Study On Quality Evaluation And Stability Management Model Of Grass/white Clover Grassland In Northwest Guizhou

Grass/white clover grassland has high yield and good quality.It is widely planted in karst areas in southern China and has become an important forage resource for local animal husbandry.However,with the extension of grassland utilization time and improper grassland management,the grassland quality and community stability are easily reduced.So,grassland management is the key to maintaining quality and stability of grass/white clover grassland.Grass/white clover grassland is a deviant succession community under intense human intervention and establishment purpose,which results that its stability evaluation is different from that of natural grassland.In this study,the quality of grass/white clover grassland of four management modes(Sample plot Ⅰ: long-term mowed in early stage + grazing in late stage;Sample plot Ⅱ:continuous grazing;Sample plot Ⅲ: rotation grazing is the main thing,and grazing once or twice when rotation grazing is insufficient;Sample plot Ⅳ: continuous grazing with typical hilltop topography)and natural grassland(Sample plot V:continuous grazing)of Zhuopu Grassland in Weining,Guizhou Province were evaluated,and the elements composition of stability evaluation of grass/white clover grasslands were clarified.The relatively suitable management mode among the four types of artificial grasslands in the study area was also determined.The main results are as follows:The indices of quality evaluation for grass/white clover grassland were vegetation structure(biomass ratio of sown to unsown forage,biomass ratio of white clover to sown grasses),forage palatability index and nutrients(CP,organic matter,the Metabolizable Energy(ME),Relative Forage Value(RFV)and herbage Grading Index(GI)),and soil p H and nutrients(organic matter,total nitrogen,alkaline hydrolysis nitrogen,total phosphorus and available phosphorus).The soil p H values was low,ranged from 4.67 to 5.24,and forage nutrients were below or away from optimal values,while soil nutrients were high.Based on the data of forage and soil characteristics,the comprehensive evaluation of grassland quality was carried out by weighting method.The quality of grassland was higher in plot Ⅲ and plot Ⅰ,lower in plot Ⅱ and plot Ⅳ,and lowest in plot V.The stability of artificial grassland community is a balance among production stability(yield),ecological stability(number of species)and quality stability(quality).Ecological stability is usually measured by species diversity and succession degree.The ecological stability of the sample plot Ⅲ was better than that of the sample plot IV.Grass/white clover grassland is easily degraded due to improper management,and the degradation degree of sample plots Ⅰ and Ⅲ was highest,and for the sample plots Ⅱ and Ⅳ it was relative large,while for sample plots V it had a low herbage nutrient content and a high grassland stability.It is difficult to maintain the stability of grasslands with better quality,and the quality of grassland is related to its stability and is affected by topography.The management mode of grass/white clover grassland in the study area was extensive,and the management mode of long-term mowed in early stage + grazing in late stage and rotation grazing was relatively conducive to maintenance of grassland quality.In the future grassland management,in order to maintain the stability of grass/white clover grassland,it is suggested to apply lime,nitrogen and phosphorus fertilizer in a timely manner,as well as make precise mowing and grazing system and intensity.