Abstract
The application of urea-based fertilizers in developing countries has gained significant momentum over time. urea usage is to meet demand and supply gap of food resources as world population is increasing at a fast pace. urea contains largest content of nitrogen (46%) among all the solid nitrogenous fertilizers. However, main drawback of urea is its higher dissolution rate. After soil application, most of urea nitrogen is lost through a leaching, runoff, nitrification-denitrification and ammonia volatilization. To tackle urea related environmental pollution, development of slow-release urea fertilizer is a need of the hour and this would also increase product use efficiency in terms of crop productivity and its N uptake. We studied the usage of polymeric materials in combination with inorganic substances like sulfur and plaster of Paris as effective and biodegradable coating substances for urea prills. For coating on urea prills, fluidized bed coater was used whereas paraffin wax and molasses were used as binding agents. The urea was coated with four different formulations, i.e., C-1: PVA 5% + plaster of Paris 10% + sulfur 5% + paraffin wax 2%, C-2: PVA 5% + starch 10% + sulfur 5% + paraffin wax 2%, C-3: gelatin 5% + plaster of Paris 10% + sulfur 5% + paraffin wax 2% and C-4: PVA 5% + starch 10% + sulfur 5% + paraffin wax 2.5% + molasses 2.5%. Each formulation along with uncoated urea prills (C-0) were evaluated for characterization and N release kinetics. All the formulations along with uncoated urea were applied to spinach crop in pot experiment. A control (No N: untreated) was also kept. Spinach biomass yield and N uptake were determined. The formulation C-1 yielded highest urea-N release efficiency and spinach N uptake of6.87% and 1.93 g N/pot, respectively. Themodified Schwarz and Sinclair formula gave the excellent representation of release of nutrient-N from coated urea prills. It is concluded that coating urea prills with organic and inorganic blends is better option to slow down N release kinetics and improve spinach productivity. Therefore, by using coated fertilizers, farmers can improve agro-environmental value of urea, worldwide.
Highlights
Nitrogen (N) is a vital constituent for any crop to complete its lifecycle and forms basics of sustainable agriculture [1]
The objectives of the study are (i) to evaluate the characterization and N release kinetics of urea prills coated with biodegradable polymers and (ii) study the effect of these coated fertilizers on N uptake and foliage yield of spinach
Coating test materials of analytical grades, i.e., sulfur, starch, polyvinyl alcohol, gelatin and paraffin wax were purchased from Daejung-Korea
Summary
Nitrogen (N) is a vital constituent for any crop to complete its lifecycle and forms basics of sustainable agriculture [1]. Inorganic N compounds mostly exist in the form(s) of ammonium, nitrite and nitrate ions [2]. Crop plants utilize the N ions as nitrate and/or ammonium to fulfill their N demand [3]. Natural and synthetic fertilizers are being used since decades to replenish the soil with essential plant nutrients. After application of various N fertilizers in soil, mineralization process starts. In case urea is applied to soil, urea–nitrogen starts loosening from the fertilizer core and is taken up by crops as well assoil microorganisms, present within the soil environment after due process of nitrification [5]. The process of mineralization/nitrification is affected by many ambient conditions like soil moisture content, soil types, fertilizer granule structure, atmospheric temperature, presence and type(s) of microorganism and enzymes [6]. Breakdown of N fertilizers into various constituents is a result of above mentioned factors including oxidation and reduction
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