| slow/controlled release fertilizer can be made by hydrophobic low permeability of the membrane covering up the fertilizer; on the other hand, it can be made by adding the inhibitor to improve nutrient utilization and crop production. In this experiment, we used the method of indoor simulation combining field experiments. We made homemade slow release fertilizer by using superfine phosphate rock powder and biological inhibitors. And the physical and chemical properties of fertilizer, nutrient release characteristics and biological effects were studied. The main results are as follows:1. Four types of controlled release fertilizers, CRF2, CRF3, CRF4and CRF5, were prepared out of a common compound fertilizer (N-P2O5-K2O:15-15-15) by coating it with superfine phosphate rock powder (SPRP), which accounted for0%,40%,50%and60%of the total coating in mass, separately. Electronic microscope scanning, static water releasing, soil incubation and a field experiment were conduced to explore characteristics of their nutrient release and their effects on physiologic traits of Chinese cabbage. Results show that the use of superfine phosphate rock powder in coating markedly improved evenness and density of the surface of the coating and hence its capability of controlling nutrient release, and the effect increased with the proportion of the powder in coating. The four kinds of homemade SPRP-coated fertilizers had a nutrient releasing period,58-68days longer than the common compound fertilizer had but still shorter than88days the resin coated fertilizers (CRF1) had. However, their apparent nitrogen release rates were approximate to that of CRF1. Besides, the four SPRP-coated fertilizers increased the chlorophyll content, photosynthetic rate, and transpiration rate in the leaves of the plant during its middle and late growth stages, the activities of SOD, CAT and POD during its balling period, the biomass per head by0.17-0.77kg, the yield by6.66%-35.5%, and sugar/acid ratio, soluble sugar content, and VC content of the head of the plant at the harvest stage. Comparison with CRF1shows that they made no big differences in physiological traits of the plant. In terms of nutrient release and effects on physiological traits of the plant the four homemade fertilizers follow the order of CRF4≈CRF5>CRF3>CRF2.2. Four kinds of slow release fertilizers were prepared out by coating a common compound fertilizer (N-P2O5-K.2O:15-15-15) with four kinds of superfine phosphate rock powder (SPRP) which accounting for60%of the total coated materials in mass. Electronic microscope scanning, static water releasing test, soil incubation experiment and a field experiment were conduced on their nutrient release mechanisms and their effects on physiologic traits of Chinese cabbage. The results showed that all these four kinds of SPRP could markedly improve microstructure and thus release rate. However, their capacity was inferior to controlled release fertilizer (CRF); besides, four homemade fertilizers increased chlorophyll content, photosynthetic rate, transpiration rate in the leaves of Chinese cabbage during its late growth stage, and improve the SOD, CAT, POD enzyme activity during its ball period. In addition, four fertilizers improved yield by18.94～24.44%than common compound fertilizer, and improved sugar-acid and soluble sugar and Vc contents of the head of Chinese cabbage at the harvest stage; more, there are not obvious differences of physiological traits between the JCRF2, YCRF2and CRF. Nutrient release characters and agricultural effect of four homemade fertilizers follow the order:JCRF2≈JCRF2>JCRF1=YCRF1.3. Four homemade compound fertilizers with nitrification inhibitor dicyandiamide (DCD) being ratio0%,1%,2%and4%, separately were prepared out of common compound fertilizer by coating them with fly ash as major material. Soil incubation experiment and field experiment were used to study N-release characteristics of the fertilizers and their effects on Chinese cabbage. Results showed that:(1) Using four kinds of fertilizers could keep N as NH4+-N for a long time, consequently, reduce the risk of nitrate N losses. The effects of four kinds of fertilizers on nutrient release property were4%>2%>1%>0%;(2) Four kinds of fertilizers increased chlorophyll content, photosynthetic rate, transpiration in the leaves of the Chinese cabbage during its mid and late growth stage, and the two kinds of which ratio being1%and2%were better than others; the fertilizer added by4%ratio DCD was lowest. However, the other three kinds of fertilizers improved the yield by14.0%～17.2%, income by14.5%～17.5%, and there were not obvious differences between the latter kinds and thermoplastic resins coated fertilizer. In addition, they decreased nitrate and organic acid contents by a certain extent in the functional leaves of the plant, and improved sugar-acid ratio and soluble sugar and Vc contents of the head of the pant at the harvest stage. Moreover, the effects are not obvious comparing with common compound fertilizer and resin coated fertilizers.4. Four kinds of new developed urea amended with biological inhibitors and coated or only coated with inorganic materials were prepared by coating conventional granular urea (N46.0%). Using a coated urea (resin coated urea,90day, RCU) made in China and a conventional granular urea as check, their effects on physiological characteristics, yield and quality of peanut were examined in a field experiment. The results indicated that, four kinds of urea kept higher ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3VN) contents at flowering stage (FS) and podding stage (PS) compared to conventional urea, and CU+HQ+DCD (coated urea+dicyandiamide+hydroquinone treatment) had the highest contents, being similar to RCU treatment. At FS and PS, the chlorophyll content, photosynthetic rate, transpiration rate and chlorophyll fluorescence parameters were significantly increased upon CU+DCD, CU+HQ and CU+HQ+DCD treatments. In addition, CU+HQ+DCD treatment produced27.3%more pod yield,6.7%more total yield, increased9.17%more protein content, and decreased46.56%NO3--N content than that of conventional urea treatment. This product with excellent slow release capacity, being easy to get at a low price and environment-friendly, could be especially useful in agricultural application. |
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