Review: Modified Urea Fertilizers and Their Effects on Improving Nitrogen Use Efficiency (NUE)

Abstract

Urea has served as the primary nitrogenous fertilizer globally since the early 1950s. It is widely recognized as the most concentrated nitrogen source, containing approximately 46% nitrogen. Presently, around 220 million t/year of urea compounds are manufactured globally to fit the requirements of the agricultural sector. However, a significant drawback of this is that approximately 30–35% of the urea used in soil can be lost to the environment because of its limited effectiveness. Enhancing the efficiency of urea utilization can be achieved by regulating the release of urea-nitrogen in the soil. Numerous researchers have reported that the use of slow or controlled fertilizers can regulate the release and accumulation of nitrogen in the soil. Moreover, the augmentation of soil nitrogen levels can be accomplished by using the slow or controlled release of urea fertilizers. The regulation of the release process can play a vital role in the peril of N loss. This can be effectively alleviated by delaying the release of nitrogen in ammonium form configuration for several days. This delay functions to diminish nitrogen losses, which are caused by the rapid hydrolysis of urea, and loss by leaching or volatilization. Therefore, this review aims to comprehensively explore the use of conventional urea and various materials employed for modifying urea. It will explain the distinctions among modification processes and their respective mechanisms. This review will also discuss the pros and cons of applying slow- and controlled-release nitrogen, the impact of modified urea compounds on crop productivity, and nitrogen use efficiency (NUE).

The Effects of the Co-Application of MCPA Herbicide and Urea on Grass Rhizosphere Microcosms

“…Furthermore, Tejada et al [45] demonstrated that urease and dehydrogenase were less affected by MCPA in soil containing higher contents of OM due to enhanced herbicide sorption and, therefore, reduced exposure of microbes to this ecotoxic molecule. The positive effect on urease activity after the incorporation of MCPA could result from the organic nature of the soil employed in the study (15% OM), or possibly the adaptation of rhizospheric microbes to similar compounds, as the soil sample was collected from a pasture that receives regular applications of the herbicide 2,4-D [9]. However, the lower urease activity observed in the co-application of urea and MCPA could be related to the enhanced ecotoxicity of the herbicide on more sensitive microbial populations that are involved in N-cycling, as observed previously for other pesticides [41,45,46].…”

“…Whilst our study did not evaluate the transformation of soil OM to associate urea mineralization and pH shifts with the sorption of MCPA residues, our findings concerning enzymatic activities, particularly urease, provide evidence on how microbial urea mineralization and soil acidification can increase MCPA adsorption and slow its dissipation in organic soils in the long term. In this context, a recent study linked the active participation of ammonia-oxidizing bacteria with significant reductions in the dissipation of 2,4-D (>28%) in the presence of urea, highlighting the contribution of soil microbes in the interaction between urea fertilizers and acidic herbicides in soils [9]. On the other hand, increasing the bioavailability of MCPA to degrading microorganisms resulting from urea mineralization appears to be desirable.…”

“…Pasturing in volcanic soils needs a suitable supply of nitrogen (N) fertilizers to cover the requirements of different plant species [8]. From the vast range of N-based fertilizers, urea has historically been one of the most used inorganic fertilizers on pastures due to its favorable cost-benefit properties; indeed, constant research is being performed to improve efficiency [9]. Despite this, up to 30% of applied urea can be lost after its hydrolyzation into volatilizing ammonia (N-NH3 + ) or leaching after being transformed into ammonium (N-NH4 + ) or nitrate (N-NO3 − ).…”

Mine Site Restoration: The Phytoremediation of Arsenic-Contaminated Soils

“…Clearly, further research is required to understand the association between N fertiliser addition and phytoremediation, particularly with As. Although cost-effectiveness is reported as an advantage [139] of N fertiliser, significant negative environmental impacts result from its addition, including atmospheric pollution and leaching. It is expected that N pollution will increase by up to 156% by 2025 [140].…”

Improving Ammonia Emission Model of Urea Fertilizer Fluidized Bed Granulation System Using Particle Swarm Optimization for Sustainable Fertilizer Manufacturing Practice

“…The granulation process is also instrumental in urea fertilizer production. Urea fertilizer stands out as the most widely utilized solid nitrogenous fertilizer globally due to its excellent water solubility [3,4]. Compared to other nitrogenous fertilizers, urea provides a higher quantity of nitrogen to plants and soil owing to its concentrated nitrogen content of 46%.…”