Dinitrogen and Nitrous Oxide Flux from Urea Basally Applied to Puddled Rice Soils

Abstract

Nitrification‐denitrification is often regarded as an important N loss process in puddled rice soils, but few direct field measurements of denitrification loss have been reported. Field studies were conducted on a Typic Tropaquept in Thailand, an Aeric Tropaqualf in Indonesia, and an Andaqueptic Haplaquoll in the Philippines to measure (N2 + N2O)‐15N flux, (N2 + N2O)‐15N trapped in soil, and total gaseous 15N loss following basal application of 15N‐labeled urea (87 kg N ha−1) to irrigated rice (Oryza sativa L.) grown on puddled soils. Urea treatments included broadcast applications with and without incorporation to 0.07‐m soil depth. Directly measured (N2 + N2O)‐15N flux during the 10 d following urea application by each method was less than 0.1% of the applied N at the Thailand and Indonesia sites. The (N2 + N2O)‐15N collected from the soil after 10 d did not exceed 0.02% of the applied N. Total gaseous N loss determined from a 15N balance at 10 d after N application without incorporation was 34% of the applied N in Thailand and 31% in Indonesia. Incorporation reduced total N loss to 22% in Thailand and 10% in Indonesia. In the Philippines, the measured (N2 + N2O)‐15N flux during the 15 d immediately following urea application with incorporation was 2.2% of the applied N with chambers placed between rice plants and 3.0% with chambers over the plants. Total N loss at the Philippine site was 40% of the applied N. Ammonia volatilization appeared to be much more important than nitrification‐denitrification as a mechanism of urea‐N loss at the three irrigated lowland study sites.

Model estimates of nitrous oxide emissions from agricultural lands in the United States

“…Nitrous oxide emissions from agricultural soils are known to be highly variable over hourly-to-interannual timescales [Hutchinson and Mosier, 1979;Duxbury et al, 1982;Terry et al, 1981]. Short-term temporal variability of N20 emissions is influenced by interactions of variations in weather and climate with changes in agricultural practices [Colbourn, 1992;Breitenbeck and Bremner, 1986;Buresh et al, 1991;Li et al, 1994a, b]. Longer-term variability may also be influenced by changes in soil composition, especially in soil organic content [Li et al, 1992a].…”

Differential responses of nirK‐ and nirS‐carrying bacteria to denitrifying conditions in the anoxic rice field soil

“…With the invention of novel high yielding and fertilizer‐demanding rice varieties, the fertilization N application in the Asian rice fields is increasing steadily (Ghosh and Bhat, 1998; Zheng et al ., 2002). The high N input leads to active nitrification and denitrification in the rice fields which end up with high N loss (Galbally et al ., 1987; Buresh et al ., 1991; Dedatta et al ., 1991) and emission of nitrous oxide (Xing et al ., 2009), a potent greenhouse gas contributing to global warming and ozone layer disruption in the atmosphere (Robertson et al ., 2000).…”

Dynamics of ammonium and pH in the solution of soils with different salinity levels, growing irrigated rice

“…in addition, high root densities in flooded soils can increase the total area of aerobic zones and create favorable conditions for nitrification (reddy & Patrick, 1984). when not taken up by the roots, the nitrate produced can migrate to the adjacent reduced zone and undergo denitrification, which may result in significant n losses in the form of nH 3 (Buresh et al, 1991). in this study, regardless of the soil salinity level and depth, there was a marked decrease in the levels of exchangeable nH 4 + during rice growth (figure 1).…”