Effects of Herbage on Soil Respiration and Hydrothermal Environment of Apple Orchard in High Altitude Areas of Guizhou
[Objective]The soil respiration characteristics as well as its relationship with soil water and heat under different herbage mulching in apple orchards were explored in apple-growing areas of cold highland in Southwest China,which provided references for screening suitable herbage species in apple orchard.[Method]Taking clean cultivation as CK,eight herbage treatments of Vulpia myuros(VM),Dactylis glomerata(DG),Lolium perenne(LP),Trifolium repens(TR),Vicia villosa(VV),VM+DG+TR,LP+TR+DG and VM+LP+TR in apple orchards were set up.The soil respiration rate was determined by LI-6400XT portable photosynthesis system matching with the soil respiration chamber(6400-09),and the effects of different herbage treatments on soil respiration and soil hydrothermal environment were analyzed by nonlinear regression and exponential model.[Result]Herbage treatments significantly increased the soil respiration rate in the orchard,which was 0.07%to 256.39%higher than that of clean cultivation,among which LP+TR+DG treatment had the highest increment.Herbage mulching significantly improved soil water retention capacity,and the effect on 0-20 cm soil layer was the most obvious,and the obvious difference in soil moisture among different herbage treatments in the same month was observed,meanwhile the soil moisture capacity of the mixed sowing treatments was better than that of the single sowing treatment.Herbage mulching significantly reduced the soil temperature in the top soil layer(0-5 cm)in summer(May-July).The quadratic function fitting between soil moisture content and soil respiration of different herbage mulching treatments was the best,and their determination coefficients R2 ranged from 0.242 to 0.989,which indicated that the goodness of fit was relatively high.Soil temperature and soil respiration showed an exponential function relationship in each herbage treatment,and the average values of determination coefficients R2 of the fitted model in the 0-5 cm and 5-10 cm soil layers were higher than that in 10-15 cm and 15-20 cm soil layers.The synergistic effects of soil temperature,moisture and their interaction on soil respiration were higher than those of soil single factor.[Conclusion]Herbage cultivation can significantly improve the soil respiration of apple orchards,significantly increase the soil moisture retention capacity of 0-20 cm soil layer,reduce top soil(0-5 cm)temperature of orchard in summer,effectively improve the growth environment of apple roots,and be conducive to tree growth and development.Among all the herbage treatments,the effect of mixed sowing of LP+TR+DG treatment is the best.
apple orchardherbagesoil respirationhydrothermal environmenthigh altitude areaGuizhou
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