Nitrogen transformations and ammonia volatilization losses from ¹⁵N-urea as affected by the co-application of composted pig manure

Abstract

S. M. 2007. Nitrogen transformations and ammonia volatilization losses from 15 N-urea as affected by the co-application of composted pig manure. Can. J. Soil Sci. 87: 485-493. Co-application of composted manure (compost) and urea is considered an environment-friendly fertilization practice; however, the high urease activity in compost may stimulate NH 3 volatilization and cause N loss from co-applied urea. To test the above hypothesis, we investigated the fate of urea co-applied with compost in a loam-textured soil through two laboratory incubation experiments. Urea (150 mg N kg -1 ) was co-applied with 0, 4.9, 9.8, and 14.6 g of compost (oven-dry basis) kg -1 of soil, designated as treatments UC0, UC1, UC2, and UC3, respectively. Co-application of compost and urea enhanced urea hydrolysis and increased the 1st order rate constant of urea hydrolysis from 0.047 h -1 in the UC0 to 0.139 h -1 in the UC3 treatments. Soil pH increased from 7.0 for UC0 to 7.6 for UC3, leading to greater NH 3 volatilization (up to two times more) in the soils receiving 9.8 g kg -1 or more of compost. Compost co-application also increased the immobilization of urea-derived N, probably because the organic matter added in compost stimulated microbial growth or NH 4 + fixation. Between 15 and 17% of urea-N was not recovered at the end of the incubation, but there was no difference in N loss among the treatments resulting from the contrasting effects (NH 3 volatilization vs. NH 4 + immobilization) of compost on N losses. Our results clearly show that application of compost with high urease activity increases NH 3 volatilization loss of N from the co-applied urea, but the total amount of N lost is also affected by immobilization of NH 4 + by the organic matter added to the soil through the applied compost. Le pH du sol augmente de 7,0 à 7,6 pour les traitements UC0 et UC3, ce qui accélère la sublimation du NH 3 (jusqu'au double) dans les sols enrichis avec 9,8 g ou plus de compost par kg. L'application simultanée de compost intensifie aussi l'immobilisation du N de l'urée, sans doute parce que la matière organique du compost stimule la multiplication des microorganismes ou la fixation du NH 4 + . De 15 à 17 % du N uréique n'avait pu être récupéré à la fin de l'incubation, mais la perte de N ne varie pas entre les traitements malgré les effets contrastants (sublimation du NH 3 c. immobilisation du NH 4 + ) du compost. Les résultats indiquent clairement que l'application de compost riche en uréase augmente les pertes de N par sublimation du NH 3 que contient l'urée appliquée simultanément, mais que la quantité totale de N perdue est aussi affectée par l'immobilisation du NH 4 + résultant de l'addition de matière organique au sol par le compost.

Kinetic Responses of Soil Carbon Dioxide Emission to Increasing Urea Application Rate

“…Hydrolysis of urea is known to be very rapid; e.g. Choi et al (2007) reported that urea was hydrolyzed completely within 3 days of application into the same soil used in the present study. Therefore, these results suggest that application of urea may result in a higher CO2 emission from soils compared Values in the same column followed by a different letter are significantly different at ＝0.05.…”

“…org/ifa/homepage/statistics). Because elemental C content of urea ((NH2)2CO) is 20% that is converted to CO2 during urea hydrolysis ((NH2)2CO＋3H2O → 2NH4 ＋ ＋CO2＋2OH -), application of urea as a N fertilizer may further increase CO2 emission from the soil (Choi et al, 2007;Jassal et al, 2010;Serrano-Silva et al, 2011). However, as far as our knowledge, no attempt has been made to investigate soil CO2 emission responses to increasing rate of urea fertilization.…”

Sensitivity of soil CO2 emissions to fertilizer nitrogen species: urea, ammonium sulfate, potassium nitrate, and ammonium nitrate

“…days after application to soils [Choi et al, 2007], its contribution to soil CO 2 emission is obvious in the early period of incubation, as seen in the present study (Fig. 1A).…”

Ammonia Volatilization from Rice Paddy Soils Fertilized with15N-Urea Under Elevated CO2and Temperature

“…It is well recognized that temperature is one of the most important driving forces of ammonia volatilization from soils [10][11][12] . Therefore, it can be simply expected that ammonia volatilization from paddy soils under global warming may increase as compared with the current temperature.…”