Nitrogen Pollution Impact and Remediation through Low Cost Starch Based Biodegradable polymers

The world does not have too much time to ensure that the fast-growing population has enough land, food, water and energy. The rising food demand has brought a positive surge in fertilizers’ demand and agriculture-based economy. The world is using 170 million tons of fertilizer every year for food, fuel, fiber, and feed. The nitrogenous fertilizers are being used to meet 48% of the total food demand of the world. High fertilizer inputs augment the reactive nitrogen levels in soil, air, and water. The unassimilated reactive nitrogen changes into a pollutant and harms the natural resources. The use of controlled-release fertilizers for slowing down the nutrients’ leaching has recently been practiced by farmers. However, to date, monitoring of the complete discharge time and discharge rate of controlled released fertilizers is not completely understood by the researchers. In this work, corn starch was thermally processed into a week gel-like coating material by reacting with urea and borate. The granular urea was coated with native and processed starch in a fluidized bed reactor having bottom-up fluid delivery system. The processed starch exhibited better thermal and mechanical stability as compared to the native starch. Unlike the pure starch, the storage modulus of the processed starch dominated the loss modulus. The release time of urea, coated with processed starch, remained remarkably larger than the uncoated urea.

Attributes of natural and synthetic materials pertaining to slow-release urea coating industry

Urea is one of the spirited input materials for plant growth. However, more than half of conventional urea applied to the soil may not reach the plants and be washed off by rain and irrigation water. The high lost proportion results not only in economic losses but also in environmental pollution. Alleviation in cost and nitrogen pollution is possible by mitigating the nitrogen release rate and synchronizing it with the plant’s need. A wide range of synthetic and natural materials are being tested for production of slow-release fertilizers. Each one of these materials has its own merits, with accompanying disadvantages. This study critically reviews the most featured natural and synthetic materials pertaining to the slow-release urea industry. The focused review was aimed at elaborating the benefits and limitations of polymeric and nonpolymeric coating materials, release mechanism of conventional and coated urea, methods to characterize the coated urea, slow-release characteristics imparted by a coating to the coated urea, and release patterns of conventional and coated urea. This discussion was further extended to commercially available coatings and slow-release potential of superabsorbent, urethane, and starch-based coatings.