Application Of Mycorrhizal Technology In The Control Of Nitrogen And Phosphorus Loss In Paddy

Since the 20th century, early 80's, extensive use of agricultural chemicals has occurred with population growth and increased demand for food in China.But the backward techniques of fertilization and irrigation has resulted in low utilization of chemical fertilizers and pesticides, and most has been ultimately lost into the environment through different ways. Therefore the phenomenon of the agricultural non-point source pollution continues to deteriorate.To solve the problem, a new type of biological agents will be applied to paddy in this study. Under different amount of fertilizer applied,the mycorrhizal effect on Growth-promoting of rice was investigated through examining rice growth and percentage of AMF on root Colonization. Furthermore, the impact of temporal and spatial variation of nitrogen and phosphorus caused by AMF has also been studied. While the mechanism of mycorrhizal symbiosis was preliminary studied,to provide reference for the engineering applications of mycorrhizal technology in controlling non-point source pollution.Rice dependents upon mycorrhizal fungi greatly while the amount of 75% fertilizer is most suitable for the growth of AMF, which make AMF reach stable infection rate of 20% to 30%.Mycorrhizal plants have greater Intensity of photosynthesis and biomass, relative to non-mycorrhizal plants,which could accelerate the establishment of self-organization during vegetative growth stage of rice, to reserve rich matter and energy for the reproductive phase.AMF combining with has better effect than agents or fertilizer alone in promotion of Crop yield. In addition, the gradient of 75% fertilizer is the most cost saving and environmentally friendly fertilization mode in the inoculated treatment,the yield of which have a 4.7% increase over 100%fertilizer alone.While AMF inoculation enhanced r strategy in the reproductive strategy, resulting in a large number of small seeds.Mycorrhizae can improve the content of available nitrogen and phosphorus in soil, enhance the capacity of soil in retaining nutrition,and reduce the content of NH₄⁺-N and PO₄^3--P in the surface water of paddy,which constitute the main components of non-point source. Because AMF combined with 75%fertilizer is the most suitable fertilization, is able to reduce the amount of fertilizer by 25%,equivalent to (NH₄)₂SO₄ of 34.72kg/hm². In inoculation treatment, the shoots of the mature rice have 11.82kg/hm² nitrogen and 2.52kg/hm² phosphorus more than non-mycorrhizal plants,while underground parts of rice have 5.27 kg/hm² nitrogen and 1.70 kg/hm² phosphorus than non-inoculated treatment.Mycorrhizae can increase soil porosity and water holding capacity, lower soil bulk density to improve the physical structure in the soil. Meanwhile,it can increase organic matter content and pH value of soil to regulate the micro-environment for survival of organisms and plants.Therefore, the microbial community structure in the rhizosphere has been improved,soil biological activity and crop growth promoted as well. The process above benefits the source control of agricultural area source pollution through reducing the amount of pesticides and fertilizers applied.