Abstract:

At present, it is becoming the mainstream to develop largescale livestock farms in China.However,largescale livestock farms not only make great economic benefits,but also cause heavy environment pollution.Then,it is a key problem whether there is an optimal scale for livestock farms from the view of the pollution controlling. Based on the N/P capacity of the farmland,transport cost,pollution charge and other variables,a mathematical model was built to analyze the optimal scale of a livestock farm that would maximize its profit.When the livestock farms chose the scale as the control variable,the optimal scale would increase with the price of the livestock and the N/P capacity of the farmland, and would decrease with the increase of the sum of the directive production cost and manure treat cost,the N/P surplus after the treatment,transport cost,pollution charge.When the livestock farms chose the proportion of the N/P surplus emitted directly as the control variable,the optimal proportion of the N/P surplus emitted directly would decrease with the increase of the pollution charge.Finally,it was concluded that the limit on the scale of livestock farm would be an option to control the livestock pollution when the N/P could not be removed effectively by current technologies，and it was difficult to supervise the livestock whether to treat the N/P surplus properly