| The rapid development of dairy industry of Hohhot in Inner Mongolia has increased the demand for high-yield and high-quality forage, and resulting in contradiction in forage supply and demand. Mixed pasture of Medicago varia with grass and mono pasture of each species were planted in Halaqin village Gonglama town Helinge`er county Hohhot city in 2011. Plant community characteristics were measured under natural growing, clipping frequency, stubble height and clipping time. Plant community characteristic, composition, interspecific relationships were analyzed to reveal the potential productivity and suitable under different management, and to explore plant community dynamics of mixed pasture and its productivity maintenance mechanism. A appropriate alfalfa`s mixed pasture establish combination and clipping management were provide for supporting the development of forage industry in Hohhot district. The result showed:In the early established year, forage yield of E.sibiricus + M.varia was obviously higher than mono-M.varia, mono-E.sibiricus and mono-B.riparius(P<0.05). Yield of B.riparius + M.varia was lower in the second planting year, but obviously higher than E.sibiricus + M.varia mixed pasture and three mono-culture in the fourth year of establishments(P<0.05). As the establishment year increased, the yield of two mixed pasture and mono-M.varia were significantly increased(P<0.05), while the yield of both mono-B.riparius and mono-E.sibiricus were significantly decreased(P<0.0). Under mixed conditions, forage yield and plant height of M.varia, E.sibiricus and B.riparius were higher than mon-oculture(P<0.05), but nutritional value of E.sibiricus and B.riparius were lower than alfalfa monoculture(P<0.05). The component ratio and important value of M.varia in mixed communities were obviously increased year by year, M.varia took dominant position in the community, while the component ratio E.sibiricus and B.riparius were reduced year by year.There’s no difference between the yield of B.riparius + M.varia and mono-M.varia(P>0.05) with low stubble(0~3cm) or high frequency(3~4 times/year) clipping, while the yield of E.sibiricus + M.varia was significantly lower than mono-M.varia(P<0.05). Clipping 2 times a year improved pasture yield, but the yield was significantly reduced with the increase of clipping frequency(P<0.05). Both yield and regeneration rate of mono-M.varia was significantly increased in 0cm stubble(P<0.05), but significantly weaken regenerative capacity of E.sibiricus and B.riparius(P<0.05). At 7~10cm stubble was in favor of regeneration of E.sibiricus and B.riparius, but reduce the regrowth yield of M.varia. Yield of two mixed pasture and mono-M.varia were significantly higher than mono-B.riparius and mono-E.sibiricus in full bloom stage of M.varia(P<0.05), and the yield component ratio and important value of M.varia in mixed pasture were increased with delayed clipping period, yield component ratio and important value of E.sibiricus and B.riparius were significantly decreased.Evaluation results showed that, the overall performance of B.riparius + M.varia was the best, secondly was mono-M.varia, while E.sibiricus + M.varia was lower than mono-M.varia, but better than mono-B.riparius and mono-E.sibiricus. Moreover, component of B.riparius + M.varia mixed communities was relatively stable than E.sibiricus + M.varia mixed pasture. Suitable clipping periods for both B.riparius + M.varia and E.sibiricus + M.varia in dry land condition Hohhot region was M.varia full bloom time, and the best clipping frequency is two times a year. M.varia + E.sibiricus have the best yield and stability at 7 cm stubble height, while M.varia + B.riparius preferred to 5cm stubble height. |
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