Open AccessInfluence of Contrasting Soil Moisture Conditions on Carbon Dioxide and Nitrous Oxide Emissions from Terminated Green Manures
Author(s) -
Singh Hardeep,
Kandel Tanka P.,
Gowda Prasanna H.,
Somenahally Anil,
Northup Brian K.,
Kakani Vijaya G.
Publication year - 2019
Publication title -
agrosystems, geosciences and environment
Language(s) - English
Resource type - Journals
ISSN - 2639-6696
DOI - 10.2134/age2019.03.0012
Subject(s) - nitrous oxide , carbon dioxide , environmental science , mineralization (soil science) , moisture , water content , legume , agronomy , biomass (ecology) , mesocosm , soil water , environmental chemistry , chemistry , soil science , nutrient , biology , geotechnical engineering , organic chemistry , engineering
Core Ideas Impacts of soil moisture at incorporation of two legumes on the CO 2 and N 2 O emissions were studied. Availability of soil moisture led to rapid mineralization of biomass C and N. Legume incorporation based on short‐term rainfall forecast did not avoid large N 2 O emissions. Carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) emissions from decomposing legume green manures largely depend on soil moisture. A potential management to mitigate N 2 O emissions could be to incorporate legumes during dry periods based on the short‐term rainfall forecast. The present mesocosm study was designed to examine the impact of soil moisture due to different timing of rainfall after incorporation of legume cover crops on CO 2 and N 2 O emissions. Two timings of rainfall were simulated as early and late rainfall that received 80 mm deionized water at or 1 wk after incorporation of the legumes. An additional 20 mm water was added after 2 wk of the first simulated rainfalls. Gas fluxes of CO 2 and N 2 O were measured using closed chamber method for 28 d incubation assay. Soil concentrations of NH 4 + and NO 3 – , concentrations of N in undecomposed biomass, and abundances of denitrifier bacterial genes ( nir K, nir S, and nos Z) and arbuscular mycorrhiza fungi (AMF) were determined at weekly intervals. Carbon dioxide emissions increased immediately after the first simulated rainfall events and peaked around Day 2 to 3, whereas N 2 O emissions reached peak level around Day 8 to 10 from both legume treatments. After the first rainfall simulations, soil NH 4 + and NO 3 – concentrations increased, whereas biomass N concentrations decreased rapidly. Abundance of nir K, nos Z, and AMF was positively correlated ( P < 0.05) to N 2 O emissions. Dynamics and magnitude of emissions after first rainfall events remained similar irrespective of the timing of simulated rainfall. In conclusion, our results indicated that soil incorporation of legumes based on a short‐term rainfall forecast may not be an effective tool to avoid large N 2 O emissions.