| By means of the analysis on statistic data, survey and field test, researches of transition, principle, and development trends of farming system for triple cropping distract of Hunan province in China were carried out. Technological strategies and technological system of high-yield and good profit on planting-pattern in the future were also studied. 1.Evolving regularity of farming system from 1949 to 1998 Analysis on production of grain: 1) Total grain output in Hunan Province from 1949 to 1998 ascended four steps (5000,000t/step). Since second step, the time interval for each step increased from 7 years to 10 years. The difficulty was greater than that of past for the increase of total grain output. Grain output related to the innovation of farming system. 2) Grain output development passed four phases. In the first phase (1949-1957), acreage under cultivation and planting area were main factors of the increase of grain output. In the second phase (1958-1979), application of variety and technique of farming were main factors. In the third phase (1980-1989), condition of the production, variety and technique of farming were main factors. Forth phase (1990-1998), integration of modern agricultural technology and market demand were main factors. 3) The grain output increase in Hunan Province mainly depended on scientific technology since 1957, the contribution rate of scientific technology increased from 0.7% to 50.5%. 4) The contribution of cropping index on grain output increase was from 47% to 81%, and it played an important role in regulation of planting structure. The stabilization of rice planting area was important means of grain yield increased. The alert line of acreage under cultivation per capita was 0.0461 hectare in Hunan Province. Characteristic of farming system evolvement: 1) Crop composition and distribution were optimized continuously. The ratio of grain crops reduced 21 percent and the proportion of cash crops increased 11 percent in sown area. The ratio of double rice decreased 4.92 percent in planting area. 2) Cropping index has increased to 242.3% from 114.3%, but it hovered recently. The area of triples cropping decreased 16.7 percent compared to 1991. 3) The type of multiple cropping has increased. The area of 15t/ha in grain yield has extended 38.3% of cultivated area. The type and area of crop rotation has decreased. The area of succession cropping has increased. The area of double rice has occupied about 43% of cropping sown area. 4) The means of maintain the land has changed from organic manure to fertilizer. The area of green manure has reduced to 13.23% of that of grain cropping. The quantity of pure fertilizer of per unit cropping sown area has enlarged to 227kg/ha. 5) The content of science and technology in grain production has gone up. The cultivated area per capita has decreased 56.8%. The quantity of grain per capita has increased 102.2%. 6) The important factors of effect on farming system were market demands, rice variety, the condition of water and fertilizer, and the development of scientific technology. The principle of farming system evolvement: In addition to keep the essential principle of farming system, there were characters for the development of farming system in Hunan Province as follows: 1) The demand, variety and scientific technology were three basic factors of farming system development. The perfect of system of production, process, and distribution were basic guarantee of farming system development. 2) Cropping index become direct ratio with the amount of grain demand and inverse ratio with arable land per capita, proportion of grain crop area, and grain output per unit area. 3) Winter crops development required the crops with good benefit and scale planting. 4) The application of double crop rice increased. The orientation of adjustment of the structure of crop planting was high efficiency.5) Integration of modern technology was the impetus of farming system development. 6) Pluralistic of planting structure and the area of 15t/ha in grain yield were the development trend of farming system. 7) The means of maintain the land become simplification and rationalization step by step. Planting combined with stock raising promoted the exertion of the potential of grain production. 2.Forecast for farming system from 2000 to 2015: 1) Farming system, agriculture in future will achieve sustainable development with two aims: improving agricultural product's quality and increasing benefit. The development of resource-saving and resource-protecting farming system will ensure yield increase. 2) Arable land per capita will decreased 18% at least. The amount and quality of labor force will descend. Availability irrigation area will difficult to enlarge without plentiful funds devotion. Total grain output will increase 11%-15%. Total grain demand amount will increase 17%-30%, and request to enhance 25.3% unit area yield. 3) Cropping index will be increased to 269%, when the demands and benefit of farm products were favorable. The area of triplecropping will be determined by the problem of quality of early rice and benefit of winter crop. Grain planting area will be 5000,000ha. Grain yield per unit area will reach 7.6t over /ha. Availability irrigation area will reach 90 percent. Pure fertilizer application amount 2040,000t. 4) Some high yield and high efficiency triple cropping will expand. The area of triple cropping will develop to 60 percent of arable land. The area of 15t/ha in grain yield will increase to 125.8% of arable land. The target of winter crop will be to add income. The continuous cropping of rice will be important planting pattern yet. The contribution rate of scientific technology will increase to 60 percent. The renewal interval of crop variety will cut to 3 or 4 years. The area of vegetable will increase to 53.8%. The reasonable structure are that the ratio of grain crop, cash crop and feed crop will be 1:0.23:0.28, and the ratio of rice, wheat and corn will be 5.75:0.08:1. 3.The strategy of farming system development: The fundamental strategies are to increase cropping index, keep stable planting area of rice, increase yield of unit area of grain crops and other crops, and boost good circulation of production of agricultural products. 1) Optimize agricultural structure and raise producing efficiency. Increase the ratio of production value and the numbers of labor force of second and thirds industry. Develop the agriculture, forestry, stock raising, homework and fishery evenly. Buildup stock raising and promoted the increase of value of planting products. Change the single planting structure; develop the reasonable structure of grain crops, cash crops, and feed crops. 2) Stabilize area of double rice, and develop area of winter crops. 3) Adopt technological strategies of intensive, high yield and high efficiency: Multiple cropping + optimize essential production, increase efficiency of arable land. 4) Expand crop varieties with high quality, boost up competing power of agricultural products in the market. Keep the farm products salability by the application of order agriculture. Establish farm products industry, develop the approach of combination of industry, agricultural base and farmer. 5) Apply the policy of district development, exert the superiority of zone bit. 6) Intensify the infrastructure of cropland, enhance the potency of fight natural calamities. 7) Establish the technology system of triple cropping with high-yield and high efficiency. 8) Enhance planting index and increase unit area yield. 9) Strengthen the research of resource saving and resource-protection.
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