Senescence and decomposition of white clover stolons in grazed upland grass/clover swards

The fate of marked sections of stolons of white clover (Trifolium repens) over a 50-week period from May 1987 was followed in grazed grass/clover swards maintained at 5-cm sward surface height with and without N fertiliser. There was little effect of N treatment on the pattern of survival of stolon sections. The proportion of live stolons recovered decreased during the experiment, and in May 1988 on average only 29% of the marked sections remained alive. At all harvests only a small percentage of stolon sections showed signs of senescence; the maximum percentage, on average 20% of those marked, occurred in autumn, 15–20 weeks after marking. Following this period, i.e. in late autumn/winter, the most rapid increase in percentage of decomposed stolons was measured. Over 50% of stolon sections were buried within the 5-week period following marking and nearly all were buried after 20 weeks; generally a much smaller proportion of stolon tips was buried. Nutrient concentrations of N, P and K fell to their lowest levels in autumn, before increasing in the following spring. Results are discussed in relation to the cycling of nutrients via stolon senescence.