Ammonia volatilization in no-till system in the south-central region of the State of Paraná, Brazil

Abstract

SUMMARYAmmonia (NH 3 ) volatilization can reduce the efficiency of urea applied to the surface of no-till (NT) soils. Thus, the objectives of this study were to evaluate the magnitude of NH 3 losses from surface-applied urea and to determine if this loss justifies the urea incorporation in soil or its substitution for other N sources under the subtropical climatic conditions of South-Central region of Paraná State, Brazil. The experiment, performed over four harvesting seasons in a clayey Hapludox followed a randomized block design with four replicates. A single dose of N (150 kg ha -1 ) to V5 growth stage of corn cultivated under NT system was applied and seven treatments were evaluated, including surface-applied urea, ammonium sulfate, ammonium nitrate, urea with urease inhibitor, controlled-release N source, a liquid N source, incorporated urea, and a control treatment with no N application. Ammonia volatilization was evaluated for 20 days after N application using a semiopen static system. The average cumulative NH 3 loss due to the superficial application of urea was low (12.5 % of the applied N) compared to the losses observed in warmer regions of Southeastern Brazil (greater than 50 %). The greatest NH 3 losses were observed in dry years (up to 25.4 % of the applied N), and losses decreased exponentially as the amount of rainfall after N application increased. Incorporated urea and alternative N sources, with the exception of controlled-release N source, decreased NH 3 volatilization in comparison with surface-applied urea. Urea incorporation is advantageous for the reduction of NH 3 volatilization; however, other aspects as its low operating efficiency should be considered before this practice is adopted. In the South-Central region of Paraná, the low NH 3 losses from the surface-applied urea in NT system due to wet springs and mild temperatures do not justify its replacement for other N sources.Index terms: nitrogen fertilizer, urea, corn, urease.(

Urease Inhibitor and Irrigation Management to Mitigate Ammonia Volatilization from Urea in No-Till Corn

“…This idea is supported by the high yield of the control treatment, where grain yield was 8.9 Mg ha -1 (Experiment II). Corroborating our study, Fontoura and Bayer (2010) found no substantial increase in corn yield in the south-central region of Paraná as a result of reduced NH 3 -N losses by the addition of a urease inhibitor to urea. They ascribed this result to the high N content of the soil and/or the amount of N exceeding the requirements of the crop for maximum yield.…”

Ammonia volatilization from enhanced-efficiency urea on no-till maize in brazilian cerrado with improved soil fertility

“…Thus, the differences would not be visible. Fontoura and Bayer (2010) did not observe any differences in maize yields when fields were fertilized with common urea and with stabilized and slow release forms. However, the yield response was considerably high (between 15 -22 kg kernel per kg applied N), an increased by 29% in relative to the control.…”

“…Urea + Cu + B (6.8% applied N) and urea coated with polymers (5.6% applied N) resulted in maximum volatilization on the 3 rd day after fertilization, while urea + NBPT (7% applied N) had the longest delay in the ammonia volatilization peak on the 4 th day (Figure 3). Field research considering different soils and climatic conditions and controlled environments indicated a longer delay and a reduction in the peak volatilization of urea stabilized with NBPT or with Cu and B when applied in various crops (Cantarella et al, 2008;Dawar et al, 2011;Faria et al, 2013;Fontoura;Bayer, 2010;Grohs et al, 2011;Nascimento et al, 2013;Stafanato et al, 2013;Zaman et al, 2009). Soares et al (2012) evaluated NH 3 -N losses in a controlled environment and reported a volatilization peak at between 7 to 9 days for urea + NBPT.…”

“…The water content of the shallow layers of soil were directly affected by soil management and climatic conditions, such as temperature, wind and relative air moisture, which generate complex interactions that affect N loss intensity by volatilization (Fontoura and Bayer, 2010;Suter et al, 2011;Zaman et al, 2009).…”

“…Fontoura and Bayer (2010) reported the average accumulated NH 3 -N losses for four maize crops under notill following surface applied urea (12.5% total applied N), incorporated urea (1.1%), urea + polymers (13.5%), urea + urease inhibitor (6.6%), ammonium sulfate (1.9%) and ammonium nitrate (1.0%) fertilizer treatments. Jantalia et al (2012) evaluated NH 3 -N losses in semi-arid regions when using slow release N sources, such as Super U ® , urea, polymer-coated urea and a ureaammonium nitrate solution in irrigated maize (16 and 19 mm).…”