Effect of the Previous Crops on the Initial Stage of Establishment of a Mixed-Sowing Grassland

A study was carried out to determine the effect of growing grass,the grass yield,and the grass summer survival rate of a stretch of mixed-sowing grassland on three plots of former cropland along the Three Gorges Region.The displaced growths on the former croplands were rice,Manila grass, and soybean.The mixed grasses used in the study were white clover(Trifolium repens),alfalfa(Medicago sativa),orchardgrass(Dactylis glomerata),and tall fescue(Festuca arundinacea).The results show that soil condition significantly influenced the population structure and yields of the grassland.The growth of gramineous grasses was retarded in the poor soil of the former manila grass land,whereas in which legumes grew better,though the yield was the lowest compared to that of grasses sowed on the former rice or soybean cropland.Gramineous grasses grew well on the fertile soil of the former soybean land,but the soil sod inhibited the growth of legumes.The population structure of mixed-sowing grassland was relatively stable on the soil of the previous rice cropland.Compared with alfalfa(M.sativa),white clover(T.repens) was better suited to be mixed with orchardgrass(D.glomerata) and tall fescue(F.arundinacea),and could enhance yield in such soil.The soil fertility also influenced the summer survival rate of cold-season grasses in the Chongqing municipality area.Moreover,rich coverage rate of sod prior to the arrival of the scorching summer of the area ensured the grasses summer survival rate.