Effects On Soil Physical,Chemical Properties Of Sowing Perennial Grass In The Agro-pastoral Thansitional Zone Of North China

It was studied that the effects on soil physical properties of wheatgrass, smooth bromegrass , russian wildryegrass and oat having planted 3years in the grassland research station of China Agricultural University (Saibei Administration District,Zhangjiakou,Hebei , Guyuan) . The results showed that: after a period of growing season in the third planted year, soil bulk density decreased 9.29%, 8.64%, 6.38%in the forage plots in depth of 0-10cm,10-20cm,20-30cm respectively. Soil water content was clearly higher in forage plots than that in oat plots. Soil total porosity in the forages plots creased 6.45% in the depth of 0-10cm, and in the oat plots reducedl.04%; in the forage plots creased 7.15% in the depth of 10-20cm, and in the oat plots creased 1.49%. The soil total number of ≥0.25mm aggregates in depth of 0-30cm was 8.45% higher in the forage plots (mean73.89%) than that in oat plots(mean65.44%). Effects on Soil Physical, Chemical Properties of forages descreased with the depth deeper.The above-ground biomass of the third forages having planted 3years creased in July, became the most in Agu.decreased in Sept.The biomass of smooth bromegrass was the greatest one, wheatgrass was lower, russian wildryegrass was lowerest.The contents of solid were the most in Sept, lower in Agu, the lowest in July by the ratio of dried and freshed forages.The growing period of oat was shorter than forages, the above-ground biomass got the greatest in the shorter period.The result of the below-ground biomass of the forages and oats showed: the below-ground biomass of the forages was larger than the oats.The below-ground biomass Of artificial grassland in 0-30cm depth got the lowest value in Jly, the highest value in Agu, then accumulated in Sept.The below-ground biomass of forages was greater than the oats in the 0-10cm depth respectively.Afer Fertilizer application, the total nitrogen was the highest in the 0-20cm depth of oats in July. After a period of growing season ,the total nitrogen in the 0-10cm depth of forages plots was 0.07% higher, in the 10-20cm depth was 0.11% higer, in the 20-30cm depth was 0.09% higher than that in oat plots.In July after Fertilizer application, the total phosphorous in the 0-20cm depth of oats was higher than other forages. The total phosphorous in oats was lower than that forages in Jun, Agu, Sept restectively. Per period of growing season the total phosphorous decreased with the depth.deeper.The total phosphorous of the smooth bromegrass was the highest among the forages.Soil organic matter in the experimenting forages plots of the depth of 0-30cm creased differently after a period of growing season.The Soil organic matter increased precisely in the forages than the oats.The order of the effect on the three forages is that the russian wildryegrass> smooth bromegrass >wheatgrass.In the same growing period ,soil available potassium in the forages was higher than the oats in the same depth restectively (P<0.05) .Sowing forages increased the soil available potassium.The oats consumed a lot of soil fertilizer with the above-groundbiomass,so it descreased soil fertilizer and brought the soil quality down.