Effects Of Interplanting Herbages On Soil Aggregates And Its C, N In Wei Bei Loess Plateau Apple Orchard

Interplanting herbages is a soil management mode commonly employed for orcharddevelopment in developed countries, and it has been promoted as measures of green fruitproducing in China since1998. Researches on interplanting herbages mainly focused on theeffects of orchard grass microclimate, soil and grass effect on fruit yield and quality, andstatus quo of interplanting herbages and the interaction. But the interaction mechanisms wereseldom reported. Field trials and laboratory analysis were incorporated in this study toinvestigate the impacts of interplanting herbages on soil aggregates and its organic content ofC and N in Weibei Loess Plateau, and to explore the feedback of soil aggregates and organiccontent of C and N on interplanting herbages. This study was aimed to providing scientificbasis for revealing interaction mechanisms of the interplanting herbages complex system. Themain results are as follows:1Interplanting herbages increased the content of water stable aggregate>0.25mm and themean weight diameter (MWD) of aggregates in soil0~40cm depth, and reduced theaggregate destruction (PAD), but did not have significant effects on the content of themechanical aggregates>0.25mm, which implied that water-stable aggregates couldreflect the impacts of interplanting herbages on the characteristics of soil structure in theorchard more accurately.2Different types of interplanting herbages could influence the contents of water-stableaggregate of different sizes and the stabilities differently, and the effect on the componentsof water stable aggregates>0.25mm at different depth was different. The correlationanalysis showed that, biomass density of grass root showed significantly positivecorrelation with MWD, SOC, water stable aggregate content>0.25mm.3Interplanting herbages improved content of soil aggregates C in depth0~20mm, andchanged the vertical pattern of aggregates organic carbon. But different interplantingherbages influenced aggregates organic carbon of different sizes at different depthsdifferently.4Interplanting herbages substantially increased soil aggregates nitrogen content0~40cmbelow topsoil. Different interplanting herbages could have different effects on aggregatesnitrogen content of various sizes, at various depths. Effects of red clover, white clover and small crown flower were relatively high, and Lotus corniculatus and feet of grass low,they did not pose significant effects on the vertical distribution patterns aggregatesnitrogen content.5Interplanting herbages promoted the accumulation of aggregates C and N, and theenrichment factor varied from interplanting herbages and soil depths. In general, theaccumulative effects of smaller aggregates on C and N were greater than that of big size,and the accumulation of N was bigger than C. Though insignificant effects on the ratioof C to N at depth0~10mm, interplanting herbages decreased the ratio at depth10~40mm.