Soil N2O emissions following termination of grass pea and oat cover crop residues with different maturity levels. Issue 6 (28th October 2020)

• Record Type: Journal Article
• Authors: Singh, Hardeep; Kandel, Tanka P.; Gowda, Prasanna H.; Northup, Brian K.; Kakani, Vijaya G.; Baath, Gurjinder S.
• Is Part Of: Journal of plant nutrition and soil science. Volume 183:Issue 6(2020:Dec.)
• Page Start: 734
• Page End: 744
• Publication Date: 2020-10-28
• Subjects: biomass decomposition -- C/N ratio -- finger millet -- N mineralization -- nitrous oxide; Plants -- Nutrition -- Periodicals; Soil science -- Periodicals; 630
• DOI: 10.1002/jpln.202000239
• Languages: English
• ISSNs: 1436-8730

Abstract

Abstract: Background: Although cover crops provide many agronomic and environmental benefits, they may also increase nitrous oxide (N2 O) emissions after termination. The N2 O emissions from decomposing biomass of cover crops largely depends on the type of cover and maturity level at termination. Aim: The objective of this study was to quantify N2 O emissions following soil incorporation of a non‐legume (oat; Avena sativa L.) and a legume (grass pea; Lathyrus sphaericus Retz.) cover crop residues at two different maturity levels. Methods: Oat and grass pea were terminated at vegetative (early‐termination) and reproductive (late‐termination) stages, and stored fresh before soil incorporation (2.5 Mg dry matter ha −1 ) together in late‐May. A treatment with no cover crop was included as the control. The experiment was laid out as completely randomized block design with three replicated plots (2 m × 2 m) in each treatment combination. Finger millet [ Eleusine coracana (L.) Gaertn] seedlings were transplanted as a summer crop. The N2 O fluxes were measured with a closed chamber with a portable gas analyzer on 25 dates over an experimental period of 98 days. Results: In general, fluxes of N2 O increased after rainfall or irrigation events and approximated zero during dry periods. Cumulative N2 O emissions during the 98 days study period were higher ( p < 0.01) from all cover crops treatments than the control. Effects of maturity level at termination on cumulative N2 O emissions were significant ( p < 0.05) as 30–35% higher emissions were recorded from both cover crops terminated at the reproductive stage than the vegetative stage. Yields of finger millet biomass from oat incorporated plots were 15–19% greater ( p < 0.05) than grass pea incorporated plots, while the yields from control plots were not significantly different from plots receiving cover crop residues. Conclusions: Stage of maturity at termination alone was not a strong predictor of total cumulative N2 O emissions from decomposing cover crop residues, as maturity level interacted with environment variables ( e.g ., timing of rainfall events).