The effect of the early application of nitrogenous fertilizer and of the time of cutting in spring on the yield of rye-grass/white clover swards

1. In four different years, swards of perennial rye-grass/white clover were treated with nitrogenous fertilizer (0, 30 or 60 lb. N per acre) in mid-February to produce an early growth of grass. The effect of the time of the first cut, taken in March or April, on the annual yield was studied.

2. The total annual yield was reduced when an increasing quantity of grass was removed at the first cut because this interfered with the development of inflorescences and reduced yield at the second cut.

3. Fertilizer treatment increased early growth and advanced by 2-14 days the date in spring at which the yield was adequate for grazing; this improvement improvement was small compared with the extent to which this date was affected by differences in the weather from year to year.

4. The response in total annual yield to N averaged 17.2 and 14.9 lb. of dry matter per lb. N respectively for the 30 and 60 lb. N per acre applications. The highest responses were measured when little or no grass was removed at the first cut. Where a larger crop was removed at the first cut the response to N was reduced; exceptionally it was negative.