Slow-Release Urea Prills Developed Using Organic and Inorganic Blends in Fluidized Bed Coater and Their Effect on Spinach Productivity

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.

Biodegradable Polymer Coated Granular Urea Slows Down N Release Kinetics and Improves Spinach Productivity

“…Peaks appeared at 22 • and 24 • were attributed to gelatin and PVA respectively. Few peaks appeared around 40 • were due to presence of gum arabica in coating formulation of G-3 and G-4 [35,66].…”

“…The use of biodegradable materials to coat urea not only reduces the environmental pollution but can also decrease the harmful effects associated with conventional coatings on the proper functioning of soil and plant ecosystems [29,30]. These bio-based materials currently used as coating of fertilizers include waste palm oil [28], animal manure lignin [31], cellulose [32] and starch [33][34][35], which can be used directly or after some modification or mixing with minerals [36,37]. These materials also slowed down N release from urea that could synchronize with crop N demand during the growing season [28,34,38].…”

“…Moreover, their high biodegradability and renewability due to their derivation from natural products is forcing researchers and industrialists to search for innovative and sustainable bio-based materials that could further reduce the cost of coated fertilizer production while providing high efficiency and superior properties of controlled N release from urea fertilizer at a local scale [25,28,39]. Molasses, starch, honeybee wax and gum arabic are bio-based materials with the potential to be used as binder or coating material [35]. Recently, Irfan et al [40] compared the influence of these bio-based materials on binding and coating efficacy and Zn release efficiency from ZnO coated urea fertilizer.…”

Potassium Plus Biopolymer Coating Controls Nitrogen Dynamics of Urea in Soil and Increases Wheat Production

“…Under favorable conditions, more than 50% of the applied N from urea is volatilized [5], 30% can be leached down, runoff, or nitrified [6], and a further >30% is denitrified to the environment [7]. Hence, plants use only 30-60% of N applied through urea [6,8]; therefore, N use efficiency (NUE) of crops from conventional urea varies from 30-60%, which is very low [6,8] and could lead to economic losses for farmers.…”

Review: Synthesis of Urea in Several Methods

“…The SEM micrograph of C-3 coated urea also supported this release, probably because of insufficient coating, which looked like a fibrous rodlike structure formed because of POP and para_n wax, which possessed poor compatibility against each other. The samples composed of POP depicted better efficiency than different formulations, probably due to the sparingly soluble property of POP 20 .…”