COMPARING CROP HOG FISH AGROECOSYSTEMS WITH CONVENTIONAL FISH CULTURING IN CHINA

This research conducted in subtropical hilly Jiangsu Province, China, was aimed at developing intensive fish farming systems for better use of local resources while achieving ecological and economic benefits. A semi-intensive system with moderate inputs (crop-hog-fish agroecosyst em) was found to be more profitable than extensive or intensive fish c ulture systems and yielded twice as much as cropping alone. The techni ques for fish culture in the crop-hog-fish system consisted of a polyc ulture of fish, pond water management, green forage supply and food su pplements. Targeting gross weight output of 6 t/ha or a net output of 5 t/ha, the crop-hog-fish system consists of a 1-ha fish pond, 0.5 ha cultivated grassland to support the herbivorous fishes, 0.5 ha croplan d to provide fish food, and 2.5 heads of hog. The hog manure is used t o fertilize the pond water. The external energy subsidies include 1000 kg fish fry, 400 days of labor, certain chemicals and electricity. Th e total energy input is 193.5 GJ/ha, while the energy output is 34.3 G J/ha, yielding a transfer rate of 0.177. The output value is 2.57 time s the production costs. The authors believe the recommended model is a daptive and viable to small farms with appropriate resources, especial ly in subtropical and temperate areas.