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研究了长期定位施肥试验中连续27年(1981-2007年)施用化肥和稻草对红壤水稻土钾素固定及其影响因素的影响。本试验选择了其中5个处理:CK(不施肥)、NP(施氮、磷肥)、NPK(施氮、磷、钾肥)、NP+RS(施氮、磷肥和稻草)和NPK+RS(施氮、磷、钾肥和稻草)。结果表明,在加入外源钾浓度0.4～4.0g/L的范围内,土壤固钾量均随着加入外源钾浓度的增加而增大。5个施肥处理的固钾能力存在差异,与试前土壤相比,长期不施钾(CK和NP)处理土壤的固钾能力增强,长期施钾肥或稻草(NPK、NP+RS和NPK+RS)处理土壤的固钾能力降低,长期施用钾肥和稻草是影响土壤固钾能力的重要原因,施钾量高的处理土壤的固钾能力低。在高强度稻-稻种植条件下,水稻作物从土壤中带走大量的钾。长期不施用钾肥,会导致土壤钾素的严重耗竭,此后施入的钾则会被土壤固定,导致钾肥对当季作物的有效性降低。当土壤中钾含量相对较高时,施入钾肥则不易被吸附固定。如果施入的钾不能及时被作物吸收利用,则极易被淋失。长期施用钾肥和稻草后,土壤速效钾和缓效钾含量增加,土壤的固钾能力降低;另外,长期施用钾肥和稻草引起土壤K+饱和度的增加,也使土壤的固钾能力降低。
The effects of fertilizers and straw on potassium fixation and its influencing factors in paddy soils derived from red soil for 27 consecutive years (1981-2007) were studied. In this experiment, five treatments were selected: CK (no fertilization), NP (NPK), NPK (NPK, NPK) and NPK + RS Nitrogen, phosphorus, potash and straw). The results showed that in the range of 0.4 ~ 4.0 g / L, the amount of potassium in soil increased with the increase of exogenous potassium concentration. There were differences in potassium fixation capacity between the five fertilization treatments. Compared with the pre-test soil, the ability of potassium fixation of CK and NP increased in the long-term, but the potassium fertilization or straw (NPK, NP + RS and NPK + RS ) Decreased soil potassium fixation capacity. Long-term application of potash and straw was the main reason that affected soil potassium fixation ability. Potassium fixation capacity of soil with high potassium content was low. Under high-intensity rice-rice cultivation, rice crops carry large amounts of potassium from the soil. Long-term non-application of K fertilizer will result in serious depletion of soil K, and subsequent application of K will be fixed by the soil, resulting in a reduced availability of potash for the current crop. When the soil potassium content is relatively high, the application of potash is not easy to be adsorbed and fixed. If the potassium applied can not be timely absorbed by crops, it is easy to be leaching. Long-term application of potash and straw increased soil available potassium and slow-acting potassium, and decreased potassium fixing ability. In addition, long-term application of potassium fertilizer and rice straw increased soil K + saturation and also decreased potassium fixing capacity of soil.