施肥方式对砂姜黑土钾素利用及盈亏的影响

以砂姜黑土长期施肥试验为平台,研究砂姜黑土冬小麦—夏大豆轮作系统下作物钾素吸收量、钾素回收率、土壤钾素盈亏量和速效钾含量的演变特征,探明土壤速效钾与外源钾投入、土壤累积钾盈亏的响应关系,分析不施肥(CK)、常规化肥(CF)、化肥+麦秆(SCF)、化肥+猪粪(PCF)、化肥+牛粪(CCF)等施肥方式对土壤钾素利用及盈亏的影响,以期探寻砂姜黑土地区高产高效的施钾方式。结果表明:29 a作物钾素平均回收率在55.1%~66.1%,高低顺序为CCFPCFSCFCF。土壤累积钾盈亏与土壤速效钾增量呈显著线性关系(p0.05),土壤中钾素每盈余100 kg hm-2,CF、SCF、PCF和CCF处理土壤速效钾含量分别增加1.4、1.8、2.3和15.8 mg kg-1;土壤钾素投入量与速效钾含量呈显著线性关系(p0.05),CF处理每投入钾100 kg hm-2,土壤速效钾含量增加0.4 mg kg-1,而SCF、PCF和CCF处理每投入钾100 kg hm-2,土壤速效钾含量分别增加0.5、0.6和4.3 mg kg-1,这说明适当增施有机肥可提升土壤钾素的供应能力。综上所述,投入有机物料是影响土壤钾素利用的重要调控措施,长期增施有机肥可提高作物钾素回收率以及土壤中盈余的钾素向速效钾的转化能力,本试验条件下以增施牛粪效果最好,猪粪和秸秆次之。因此,砂姜黑土小麦—大豆轮作系统下秸秆养畜过腹还田是实现作物高产高效的一种推荐施钾方式。

Effects of Long-term Fertilization on Soil Potassium Utilization and Budgeting in Vertisol Relative to Application Method

Objective] Soil potassium is an essential macronutrient for crop growth and plays a key role in maintaining high crop yield.However,so far it is still unclear as to dynamics of soil potassium utilization,especially quantitative relationships of content of soil readily available K with input of extraneous and budgeting of cumulative soil potassium relative to fertilization method.Therefore,this study was oriented to analyze dynamics of crop K uptake,crop K recovery rate,soil K budgeting and content of soil readily available K and to explore quantitatively relationships of soil readily available K with input of extraneous K and budgeting of cumulative soil K relative to fertilization practice based on a long-term fertilization field experiment in a field of vertisol in North China.Method] The long-term experiment,located at the Mengchen Agro-Ecological-Station in the Huang-Huai-Hai Plain,North China,was initiated in 1982 and designed to have five treatments,i.e.,CK (no fertilizer),CF (mineral fertilizers),SCF (mineral fertilizers plus wheat straw),PCF (mineral fertilizers plus pig manure),and CCF (mineral fertilizers plus cattle manure),and four replicates for each.Plots,70 m2 each in area,of the treatments and replicates were laid out in a randomized block design and separated from each other with cement boards embedded 50 cm deep.Soil samples were collected randomly from the top 20 cm soil layer of each plot along a S-shaped line,after the crop of soybean was harvested in October each year,with a soil core sampler (inner diameter 7 cm).Chemical N,P and K fertilizer was applied in the form of urea,calcium superphosphate and potassium chloride,respectively,at a rate the same as the local farmers did,i.e.,180 kg N,39.3 kg P,and 112 kg K hm-2 yr-1.Soil total K was measured with the sodium hydroxide melting-flame photometry,soil slowly available K with the nitric acid boiling-flame photometry,soil readily available K with the ammonium acetate extraction-flame photometry and crop K with the vitriol peroxide/hydroxidation-flame photometry.Result] It was found that the mean crop K recovery rate varied in the range of 55.1％ ～ 66.1％,relative to treatment and displaying an order of CCF ＞ PCF ＞ SCF ＞ CF.The content of soil readily available K increased somewhat in all the treatments except in CK,where the content declined steadily over time.The over-year mean content of soil readily available K exhibited an order of CCF (289.5 mg kg-1) ＞ PCF (133.0 mg kg-1) ＞ SCF (128.4 mgkg-1) ＞ CF (82.4 mg kg-1) ＞ CK (72.3 mg kg-1).On the whole,a significant (p＜0.05) positive linear relationship was observed between soil K budgeting and content of soil readily available K.The gain of each 100 kg hm-2 in soil K budgeting raised the content of soil readily available K in Treatment CF,SCF,PCF,and CCF by 1.4 mg kg-1,1.8 mg kg-1,2.3 mg kg-1 and 15.8 mg kg-1,respectively.Besides,a significant (p ＜ 0.05) positive linear relationships between input of soil K and content of soil readily available K was also observed in all the fertilization treatments.The input of each 100 kg hm-2 increased the content of soil readily available K by 0.4 mg kg-1,0.5 mg kg-1,0.6 mg kg-1 and 4.3 mg kg-1 in Treatment CF,SCF,PCF,and CCF,respectively.Compared to the increase in Treatment CF,that in the treatment amended with organic material (wheat straw,pig manure or cattle manure),that is,Treatment SCF,PCF and CCF was 25％,50％ and 975％ higher,respectively,which indicates that application of a proper rate of organic material may improve soil K supply capacity in soils the same in input of extraneous K and soil K budgeting.Conclusion] To sum up,application of organic material is an important practice regulating soil potassium utilization.Long term application of organic manure,especially cattle manure in the study,may increase crop potassium recovery rate and transformation rate of surplus soil K into readily available K.Therefore,the application of animal-digested crop straw is a recommended practice to achieve stable and high crop yields in fields of vertical under wheat-soybean cropping system in North China.