Regional Livestock Density Under Environmental Capacity Based on Nitrogen and Phosphorus Budget of Farmland:A Case Study of Yucheng County in Shandong Province

WU Lan-fang,OUYANG Zhu(Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China)

livestock density;carrying capacity;load index;regional scale;Yucheng County,Shandong Province

Livestock manure provides a valuable nutrient source for crop and substitute for chemical fertilizer.However,the environmental risks of livestock manure have increased in regions where livestock manure is overproduced compared to land capacity.According to the nu-trients demand and available loses of current cropping system,livestock density under environmental capacity in Yucheng County,Shandong province was analyzed on the basis of nutrition budget of cropland by different input scenarios of manure N and manure P2O5.Nutrient needs were calculated by multiplying the output of each crop with the standard mount of nutrients needed for each crop and summing up individual crops.Nutrients input mainly consist of the amount of chemical fertilizer and the amount of organic fertilizer converted from livestock manure.When the input of manure N accounted for 100%,60% and 30% of total input of N in cropland,the carrying capacity of livestock on the farmland was 13.8 LU.hm-2,8.3 LU.hm-2 and 4.1 LU.hm-2 and the corresponding load index of the farmland was 0.7、1.1 and 2.2 respec-tively.When the input of manure P2O5 accounted for 100%,60% and 30% of total input of P2O5 in cropland,the carrying capacity of livestock on the farmland was 22.5 LU.hm-2,13.5 LU.hm-2 and 6.7 LU.hm-2 and the corresponding load index of the farmland was 0.4、0.7 and 1.3 re-spectively.Those showed that the carrying capacity of livestock depending on soil-surface nitrogen budget was smaller than the carrying ca-pacity of livestock depending on soil-surface phosphorus budget;meanwhile the load index by nitrogen budget was higher than load index by phosphorus budget.Furthermore,the obviously differences were existed among township regions of Yucheng County.Therefore,to prevent en-vironment from deterioration with respect to livestock manure in the region the livestock density and the quantity manure should be restricted base on the assimilative capacity of the cropland to nitrogen,also the livestock and manure should be distributed evenly within the region.