Effect of nitrogen fertilization, cropping and irrigation on soil air composition and nitrous oxide emission in a loamy clay

Abstract

Summary Most of the nitrous oxide (N2O) in the atmosphere, thought to be involved in global warming, is emitted from soil. Although the main factors controlling the production of N2O in soil are well known, we need more quantitative data on the interactions of soil and the environment in the soil that affect the emission. We therefore studied the effects of irrigation, cropping (fallow, barley with grass undersown) and N fertilization (unfertilized, 103 kg N ha−1) on the composition of soil air and direct N2O emission from soil (using the closed chamber method) in a factorial field experiment on a well‐structured loamy clay soil during 1 June−22 October 1993. The measurements were made weekly during the growing season and three times after harvesting. The composition of the soil air did not indicate severe anoxia in any treatment or combination of treatments, but the accumulation of N2O in the soil air indicated that hypoxia was common. At the start of the irrigation the emissions were small, even though there was much ammonium and nitrate in the soil and therefore a potential for emission of N2O produced by both nitrification and denitrification. Larger emissions occurred later. The largest emissions were found when 60–90% of the soil pore space was filled with water. Irrigation and fertilization with N both roughly doubled the cumulative N2O emission. Growing a crop decreased it by a factor of 3–7. Most N2O was lost from the irrigated fertilized soil under fallow (3.5 kg N ha−1), and least from the unirrigated unfertilized soil under barley (0.1 kg N ha−1).

Meeting Cereal Demand While Protecting Natural Resources and Improving Environmental Quality

“…portional loss may vary considerably as influenced by management practices, crop vigor, climate, and soil properties (118,119,120). Losses also differ among N fertilizer formulations with the greatest losses occurring from anhydrous ammonia (121).…”

“…However, most of these estimates were obtained from small experimental field plots, which may not be representative of production-scale fields. Therefore, most currently used simulation models fail to account for large pulses of N 2 O emissions caused by spring thawing (130), rapid soil warming (131), tillage and irrigation events (132), and N application (120), which may greatly affect annual emission rates and the net global warming potential of an agroecosystem (133). And although C sequestration is often increased in systems that receive N fertilizer, the energy costs of N fertilizer and associated CO 2 emissions must also be included in the net greenhouse forcing budget (134).…”

N<sub>2</sub>O, NO and CH<sub>4</sub> exchange, and microbial N turnover over a Mediterranean pine forest soil

“…Forest soils have been identified to be significant sources for these N trace gases (Brumme and Beese, 1992;Skiba et al, 1994;Papen and Butterbach-Bahl, 1999;Gasche and Papen, 1999), but also net N 2 O or NO consumption by soils has been observed (Baumgärtner et al, 1996;Schiller and Hastie, 1996;Goossens et al, 2001;Papen et al, 2001). Soil aeration (Simojoki and Jaakkola, 2000;Vor et al, 2003), N availability (Bouwman 1996;Del Grosso et al, 2000) and acidity (Granli and Bøckmann, 1994) have been identified to be key factors influencing exchange dynamics of N 2 O and NO x between soils and the atmosphere. CH 4 is next to H 2 O and CO 2 the third most important greenhouse gas, and its atmospheric concentration is increasing constantly due to anthropogenic activities (IPCC, 2001).…”

Nitrous Oxide Fluxes and Soil Oxygen Dynamics of Soil Treated with Cow Urine

“…The extent to which chemical, hydrological, and soil physical properties influence soil O 2 , and in turn, influence surface N 2 O emissions, is difficult to quantify. Previous work has added labeled 18 O-and 15 N-labeled compounds to evaluate scenarios of O 2 exchange in various microbial pathways (Kool et al, 2009) but few studies have simultaneously measured both N 2 O emissions and soil O 2 concentrations in the field (Simojoki and Jaakkola, 2000;Owens et al, 2016).…”