Comparison Study Of Soil And Physiological Character Of Grazing Between Karst And Non Karst In Guilin Maocun

Karst ecosystem is an ecosystem controlled by karst environment.Karst area in southwest China is a typical flimsy ecological area which is the biggest in acreage and the most strong in karst growth in the three karst centralized areas in the world,its acreage is 500 thousand square kilometer,including mostly of Guizhou and a portion of Guangxi,Yunnan, Szechwan,Chongqing,Hubei,Hunan. Karst rocky desertification not only destroy entironment, attenuate soil productivity,but also influence the production of agriculture, forest and stockbreeding severely,and even endanger human survival.So, Karst rocky desertification has become the most severe ecological geologic environmental problem which restricts the continuable development in Southwest China.The flimsy karst condition is a research hotspot in international geology nowadays,after the IGCP299"geology,climate, hydrology and karst formation"and the IGCP379"karst effect and carbolic circulation",Chinese national academician Yuan Daoxian has brought forward and brought into effect the IGCP448"global karst ecological comparison",its core question is the expatiation of the functional disciplinarian of karst ecosystem and the promotion of the flimsy karst ecological administration and the continuable development of the western exploitation.Aiming at retrograde vegetation,serious water and soil loss,declining soil fertility as well as growing rocky desertification of Guangxi fragile eco-environment,aiming for the sustainable development of region,the study choose species which have more economic,ecological and social benefit,to plant forming a complete set.This research has planted four grazing in karst and non karst: Cichorium intybus L., Stylosanthes guianensis (Aubl) SW., Euchlaena mexicanna Schrad.and Cajanus cajan Linn. to learn the biological character of grazing and soil improvement in karst,in order to know their adaptability and provide theoretical evidence.It is good for the choice and generalization of grazing used for soil improvement in karst and vegetation renew in mountainous region.Researching methods: comparative experiment in field.The paper studys comparatively the soil improvement of grazing by the mensuration of soil organic matter,total nitrogen,total phosphorus and total potassium, alkali-soluble nitrogen, available phosphorus and available potassium,calcium and magnesium before and after soil improvement;Researching the change of soil enzyme by the mensuration of soil protease and urease activities; Mensurating the dynamic change of photosynthetic rate and transpiration rate of grazing by Li-Cor6400; The biomass had been measured by reap method and grazing quality indexs: rude protein,rude fattiness,rude fibre,rude ash were mensurated.Studying comparatively the dynamic change of grazing nutrient content between karst and non karst.The results showed that:1,After grazing planting, soil organic matter,total nitrogen,total phosphorus and total potassium have little change and alkali-soluble nitrogen, available phosphorus and available potassium have increased evidently. Calcium was 4.55g/kg in karst soil, 1.90g/kg in non karst soil.2, Soil protease and urease activities in karst soil were 0.86NH₂-N mg·g^-1·d^-1 and 1.21 NH3-Nmg·g^-1·d^-1 respectively before grazing planting,afer grazing planting ,they both had increased evidently, as to soil protease, Cajanus cajan(Linn.) Millsp. >Stylosanthes guianensis (Aubl) SW. >Euchlaena mexicanna Schrad.>Cichorium intybus L.,as to soil urease, Cajanus cajan(Linn.) Millsp. >Stylosanthes guianensis (Aubl) SW. > Cichorium intybus L. >Euchlaena mexicanna Schrad.Soil protease and urease activities in non karst soil were 0.94 NH₂-Nmg·g^-1·d^-1 and 1.32 NH3-N mg·g^-1·d^-1. Soil protease and urease activities in non karst were higher than them in karst before grazing planting,after grazing planting, soil protease and urease activities in karst were higher than them in non karst.3,In July, the photosynthetic rate of Cichorium intybus L.in karst and non karst were 12.40 and 11.60umol·m^-2·s^-1 respectively, Euchlaena mexicanna Schrad.were 27.98 and 18.99 umol·m^-2·s^-1, Cajanus cajan(Linn.) Millsp. were 17.01 and 13.98 umol·m^-2·s^-1. The transpiration rate of Euchlaena mexicanna Schrad.was less than Cichorium intybus L. and Cajanus cajan(Linn.) Millsp.As to water use efficiency, Euchlaena mexicanna Schrad.was more than Cichorium intybus L. and Cajanus cajan(Linn.) Millsp.The total photosynthetic rate of the three grazing in karst was 19.13 umol·m^-2·s^-1,and it is 14.86 umol·m^-2·s^-1 in non karst, the total transpiration rate in karst was 7.45 mol·m^-2·s^-1,and it is 5.65 mol·m^-2·s^-1 in non karst.4, As to grazing biomass, Euchlaena mexicanna Schrad.>Cajanus cajan(Linn.) Millsp. > Stylosanthes guianensis (Aubl) SW. > Cichorium intybus L.,except Stylosanthes guianensis (Aubl) SW.,grazing biomass in karst were more than them in non karst;As to grazing quality indexs , Cajanus cajan(Linn.) Millsp. >Cichorium intybus L. >Stylosanthes guianensis (Aubl) SW. > Euchlaena mexicanna Schrad.5,The total calcium and magnesium of grazing in karst area were 2 and 1.5 times than them in non karst.There are biggish difference in the ability of absorb and cumulation of Ca and Mg among different species of grazing. Euchlaena mexicanna Schrad.in this research belongs to C4, its calcium content is out and away less than other three species grazing .