Study Of Water Nutrients Absorbed By Plants, Changing And Applying For Agricultural Process

Nowdays, how to control eutrophication in a biological way has been one of hot topics in ecology. With the continuous development of the ecological cycling agriculture, water-farmland nutrient recycling systems, using plants with efficient nutrients as key structures and composting with aquatic plants as the main function, has become a focal point for resource and environmental studies. This study included technology of ecological water restoration with water hyacinth, preparation of organic fertilizer and fertilizer agricultural using technology, and comprehensive evaluate eutrophicated waterbodies management and organic agricultural production processing, in order to provide basis for making decision of modern ecological agriculture in Taihu Lake and its around area. The main results are as follows:1. Greenhouse gas emissions and water restoration on the surface of water with water hyacinth research showed that:the main form of greenhouse gas emissions on the surface of water was CH4and CO2. Temperature was the main environmental factor affected greenhouse gas emissions on the surface. GWP with water hyacinth increased by63.96%, mainly attributed to increasing of CO2emissions. Calculate the whole growth period as200days, stocking1hm2water hyacinth could absorb nitrogen, phosphorus and potassium by1.46t,0.33t and2.43t, respectively and form organic carbon by20.18t. COD with water hyacinth decreased by28.71%.2. Aerobic composting of water hyacinth at high temperature research showed that:during the whole composting processing, contents of total nitrogen, organic nitrogen increased, nitrate content first rised rapidly and then dropped slightly, ammonium nitrogen content had opposite effects with nitrate and total organic carbon content always declined. Ammonia volatilization concentrated at early stage of composting at high temperature and covered94.88%of total emissions. The main form of carbon emissions was CO2. GWP of greenhouse gas was209.29mg CO2kg-1h-1. After the end of composting, carbon loss rate was47.56%, nitrogen loss rate was9.22%and the fertilizer conversion rate was56.28%, all reaching new standards of manure (NY525-2002). Adding filler reduced the content of total nitrogen and organic nitrogen, increased nitrate content significantly, made no obvious influence of ammonium nitrogen, reduced organic carbon content significantly at the end of composting. Adding filler reduced ammonia volatilization of the pile and increased comprehensived greenhouse effects and made opposite effects on carbon and nitrogen loss with water hyacinth. Adding Elodea benefit harmless treatment of water hyacinth, meanwhile sediment of pool made adverse effects.3. In the same nitrogen input conditions, research of the effects of water hyacinth organic fertilizer to yield and quality of cabbage, soil and environment showed that:the average yield of cabbage fertilized by water hyacinth was lower than the application of chemical fertilizer, while higher than chicken manure fertilizer. Compared with chicken manure fertilizer, water hyacinth increased nitrate content and VC content in cabbage significantly. With the application of organic fertilizer, speed of DTN decline was larger than fertilizer treatment, and there was no regular rules between different organic fertilizer treatments. Compared with chicken manure, application of water hyacinth organic fertilizer improved NH4+-N and NO3--N content in the soil. With the application of water hyacinth, total nitrogen and alkaline hydrolysis nitrogen decreased most at the first stubble and with the increasing of the number of stubbles, total nitrogenincreased and alkaline hydrolysis nitrogen decreasedslowly. With the application of water hyacinth, the organic material lost rapidly, and made no conducive to carbon remains in soil. Water hyacinth decreased synthesized greenhouse effect by16.96%and18.49%, compared with chemical fertilizer and chicken manure fertilizer.4. Study of water nutrients absorbed by water hyacinth, changing and applying for agricultural process showed that:stocking1hm2water hyacinth can harvest fresh water hyacinth990t every year, mixing52.47t straw to aerobic composting can make65.34t organic fertilizer, which can meet6.85hm2vegetable fertilizer, producing84.55t organic cabbage.