Evaluating the potential of biochar in mitigating greenhouse gases emission and nitrogen retention in dairy manure based silage corn cropping systems

Ashiq, Waqar (2018) Evaluating the potential of biochar in mitigating greenhouse gases emission and nitrogen retention in dairy manure based silage corn cropping systems. Masters thesis, Memorial University of Newfoundland.

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Abstract

Greenhouse gas (GHGs) emissions from the agriculture sector have been accelerating global warming potential (GWP) and greenhouse gas intensities (GHGI). About 8 % of GHG emissions in Canada are contributed by the agriculture sector mainly through methane (CH₄) and nitrous oxide (N₂O). Out of these emissions, 50 % is contributed by manure and fertilizer application to land. Biochar (BC), a stable carbon-rich product has been observed to reduce GHG emissions from soil, increase soil pH, improve soil moisture, enhance nutrient retention in soil and increase biomass production in many crop plants. However, these effects are not constant across all soil types, environmental and climatic conditions, and cropping systems. This study aimed to evaluate the effect of BC on GHGs emissions, soil nitrate and ammonium retention, soil pH, plant nitrogen concentration and dry matter production in dairy manure (DM) based silage corn cropping system in western Newfoundland, Canada. Two sources of dairy manure (DM₁, DM₂), inorganic N (IN), their combination with BC (DM₁+B, DM₂+B, and IN+B), and control (N₀) were used as experimental treatments. Results showed that BC application to DM₁, DM₂ and IN reduced cumulative CO₂ emission by 16, 25.5 and 26.5 %, CH₄ emission 184, 200 and 293 %, and N₂O emission by 95, 86 and 93 %, respectively. BC treatments exhibited significantly higher soil moisture (SM) contents at all sampling points than non-BC treatments. It also reduced the GWP by 24.9, 34.5, and 37 %, and GHGI by 30, 37.5, 43.4 %, respectively. Furthermore, BC enhanced the NO3⁻ and NH₄⁺ retention in topsoil (decreased their leaching to deep soil) which improved plant N concentration and dry matter yield of silage corn crop. Conclusively, BC application to soil exhibited to be a promising tool for the mitigation of GHGs emissions, GWP, GHGI and to enhance soil fertility and crop dry matter yield simultaneously.

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