Reducing ammonia volatilization in a no-till soil by incorporating urea and pig slurry in shallow bands

Abstract

Incorporation of broadcast pig slurry and urea into soil is incompatible with no-till production systems and alternative application methods that reduce NH 3 -N loss are required. The objective of this study was to assess the impact of incorporating urea and pig slurry in shallow furrows (banding) on NH 3 volatilization. A field study was conducted on a silty loam soil that had been under no-till for 2 years. Ammonia volatilization was measured for 29 days after urea and pig slurry (140 kg N ha -1 ) were broadcast or incorporated (5 cm) in bands. High urease activity and soil temperatures as well as an absence of rainfall combined to result in large losses of NH 3 -N from all treatments. Broadcast urea lost the greatest proportion of applied N (64%) followed by banded urea (31%), broadcast pig slurry (29%) and banded pig slurry (16%). High emissions from broadcast urea were consistent with previous reports of large volatilization losses on no-till soils. Presence of crop residues and associated high urease activity (288 lg NH 4 -N g -1 h -1 ) at the surface of no-till soils were likely important factors contributing to these high emissions. Incorporation of slurry and urea in bands was not as efficient in reducing volatilization as expected but not for the same reason. Relatively high emissions from banded slurry were the result of an incomplete incorporation of slurry in the shallow bands and indicate that the benefit of this practice is limited at high slurry application rates. In banded urea plots, hydrolysis of concentrated urea likely resulted in high localized NH 4 ? concentrations and pH, which increased NH 3 source strength and emissions. Our results therefore suggest that incorporating urea in bands may not be as efficient for reducing NH 3 emissions as incorporation of broadcasted urea which results in lower soil urea concentrations.

The molecular processes of urea hydrolysis in relation to ammonia emissions from agriculture

“…The ammonia emission rate from fields fertilized with manure slurry peaks within the first 24 h after applying the manure slurry in the field. This is probably because the volatile ammonia is already present in the manure slurry when it is applied to the field (Huijsmans et al 2001;McGinn and Sommer 2007;Rochette et al 2009;Salazar et al 2014). In contrast, the ammonia emission rate from the fields applied with synthetic urea fertilizer is more variable, and the maximum rate is not reached before 48 h to 12 days after fertilizing the field, as urea must first be hydrolyzed by the microbial urease present in the soil (Rochette et al 2009;Salazar et al 2014).…”

“…This is probably because the volatile ammonia is already present in the manure slurry when it is applied to the field (Huijsmans et al 2001;McGinn and Sommer 2007;Rochette et al 2009;Salazar et al 2014). In contrast, the ammonia emission rate from the fields applied with synthetic urea fertilizer is more variable, and the maximum rate is not reached before 48 h to 12 days after fertilizing the field, as urea must first be hydrolyzed by the microbial urease present in the soil (Rochette et al 2009;Salazar et al 2014). The cumulative emissions of ammonia from the fields applied with manure slurry compared to those applied with synthetic urea fertilizers depend very much on conditions such as the method of fertilizer application, temperature, and weather (Bussink and Oenema 1998;Rochette et al 2009;Salazar et al 2014).…”

“…In contrast, the ammonia emission rate from the fields applied with synthetic urea fertilizer is more variable, and the maximum rate is not reached before 48 h to 12 days after fertilizing the field, as urea must first be hydrolyzed by the microbial urease present in the soil (Rochette et al 2009;Salazar et al 2014). The cumulative emissions of ammonia from the fields applied with manure slurry compared to those applied with synthetic urea fertilizers depend very much on conditions such as the method of fertilizer application, temperature, and weather (Bussink and Oenema 1998;Rochette et al 2009;Salazar et al 2014). Studies indicate that the emissions of ammonia from fields fertilized with synthetic urea and manure slurry are very similar.…”

Lixiviação e volatilização de nitrogênio em um Argissolo cultivado com videira submetida à adubação nitrogenada

“…Assim, a N-NH 3 é emitida na forma de gás para a atmosfera, especialmente em maior intensidade, logo depois da aplicação do fertilizante (SANGOI et al, 2003). No entanto, a quantidade de N-NH 3 volatilizada é dependente, principalmente, das condições climáticas, como da velocidade do vento, da temperatura, da umidade relativa do ar e da precipitação; e de atributos do solo, como a capacidade de troca de cations, da umidade, da temperatura, da quantidade de matéria orgânica, do potencial de nitrificação, dos valores de pH e das concentração de N-NH 4 + na solução do solo (ROCHETTE et al, 2009).…”

Ammonia volatilization and yield components after application of polymer-coated urea to maize

“…Thus, NH 3 -N is emitted in the form of gas to the atmosphere, particularly and at higher intensity immediately after fertilizer application (Sangoi et al, 2003). However, the amount of NH 3 -N volatilization depends mainly on weather conditions such as wind speed, temperature, relative air humidity, and pluvial precipitation, as well as on soil properties such as the cation exchange capacity, moisture, temperature, amount of organic matter, nitrification potential, pH, and NH 4 + -N concentration in the soil solution (Rochette et al, 2009). …”