EFFECT OF WOOD ASH APPLICATION ON SOIL-PH AND SOIL TEST NUTRIENT LEVELS

The use of wood residue as a fuel source for pulp and paper industries has led to the production of wood ash as by-product. Land spreading is a potentially sound method for the disposal of wood ash, which is an alternative soil liming agent. This study was conducted to determine the effect of wood ash amendment on soil pH and soil test nutrient levels as measured by a pH 3, 1 M NH4OAc extractant. Wood ash and soil mixtures were incubated in the laboratory and then tested to determine soil pH and plant-available nutrient levels. The calcium carbonate equivalence of the ashes used ranged from 26 to 59%, indicating that the acid-neutralizing power of wood ash varies from source to source. The percentage of plant nutrients released from wood ash to soil varied with the particular nutrient. The average nutrient release percentages were: phosphorus (P), 5.7%; potassium (K), 40%; magnesium (Mg), 48%; calcium (Ca), 74%; sodium (Na), 16%. Wood ash application altered the equivalent fraction of K, Mg and Ca in soils. In general, the equivalent fraction of K and Mg decreased, while the equivalent fraction of Ca increased. The soils which had the least initial extractable Ca had the greatest percentage change in K, Mg and Ca equivalent fraction. Wood ash is an acceptable alternative liming agent which also provides modest amounts of P and K to soils. © 1990.