Study On Herbage Nutrients And Botanical Heterogeneity Formation Of Grass+White Clover Grassland In Guizhou Plateau

In Guizhou plateau, we selected four improved time grasslands (CK, G1993, G2010and G2011), four mowing and grazing using pattern grasslands (M, M+G, CG and RG), and dung deposition by grazing livestocks were selected in Lolium perenne+Dactylis glomerata+Trifolium Repens grasslands. The changes of the soil, herbage nutriention and botanical composition were systemical studied from2011to2013, which would eprovide a practical basis for the sustainable utilization and management for the grasslands. The main results are as follows:The values averaged among three years of each nutriention of pH, organic matter, K, Na, Mg, Fe, Cu, Zn, Mn in soils; and K, Na, Ca, Mg, Fe, Cu, Mn in forages had no significant difference among four improved grasslands. While the P concentration in forages was G2011and G2010> G1993and CK, the herbage Zn was G2011<CK, G1993and G2011. In2012, the soil nutrientions of N, P, Na, Mg, Cu, Zn concentrions were December>April and August, and the soil K was April>August>Decembe; while the herbage Fe of G2010and the herbage Mn of G1993and G2010had no siginificant difference in three samplied seasons. The P, Na, Mg, Cu, Zn in herbages were Decmber>April and August, whereas the herbage K and Ca concentions was Decmber<April and August.For the forages category biomass of four improvement years, the L.perenne of G2011was higher than the others, and the T. repens was similar among four improved grasslands; while the native grasses in CK was siginificant higher than the others, and the weeds was CK> G2011and G2010> G1993. For the forages biomass of different measured years, from2011to2013, the T. repens of CK increased and the native grasses decreased; while the G1993, G2010and G2011was2012>2011and2013. The biomass of Dactylis glomerata of G1993was higher than the other improved grasslands, for G2010the L. perenne and D. glomerata biomass decreased and T. repens biomass increased with delayed sampling year; while for G2011, the L. perenne biomass reduced, and the weeds and poisons plants biomass increased from2011to2013.The nutritions and botanical composition varied largely for four mowing and grazing pattern grasslands. The soil of CG grassland was severely acidification. The herbage Ca in M grassland and herbage P in RG grassland had higher values, the herbage Cu in M and M+G grasslands had higher values, and herbage Mg in CG was lower than other grasslands; while the each nutrition value index had no significant difference among four grasslands. The number of tillers of L. perenne was RG>M+G>M and CG, the tiller weight was M and M+G>CG and RG; while the density and weight of white clover stolon were M and RG>M+G and CG. The number of species was CG>M and M+G>RG. The community structure of CG swards was variety and dominated by Eragrostis pilosa, M grassland dominated by T. repens+Taraxacum officinale+Artemisia lactiflora; while the community structure of M+G and RG swards were simple and dominated by L. perenne+T. repens.The difference of mineral elements contents between soils and herbages was large and varied in different elements and in excretion types. The dung deposition by grazing animals declined or eliminated the positive correlational relationship existing between soils and herbage in Na, K, and Mn contents, whereas this trend was an opposition in Cu and Zn contents. The effects of dung deposition by grazing animal on botanical composition of grassland exhibited in plant population and community levels, and varied in two patch types and in different decomposing stages of animal dung. Dung deposition by grazing animals could encourage tillering and growth of L. perenne of D. glomerata, discourage growth of T. repens, increase height and biomass of herbage and reproductive shoots of L. perenne, and decrease the nutritional values of herbages. The effect on botanical composition by cow dung was more obvious than by sheep dung. The defoliation for L. perenne and D. glomerata by grazing animals in dung deposition plots was lower than that in controls, and the rejected defoliation level for dung deposition plots by cow was higher than by sheep.The ratio increase of native plant species and soil acidification can be a symbol of grassland degradation. It is necessary to adjust the pattern of mowing and grazing and use lime to prevent soil acidification. In grassland practical management, the mixed grazing by sheep and cattle, could reduce the rejected defoliation waste of dung patchy herbage and improve the utilization rate of grassland. Rotational gazing and grazing+mowing are suitable long-term utilization pattern for grass+white clover grassland in Guizhou plateau.