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It is necessary to increase the agronomic use efficiency of urea to reduce ammonia volatilization and increase crop yield. However, relying solely on urea for the enhanced efficiency technologies development could harm fertilizer integrity, resulting in reduced application quality and fertilizer storage time. The authors aimed at developing and characterizing the physical, chemical, and physicochemical quality of a novel enhanced efficiency fertilizers, synthesized from urea plus boron (B), zinc (Zn), nickel (Ni), or molybdenum (Mo) addition, with or without N-(n-butyl) thiophosphoric triamide (NBPT) associated. Hygroscopicity, hardness, salt index (SI), pH, and thermogravimetric decomposition were the parameters evaluated. Fertilizer quality was assessed through microscopic X-ray fluorescence, microtomography, and scanning electron microscopy. Micronutrients were added by coating or granulation; they were homogeneously distributed over the fertilizer’s granules. The fertilizers’ hardness increased up to 86% with Zn coated compared with uncoated. Granulated urea with B, Zn, Ni, or Mo had greater internal porosity, which resulted in lower hardness. Boron and Zn addition to the fertilizers increased the hygroscopicity in average 388% and 473%, respectively, compared with hygroscopicity observed for urea. Moreover, hygroscopicity was increased by an average of 56% with NBPT addition. Micronutrients addition to the urea granules increased the SI, while thermal decomposition stages of urea were unaffected by micronutrients addition. Enhanced efficiency fertilizers require characterization before agronomic efficiency tests due to changes in their physical, chemical, and physicochemical properties. Unfavorable changes could harm granules integrity and application efficiency in the field, resulting in economic losses to the industry and farmers. [ABSTRACT FROM AUTHOR]

Improvements in nitrogen use efficiency (NUE) in corn production systems are necessary, to decrease the economic and environmental losses caused by loss of ammonia volatilization (NH3-N). The objective was to study different nitrogen (N) fertilizer technologies through characterization of N sources, NH3-N volatilization losses, and their effects on the nutrient concentration and yield of corn grown in clayey and sandy soils in south Brazil. The treatments consisted of a control without N application as a topdressing, three conventional N sources (urea, ammonium sulfate, and ammonium nitrate + calcium sulfate), and three enhanced-efficiency fertilizers [urea treated with NBPT + Duromide, urea formaldehyde, and polymer-coated urea (PCU) + urea treated with NBPT and nitrification inhibitor (NI)]. The losses by NH3-N volatilization were up to 46% of the N applied with urea. However, NI addition to urea increased the N losses by NH3-N volatilization by 8.8 and 23.3%, in relation to urea alone for clayey and sandy soils, respectively. Clayey soil was 38.4% more responsive than sandy soil to N fertilization. Ammonium sulfate and ammonium nitrate + calcium sulfate showed the best results, because it increased the corn yield in clayey soil and contributed to reductions in NH3-N emissions of 84 and 80% in relation to urea, respectively. [ABSTRACT FROM AUTHOR]

Urea is the most used nitrogen (N) fertilizer worldwide, but its rapid hydrolysis on the soil surface results in N loss in the form of ammonia (NH3-N). Enzyme inhibitors have been investigated for their ability to reduce NH3-N volatilization, particularly from no-till and surface-limed soils. This study assessed the efficiency of stabilized fertilizers in reducing NH3-N volatilization under different lime rates and application methods. The experiment followed a 2 × 4 × 3 factorial design, with two liming methods (surface application and incorporation), four base saturation levels (50, 60, 70, and 90%), and three urea (45% N) sources: conventional urea, urea + N-(n-butyl)-Thiophosphoric triamide (NBPT), and urea + Boron (B) + Copper (Cu). NH3-N volatilization losses varied from 9.15 to 20.43 kg ha−1, accounting for 11.4 to 25.5% of the applied N rate. Base saturation did not influence NH3-N volatilization. Liming method, however, had a significant effect. Urea + B + Cu was effective in reducing volatilization loss only in soils ameliorated by lime incorporation (23% reduction compared with conventional urea). Urea + NBPT was effective in surface-limed and incorporated soils (up to 55.5% reduction). The results showed that soil management influences the efficiency of stabilized fertilizers and that urea + NBPT provides the best results. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation (BNF) is what makes soybean economically viable. However, the launch of cultivars, with a high-yield potential and abiotic factors that reduce BNF, raised doubts about the need for nitrogen (N) fertilizers for soybeans. The objective of the research was to evaluate the effects of nitrogen supply, in two application times in furrow starter fertilization and top-dressing. The experimental design was in the 3 × 6 factorial scheme. The treatments consisted of three rates of N at in furrow starter fertilization (0, 10, and 20 kg ha−1 of N), and six rates of N in top-dressing, applied at the soybean R1 stage (0, 30, 60, 90, 120, and 150 kg ha−1 of N). The highest rate in furrow starter fertilization of 20 kg ha−1 of N resulted in the increase in the leaf area index (LAI) and specific leaf area (SLA), which are attributes that maximize the absorption of light energy, thus being able to positively influence yield. However, the BNF demonstrated that the strains of the selected Bradyrhizobium are efficient and capable of supplying the required N because the supplementation of nitrogen in furrow and/or top-dressing did not result in significant differences in the yield in relation to inoculated soybean. [ABSTRACT FROM AUTHOR]

