Preparation And Application Of Plant Nutrition Functional Materials

The inconsistency among the natural resources, environment and people is getting more and more serious in21th century. Low fertilizer use efficiency and low soil fertility of the cultivated land have turned into the key factors to restrict agricultural production, and threaten national food safety. New functional materials with the character of plant nutrition to be applied for the restoration of desertification and production of slow-release fertilizers become a mainstream in high efficient use of agricultural resources and environmental friendly new material technique. It is a creative technique to prepare functional materials with the character of plant nutrition through modern chemical technology and nano-material technology using industrial and agricultural waste as main raw material. After material preparation and characterization, the functional materials were applied in slow-release fertilizer production and restoration of desertification. The risk of the functional materials in soil and environment was also evaluated in this paper. Main results were as follow:1. Preparation and characterization of plant nutrition functional material in nano and sub-nano gradeThree micro-emulsified and five chemically polymerized nano, sub-nano plant nutrition functional materials were prepared through micro-emulsification, high shear and heterogeneous polymerization techniques using waste, industrial by-product and cheap, environmental friendly chemical materials. Then the materials were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM) and laser particle size analyzer. The results showed that90%colloid particles of the materials were in the size of10-120nm as nano and sub-nano grade.2. Application of the materials as coating agent for slow-release fertilizer, the use efficiency of nitrogen increased and the soil microbial diversity improvedSpecific slow-release fertilizers for wheat, maize and rice were prepared to release nitrogen to meet the demand of crops at different stage. The crop yield enhanced by2.07%to7.17%by use of the functional materials coated slow-release fertilizers in different area comparied with regular fertilizer, soil fertility improved and nitrogen use efficiency increased by more than10%. During crop growth stage, the urease activity decreased. The bacterial Shannon index enhanced significantly comparing with the urea treatment. In all, the soil microbial diversity could be promoted, enzyme activity and microbial population enhanced by the use of slow-release fertilizers.3. Application of the materials in desert as sand-fixing and water retaining polymer, the soil characters of sand-fixing, water retaining and physical struncture improvedUsing the materials as sand-fixing and water retaining agent, the soil pore status, aggregate structure improved as its high fixing and complexing reaction with soil minerals. In addition, nano and sub-nano composite materials had huge specific surface area. They formed tight net structure on soil surface, and formed relatively thick adsorption water or water film to enhance the ability of water absorbing and retaining. It is the main reason of the materials for sand-fixing and water retaining. Field experiment with the use of the materials also showed that the soil temperature at5-10cm layer could increase0.6～2.6℃and the soil water content at0-20cm almost two times of the control. The biomass of ryegrass was two times higher than that of the control.4. In laboratory conditions, the selected five water-soluble functional materials could be degraded more than98%within4-20weeks when they mixed with microorganisms. The degradated products are small stable molecules, CO2and H2O. The number of beneficial bacteria increased while denitrifying bacteria decreased, which means decrease of nitrogen loss and increase of nitrogen use efficiency. Application of the fertilizers also enhanced the number of nematoda phylum, acari, and improved soil biodiversity.In summary, the functional materials with the character of plant nutrition performed environmental friendly characters. They could not only increase nitrogen use efficiency but also control desertification of soil. These materials are very important for cultivited land sustainable use and national food security.