长期施钾与秸秆还田对华北潮土和褐土区作物产量及土壤钾素的影响

分析了在华北平原的河北潮土和山西褐土上连续13年施用钾肥和秸秆还田下的大田作物产量和耕层土壤钾素状况。结果表明，在施用氮磷肥基础上长期施钾和秸秆还田能增加小麦和玉米产量，各施钾处理产量与氮磷处理差异显著。两定位点钾肥和秸秆还田的效应不尽相同；小麦年际间各处理产量变异（CV≤13%）小于玉米（CV14%），河北潮土上的玉米增产效果高于小麦。与山西单作制度相比，河北轮作制度下土壤钾素支出大。秸秆还田和施用钾肥较只施氮磷肥可不同程度提高河北潮土和山西褐土0-20和20-40 cm两土层水溶性钾 （河北0-20 cm平均提高5.8 mg/kg，山西16.9 mg/kg，下同）、非特殊吸附钾（21.2 mg/kg，35.9 mg/kg）、非交换性钾（75.1 mg/kg，57.5 mg/kg）、矿物钾（0.03％，0.01％）及全钾含量；降低矿物钾比例的同时提高其余几种形态钾的比例。随土层加深，除矿物钾外，其余形态钾含量和比例均下降，特殊吸附钾不受施钾措施和土层深度的影响。直接施用钾肥效果优于秸秆还田，且两种措施对上层土壤各形态钾的影响效果大于下层土。

Effect of long-term application of potassium fertilizer and wheat straw to soil on yield of crops and soil potassium in fluvo-aquic soil and brown soil of northcentral China

Experiments of long-term application of K fertilizer and wheat straw to soil in Hebei fluvo-aquic soil and Shanxi brown soil in northcentral China were started in 1992. Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The results showed that K fertilizer and wheat straw could improve yield of wheat and maize, and yield in treatments of NPK and NPK+St was significantly different from yield of the NP treatment. The effect of K fertilizer and wheat straw application differed with fixed experimental sites. In two fixed sites, variation of wheat yield in each treatment（CV≤13%) was lower than maize yield（CV＞14%）, and efficiency of yield increase in maize was higher than in wheat in Hebei. In contrast with Shanxi, the waste of soil potassium was more serious in the rotation system in Hebei. Application of K fertilizer and straw could improve the content of water-soluble K（average increase was 5.8 mg/kg in 0-20 cm layer of Hebei, 16.9 mg/kg in Shanxi, same as follows）, non-specifically adsorbed K（21.2 mg/kg，35.9 mg/kg）, non-exchangeable K（75.1 mg/kg，57.5 mg/kg）, mineral K（0.03％，0.01％）, and total K compared with NP treatment in 0-20 cm and 20-40 cm soil layers, but reduce the proportion of mineral K and improve proportion of other forms of K in the two fixed sites. The content and proportion of all forms of K decreased with depth, except mineral K. The content and proportion of specifically adsorbed K were not significantly affected by K fertilizer and straw application or soil depth. In summary, the effect of K fertilizer directly applied to soil was better than wheat straw returned to soil, and the effects of both methods on each form of K in topsoil was stronger than in subsoil.