-dry soil increased by about 7.2-7.8 times. Moreover, K diffusion coefficient in soil varied from 0.077(at 0℃ ) to 2.1(cm/s 10, at 30℃ ) . 3 ) Under the oxidation as a check, available K declined by 4-15%. Therefore it is important for paddy soil under strong reduction to drain-off the field. This will improve available K in the soil. 4 ) K diffusion coefficient increased with the increase of soil water content. In comparing 0.8 with 0.3 bar soil water content, the K diffusion coefficient increased from 0.56 to 2.4 ( cm/s 10); besides this, K diffusion coefficient in soil gradually decreased with prolonging diffusion time: this showed that in addition to suitable soil water management it was more important to supplement chemical K fertilizer timely as an effective measure to adjust K in the soil.