秸秆还田替代化学钾肥对喀斯特峰丛洼地春玉米产量及土壤钾素的影响

Spring maize yield and soil potassium balance under replacement of potassium with straw in karst peak-cluster depression

基于中国科学院环江喀斯特站2006年开展的玉米/大豆套作长期定位施肥试验,利用2010—2014年监测数据,研究等量氮磷钾投入条件下,不同处理[对照(不施肥,CK)、全量化肥(NPK)、秸秆还田替代30%化肥钾(C7S3)、秸秆还田替代60%化肥钾(C4S6)]间秸秆还田与化肥施用的效果差异,以期为喀斯特峰丛洼地农田生态利用秸秆还田替代化肥量提供科学依据。结果表明:1)施肥处理5年春玉米平均产量是不施肥处理的4.12~4.17倍,C7S3和C4S6处理产量分别是NPK处理的98.3%和98.7%,施肥处理玉米产量及秸秆量均随时间呈增长趋势。2)施肥使玉米秸秆中含钾量、春玉米籽粒吸收氮磷钾量均显著高于不施肥处理,但施肥处理间无显著差异(P>0.05)。3)在钾素回收率、钾素吸收利用率、钾肥农学利用率以及钾肥偏生产力方面,C7S3和C4S6处理与全量化肥NPK处理间均无显著差异(P>0.05)。4)NPK处理年均钾素盈余量为3.00 kg·hm^(-2),显著高于C7S3处理(-1.90 kg·hm^(-2));而C4S6处理钾素年均盈余量最大,为8.22 kg·hm^(-2),实际平衡盈余率为7.4%。5)与试验初期相比,不施肥处理土壤速效钾含量下降15.9%,施肥处理极显著增加了土壤中速效钾含量(P<0.01);5年间施肥处理间年均速效钾含量增幅大小依次为:NPK>C7S3>C4S6,各处理间差异不显著(P>0.05)。6)经过8年耕作,土壤缓效钾含量在CK和C4S6处理中分别下降10.9%和4.9%,NPK和C7S3处理分别增加1.3%和22.4%。综上所述,秸秆还田替代部分化肥钾的施肥措施运用在喀斯特峰丛洼地可在保持春玉米较高产量的同时,维持土壤钾素动态平衡;其中60%秸秆钾替代量更有利于维持钾素表观平衡,而30%的秸秆钾还田量则更有利于土壤缓效钾的积累。

Based on a long-term experiment on maize-soybean relay intercropping system in Huanjiang Observation and Research Station for Karst Ecosystem,Chinese Academy of Sciences,the effects of straw in place of chemical potassium on spring maize yield and soil potassium(K)balance were investigated,aiming to provide scientific basis for the rational use of straw and fertilizer in karst peak-cluster depression.The experiment was started in2006,and the data were collected during2010-2014.Four treatments with four repetitions were set in this study,including CK(no fertilizer),NPK(chemical fertilizer),C7S3(30%K from straws and70%K from chemical fertilizer),C4S6(60%K from straws and40%from the chemical fertilizer).The results showed that:1)the annual yields of spring maize in fertilization treatments from2010to2014were4.12-4.17times that in CK treatment.The spring maize yields in C7S3and C4S6were98.3%and98.7%of that in NPK,respectively.The yields of grain and straw increased with time under fertilization treatments.2)Compared with CK,fertilizationtreatments significantly increased K amount in maize straw,with2.21-2.53times that in CK.N,P and K absorption amounts in maize grain under fertilization treatments significantly increased(P<0.01),but there was no significant difference among fertilizer treatments(P>0.05).3)There were no significant differences in recovery efficiency,absorption efficiency,agronomic efficiency and partial factor productivity of K among treatments of NPK,C7S3and C4S6.4)The annual surplus amount of K in NPK treatment was3.00kg·hm-2,which was significantly higher than that in C7S3(-1.90kg·hm-2).The most annual surplus amount of K was in C4S6,8.22kg·hm-2,with the surplus rate of7.4%.5)Compared to the beginning of the experiment in2006,soil rapidly available K declined by15.9%in2014.The fertilization treatments significantly increased amount of soil rapidly available K(P<0.01).The order of annual increase of soil rapidly available K from2010to2014in fertilization treatments were NPK>C7S3>C4S6,but no significant difference among treatments was observed(P>0.05).6)After8years of cultivation,soil slowly available K declined by10.9%and4.9%in CK and C4S6,while increased by1.3%and22.4%in NPK and C7S3,respectively.Overall,the straw returning to replace some K fertilizer was suitable for the soil in karst peak-cluster depression,which not only maintained the yield of spring maize,but also sustained soil K dynamic balance.And60%of the straw K substitution was more suitable for sustaining K balance,while30%of the straw K substitution was more beneficial to improve soil slowly available potassium.