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通过室内恒温(25℃)培养试验,研究了不同用量水稻秸秆钾和化肥钾在水-土体系中的释放与分布特征。结果显示,施用水稻秸秆钾300 mg/kg处理,表层水溶液pH经历了一个弱酸化到弱碱化的过程,而化肥钾的施用则降低了表层水溶液的pH。稳定态时相关分析表明,pH与水稻秸秆钾用量正相关(R2=0.938**),与化肥钾负相关(R2=0.993**)。试验开始当天外加300 mg/kg化肥钾处理表层水溶液钾浓度达到最大值,为50.64 mg/L,随后呈下降趋势。5天时土壤缓效钾含量达到最大值414.51 mg/kg,并保持相对稳定,而速效钾钾含量继续升高,25天后变化较小。外加300 mg/kg水稻秸秆钾处理表层水钾浓度在第3天达到最大值,为52.70 mg/L,之后呈下降趋势,但在相同时期时,秸秆钾处理表层水溶液钾含量高于化肥钾处理。不同钾素用量结果表明,施钾量为150 mg/kg时,两种来源钾主要以交换态钾存在,其次是水溶态钾;随着钾素用量的增加,钾离子被土壤固定,且在等量条件下,水稻秸秆钾处理的交换态钾比例高于化肥钾处理,而非交换态钾所占比例则相反。因此,在一定钾素用量范围内,土壤对秸秆钾和化肥钾的固定没有显著差异,而当用量超过阈值时,秸秆的投入会降低土壤对钾素的固定。
The indoor temperature (25 ℃) culture experiments were conducted to study the release and distribution of potassium and potassium in rice straw in water-soil system. The results showed that the pH of surface aqueous solution undergone a weak acidification to weak alkalization when rice straw 300 mg / kg K was applied. However, the application of chemical fertilizer potassium decreased the pH of the surface aqueous solution. The steady state correlation analysis showed that pH was positively correlated with rice straw (R2 = 0.938 **) and negatively correlated with potassium (R2 = 0.993 **). At the beginning of the experiment, the concentration of potassium in the surface aqueous solution was increased to 50.64 mg / L with the addition of 300 mg / kg potassium fertilizer, and then decreased. After 5 days, the soil slow-acting potassium content reached the maximum of 414.51 mg / kg and remained relatively stable while the available potassium and potassium levels continued to increase and changed little after 25 days. The concentration of potassium in the surface water treated with 300 mg / kg K showed the highest value at the third day, which was 52.70 mg / L, and then decreased. However, at the same time, the content of potassium in the aqueous K by straw was higher than that of the fertilizer K . The results of different K application showed that potassium was mainly exchanging potassium and potassium was soluble in water when K was 150 mg / kg. Potassium was fixed by soil with the increase of K, Under the same amount of conditions, the exchangeable potassium content of rice straw was higher than that of chemical fertilizer potassium treatment, while the proportion of non-exchangeable potassium was the opposite. Therefore, within a certain range of potassium content, there was no significant difference in the fixation of K and K between soil and straw, but when the amount exceeded the threshold, straw input could reduce the fixation of K in soil.