EFFECTS OF APPLYING INORGANIC FERTILIZER AND FARMYARD MANURE ON FORAGE PRODUCTION AND ECONOMIC RETURNS IN EAST-CENTRAL SASKATCHEWAN

Abstract

Over a 4-yr period, annual application of inorganic fertilizer (IF) at 55 kg/(ha∙yr) nitrogen (N) plus 12 kg/(ha∙yr) phosphorus (P) and two times this rate or farmyard manure (FYM) at 11 or 22 tonne/(ha∙yr) significantly increased dry matter (DM) yields, nitrogen (N) and phosphorus (P) uptake and P content of alfalfa, bromegrass, crested wheatgrass and the grass-alfalfa combinations. Inorganic fertilizer produced larger yield increases of bromegrass, crested wheatgrass and their mixtures with alfalfa than FYM containing slightly more N and P. Each fertilizer form was as effective at increasing forage P, but IF increased the N content of crested wheatgrass or bromegrass by 0.1–0.5% more than a comparable rate of FYM. Utilization of P was 14–20% of that applied as IF and 6–13% of P applied as FYM. Utilization of N by the grasses was 44–52% for IF and 7–29% for FYM. At the relatively low levels applied, each fertilizer form increased bicarbonate-extractable soil P, but had no significant effect on total soil N, P or carbon. Based on forage market values that were related to the nutritional requirements of beef cattle, the net returns for the fertility treatments ranged from $121 to $261/ha for alfalfa, from $53 to $237/ha for grass-alfalfa mixtures and from a $48/ha loss to a $135/ha gain for grass only treatments. Application of IF was equally or more profitable than no fertilizer for all forage types. When FYM was priced on the basis of its total N and P contents, net returns for the 11 and 22 tonne/ha rates of FYM averaged $54/ha or 33% and $112/ha or 62% lower than those for the comparable IF treatments, respectively, and $25/ha or 19% and $65 or 39% lower than for the check treatments. When considering the alfalfa and alfalfa-grass treatments, the break-even value of FYM as a substitute for IF varied from $0 to $6/t of DM.Key words: Inorganic fertilizer, farmyard manure, forage yield, forage protein, economic worth of forage