Study On Mixed-sowing Modes Of Alfalfa And Grasses In The Farming Pasture Region

In order to promote the development of alfalfa-dairy industry in farming-pasture region widely, thiswork has made a lot of research on mixed-sowing modes and techniques of alfalfa (Medicago sativaL.), smooth brome (Bromus innermis Leyss), siberian wildryegrass (Elymus sibiricus L)andupright-spikelet roegneria (Roegneria turczaninovii (Drob.) Nevski) for3years in the Tumochuanregion of Inner Mongolia,China. The results show that:1) Mixed-sowing mode of alfalfa and siberian wildryegras is optimal for the short-termhigh-production cutting used grasslands with3:1or2:2row ratio and3:1or1:1broadcast ratio ininterlacing drill mode respectively. Mixed-sowing mode of alfalfa and smooth brome is optimal forthe long-term grazing-cutting used grasslands with2:2row ratio and1:1broadcast ratio ininterlacing drill mode. Mixed-sowing mode of alfalfa and upright-spikelet roegneria is optimal forthe dry-land long-term cutting used grasslands with1:1or2:2row ratio and1:1broadcast ratio ininterlacing drill mode.2) The total capacity of the soil weed seedbank is not affected by mixed-sowing. It proves that thestructural characteristics of the soil weed seedbank could not factually changed by the biomass ratioof mixed grasses. However, weeds seasonal storage changes more significantly by the plant speciesthan by that of the mixed sowing combination or row ratio and broadcast ratio. Among that, grassesis higher than alfalfa. Smooth brome is the most vulnerable. So, it is indicated to prevent andcontrol of weeds for the mixed-sowing of alfalfa and smooth brome before the peak of weedsstorage in June and August of each year.3) The total output of mixed pastures is effected by irrigation,fertilization and the coupling effect ofthem. Among it, the significant effect of increase production is cased by irrigation and fertilization,but the coupling effect of irrigation and fertilization is not significant. Alfalfa is sensitive toirrigation, while siberian wildryegrass is sensitive to fertilization. The range of reduction of outputwhich caused by lacking of water can be appropriate eased by reasonable fertilization. The soilmoisture content of the mixed-sowing should be maintained above65%of the field capacity at least.At the same time, the fertilization(㎏/hm2) proportion of N:P:K at3.5:1.2:0.7or3.5:3.5:2.0canincrease significicant the production. And this will affect the mixture forage nutritional value andfeeding value significantly.4) Alfalfa population controls the direction of the community competition in the alfalfa and grassesmixed-sowing region. Populations' competition relationship is not built in the first year because ofunformed; then the populations compete intensely in the second year in order to usurp the dominantniche, finally they tend to be steady in the third year with a stable niche. The stable density ratio is33.4:66.6of alfalfa and siberian wildryegras,63.3～50.0:36.7～50.0of alfalfa and smooth brome,43.7～46.4:56.3～53.6of alfalfa and upright-spikelet roegneria respectively.5) This dissertation proposes green optimized soil adjusted vegetation index (GOSAVI) caculated bynear-infrared light (760nm) and green light (600nm). Based on GOSAVI, the optimal quadratic equation estimation model of fresh total production of alfalfa and smooth brome mixed grassland isalso established.6) The leaves amount of hay yield, hay nutritional value and cows feeding value of mixed-sowingmode is higher than the single-grass mode. Smooth brome mixture is the best choice. Comparedwith it, siberian wildryegras could decrease cows feeding value and upright-spikelet roegneria coulddecrease the nutritional value and yield.