Changes In Soil Fertility And Environmental Quality In Red Soil Region Under Intensive Agricultural Use And Their Control

The property of intensive agricultural uses to boost up yield per unit area of crops relieson large devotion of high quality seeds, chemical fertilizers, pesticides, the sound irrigationand the appliance of mechanization. So the conflicts between the large population and thelack of cultivable have been relieved to a large degree. China has a large population, butproportionately limited land resources. Thus we considered intensive agriculture as the onlyway for agricultural development of China. (only to pursue the intensive agricultural useand the devotion of means of production unilaterally is a waste and will exert great pressureon soil and entironment regardless of local, regional or global.) It is a waste only to pursuethe intensive agricultural use and the devotion of means of production unilaterally andexerts great pressure on soil and entironment regardless of local, regional or global. Thecoverage of total red soil (including the area of torrid zone and subtropical zone etc.) makesup 45.2% of that of global soil, while the population there accounts for 48% of the total. InChina, the coverage of red soil in south takes 1/5 of that of total soil with 2/5 of populationand 3/10 of cultivated land, but surprisingly with 1/2 agricultural production value supplieswhich can supply about half of the population. It plays an important part in agriculture inChina. This paper focuses on some representative areas of intensive agricultural uses in theSuburbs of Nanchang City and Yujiang County in Jiangxi Province and attaches greatemphasis on analyzing changes of soil fertility and environment with intensive agriculturaluse, finding out main driving forces and proposing some management measures. Byresearch, the results are as follows:Soil fertility and environment changes under intensive agricultural use:1, Soil fertility has increased with intensive agricultural use. In detail: soil organic matter,soil total nitrogen, soil available phosphorus, soil available potassium and soil fertilityindex are increase, but the extents of their growth are different, soil available phosphorusand soil available potassium increase fast but total nitrogen increase slow. The soil fertility integration index of Nanchang city is higher than that of Yujiang County, and the soilfertility integration index of vegetable plot is higher than that of paddy field.2, Soil pH has a signification decreasing tend with intensive agricultural use. Vegetableplot decrease more than paddy field and the soil acidification is much more distinct.3, Soil salt with intensive agricultural use gathers to the surface. The content of salt invegetable plot is higher than that of nursery garden and dry land.4, Heavy mental pollution of surface soil (0～10cm) have taking place in some farmlands.The pollution index include single and integrative of vegetable plot is higher than paddyfield. From analyzing the difference of pollution index in vegetable plot in Suburb,personally used vegetable plot and paddy field, the results show that the integrative indexvegetable plot in Suburb is higher than personally used vegetable plot, and personally usedvegetable plot is higher than paddy field.5, Soil NO₃^-N is at a low level in February of year 2003, but soil available phosphorusaccumulates too much, and soil available potassium is suitable but with excessive samplepoint. Researches show that the content of soil available phosphorus and soil availablepotassium in Nanchang city is higher than that of Yujiang county.The main driving forces of the fertility and environment changes with intensiveagricultural use are as following: adjustment of the agricultural cultivation structure; landuse change; dosage of chemical fertilizer especially the proportion of Nitrogen, Phosphorand Potassium; manure use and the influence by industrial production. Some suggestionsare as following: (1) Reducing fertilizer input in a short time, combining with nutritionaccelerant and fertilizing slow-release fertilizer to improve fertilizer efficiency can controlexcessive soil nutrition enrichment or unbalance to some extent. (2) Optimize the structureof the fertilization and control the dosage of nitrogenous fertilizer. The proper applicationof alkaline ameliorator as calcareousness was an important measure to prevent and amendsoil acidification. (3) Adjust the way of using soil according to the pollution of heavy metal.For heavy polluted area, food production should be forbidden as soon as possible whilefibre plant or grass is available. For the slightly polluted area, chemic ameliorator and superaccumulation plant can be used to restore it.