Study On Trend Of Soil Salinization And Soil Productive Poentialty In Pingluo Country Ningxia

Soil salinization is main factor that currently restrict the development of agriculture in irrigation area of Ningxia, research its development rule and trend which are helpful to provide scientific suggestion for reasonable development and utilization of local saline soil. Soil productive poentiality provide scientific reference for resolve the conflicts human, land and environmental resources. By collected and investigated data about land use of Pingluo country, not only analyzed local land use status , also analyzed the change trend and rule of saline soil. Based on collection of local weather data, through the pot experiment of wheat and soil sample analysis, by using the mechanism method, the potential productivities of saline soil, alkali soil, modified saline-alkali, irrigation-silted soil as well as spring wheat, corn, rice, oil sunflower were calculated. In the process of estimation, also estimated the modification coefficient of temperature, water and soil. The modification coefficient of water were calculated under precipitation and irrigation, there were soil salt and other 9 soil indicators which estimated the modification coefficient of soil. The main results in the research are as follows:1. The farmland area is largest among the all land types, the area proportion account for 58.1%; the cutivated land area is main type of land use in farmland, and the irrigated field is 93.3% of cutivated land area. Grassland area proportion account for 23% of total land, forest land and garden plot area are small. The result showed traditional agriculture play an important role Pingluo, and the development of agricultural Structure is unbalance. Unused land is 36.2% of total land, which saline-alkali soil account for 43.7%, Waste grassland and waters account for 23.7%. So the unused land have great exploitation potential.2. The change trend of saline soil has experienced three stages from 1958 to 2005: the trend of salinization was aggravated from 1958 to 1962; redued from 1962 to 1989; and again aggravated from 1989 to 2005. General trend of change was balance, partial area were aggravated.3. The restriction of temperature is different to the crop, the estimated results about temperature modification coefficient of spring wheat, corn, rice and oil sunflower were 0.685, 0.628, 0.656, 0.628. In the rainfall condition, the water modification coefficient of spring wheat, corn, rice and oil sunflower were 0.0904, 0.0547, 0.0896, 0.0896. under the irrigation were 0.7765, 0.7703, 0.7386, 0.7425. Showed the water is main limiting factors of local crop potential productivity, crop hardly growed in the rainfall condition, only by irrigating that crop could obtain harvest.4. The soil modification coefficient were different with the soil types different. Soil modification coefficient of saline soil was 0.3045, alkali soil was 0.2206, modified saline-alkali was 0.4806, irrigation-silted soil was 0.6188. Nutrient depletion and poor soil structure were main limiting factors of soil quality in Pingluo. 5. The potential productivity of irrigation-silted both were highest in the rainfall and irrigation condition. Under irrigation condition, the potential productivity of spring wheat was 5696 kg / hm2, corn was 7642 kg / hm2, rice was 8658 kg / hm2, and oil sunflower was 6338 kg / hm2. The potential productivity of modified saline-alkali were second, alkali soil were lowest. Moreover, The potential productivity of rainfall condition only account for about 10% of potential productivity under irrigation condition.6. The monthly climatic potential productivity of natural grassland changed as monthly average temperature and precipitation changed. The climatic potential productivity was highest from from June to September. The annual climatic potential productivity of natural grassland was 3287 kg / hm2, the man-made grassland was 7023 kg / hm2, and the yield of man-made grassland increased twice. The potential productivity of man-made grassland was higher in the modified saline-alkali soil compared to the saline soil and alkali soil.Based on those results, Discussed the limitation of experiment, there was an error between the results of potential productivity and actual yield, and experiment lack of verification. As well as put forward the suggestion about improve the potential productivity of soil, in order to improve the potential productivity of crop, and promote the sustainable development of land resources.