Nitrogen Dynamics in Tropical Soils Treated with Liquid and Granular Urea Fertilizers

Abstract

The mineralization of urea fertilizer mostly regulates the nitrogen dynamics in the soil. A laboratory-scale study was conducted to compare the nitrogen dynamics in two tropical soil series incubated with either liquid urea (LU) or granular urea (GU) at 0, 300, 400 or 500 mg/kg of soil. The soils samples used in the experiment were the Bungor and Selangor soil series which have a sandy clay loam and clay texture, respectively. The NH4+-N, NO3−-N concentration in the soils were measured for four weeks to determine the urea-N mineralization while ten pore volumes of water were used for the NH4+-N and NO3−-N leaching loss. At the same application rate, higher NH4+-N and NO3−-N concentrations were recorded in the LU applied soils throughout the incubation period in case of N mineralization. Urea-N recovery was higher in GU than LU treated soils in the first two weeks while no urea-N was present in both GU and LU treated soils after the third week of incubation. The leaching of N (NH4+-N and NO3−-N) was higher in GU treated soils than that of LU and leaching was increased with increased application rate in both LU and GU in both soils. The NH4+-N and NO3−-N concentrations were higher in the Selangor soil whereas the total N leaching loss was higher in Bungor soil. The results suggest that the LU was a better N fertilizer source than GU for rapid mineralization, quicker N availability and lower N leaching loss.

Effects of Liquid Urea Rates on Nitrogen Dynamics, Growth, and Yield of Grain Corn (Zea Mays L.)

“…Liquid urea application has also been reported to increase grain yield by 15-20% due to higher N availability than GU [17,26,44]. The higher plant N uptake by the LU-treated crops was due to the higher urea mineralization and adsorption of N by the soil particles, which increases N availability and reduces N losses (e.g., gaseous and leaching), where, the gaseous (NH 3 and N 2 O) losses and leaching loss were signi cantly lower in LUtreated soil than that of GU at same application rate [24,27].…”

“…Liquid urea has the potential to be an alternate source of N for improving crop yield. Its application resulted in higher N mineralization, exchangeable NH 4 + concentration, yield and NUE of corn while reduced N loss (e.g., N 2 O emission, NH 3 volatilization and Nitrate leaching) than GU application [24,27].…”

Enhanced nitrogen use efficiency, growth and yield of wheat through soil urea hydrolysis inhibition by Vachellia nilotica extract

“…Nitrogen (N), one of the essential primary macronutrients, is needed for the proper functioning of chlorophyll biosynthesis, photosynthesis, carbon assimilation, and protein synthesis processes in terrestrial plants (Leghari et al, 2016). Considering the high N concentration (46%), water solubility, and ease of use, urea is the widely used source of N accounting for almost 50% of the total N consumption worldwide (Motasim et al, 2021;Tanan et al, 2021). However, urea is hydrolyzed to ammonia and carbon dioxide in soil, whereas the presence of urease enzyme escalates this process 8 × 10 7 times (Rana et al, 2021).…”