Wood Ash Improved Soil Properties and Crop Yield for Nine Years and Saved Fertilizer

Wood ash may be used to mitigate soil acidity and improve crop production. We compared effects of wood ash and recommended fertilizers on soil properties of a Gray Luivsol, crop yields and contribution margins in southeast Peace, Alberta, Canada. The CHK (no fertilizer, inoculation or wood ash), FRT (recommended fertilizers or inoculation), ASH (wood ash rate to supply amounts of phosphorus equivalent to the FRT treatment); and ASH+N (same as ASH + N fertilizer or inoculation) treatments were applied in 2006 and 2007. Their effects were studied from 2006 to 2014. Wood ash had all the essential plant nutrients, except nitrogen. Soil samples collected in 2007, 2008 and 2013 had or tended to have higher pH, P, K, Ca, Ca-Mg ratio, S, Cu, Zn and B levels for the ASH and ASH+N treatments than the CHK and FRT treatments. In the 2006 and 2007, the seed yields were ASH+N > FRT > ASH > CHK. The seed yields in 2008, 2010, 2012, 2013 and 2014 were greater from both the wood ash treatments than other treatments. Extra contribution margin from the ASH+N over the FRT treatment was $751/ha, i.e. $97 Mg-1 of applied wood ash. Overall, wood ash reduced fertilizer expenditure and improved seed yield, contribution margin and soil properties, with residual effects observed up to seven years and likely for few more years.