长期施钾对水旱轮作系统产量及土壤团聚体钾分布的影响

Effects of long term potassium fertilizer application on crop yield and potassium distribution in soil aggregates in paddy-upland rotation system

【目的】研究长期施用钾肥对水旱轮作系统产量、土壤团聚体分布及有效钾含量的影响,探明水旱轮作系统中钾素在土壤团聚体组分中的分配规律,进而为土壤结构改良、钾库管理和钾肥合理施用提供理论依据。【方法】2011~2017年在湖北省江汉平原布置中稻—冬油菜轮作定位试验。试验选择氮磷肥(不施钾肥,-K)和氮磷钾肥(施钾肥,+K)处理,对比分析施用钾肥对中稻—冬油菜轮作系统的产量及不同深度土壤有效钾含量和团聚体分布产生的影响。【结果】轮作系统产量变幅受年份和施肥的双重影响,与不施钾肥处理相比,施用钾肥后水稻和冬油菜的年均增产量为0.51和0.33 t/ha,增幅分别达7.5%和14.1%。连续7年施用钾肥对土壤团聚体的垂直分布无明显影响,但可增加20~30和30~40 cm土层的水溶钾和速效钾含量及各粒级团聚体中速效钾含量。通过不同土层土壤团聚体速效钾的盈缺值计算得出,10~20和30~40 cm土层的土壤速效钾盈缺值变幅最明显。【结论】与2011年农田初始有效钾含量相比,2017年钾肥用量会导致农田钾素含量持续缓慢下降,因此,应重视秸秆还田和有机钾肥的补充,以维持轮作系统生产力和农田钾素平衡。

【Objective】The effects of long-term potassium（K）fertilizer application on yields in paddy-upland rotation system,distribution of soil aggregate,and available K content were studied to ascertain the distribution rules of K in the soil aggregate components in paddy-upland rotation system,and then to provide theoretical basis for soil structure improvement,potassium pool management and reasonable application of K fertilizer.【Method】Rice-winter oil rapeseed rotation experiments were carried out in Jianghan Plain,Hubei Province from 2011 to 2017. Two treatments namely,nitrogen phosphorus fertilizer（application without K fertilizer,-K）and nitrogen,phosphorus and potassium fertilizer（application of K fertilizer,＋K）were selected in this study to make comparative analysis on the effects of K fertilizer application on the yields in rice-winter oil rapeseed rotation system,available K content and soil aggregate distribution at different soil depths.【Result】The output in the crop rotation system was affected by both year and fertilization. Compared with the K treatment,after application of ＋K treatment the average annual yield increases of rice and winter oil rapeseed were 0.51 and 0.33 t/ha respectively,with the growing rates of 7.5% and 14.1%. The long-term application of K fertilizer（7 years）had no obvious effects on the vertical distribution of soil aggregates,but it could increase the water-soluble K content and available K content at soil layers of 20-30 and 30-40 cm,and the available K content in each size fraction aggregates.In addition,the amplitude of available K balance in the 10-20 and 30-40 cm soil layers were the most obvious through calculating the surplus-deficit of available K in soil aggregates at different soil layers.【Conclusion】Compared with the initial available K content of farmland in 2011,the application rate of K fertilizer in 2017 will lead to a sustained and slow decline in the soil K content of the farmland. Therefore,it is suggested to pay attention to straw returning and the supplement of organic fertilizer to maintain the productivity of rotation system and K balance in farmland.