PlotSpike 16-4-8 Fertilizer, 40-Pound (Discontinued by Manufacturer) Covers .25 acre For best results, test the soil and apply the amount of Plot Spike 16-4-8 indicated by the results of the soil test If no soil test is available, apply at a planting rate of 40 lb. per .25 acre When spreading the fertilizer, calibrate the spreader according to manufacturers recommendations Apply fertilizer every 6 to 8 weeks throughout the growing season for optimum forage production