灌淤土区长期施钾对作物产量与养分及土壤钾素的长期效应研究

Effect of long-term potassium application on irrigated soil potassium and on the yield and nutrient of crops

通过在宁夏灌淤土区长达14年的连续施钾和小麦秸秆还田试验, 研究钾素投入对作物产量、养分和土壤钾素状况的影响。结果表明：小麦秸秆还田和长期施用钾肥均可不同程度提高小麦和玉米的经济产量, 其中施钾年平均增产小麦244 kg·hm^-2, 玉米397 kg·hm^-2, 处理之间产量表现为氮磷钾肥配合秸秆还田〉施用氮磷钾肥〉氮磷肥配合秸秆还田〉只施用氮磷肥。定位后8-10年施钾肥开始显著有效, 玉米显效时间早于小麦；秸秆还田和钾肥的投入均可提高籽粒和秸秆的钾素吸收量, 秸秆含钾丰富, 籽粒钾含量仅占植株钾总量的13%-17%；施用钾肥可提高作物籽粒大中微量元素含量而降低秸秆中、微量元素含量, 促进籽粒对大部分元素的吸收；长期不施钾肥处理（NP和NP＋St）0-20 cm土层土壤速效钾和缓效钾含量较定位开始时下降; 所有处理土壤全钾含量均表现下降, 下降幅度为0.8-1.2 g·kg-1。

An experiment on the long-term application of potassium （K） fertilizer and wheat straw in irrigated soils of Ningxia, northwestern China began in 1993. The objective of the experiment was to determine the effect of K fertilizer application and wheat straw return to soil on crop nutrient content and yield and the status of soil K in plowed soil layers. The results show that K fertilizer and wheat straw increase yield of wheat and maize. K fertilizer treatments increase wheat yield by 244 kg·hm-2 and maize yield by 397 kg·hm-2 annually. The order of all treatments effect on yield is as follows： NPK＋straw 〉 NPK 〉 NP＋straw 〉 NP. K fertilizer has a significant effect on crop yield when it is continuously applied for 8-10 years. Significant response of yield to K application occurs earlier in maize than in wheat. Furthermore, K fertilizer and wheat straw return to soil increase potassium content in the kernel and straw of the crops. There is a higher potassium content in straw, while it in kernels accounts for only 13%-17% of the total potassium content of plant. Furthermore, K fertilizer enhances the elements contents of kernels and accelerates element absorption by kernels. However, K fertilizer reduces trace- and micro-elements in straw. The content of 0-20 cm soil available K and slowly available K in non-potassium （NP and NP＋Straw） treatments for long-term application decrease. Total K content in all treatment declines at a rate of 0.8-1.2 g·kg^-1.