Novel strategies for biochar application to densely populated livestock regions in North America –
C Li, CM Romero, J Owens, GO Ribeiro, T McAllister, E Okine, X Hao. 2019. Novel strategies for biochar application to densely populated livestock regions in North America–Impacts on soil nutrient cycling and greenhouse gas emissions. AGU Fall Meeting 2019. Dec 9-13, 2019. San Francisco. USA
Plain language summary
1. Biochar application did not alter cumulative CO2 , N2O, or CH4 emissions from soil and the pyrolyzed-C at low application rates (<3 Mg/ha ) has little effect on the cycling of soil nutrients and storage of soil organic matter (OM).
2. Cumulative CO2, C2O and CH4 emission from soil amended with feedlot manure from cattle on diet with or without 2% biochar as feed supplement.
3. Soil amended with manure from cattle on 2% biochar feed supplement had higher available phosphorus levels manure with no biochar in cattle diet.
Biochar is now considered a global applicable resource to address the increasing complexity of modern-day farming from an agro-environmental perspective. However, its use in ruminant husbandry (i.e., as animal feed additive) is currently only a potential management strategy that needs more systematic research; particularly when considering manure-induced secondary effects on soil fertility and soil-borne greenhouse gas (GHG) emissions. A 70-day soil column experiment (21°C; 60-80% WHC) was conducted within two surface (0-15 cm) prairie-fertile Mollisols of contrasting texture (i.e., sandy clay loam and clayey) to evaluate the effects of pine
wood biochar (3 Mg ha ) on cumulative GHG emissions and related fertility attributes in the presence or absence of cattle manure (120 Mg ha ). We compared ¦ve treatments: (i) nonamended soil (CK); (ii) soil amended with pine wood biochar (B); (iii) soil amended with beef cattle manure (i.e., manure from cattle on control diet) (M); (iv) soil amended with biochar manure (i.e., manure from cattle on control diet supplemented with 2% of diet dry matter as biochar) (BM); and (v) soil amended with B and M at the aforementioned rates (B+M). Regardless of soil type, application of biochar-only did not alter cumulative CO , N O, or CH emissions over CK, implying that addition of pyrolyzed-C at low application rates (<3 Mg ha ) has little effect on the cycling of soil nutrients and storage of soil organic matter (OM). Contrarily, amending both soils with manure or biochar-manure mixtures increased (P<0.05) cumulative CO (2.2 to 3.8-fold) and CH (17.6 to 34.6-fold) emissions over CK and B, mainly through a large, enriched pool of dissolved OM. After 70 days, BM increased PO -P availability over M and B+M treated soils, suggesting that passage of biochar through the ruminant digestive tract may have improved the agronomic value of beef cattle manure. We conclude that biochar and manure and/or biochar manure have contrasting short-term effects on the biogeochemistry of Mollisols. At relatively low application rates, biochar does not necessarily counterbalance manure-derived inputs. Although
BM did not mitigate the flux of GHGs over M, biochar-manure has the potential to improve nutrient recycling in temperate agro-ecosystems.