【作者】 王志勇；

【导师】 白由路；

【作者基本信息】 中国农业科学院 ， 植物营养学， 2012， 博士

【摘要】 试验于2008年10月-2011年10月在中国农业科学院国际高新技术园区国家测土施肥中心实验室试验基地（河北省廊坊市）进行。本研究试验处理设秸秆还田配施钾肥（NPK+St），施用钾肥（NPK）、秸秆还田（NP+St）、对照（NP）4个处理，试验为随机区组设计。通过3年6季的试验，在我国华北平原冬小麦/夏玉米轮作条件下，研究秸秆还田和施钾肥对作物产量的影响、作物—土壤系统钾素表观平衡和秸秆还田替代化学钾肥比率。同时，从试验区取0~20cm土样，应用不同的浸提剂提取土壤不同形态钾素，研究不同形态钾素在土壤的动态平衡；通过加入不同浓度的外源钾素研究土壤对外源钾素固定能力；通过采取振荡平衡法，利用0.01mol/LCaCl2和0.01mol/L草酸为浸提介质研究土壤非交换性钾释放规律。主要结论如下：与NP处理相比，NPK+St、NPK和NP+St处理均有明显的增产效应，NPK+St处理的效果最好，小麦产量为4148.0kg/hm~2，与对照相比增产13.3%，玉米产量为6416.1kg/hm~2，与对照相比增产17.4%。施钾在小麦上增产318.9kg/hm~2，增产幅度为8.6%，在玉米上增产688.7kg/hm~2，增产幅度为12.4%，施钾在玉米上的增产效果优于小麦。秸秆还田在小麦上增产169.3kg/hm~2，增产幅度为4.5%，在玉米上增产259.8kg/hm~2，增产幅度为4.5%。小麦季玉米秸秆还田的替钾率在25.2%，玉米季小麦秸秆还田的替钾率在20.3%。秸秆还田配施钾肥处理的钾肥回收率、农学效率、偏生产力均大于施用钾肥处理。与NP处理相比，NPK+St、NPK和NP+St处理均可提高土壤水溶性钾、非特殊吸附钾、特殊吸附钾、非交换性钾含量，对土壤矿物钾以及全钾含量影响不大。NPK+St、NPK和NP+St处理也可提高土壤水溶性钾、非特殊吸附钾在速效钾中的比例，增加土壤速效钾和非交换钾在全钾中的比例。NPK+St处理下土壤各形态钾素与试验开始相比均有提高，NPK、NP+St和NP处理的土壤各形态钾素均有下降，NP处理下降幅度较大。秸秆还田和施钾肥可提高作物钾素吸收总量，除NPK+St处理外，其它各处理的钾素支出总量均高于钾高投入量，造成土壤钾素不同程度的亏缺，NP处理的亏缺量最大。NP处理3年的K2O亏缺总量为720.1kg/hm~2，NPK处理的土壤钾素也有相当数量的亏缺，3年的K2O亏缺总量为497.8kg/hm~2，NP+St处理土壤钾素3年的K2O亏缺量为63.5kg/hm~2，而NPK+St处理的土壤钾素有盈余，3年的K2O盈余量为248.9kg/hm~2。钾素表观平衡系数除NPK+St外，均小于1，NPK+St、NPK、NP+St处理的表观平衡系数分别为1.26、0.42、0.92。在外源钾加入浓度400～3600mg/L的范围内，秸秆还田和施钾肥可显著降低土壤对外源钾素的固定量，土壤固钾量随外源加入钾素浓度的增加而增加，但固钾率下降。在同一浓度外源钾加入水平下，NPK+St处理土壤固钾量最低，NPK和NP+St处理次之，NP处理土壤固钾量最高。NPK+St处理土壤固钾量与试验开始相比下降，而NPK、NP+St和NP处理土壤固钾量与试验开始相比增加，NP处理固钾量增加幅度较大。秸秆还田和施钾肥可能通过影响土壤速效钾含量、缓效钾含量、有机质、土壤K+饱和度（KSR）和阳离子代换量（CEC）的变化而改变土壤对外源钾素的固定能力。在0.01mol/L CaCl2和0.01mol/L草酸两种浸提剂中土壤非交换性钾的释放特征基本相似，各处理土壤的最大释放量也表现为：NPK+St>NPK>NP+St>NP。土壤非交换性钾最大释放量与试验前相比，NPK+St处理在241小时最大释放量在两种浸提剂中分别增加了9.2mg/kg和21.5mg/kg，NPK处理与NP+St处理变化不明显，而NP处理241小时最大释放量在两种浸提剂中分别减少8.8mg/kg和61.5mg/kg。用一级反应方程可以较好的对土壤非交换性钾的释放进行描述，各处理土壤在两种浸提中非交换性钾释放速率参数大小表现为：NPK+St>NPK>NP+St>NP（0.01mol/LCaCl2浸提剂）和NPK+St> NP+St> NPK>NP（0.01mol/L草酸浸提剂），钾素投入较高的处理土壤非交换性钾释放量较大，释放速率也大，土壤的钾素供应能力较强。NP处理土壤最大释放量和释放速率较小，土壤供钾能力较弱。更多还原

