Standing corn residue effects on soil frost depth, snow depth and soil heat flux in Northeast China

Standing corn residue has been proven to reduce wind erosion in Northeast China, but how standing corn residue affects soils during winter remained unclear. Our objective was to compare soil frost depth associated with two zero-tillage methods [i.e., chopping corn stalks into small sections then spread them on soil (hereafter referred to as 'CCR') and standing corn residue (hereafter referred to as 'SCR')]. Frost tubes were used to determine soil frost depth, and soil heat flux plates were used to measure soil heat flux 8-cm beneath the soil surface. Compared with CCR treatment, SCR reduced maximum soil frost depth significantly (p < 0.05) due to thicker snow cover, which insulated the soil surface from cold winter air. And the thicker snow cover hastened the frozen soil completely thawed approximate 20 days, which has implications for early sowing. Early sowing meant that corn could have longer growing time, which could help long-growing-time corn varieties become maturity before killing frost in cold areas, longer growing time could also result in fully filled grain, and increase economic profit for farmers.