These changes mainly decrease inputs into rice cultivation. The fish eat weeds that compete with rice for fertilizer. The fish also help control plant diseases and insect pests and, therefore, reduce the need for pesticides and the amount of labour needed for weeding. Rice fish culture improves labour productivity. Labour productivity is a measure of the total products produced in a certain period.
Labour productivity reflects the level of fish-raising in ricefields.
Low-level rice fish farming has lower labour productivity than rice farming. When the ricefield is used to cultivate fry and fingerling the labour input is increased a little. Land and Water Resources China is a large country with a large population and a scarcity of agriculture land. Survey of rice fish culture in Sichuan and Jiangxi in 1984. 67.5 Rice alone cannot make full use of the materials and energy in the ricefield.