The response of grass-clover and pure-grass leys to irrigation and fertilizer nitrogen treatment. II. Clover and fertilizer nitrogen effects

1. The effects of irrigation and fertilizer nitrogen treatments on four swards were studied for 3 years in an experiment at the Hannah Institute. This paper describes only the effects of the fertilizer nitrogen treatments and their interactions with the presence or absence of clover in the sward, since those of the irrigation treatments have been reported previously. 2. Annual applications of 0, 104, 208 or 312 lb. of fertilizer nitrogen per acre were made on swards of S 23 rye-grass or S 37 cocksfoot with or without S100 white clover. 3. The yields of the grass + clover swards exceeded those of the pure-grass swards at all fertilizer nitrogen application rates in the first 2 years and at the 0 and 104 lb./acre rates in the third year.