Research On Nutrient Flow And Cycle Model In China Nutrition System

In the 21st century, China will face the problem of "population - resources -environment - grain". It makes us have to think about Whether the hunger can sound China's door once more? This article takes nutrient resources as research object. We establish "Nutrient Flow and Cycle Model in China Nutrition System" through the method of the nutrient flow. The model takes the nationality's demand to the nutrition and the influence to the environment as a driving force, and takes nutrient flow in plant, animal and family system as a chain link. We expand the nutrient flow and cycle research to the entire social circle. We establish database with Microsoft Excel 2003 . We use Visual Basic 6.0 to program.The model functional system is composed of inquiry system, computing system. The inquiry system is just the CNFC model 1.0 editions. It can realize the inquiry function of the nutrient quantity of N and P of each input and output item of the plant system, animal system and family system from 1980 to 2004. The computing system is just the CNFC model 2.0 editions. It can realize the automatic computation function of the N and P nutrient of each input and output item of the plant system, animal system and family system. The model result indicates:1. The nitrogen, phosphorus nutrient input value of plant system of China respectively was 44.88 million tons and 9.38 million tons in 2004. And the nitrogen, phosphorus nutrient output value of plant system of China respectively was 3,2.66 million tons and 6.41 million tons. The nitrogen, phosphorus earnings of China plant system respectively were 12.22 million tons and 2.97 million tons.2. From 1980 to 1985, the nitrogen earning of the plant system was negative, and it lacked 6.89 million tons. But after 1986, the nitrogen earning of the plant system has became a positive value and it is 135.69 million tons. So is the phosphorus. From 1980 to 1989, it lacked 10.42 million tons. But after 1990, the phosphorus earning was 27.98 million tons.3. In 1980, the nitrogen which enters atmospheric and the water body of plant system respectively were 4.69 million tons and 1.89 million tons. But in 2004, the nitrogen which enters atmospheric and the water body of plant system respectively were 10.83 million tons and 2.47 million tons, which were 2.3 times and 1.3 times that of in 1980. In 1980, the nitrogen which enters atmospheric and the water body of animal system respectively were 1.29 million tons and 1.33 million tons. But in 2004, the nitrogenwhich enters atmospheric and the water body of animal system respectively were 3.33 million tons and 3.57 million tons, which were 2.6 times and 2.7 times that of in 1980. In 1980, the nitrogen which enters atmospheric and the water body of family system respectively were 0.53 million tons and 1.19 million tons. But in 2004, the nitrogen which enters atmospheric and the water body of family system respectively were 0.56 million tons and 2.38 million tons, which were 1.1 times and 2.0 times that of in 1980. The proportion of nutrient which enters environment in animal system is increasing year by year,4. The load of animal excretion per hectare of cropland of Liaoning, Jilin and Heilongjiang respectively were 24 t ? hm'2, 20 t ? hm'2 and lit" hm"2 in 2003. It distributed in the space was not extremely balanced.The load of animal excretion per hectare of cropland of Hebei was 38 t ? hm"2 in 2004. The load of animal excretion N per hectare of cropland is 182 kg ? hm"2, and P is 54 kg ? hm'2. The greater mainly distributed in Shijiazhuang, Tangshan, Handan and Baoding.5. In 2004, we optimize China plant system , which would save the nitrogen resources 6.33 million tons mostly.We optimize China animal system, which would save the nitrogen resources 12.99 million tons mostly.After optimizing, the nitrogen which enters atmospheric and the water body of crop production system would reduce to 5.89 million tons and 1.24 million tons, which would reduce 54%, 50% respectively. And the nitrogen which enters atmospheric and the water body of animal system would reduce to 2.58 million tons and 3.02 million tons, which would reduce 77% and 85% respectively.