Impact of Amendment with Hog, Cattle Manure, and Biochar on N.sub.2O, CO.sub.2, and CH.sub.4 Fluxes of Two Contrasting Temperate Prairie Agricultural Soils

• Published in: Bioenergy research Vol. 16; no. 2; p. 1173
• Main Authors: Hangs, R. D, Schoenau, J. J
• Format: Journal Article
• Language: English
• Published: Springer 01.06.2023
• Subjects: Agricultural industry; Air pollution; Greenhouse gases; Pyrolysis; Soil amendments; Soils
• ISSN: 1939-1234; 1939-1242
• DOI: 10.1007/s12155-022-10485-3

Liquid hog manure (LHM) and solid cattle manure (SCM) are valuable soil amendments for the nutrients and organic matter they augment. However, desire to mitigate the N.sub.2O, CO.sub.2, and CH.sub.4 fluxes attendant with their use has led to the question of whether biochar co-applied with LHM and SCM could mitigate these greenhouse gas fluxes. A split-plot design was used at two agricultural field sites with contrasting soil types (Brown Chernozem and Black Vertisol) in Saskatchewan, Canada, to assess the effect of LHM and SCM (100 kg N ha.sup.-1), alone and in combination with two different biochars applied at 8 Mg C ha.sup.-1; produced using either slow or fast pyrolysis of willow (Salix spp.) feedstock. Intact cores were collected from the plots and the N.sub.2O, CO.sub.2, and CH.sub.4 fluxes were measured during a 6-week (42 days) lab incubation. The impact of manure amendment on greenhouse gas fluxes, was more apparent with LHM than SCM; reflecting higher inorganic N content, narrower C:N, and more easily mineralizable carbon in LHM. Co-applying biochar with the manure sources reduced the manure-related N.sub.2O emissions 31.5 to 43.1% and increased CH.sub.4 consumption 94.1% to 2.1 x compared with manure alone. Regardless of soil type, neither biochar co-applied with the manures affected the net CO.sub.2 fluxes compared with manure alone. The N.sub.2O emissions were principally influenced by the impact of biochar addition on NO.sub.3-N supply and pH, while the net CO.sub.2 fluxes were controlled by the opposing effects of heterotrophic (i.e., CO.sub.2 production) and postulated autotrophic (i.e., CO.sub.2 consumption) respiration. The CH.sub.4 consumption was related to the NH.sub.4-N supply and its influence on autotrophic methanotrophy.