Emission of nitrous oxide (N2O) can be reduced using enhanced efficiency nitrogen fertilizers (EEFs), such as urease inhibitors and coating technologies. In this study, we evaluated the potential of EEFs to reduce N2O emissions in maize in a clayey Inceptisol subjected to no-till management under summer subtropical conditions, in southern Brazil. The EEF sources used included urea containing N-(n-butyl) thiophosphoric triamide (UR-NBPT), polymer-coated urea (UR-pol), in addition common urea (UR), nitrate (CN) and control treatment without the application of nitrogen fertilizer. N2O emissions were assessed using the static chamber method during one maize season and analyzed through non-linear regression, using a logistic model. The accumulated emission was 0.817, 0.613, 0.457 and 0.393 kg N2O ha−1, for CN, UR, UR-pol and UR-NBPT, respectively. The maximum daily emission of N2O did not vary between amidic forms, however for CN it occurred on the 4th day after application (DAA), while for urea forms it occurred on average at 5.3 DAA. The average N2O emission factor (FE-N2O) was 0.51%, approximately half the standard factor proposed by the Intergovernmental Panel on Climate Change (IPCC), which is 1%. The application of nitrogen increased the maize yield in relation to the control, but the sources of nitrogen did not differ, with an average yield of 10,455 kg ha−1. Based on our findings, the use of UR-NBPT and UR-pol in subtropical agroecosystems provides environmental benefits, by reducing N2O emissions in comparison with conventional nitrogen fertilizers (CN and UR), however, the EEFs did not offer agronomic advantages in maize yield. [ABSTRACT FROM AUTHOR]

Knowledge on the behavior of cumulative N-NH3 volatilization is important for defining the strategies to reduce the N losses, as well as increasing the efficiency of nitrogen fertilization in different environments. The present study, which uses nonlinear models, aims at assessing the cumulative N-NH3 losses through volatilization by applying different rates of urea over time to two soils cultivated with second-season corn. Two experiments were carried out; one in a clayey Oxisol, and another in a sandy-clay loam Ultisol in a randomized block experimental design. N-NH3 volatilization was quantified by using semi-open static chambers and spectrophotometry (salicylate blue). The cumulative N-NH3 losses were similar at both rates of urea and in both soils assessed, ranging from 34.04% to 43.15% of the N applied. The highest N-NH3 volatilization occurred from 1.03 to 6.48 days after applying the fertilizer, and the highest volatilization rates ranged from 0.90 to 2.91 kg ha-1 d-1. The shortest time to reach the highest volatilization rate, associated with the highest daily rate of N-NH3 volatilization, was seen in the Ultisol. Although the volatilizations accumulated in both soils were similar, this result was only seen due to the climatic conditions after applying the fertilizer, which contributed to minimize the N-NH3 losses. The use of nonlinear models has shown an appropriate data adjustment, providing parameters that help to understand the behavior of N-NH3 volatilization accumulated over time in second-season corn. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate the effect of foliar application of urea and urea-formaldehyde, triazone-based fertilizers on soybean and corn crops. Four experiments were carried out, two on soybeans, one on first season corn, and the other on second season corn. The experiments were conducted using a randomized block design, with 5 treatments studied: T1—control without application of foliar nitrogen (N); T2—foliar application of conventional urea solution and three treatments with Hexion foliar fertilizers based on urea-formaldehyde and triazone (N-Hexion®), with varying levels of N and slow-release components; T3—Hexion 1; T4—Hexion 2; and T5—Hexion 3. The foliar application of conventional urea showed no statistically significant difference in relation to the control for the yield components and grain yield for the soybean crops in seasons 2018–2019 and 2019–2020. Urea-formaldehyde/triazone treatments showed a significant increase in yield for soybeans in the 2018–2019 season compared to the control and to conventional urea. Nitrogen fertilizers with high percentages of slow-release compounds promote nitrogen release more slowly, which led to no significant increase in yield for Hexion 1. No statistical differences were observed in the corn yield for the first and second crop. [ABSTRACT FROM AUTHOR]