【Abstract】 The experiments were conducted from October2008to October2011in the experiment station ofNational Laboratory of Soil Testing and Fertilizer Recommendation of Chinese Academy ofAgricultural Sciences, which is located in Langfang city of Hebei Province. Four treatments weredesigned as a randomized complete block with three replications. Treatment1: no straw returned and noapplication of chemical potassium fertilizer (denoted as NP); treatment2: no straw returned andapplication of chemical potassium fertilizer (represented by NPK); treatment3: crops straw returned andno application of chemical potassium fertilizer (represented by NP+St); and treatment4: crops strawreturned and application of chemical potassium fertilizer (represented by NPK+St). Under the summercorn and winter wheat rotation system in North China Plain, a field experiment with six crops seasonsand three rotation systems was carried out to investigate the effects of crops straw returned to soil andapplication of chemical potassium fertilizer on the crops yield, K balance in soil-crops system, and theratio of chemical K replacement by straw. Meanwhile, the topsoil of0~20cm in the experiment wassampled to extract different forms of K by several solutions and study the distribution characteristics ofthe different forms of K in soil; to study the fixation ability of different concertrations of additive K; andto study the release characteristics of nonexchangeable K by the method of centrafiuge-balance with0.01mol/L CaCl2and0.01mol/L oxalic acid extractant. The main results as following:Compared with treatment NP, there were significant yield increasing in treatments NPK+St, NPKand NP+St, the optimal treatment was NPK+St, the yield of winter wheat and summer corn were4148.0and6416.1kg/hm~2, which increased by13.3%and17.4%in contrast to treatment NP, respectively.Application of potassium fertilizer could increase wheat and corn yield by318.9and688.7kg/hm~2, andthe yield increment was8.6%and12.4%in wheat and corn season respecitively. Generally speaking,the yield increase of corn was greater than that of wheat. Crops straw returned to soil could increasewheat and corn yield by169.3and259.8kg/hm~2, and the yield increment was4.5%and4.5%in wheatand corn season, respecitively. The ratio of chemical K replacement by corn straw was25.2%in wheatseason, and that by wheat straw was20.3%in corn season. Compared with treatment NPK, there hadhigher recovery efficiency, agronomic efficiency and partial factor productivity from applied K intreatment NPK+St.In contrast to treatment NP, treatments NPK, NP+St and NPK+St significantly increased watersoluble K, nonspecific adsorption K, nonexchangeable K, mineral K and total K content; however, therewas no significant effect on specific adsorption K. The available K, slow-release K and total K in tillagesoil with crops straw returned to soil or potassium fertilizer application were significantly higher thanthose in treatment NP, and which increased with the growing seasons. Compared with the basic soil atbeginning of this experiment, soil available K content in treatment NP keeps declining. Crops strawreturned to soil and application of chemical potassium fertilizer could decrease the ratio of mineral Kaccount for total K in soil. In comparation with the application of potassium fertilizer, crops straw returned to soil significantly increased the ratio of water soluble K, nonspecific adsorption K,nonexchangeable K and mineral K account for total K.Crops straw returned to soil and application of chemical potassium fertilizer significantly increasedtotal K absorption, except the treatment NPK+St, some other treatments with lower K input had lowtotal K absoption and caused soil K deficiency, espspecially in treatment NP. Deficit of K in soil withtreatment NP was the highest, the total deficit of K2O was720.1kg/hm~2after three years; however,there was still deficit of K2O in soil with treatment NPK, which was497.8kg/hm~2after three years;treatment NP+St could nearly maintain soil K balance, only had deficit of K2O by63.5kg/hm~2; soil Kwas surplus in treatment NPK+St, which was248.9kg/hm~2of K2O. The indexes of K balance were1.26,0.42and0.92in treatment NPK+St, NPK and NP+St, respectively, which indicated that except fortreatment NPK+St, indexes of K balance in other treatments were less than1.After3years crops growing, when the concentrations of additive K were ranged from400to3600mg/L, crops straw returned to soil or application of chemical potassium could significantly decreasedthe amounts of additive K fixed in soil, and the fixation ability of K increased with the concentration ofadditive K increase, whearas the proportion of fixation decreased. At the same concentration of additiveK, the K fixation amounts were in the following order: NPK+St<NPK and NP+St<NP. Compared withthe start of basic soil, soil K fixation declined in treatment NPK+St, whearas increased in treatmentsNPK, NP+St and NP, the increament was high in treatment NP. Both crops straw returned to soil andapplication of potassium fertilizer could influence the content of soil available K, slow available K, soilorganic matter, K+saturation (KSR) and CEC, therefore, which influence the fixation ability of additiveK.There were similar characteristics of soil nonexchangeable K release in two extraction solution of0.01mol/L CaCl2and0.01mol/L loxalic acid, the maximal amounts of soil nonexchangeable K releasehad the trendicy of NPK+St>NPK>NP+St>NP. Compared with the basic soil, there was significantdifference in all treatments, the maximal amount of soil nonexchangeable K release in treatmentNPK+St was found after241hours in two extraction solutions, which increased by9.2and21.5mg/kg,respectively; there was little change in treatment NPK and NP+St; however, the maximal amount of soilnonexchangeable K release in treatment NP after241hours with two extraction solutions decreased by8.8and61.5mg/kg, respectively. Soil nonexchangeable K release could be well discribled by first-orderrelease kinetic equations. According to different K input treatments, the parameters of release rate ofnonexchangeable K in two different extraction solutions were NPK+St>NPK>NP+St>NP or NPK+St>NP+St> NPK>NP, and the release amounts and rates of nonexchangeable K, and soil K supplyingability were greater in high K input treatment. The release amounts and rates of nonexchangeable Kwere small in treatment NP, and soil K supplying ability was very limited.更多还原