| The Four-lake lowland district, a traditional intensified farming area and susceptible to waterlogging as well, is located in Jianghan Plain, the middle reaches of the Yangtze, China. Under the guidance of sustainable land management (SLM) and aiming at the establishment of the two model zones Cenhe and Gaochang for an integrated development of these areas, the climate, the vegetation, the soils, the topography, the geological settings, the hydrology, and the socio-economics of the areas were studied, and some field investigations and plot trials were made in year 1997~2001. The author first discussed the biophysical structures and the socio-economic state of the areas, then analyzed the developmental strategy, the possible key techniques, the planning and its implementation, and the developmental approaches, and finally, a working course as "evaluation-planning-implementation" was fulfilled in the two model zones. The objectives of the study are to discuss the principles and methods of land planning under large-scale conditions (micro-zone) and the farming approaches in the traditional intensified farming lowland district for a sustainable development. The results are as follows:1) The Four-lake district was formed in between the rivers and characterized as property change with a successive change in elevation across the sector of the land. The two model zones in this study were chosen to locate in two different elevation points with different relation to water-logging threat. Analyzing to the dish-like micro-zone- Gaochang model zone, one of the typical water-logging-susceptible areas deprived from the reclaimed lake, we observed that some of the biophysical characteristics remained to be the properties determined mainly by the lake properties. The result revealed that the soil taxonomy, soil profile structure, soil water level below the soil surface, and soil physical and chemical properties, and the conditions for drainage and irrigation, conditions for accommodations were characterized by the terrace-divergence according to the successive changes in altitude across the sectors of the land, and the area generally was divided into five step divergences. Several plans to improve the biophysical structure and to change the use direction of the land were put into experiment. Based on which an utilization model "development in a step way" was developed, including reforming and amalgamation of steps by reclamation, the improvement and enlargement of the middle part of the land and the restoration criteria of the land from a rice planting utilization to a fishing pool utilization.2) In the transition from the first step to the second step of the Four-lake district, where Cenhe model zone is located, the most part of the land was ameliorated into quality land suitable for rotation between paddy and dry land. The matching between crops, the cropping systems and the improved land were made by means of field trials from a viewpoint of SLM theory. Melon and vegetable crops were introduced into a series of cropping systems to form the quality cropping systems, namely the optimum models. And eventually, 8 optimum models were developed. By use of the optimum models in the ameliorated area, the productivity and economic efficiency of the land were improved times than before. And the nutrient recycle in the field was sped up, the pollution from the chemicals decreased, the water-logging damages were alleviated, and most of all, the farmers were encouraged to use much more organic manures in cultivation management. In this way, a balance between the consumption and investment of nutrient materials in the field under intensified conditions, and that between crop yieldsand the economic outcomes the farmers could received were attained. The example might point a direction for the future development of the water-logging-susceptible low land.3) In the evaluation of the water-susceptible low land under the large-scale condition (micro-zone), the Delphi method was used to select the fact... |
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