[目的]基于连续30年南方低产黄泥田培肥定位试验,研究土壤全钾、速效钾、缓效钾含量与钾素盈亏特性,明确钾肥投入量与产量的关系,以期为黄泥田钾素肥力定向培育及水稻钾肥施用提供科学依据.[方法]定位监测不施肥(CK)、单施化肥(NPK)、化肥+牛粪(NPKM)、化肥+全部稻草还田(NPKS)四种施肥处理代表性年份耕层土壤钾素含量动态变化,分析各形态钾素间及与有机碳含量的关系,并于相邻集中年份2010、201 1、2013、2014年采集植株样品以评价土壤钾素水平、土壤钾素盈亏、植株养分对钾肥投入量的响应. [结果]30年施肥处理下,土壤全钾含量平均较CK增加2.2％～5.0％,且双季稻年份不同处理差异较单季稻年份大,速效钾含量历年平均较CK增加43.9％～102.4％,以NPKS增加最为明显,而不同处理的土壤缓效钾含量无明显差异.土壤速效钾含量与全钾呈显著正相关,土壤全钾、速效钾含量与有机碳均呈极显著正相关.各施肥处理提高了收获期植株钾含量与累积量.NPKS处理每年盈余钾素(K2O) 101.1 kg/hm2,其余处理每年亏缺幅度为-89.4～-18.6 kg/hm2.钾肥用量、速效钾含量、土壤钾素盈亏量相互间呈极显著正相关,可推算出外源钾肥(K2O)每年投入量达到161.8 kg/hm2时,土壤钾素处于持平状态,其对应的土壤速效钾含量为95.3mg/kg.钾肥用量、速效钾含量、土壤钾素盈亏量及籽粒钾含量均与植株产量呈显著正相关. [结论]水稻增产效果与土壤钾肥投入量、速效钾含量及钾素盈亏量有关.黄泥田土壤速效钾较缓效钾、全钾更直接反映生产力水平.长期施肥提高了黄泥田土壤全钾与速效钾含量,NPK化肥加秸秆还田对增加土壤钾素盈余与提升速效钾效果要明显优于单施NPK化肥或NPK肥配合粪肥.%[Objectives] The study is aimed to reveal the evolution of different soil potassium fractions and the balance of potassium in yellow paddy soils after long-term fertilization,in order to provide scientific basis for improving soil potassium fertility and fertilizer application.[Methods] Four fertilization treatments were designed as control (CK),pure chemical fertilizer (NPK),NPK plus cattle manure (NPKM) and NPK plus straw (NPKS).The potassium contents of different potassium fractions in the topsoil,the organic carbon content were determined in selected years.Plant samples were collected to analyze relationship between soil potassium level,soil K balance,plant nutrient and input of potassium in 4 consecutive years.[Results] Compared with CK,the average soil total potassium contents in the fertilization treatments were increased by 2.2％-5.0％,the differences among the treatments were higher under double cropping rice system than under single cropping system.The soil readily available potassium contents were affected more than other potassium forms in all the fertilization treatments,the increases were in range of 43.9％-102.4％,and the largest increment was in the NPKS treatment.The slowly available potassium was not significantly different in all treatments.The soil readily available potassium content is significantly and positively correlated with the total potassium.There were most significantly positive correlations among soil total potassium,readily available potassium and organic carbon contents.The potassium contents and potassium uptakes in the plants were increased in the fertilization treatments at the harvest time,with the significant difference found in the NPKS treatment.In the NPK,NPKM treatments,the annual soil potassium was deficit of 89.4 and 18.6 kg/hm2,while in NPKS treatment,that (K2O) was surplus of 101.1 kg/hm2.The potassium application rate,readily available potassium content and potassium balance were significantly and positively correlated to each other.The calculated soil potassium exhibited an equilibrium state when the annual application rate of exogenous potassium reached 161.8 kg/hm2,and corresponding soil available potassium content was 95.3 mg/kg.The readily available potassium contents,potassium balance and potassium contents in the plants were significantly and positively correlated to plant yields.[Conclusions] The soil total potassium and readily available potassium contents were improved by long-term fertilization,with the largest increment of readily available potassium in the NPKS treatment.The yield increment is positively correlated with the readily soil available potassium content and potassium balance.The soil readily available potassium is more sensitive in directly reflecting the productivity than slowly available potassium and total potassium.Chemical NPK fertilizer combined with straw treatment produces obviously more soil potassium surplus than the NPK and NPKM,and thus leads to significant increase in soil readily available potassium content.
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