Nitrogen will be a driver of grass growth in the Autumn as much as any other time. Spreading up to 30 units per acre in the last round of fertiliser in early to mid-September will help sustain good grass growth rates. Autumn is the ideal time to replace potassium (K) offtakes and build up soil K levels where fertility is low. Normal offtake levels for grazing are typically 30-40 units/acre of K per year. Silage removes a lot more, up to 100 units for first cut, and another 80 units for second cut. Low K soils (Index 1) require 50 units/acre of K to build fertility in the soil.