Characteristics Of Energy And Matter Balance In The Integrated Crop-livestock Production System In Loess Plateau Of Eastern Gansu

Loess Plateau in eastern Gansu province locates in the core zone of Loess Plateau and is also in traditional farming-pastoral ecotone. The dominant agricultural type is integrated crop/rangeland- production and both environmental deterioration and farmer poverty are serious problems as a result of unreasonable farming. Through analyzing input and output of energy and economic, soil moisture and organic carbon of farming systems on basis of farm investigations and field experiments, this research was to identify characteristics of energy, economics and matter balance of integrated system in northern part, center part and southern part of eastern Gansu Loess Plateau.1. In crop production subsystem of northern part, buckwheat, potato and alfalfa were sown 72.1-84.9% of total cropland whist the planted areas of winter wheat, buckwheat, alfalfa and broom-millet accounted for 59.3-81.9% of all cropland in center part and the planted of areas of winter wheat, corn and apple accounted for 74.7-86.3% in southern part. Along with increase in annual mean rainfall, the planted areas of wheat and corn rose, but alfalfa, potato and buckwheat reduced. The planted area of main crops had no significant difference between wet year and drought year. The livestock amount was the most in northern farms, but the least in southern. And draft power for crop production mainly came from donkey in the northern farms, but cattle in the southern farming systems and central farm systems. Number of goats increased with rainfall reducing.2. Labor was the main energy input for alfalfa and the ratio to all energy input was 66.6-91.2% (average 78.9%). Fertilizer was the main input for other crops, which was about 84.0-97.5 % (average 90.8%). The differences of energy input and output of other crops between two years were significant as a result of rainfall. But the differences of energy input structure between two yeas were not significant. Energy efficiency was calculated by energy output to input. Alfalfa was the best in energy efficiency of all crops. Energy efficiency of potato in the north, all crops except alfalfa in central part and fruit trees in the south were below one for more fertilizers input. Energy efficiency of crop sub-system in central part was below one and that of southern was the best of three sites. Energy input for livestock sub-system of southern was more than others. Energy efficiency for livestock sub-system was below one except that of central part in 2006. Energy input and output for integrated system of southern were the most of all. Energy efficiency of south (2006) and central part (2007) were the most. It was specially affected by rainfall in central part. And there was less precipitation in 2006 than 2007. Energy benefit of livestock sub-system of southern part, economic output minus input, was the best and that of northern part was the lowest. 3. Seed input was the main economic input for alfalfa. Paper bag and fertilizer were main economic input for fruit trees in the south. About 51.7-88.0% (average 69.85%) of all economic input was fertilizer for all other crops. Energy input of potato was the most in the north, corn in central part and fruit trees in the south. Economic input of alfalfa was the lest(ï¿¥12-15/ha) in all crops. The most economic output were potato in the north in 2006 and 2007, corn in central part(2006), alfalfa in central part (2007) and fruit trees in southern(2006 and 2007). Economic efficiency of alfalfa, economic output to input, was much more than others and the rank of three sites was south>central part>north. Winter wheat and fruit trees were low in economic efficiency. The most economic benefit, output economic minus input, were potato in the north, corn (2006) and alfalfa (2007) in central part and fruit trees in the south. Economic input, output and benefit of crop sub-system in the south were significantly higher than other sites. Economic input, output and benefit of integrated system of south were significantly higher than others. But northern part was prominent in economic efficiency.4. Soil water content of wheat after harvesting was lower than that before seeding by 40-50%. Soil water content of alfalfa after second cut in September was higher than that after the first cut in July in 2007 because there was most of precipitation from July to September. Soil content in vertical distribution of central part was changed slower than that of northern part. But soil water content of northern part based on agriculture system was higher than that of central part. Soil water content of broom-millet in the north, buckwheat in the central part and alfalfa in the south were the highest at the same time, July of 2007. Soil water content of southern part was higher than others based on the crop production system.5. The rank of SOC for alfalfa was south>north>central part and that for other crops and rangeland were separately southern>central part>northern and central part>southern >northern. SOC density of crop sub-system in southern was 1.12 and 1.79 times of central part and northern part separately.The research was finished in order to make sure the structure and functions of agriculture system in Loess Plateau of eastern Gansu. The result will be useful to analyze agriculture-pasture transition zone and try to supple theory and technology foundation for agriculture structure optimization.