Effects Of Long-Term Different Mowing Regimes On Soil Aggregate Stability And Distribution Characteristics Of Organic Carbon In Steppe Grassland

Soil aggregate is the basic unit of soil structure,and its stability is of great significance for maintaining the soil structure function and nutrient cycling of grassland ecosystem.Mowing is one of the important ways of using natural grassland.For a long time,the influence of different mowing regimes on the stability of natural grassland soil aggregates has not been very clear.Therefore,For this reason,this study took the long-term mowing sample plot in the typical grassland of Inner Mongolia as the research object.This study explored the effects of four mowing regimes(mowing once every two years,mowing twice every three years,mowing once every year,and mowing twice every year)on the quantity,physical and chemical properties of soil,distribution characteristics of soil aggregates,stability and distribution characteristics of organic carbon.The main findings are as follows:(1)In typical grasslands under long-term different mowing regimes,the mowing measures reduced the aboveground biomass of the grassland,and showed a gradual decrease with the increase of mowing intensity.Under no mowing treatment,the soil water content and nutrient content of each soil layer were the highest,which decreased significantly with the increase of mowing intensity(P<0.05).And with the increase of soil depth,the content decreased significantly,and the change law of soil p H value was the opposite.(2)In each treatments,most of the aggregates were >0.25 mm in different soil layers.Long-term mowing measures significantly reduced the aggregate content of0?10 cm soil layer > 2 mm,and gradually decreased with the increase of the mowing intensity(P<0.05),and the percentage of aggregates in the remaining particle size fractions was opposite.In the 10?30 cm soil layer,the treatments of mowing twice in three years,mowing once a year,and mowing twice a year are mostly 0.25?0.053 mm aggregates,and the change pattern of aggregates is similar to that of the surface soil layer.(3)Long-term mowing treatment significantly reduced the stability of the aggregates of each soil layer,and with the increase of the mowing intensity,the stability of the aggregates gradually decreased(P<0.05).This study found that soil >2mm aggregates had a very significant positive correlation with soil bulk density,water content,soil nutrients and underground biomass,while <0.25 mm aggregates had a very significant negative correlation with them(P<0.01).(4)Under the long-term mowing treatment,the soil organic carbon content in the 0?10 cm surface soil layer is the highest,of which organic carbon is mainly distributed in aggregates >0.25 mm,mowing measures significantly reduce the aggregates of each soil layer >2 mm organic carbon(P<0.05),and gradually decreased with the increase of mowing intensity.The organic carbon in the 10?20 cm soil layer is mainly distributed in aggregates> 2 mm and 0.25?0.053 mm,and with the increase of mowing strength,the organic carbon content of aggregates> 0.25 mm gradually decreases,and the agglomerates of 0.25?0.053 mm Instead,the organic carbon content increased.In the 20?30 cm soil layer,soil organic carbon is mainly distributed in aggregates >0.25 mm,and gradually decreases with the increase of mowing intensity.In summary,the content of macroaggregates(>0.25 mm)in each soil layer under the two-year mowing once treatment is relatively high,and the aggregates have relatively high stability and strong erosion resistance,which is conducive to the storage of soil organic carbon.Conducive to the long-term sustainable use of typical grasslands.