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Mechanism and Evaluation of Nutrient Release of Slow and Controlled-Release Fertilizers

Author: DuanLuLu
Tutor: ZhangMin
School: Shandong Agricultural University
Course: Soil
Keywords: Slow release fertilizer Microstructure Controlled release mechanism Nutrient Release Characteristics Scanning electron microscopy
CLC: S145.6
Type: PhD thesis
Year: 2009
Downloads: 860
Quote: 3
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With the population - resources - environmental issues have become increasingly prominent, agricultural production for the protection of high-yield fertilizer application even more attention. Application of fertilizer to improve fertilizer efficiency, reduce waste of resources and reduce environmental pollution to protect soil resources sustainable use objectives and key. Slow release fertilizer can significantly improve the utilization of fertilizer to reduce volatilization and leaching losses of nutrients, reduce fertilizer pollution of the environment, to improve crop growth and development, improve crop yield and quality, and thus received extensive attention from researchers . Production and application of slow-release fertilizer has become one of the main trends in the development of fertilizer industry, but also the development of modern agriculture, an inevitable requirement for the implementation of sustainable development strategies. Slow release fertilizer can improve nutrient utilization and nutrient release characteristics of nutrient release rate and release and nutrient release and crop nutrient absorption synchronization, so its release properties of the establishment of research and evaluation methods evaluation of slow release fertilizer quality and performance of the key link. In this study, water extraction, saturated salt solution, vapor pressure, soil culture and fertilizer landfill to explore different types of slow release fertilizers release mechanism, and in accordance with the slow-release fertilizer industry standard (HG / T 3931 - 2007), sulfur coated urea industry standards (HG / T 3997-2008) and the European Committee for Standardization (CEN) recommended controlled-release fertilizer and sulfur coated urea evaluation criteria, 15 slow release fertilizer nutrient release characteristics of the research and evaluation. By scanning electron microscopy and infrared spectroscopy to study the microstructure of the slow-release fertilizer. At the same time, the use of pot and field trials, evaluation of slow release fertilizer nutrient release characteristics of crop fertilizer laws consistent. The main findings are as follows: 1. Temperature is the main factor of slow release fertilizers release. For thermoplastic resin coated urea, thermoplastic resin coated compound fertilizer, thermosetting resin coated compound fertilizer, sulfur coated urea, iso-fork two urea, the higher the temperature, the faster the rate of nutrient release, release period relatively more short. Polymer coated controlled release fertilizer in the water release curve \Nitrogen release rate versus time relationship in the different culture temperature conditions for availability order kinetic equation S = NO (1-e-kt) Elovich equation S = a blnt and parabolic equations NT the = a bt0.5 Characterization at 25 ° C and 40 ° C, the best fit of a kinetic equation. Quantitative description of the first-order kinetics equation is more effective nitrogen nutrient release kinetics equation. Nutrient Release of polymer coated compound fertilizer nitrogen release rate of the fastest, followed by potassium, phosphorus release rate is slow. Coated controlled release fertilizer nutrient release is coated inside and outside the water vapor pressure difference caused by the release rate constant k increases with the water vapor pressure difference. Vapor pressure greater the difference, the greater the nutrient release rate, the smaller the contrary. In the same water vapor pressure, coated fertilizer nutrient release rate increases with prolonged incubation time; same incubation time, nutrient cumulative release rate performance for H2O GT; KH2PO4 saturated solution gt; KCl saturated solution. Coated controlled release fertilizer film inside and outside the water vapor pressure difference is the speed of the underlying factors that control nutrient release rate. The release rate of soil water content of slow release fertilizers have a greater impact. When the soil water content of field capacity, with the increase in soil moisture, nutrient release to accelerate. Coated urea under different soil moisture curve fitting correlation coefficient between 0.9740 to 0.9972, the standard error of between 0.0015 to 0.0022, reaching a significant level (p = 0.0001). For coated compound fertilizer, test samples for CRF1 and CRF2 nitrogen release rate in each of the training period with the increase of soil water content increases. For sulfur coated urea, SCU release rate is higher than in the soil cultures in the release rate in still water extraction. The release rate of of isobutyl Diurea in water is always faster than the rate of soil cultures in the release. Scanning electron mirror tests showed that different coating materials, envelope in the structure of the film on the surface of the fertilizer granules. The surface of the thermoplastic resin film has tiny pores, these pores is the release of nutrients channel; the thermosetting film surface are relatively dense, are a type of solid particles to the projection, it is difficult to see that the presence of micropores. Sulfur coated urea film surface is very smooth, the dense arrangement between the coating material and the accumulation. Thickness of the film can be seen from Creep, test samples for PCU1, of CRF1, CRF2 Nutricote, Osmocote and SCU1 film thickness 59.5μm, 58.6μm, 41.4μm, 107μm, 46.3μm and 55.1μm, while six fertilizer uniform, good quality envelope. The infrared spectroscopy Test showed that there are significant differences in the infrared spectrum of the type of membranous material. Two thermoplastic resin coated compound fertilizer (CRF1 and Nutricote) membrane material at the wavelength of 3447 cm-1, 2919 cm-1, 2850 cm-1, 670 cm-1 near infrared absorption material of the two membranes the similar, compare the infrared spectrum of the visible spectrum similarities; two thermosetting resin coated compound fertilizer (CRF2 Osmocote) spectra are very similar, the difference is Osmocote containing aliphatic acid functional group; the SCU1 infrared spectra shows not only the the the SCU1 film similar to the ethylene oxide polymer or polyethylene wax and other additives, further comprising in addition to the inorganic sulfur majority. 25 ℃ temperature extraction method for the determination of measurement, and 100 ° C rapid extraction method to accelerate the latter nutrient release rate. Available 100 ° C rapid extraction method to establish the forecast slow release fertilizer at room temperature (25 ° C) release of the regression equation (a quadratic equation, correlation coefficient greater than 0.98), a difference of 1 to 3d predicted and measured values. The determination of the release of 25 ° C room temperature extraction method for 66d and 84d coated controlled release fertilizer the CRF2 and the CRF3 100 ° C conductivity method to predict the nutrient release of 65d and 81d, the relative error is less than 3.5%, showing that conductivity method can accurately predict the coated controlled release compound fertilizer nutrient release rate and the release period. Initial nutrient release rate, the average release rate and nutrient release period and other parameters can be used for comprehensive evaluation of slow-release fertilizer. 7 slow release fertilizer nutrient release characteristics of water, soil two media have a certain relationship, nutrient release characteristics of four kinds of slow-release fertilizer in the water immersion method and soil culture can be fitting the binomial equation together, there is a certain correlation between two methods. Therefore, evaluation of slow release fertilizer in agriculture, on the basis of laboratory flooding method, incubation test, and then measured the crop nutrient uptake, and combined with crop growth and yield results be specific analysis. The results of this study show that the resin coated controlled release fertilizer release rate can be measured in the water at the same temperature forecast in the soil nutrient release rate. 8 release fertilizer nutrient release by the adjustment of the production process and improve it with crop nutrient uptake phase synchronization, the role of the crop yield and efficiency, CRF1 CRF2 processing, rapeseed nutrient uptake and biomass significantly higher than other treatments, to CRF2 treatment for the highest and nutrient release characteristics of CRF1, CRF2 closer rapeseed fertilizer requirement of the law. Evaluation and prediction of the types of fertilizer and crop matching the two together can create a special controlled-release fertilizer suitable for a variety of crop growth and development.

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > FERTILIZERS > Fertilizer formulations > Limitation of fertilizer
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