| Technology of planting pastures in orchards as a bright spot in modern agriculture,has been widely used in the world.However,in China,due to the incomplete understanding of the technology by the fruit farmers and the problems existing in the technology itself,the development of the current orchard still relies on the traditional “Clear tillage system” as the daily management mode.As a result,the orchard environment was deteriorated,the fruit tree yield was decreased,the fruit quality was declined,and the soil fertility of orchard often at lower level.In order to improve and solve the existing problems in the orchards,increase the economic and environmental benefits of the orchard effectively,so in this study,the effects of these two measures on the physical,chemical and biological properties of the orchard soil were investigated by planting pastures in orchards and turnover of pastures,and using traditional clear tillage as a control.It aims to provide data and theoretical support for the promotion feasibility of planting pastures in orchards and turnover management,and to improve the status of orchard and farmers' economic income while gradually completing the modern agricultural technology promotion.The results showed that:1.In terms of the physical properties of the soil: In the period of insufficient rain,the soil moisture content of each pastures under natural growth was lower than that of clear tillage.Long-term natural growth would significantly reduced the soil bulk density of 0-10 cm soil layer: After 5 years growth of white clover,3 years growth of Lotus corniculatus and 4 years growth of ryegrass,the soil bulk density was decreased by 7.03% and 8.59%,10.37% and 8.52% respectively.With the growing of pastures,the aggregate size of each particle in the soil water-stable agglomerate was increased,especially the particle size of >2 mm and 2-0.25 mm,the content of <0.25 mm particle size agglomerates in mechanically stable aggregates was decreased.Planting grasses in orchards would reduce the temperature of the soil in 0-20 cm soil layer significantly,and the average ground temperature in the 0-5 cm,5-10 cm,10-15 cm,and 15-20 cm soil layers were reduced 6.3°C,5.2°C,4.1°C and 3.6°C respectively.However,the Lotus corniculatus was the best to reducing 7.8°C,6.2°C,5.8°C and 4.8°C in each layer respectively.After turnover,the soil moisture content has no obvious regularity,but significantly reduced soil bulk density,which was less than the natural growth,and could reduced the content of <0.25 mm particle size agglomerates in mechanically stable aggregates and >0.25 mm particle size in water-stable agglomerates,increased PAD.2.In terms of the chemical nature of the soil: With the natural growth of pastures for many years,in 0-20 cm soil layer,the contents of soil organic matter,DOC,ROC and exchangeable Mg,soil acidity were increased,the content of AN and exchangeable Ca were decreased first and then increased,while the content of AP and AK were decreased.For example,AN(77.91%)and ROC(5.55%)under the natural growth of white clover in cherry orchard,and AN(87.90%)and ROC(2.06%)in natural growth of Lotus corniculatus treatment were increased significantly.After the pasture was turned over,except the ryegrass,AN,OM,DOC,ROC,and exchangeable Mg were increased under the influence of other grasses,the effects was better than that of natural growth.Only the exchangeable Ca content in the soil was decreased and the soil pH was increased.Among them,DOC(32.81%)and ROC(4.46%)under the turnover of white clover in the persimmon orchard,the AN(65.48%)and OM(26.78%)under the turnover of white clover in the cherry orchard,the OM(23.62%)after turnover of Lotus corniculatus and ROC(5.65%)after turnover of ryegrass were significantly increased.3.In terms of the biological properties of the soil: With the growth of grasses,microbial biomass C,N in soil,?-1,4-glucosidase,cellobiohydrolase and ?-1,4-xyloside associated with cellulose and hemicellulose were increased and urease,sucrase,catalase and alkaline phosphatase enzyme activities were significant increased.In addition to,the growth of leguminous pastures increased the number of bacterial populations in the soil,especially Bacteroides.In the 0-20 cm soil layer,the MBC content were increased only in natural growth of white clover in cherry orchard and ryegrass,which were promoted 62.69% and 97.97%,respectively.The BG activity value only was increased significantly by 44.83% in natural growth of white clover in persimmon garden.After turnover,the microbial biomass C/N,the activities of BG,CBH and BXYL were increased,and the effects were better than natural growth.The URE,SUR,CAT and ALP activities were increased significantly in all soil layers,but the growth rate was lower than the natural growth of grasses.In the 0-20 cm soil layer,the activities of BG,CBH and BXYL were increased significantly only in turnover of white clover in persimmon garden,by 46.86%,47.44% and 44.79%,respectively.The MBN content and CBH activity were increased significantly only in treatments of turnover of Lotus corniculatus and ryegrass were 173.32%,101.98%,144.01%,and 119.53%,respectively.In general,long-term planting pastures in orchards and grasses turnover could improve soil nutrient status and comprehensive fertility level,regulate soil micro-environment.It can be seen that: planting pastures in orchards is an excellent modern cultivation mode,and turnover of grasses also can be further promoted as an effective orchard management method. |
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