Banding of Urea Increased Ammonia Volatilization in a Dry Acidic Soil

Abstract

Volatilization of ammonia following application of urea contributes to smog formation and degradation of natural ecosystems. The objective of this study was to evaluate the impact of (i) incorporation and banding of urea and (ii) surface broadcast of slow-release urea types on NH(3) volatilization in a dry acidic soil. Volatilization was measured using wind tunnels for 25 d after standard urea (140 kg N ha(-1)) was broadcast, broadcast and incorporated (0-5 cm), or incorporated in shallow bands (3-5 cm) to a conventionally tilled silty loam soil. Urea supplemented with a urease inhibitor or coated with a polymer was also broadcast at the soil surface. Little N diffused out of the polymer-coated granules and ammonia losses were low (4% of applied N). Use of a urease inhibitor also resulted in a low NH(3) loss (5% of applied N) while maintaining soil mineral N at levels similar to plots where untreated urea was broadcast. The rate of hydrolysis of urea broadcast at the soil surface was slowed by the lack of moisture and NH(3) loss (9% applied N) was the lowest of all treatments with standard urea. Incorporation of broadcast urea increased emissions (16% applied N) by increasing urea hydrolysis relative to surface application. Furthermore, incorporation in band also increased emissions (27% applied N) due to a localized increase in soil pH from 6.0 to 8.7. We conclude that incorporating urea in bands in a dry acidic soil can increase NH(3) volatilization compared to broadcast application followed by incorporation.

Fontes e doses de nitrogênio e alterações nos atributos químicos de um latossolo cultivado com capim-mombaça

“…De acordo com Tasca et al (2011), a formação do amônio a partir da hidrólise da ureia produziu inicialmente aumento do pH do solo, em razão do consumo de íons H + . Porém, após a nitrificação do amônio, o pH decresceu para valores inferiores aos originais, por causa da geração de íons H + (Rochette et al, 2009 um Latossolo Vermelho-Amarelo distrófico, cultivado com capim-xaraés, ao final do período experimental de nove meses, redução do pH do solo de 0,7 e 0,3 unidades, quando a pastagem foi submetida à aplicação de 400 kg ha -1 de N, utilizando as fontes sulfato de amônio e ureia, respectivamente.…”

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

“…According to Rochette et al (2009), soil moisture directly influences urease activity, which is lower in dry soils and increases as soil moisture increases, thus also increasing N losses. In a laboratory study, Tasca et al (2011) examined the effect of soil moisture on NH 3 -N losses and found approximately 30 % of common urea to be lost by volatilization when applied to the surface of a soil with 10 % moisture.…”

Increasing NBPT rates to reduce ammonia volatilization losses from urea applied over sugarcane straw

“…forms prevail resulting in NH3 volatilization losses as water is evaporated from soil solution (ROCHETTE et al, 2009 The soil moisture content is determinant to NH3 losses. Under dry soil conditions the volatilizations losses are practically null due to the inhibitory effect of the lack of humidity over the urease activity (TASCA et al, 2011).…”

“…Nömmik (1973) attribute that to the retarded hydrolyses by a slower dissolution of the large-pellet urea, enhancing the chance to occur a rainfall before the urea be entirely hydrolyzed, and so burry the fertilizer. Largest NH3 volatilization are also observed when the fertilizer is banded applied, what can be related to the concentration of fertilizer N in a smaller area, increasing the concentration of NH4 + near a high pH zone (VITTI et al, 2007;ROCHETTE et al, 2009). …”

“…The fertilizer incorporation into the soil reduces substantially NH3 volatilization losses (ROCHETTE et al, 2009;TASCA et al, 2011). However, in the GCTB system, the large amount of straw on the soil surface makes the incorporation a difficult, expensive (CANTARELLA et al, 2008), and frequently inefficient practice.…”