The Trend Of Natural Grassland Nutrient Flow In Inner Mongolia From The Perspective Of Forage Supply

As the largest animal product production province in China,the natural grassland in Inner Mongolia has carried the double pressure of economic growth and ecological security for many years.In the production process of natural grassland livestock husbandry,nitrogen and phosphorus nutrients flow out from the natural grassland with forage grass,and mainly in the form of herbivorous livestock manure.Starting with forage supply and demand in Inner Mongolia,this thesis estimates the forage demand and forage supply data of herbivorous livestock in animal husbandry in each cities of Inner Mongolia Autonomous Region,and calculates and predicts the trend of nitrogen and phosphorus nutrient flow in the natural grassland of Inner Mongolia.The study results are as follows:(1)The overall supply and demand of forage grass in Inner Mongolia are in short supply,and the forage gap exists for a long time.In recent 30 years,there are no forage gaps in Inner Mongolia,Hulunbuir,Xilin League and Alxa League,forage gaps in Xingan League,Chifeng,Tongliao and Ordos,and no natural grassland and small grazing livestock in Wuhai City.(2)The overall natural grassland in Inner Mongolia shows a trend of nitrogen surplus and phosphorus deficit.Due to the difference of the types of natural grassland and herbivorous livestock feeding and proportion structure,12 cities in Inner Mongolia,nearly30 years city natural grassland present nitrogen surplus,wulanchabu,Xingan league,Alxa league,Tongliao city natural grassland phosphorus deficiency phenomenon,the rest of the city natural grassland phosphorus nutrients also present the surplus state.(3)The results of scenario analysis showed that,If the future forage demand maintains the current growth rate of herbivorous livestock forage demand in Inner Mongolia,From 2021 to 2030,The natural grassland nitrogen surplus is between 12.65-14.68 kg / ha per hectare,Phosphorus surplus is between 2.22-4.07 kg per hectare;If the future forage demand maintains the current growth rate of forage demand for herbivorous livestock in Inner Mongolia,From 2021 to 2030,The natural grassland nitrogen surplus is between 12.65-13.77 kg / ha per hectare,Phosphorus surplus is between 2.22-2.84 kg per hectare;When the actual load of animal husbandry in Inner Mongolia is equal to the theoretical load,The overall nutrient flow of nitrogen and phosphorus in the natural grassland of Inner Mongolia shows a nitrogen and phosphorus surplus,But the nutrient surplus per hectare is even smaller,For a nitrogen surplus of 7.20 kg per hectare,Phosphorus surplus is 0.85 kg per hectare.In conclusion,in the grassland livestock husbandry,the herbivorous livestock yield and the natural grassland yield determine the local forage supply and demand relationship,the more the natural grassland is,and the value will vary with the proportion of different species.