西北黄土区主要作物茬口对土壤理化性质和冬油菜农艺性状的影响

Effects of main preceding crop stubbles on soil physicochemical properties and agronomic traits of winter rapeseed in Northwest Loess Area

为了探讨不同茬口对土壤肥力及后茬油菜产量的影响,以休闲田为对照,研究了西北黄土区冬油菜、马铃薯、玉米、冬小麦、春小麦、蚕豆等6种主要农作物茬口土壤耕作层肥力效应及其对后茬白菜型冬油菜产量和农艺性状的影响,结果表明:(1)不同作物茬口土壤养分含量总体表现为越冬作物>休闲田>春播作物,除固氮作物蚕豆茬口碱解氮含量较高外,冬油菜茬口土壤营养各项指标、土壤微生物种群结构及土壤物理性状均显著优于其它作物茬口,其有机质、全氮、全磷、全钾、碱解氮、速效磷、速效钾含量分别比休闲田增加32.6%、12.1%,5.9%、7.2%、11.6%、99.8%、44.2%,其次为蚕豆、冬小麦茬口和休闲田,玉米和春小麦茬口肥力状况较差;与休闲田相比,冬油菜、冬小麦和蚕豆茬口耕层(0~20 cm)土壤容重分别降低10.14%、5.80%和5.80%,而冬油菜茬口土壤总孔隙度、毛管孔隙度和田间持水量分别提高7.33%、4.12%和5.65%,马铃薯、玉米、春小麦茬口均有不同程度下降,冬小麦与蚕豆茬口无明显差异;(2)前茬对白菜型冬油菜农艺性状的影响主要表现在株高、根量、全株角果数、角果粒数及千粒重等指标,其中蚕豆茬口白菜型冬油菜比休闲田增产4.50%,冬小麦茬口与休闲田相当,而马铃薯、玉米、春小麦、冬油菜茬口分别较休闲田减产11.05%、15.04%、16.27%、21.14%。白菜型冬油菜的最佳前茬是豆类作物,休闲田和冬小麦茬口次之,但白菜型冬油菜连作可能会产生自毒作用或病害加重,从而造成显著减产。

The purpose of this study was to examine the effects of different stubbles on soil fertility and rapeseed yield in the following season.Using traditional field experiment,with fallow field as control,the stubble soil ploughing layer of six main crops(winter rapeseed,potato,corn,winter wheat,spring wheat,and broad bean)in Northwest Loess Area and its effect on the yield and agronomic characters of winter rapeseed in the following season were studied.The result showed that:(1)The overall soil nutrient content of different crop stubbles showed that overwintering crops>fallow fields>spring sown crops.Except the broad bean stubble had a higher alkaline nitrogen content of nitrogen-fixing,the winter rapeseed stubble had a significant better result than those of other crops in soil nutrient indexes,soil microbial population structure and soil physical properties.Their organic matter,total nitrogen,total phosphorus,total potassium,alkaline nitrogen,fast-acting phosphorus,and fast-acting potassium contents were 32.6%,12.1%,5.9%,7.2%,11.6%,99.8%and 44.2%higher than the control treatment.Followed by bean,winter wheat stubble and fallow fields,the corn and spring wheat stubbles had a poorer fertility status.Compared with the fallow field,the soil bulk density of tillage layer(0~20 cm)of winter rapeseed,winter wheat and broad bean stubbles decreased by 10.14%,5.80%,5.80%,respectively.The total soil porosity,capillary porosity and field water holding capacity of winter rapeseed stubbles increased by 7.33%,4.12%and 5.65%,respectively,while potato,corn and spring wheat stubble all decreased to different degrees.There was no significant difference between winter wheat and broad bean stubbles.(2)The effects of previous crop on agronomic traits of winter rapeseed were mainly reflected in plant height,root weight,number of whole plant,number of pod and 1000-grain weight.Among them,the yield of winter rapeseed in broad bean stubble was 4.50%higher than that in fallow field,and the stubble of winter wheat was equivalent and winter wheat stubble was similar to fallow field.The yield of potato,corn,spring wheat and winter rapeseed stubbles decreased by 11.05%,15.04%,16.27%and 21.14%,respectively,compared with that of the fallow field.The best preceding crop of winter rapeseed was bean crop.The fallow field and winter wheat crop were also good preceding crops.However,continuous cropping of winter rapeseed could produce autotoxicity or aggravate disease,which would significantly affect the yield,so it is not suitable for continuous cropping.