Reducing Ammonia Loss from Urea by Mixing with Humic and Fulvic Acids Isolated from Coal

Abstract

Problem statement: Ammonia volatilization is a major pathway for nitrogen loss from surface applied urea. While all top-dressed ammonia and ammonium based N fertilizers can volatilize, the potential loss is greatest with urea and fluids containing urea. As much as 20-50% of N applied to soils is lost through volatilization alone. Thus, the objective of this laboratory study was to reduce ammonia loss from urea via mixing with humic and fulvic acids isolated from coal. Approach: This study compared four different types of treatments which were urea without additives (T1), urea with humic acid-powdered form (T2), urea with fulvic acid-liquid form (T3) and urea with humic and fulvic acids-liquid form (T4). Comparisons were made based on ammonia loss, soil NH 4 and NO 3 − contents as well as exchangeable cations in the treated soils. Soil samples from typic paleudults (Bekenu series) were used. Humic substances were isolated using standard procedures. Daily ammonia loss from soil was measured using a modified closed-dynamic air flow system method. Results: All of the treatments with humic substances significantly reduced ammonia loss ranging between 13 and 25% compared to urea alone. The treatment with both humic and fulvic acids (T4) showed pronounced ammonia loss reduction. All treatments with humic substances significantly increased NH 4 + and NO 3 − content in soil samples compared to urea alone except for treatment having humic acid alone (T2). Treatments with fulvic acid (T3 and T4) also showed significant increase in exchangeable K + and Na + compared to urea alone. The increase in the formation of NH 4 + over NH 3 , soil exchangeable cations and temporary reduction of soil pH may had retarded urea hydrolysis in the immediate vicinity of the fertilizer. Conclusion: Surface applied urea fertilizer efficiency could be increased if applied together with humic and fulvic acids.

Use of Organic Materials to Limit the Potential Negative Effect of Nitrogen on Maize in Different Soils

“…In the experiment completed by Reeza et al [67], the addition of humic substances to soil decreased the losses of ammonia by 13% to 25%, relative to the series with urea alone. Furthermore, the application of fulvic acid elevated the content of NH 4 + and NO 3 − as well as K + and Na + ions in the soil.…”

Effect of Coated Urea with Humic-Calcium on Transformation of Nitrogen in Coastal Sandy Soil: A Soil Column Method

“…Those functional groups like phenolic-OH and carboxylic-COOH were able to capture and retain NH 4 + . This positively charged NH 4 + is in turn adsorbed to the negatively charged sites of phenolic-OH and carboxylic-COOH compounds (Reeza et al 2009). After 2 weeks incubation, NH 4 + -N in the soil was significantly reduced, and NO 3 --N still high ( Figure 2), suggesting the occurrence of the nitrification.…”

Application of Corn Straw and Woody Peat to Improve the Absorption and Utilization of 15N-Urea by Maize

“…Peat has a high content of humic acid [8], and its acidic functional groups such as carboxyl and phenolic hydroxyl groups can interact with amide groups of urea to form humic acid-urea complex [26], which can hamper the hydrolysis process of urea. Urea release and continuous nitrogen supply can be controlled [27,28]. Therefore, the presence of more carboxyl functional groups ensures the continuous supply of nitrogen, thus increasing the accumulation of maize biomass [29].…”