Deciphering the Interactions in the Root–Soil Nexus Caused by Urease and Nitrification Inhibitors: A Review

Abstract

Optimizing nitrogen (N) availability to plants is crucial for achieving maximum crop yield and quality. However, ensuring the appropriate supply of N to crops is challenging due to the various pathways through which N can be lost, such as ammonia (NH3) volatilization, nitrous oxide emissions, denitrification, nitrate (NO3−) leaching, and runoff. Additionally, N can become immobilized by soil minerals when ammonium (NH4+) gets trapped in the interlayers of clay minerals. Although synchronizing N availability with plant uptake could potentially reduce N loss, this approach is hindered by the fact that N loss from crop fields is typically influenced by a combination of management practices (which can be controlled) and weather dynamics, particularly precipitation, temperature fluctuations, and wind (which are beyond our control). In recent years, the use of urease and nitrification inhibitors has emerged as a strategy to temporarily delay the microbiological transformations of N-based fertilizers, thereby synchronizing N availability with plant uptake and mitigating N loss. Urease inhibitors slow down the hydrolysis of urea to NH4+ and reduce nitrogen loss through NH3 volatilization. Nitrification inhibitors temporarily inhibit soil bacteria (Nitrosomonas spp.) that convert NH4+ to nitrite (NO2−), thereby slowing down the first and rate-determining step of the nitrification process and reducing nitrogen loss as NO3− or through denitrification. This review aims to provide a comprehensive understanding of urease and nitrification inhibitor technologies and their profound implications for plants and root nitrogen uptake. It underscores the critical need to develop design principles for inhibitors with enhanced efficiency, highlighting their potential to revolutionize agricultural practices. Furthermore, this review offers valuable insights into future directions for inhibitor usage and emphasizes the essential traits that superior inhibitors should possess, thereby paving the way for innovative advancements in optimizing nitrogen management and ensuring sustainable crop production.

Selected Carbon and Nitrogen Compounds in a Maize Agroecosystem under the Use of Nitrogen Mineral Fertilizer, Farmyard Manure, Urease, and Nitrification Inhibitors

“…The addition of DMPP with the UAN fertilizer effectively decreased the nitrification rates in the soil, raised the content of NH4-N by 8.70%, and lowered the NO3-N concentration by 14.46% (Figures 8 and 9), which is consistent with the results of other studies [7,24,41]. DMPP extends the residence time of NH4-N in soils due to the deactivation of the enzyme responsible for the first step of nitrification, i.e., the oxidation of NH4 + to NH2OH via indiscriminate binding and suppressing ammonium monooxygenase activity [23][24][25][41][42][43]. Abalos et al [44] noticed that NI applications could diminish denitrification-induced N losses by decreasing the soil NO3-N contents for denitrification, which allows the available nitrogen to be retained in the soil and become absorbed by the plants for a longer time.…”

“…It is worth noting that, in the experiment conducted, the largest statistically significant differences were observed in the nitrogen pool under the conditions of mineral fertilization and the application of urease and nitrification inhibitors. The weaker effects of UI and NI under organic fertilization may have indicated the occurrence of their adsorption, faster degradation, and effectiveness reduction at higher SOC contents [25].…”

“…+ to NH 2 OH via indiscriminate binding and suppressing ammonium monooxygenase activity [23][24][25][41][42][43]. Abalos et al [44] noticed that NI applications could diminish denitrification-induced N losses by decreasing the soil NO 3 -N contents for denitrification, which allows the available nitrogen to be retained in the soil and become absorbed by the plants for a longer time.…”

“…Several mitigation strategies have been developed to decrease the N emissions in agroecosystems, including the application of urease and/or nitrification inhibitors (UI and NI) [20,21,23,24]. NIs delay the bacterial oxidation of NH 4 -N by depressing the activities of nitrifiers in soil, whereas UIs slow down the hydrolysis of urea to NH 4 -N by preventing its binding to the enzyme urease [23,25]. UI and NI temporarily retard the microbiological transformations of nitrogen-based fertilizers, improving the synchronization of N bioavailability with plant uptake and mitigating N losses [25].…”

The impact of mixed planting of Poaceae species in the Qinghai-Tibet plateau region on forage yield, soil nutrients, and soil microbial communities

“…Alkaline phosphatase primarily facilitates the hydrolysis of organic phosphorus compounds in the soil, converting them into readily available phosphate ions that can be directly absorbed and utilized by plants ( Bhardwaj et al., 2023 ; Guo et al., 2023 ; Lu et al., 2023 ). Similarly, urease, one of the key hydrolytic enzymes in soil, catalyzes the hydrolysis of urea into NH 3 , which subsequently undergoes protonation to form NH 4+ ( Gupta et al., 2023 ; Zhong et al., 2024 ). The heightened activities of these enzymes play a significant role in promoting nitrogen and phosphorus cycling within the soil.…”