Studies on the cutting management of grass-clover swards. I. The effect of varying the closeness of cutting on the yields from an established grass-clover sward

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Abstract
1. A 3-year experiment is described in which perennial rye-grass/white clover swards were cut to within either 1 in. of 2–2½ in. of ground level when the herbage had reached either the ‘grazing’ or the ‘silage’ stage of growth. Superimposed on the cutting treatments were several fertilizer treatments which involved application of varying amounts of nitrogen at different dates over the season. 2. Throughout the experiment cutting to within 1 in. of ground level gave greater dry-matter and crude-protein yields of mixed herbage and of clover than cutting to within 2–2½ in. of ground level, the increase in dry-matter yield ranging from 39 to 49%. 3. The response of clover to these ‘height of cutting’ treatments developed more slowly than the response of the sward as a whole, and was modified in the later stages by the particular fertilizer nitrogen treatment applied. 4. It is suggested that the greater herbage yields obtained from close- than from lax-cut swards resulted from the differential effects of the two cutting treatments on stem and leaf formation in the grasses, but the need for further investigation is stressed. 5. Discrepancies between the effects of the ‘height of cutting’ treatments in this experiment and those reported by other workers are indicated, and it is shown that these discrepancies probably result from the varying cutting frequencies adopted. 6. Cutting the sward at varying stages of growth and increasing the rate of fertilizer nitrogen application had very similar effects on mixed herbage and clover yields in this experiment to those reported previously by other workers. 7. Where the total amount of fertilizer nitrogen applied over the season was small (4 cwt. ‘Nitro-Chalk’/acre) delaying the first dressing until after the first or second cut reduced the dry-matter and crude-protein yields of mixed herbage, and had little effect on those of clover. A similar delay where greater total amounts of fertilizer nitrogen were used (8–12 cwt. ‘Nitro-Chalk’/acre) reduced the dry-matter yields of mixed herbage, and slightly increased the dry-matter and crude-protein yields of clover. Under these heavy nitrogen treatments the crude-protein yields of mixed herbage decreased only where the delay involved a reduction in the total amount of fertilizer nitrogen applied over the season. 8. Although delaying the first dressing of the season reduced mixed herbage yields at all fertilizer nitrogen levels, it resulted in a more uniform distribution of production over the season. The practical significance of this is discussed.

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