Phosphorus Cycling And Balance In "Agriculture-Animal Husbandry-Nutrition-Environment" System Of China

Phosphorus was not only the essential nutritional element for plants and animals, but also significant factor of environment pollution. Phosphorus flow and cycling in "Agriculture-Animal husbandry-Nutrition-Environment" system is the foundation of nutrient management at regional and national scale. However, the research of phosphorus flow and cycling in agricultural field was mostly paid attention to by scientists and the research in animal husbandry system and households system is very few. So in this study, P flow and cycling from agricultural system to animal husbandry system, to family nutrition system and environment system was studied.The "agriculture-animal husbandry-nutrition-environment" system of China was divided into ' plant production system (agricultural system), animal husbandry system, feed industry system, food industry system, households system, municipal making system and garbage disposal system' respectively. Then according to analyzing the characteristic of P flow in every system, P input item and output item were determined. The parameters of P input and output, example for P content in crop and animal product and so on, were derived from many different literatures. On the basis of statistic data of 1980,1990 and 2001 from China Statistic Bureau as well as P parameters, it was appraised for the status of P flow and cycling in recent twenty years in China. The results were as follows:The P balance in agricultural field was in the deficit in 1980, while it was surplus in 1990 and 2001. In 1980 the deficit of P quantity is 35 kt; in 1990 the surplus of P quantity is 1423 kt, while to 2001 the surplus is increased to 3711 kt. The P production efficiency is different within production and consumption process of various grain crops in the point of P nutrition. The P production efficiency of paddy processed into rice is 13.2%, while that of wheat processed into flour is 40.0%. From 1980 to 2001, great change had been occurred about structure of bite and sup in China, which transited from "high grain" type to "plant food and animal food paying equal" type. In 1980, the P quantity of plant food consumed by Chinese people was 461 kt, while P quantity of animal food was 27 kt. The ratio between plant food and animal food was 17.1. In 2001, the P quantity of plant food consumed by Chinese people was 524 kt, while P quantity of animal food was 112 kt. The ratio between plant food and animal food was 4.7. From 1980 to 2001, with the development of economy, grain increasing, animal husbandry growing rapidly and city...