Timing of primary growth harvest affects the yield and nutritive value of timothy-red clover mixtures

Abstract

The effects of partition of growth time between primary growth and regrowth of perennial organically grown mixed (mainly timothy and red clover) leys were studied over two years in Juva, Finland. Primary growth was harvested at three different dates and regrowth on a single occasion from all plots. Dry matter (DM) yield of primary growth increased by 116 kg per ha per day by delaying harvest (P<0.001) which was partly compensated by a reciprocal effect in the regrowth. Harvesting schedules had no effect on the botanical composition of herbage within harvests, but the proportion of red clover was lower in the primary growth (0.28) than in the regrowth (0.71). The proportion of red clover in weighted total yield decreased linearly from 0.46 to 0.35 (P<0.01) by delaying the primary growth harvest. The nutritional quality of timothy and red clover declined with advances in primary growth, the extent of which was greater for timothy. Digestible organic matter content in DM (D-value) decreased 2.6 and 5.6 g/kg per day in red clover and timothy, respectively. Reciprocal effects were observed in regrowth. However, the total yield and quality from both harvests was strongly influenced by primary growth, since it accounted for on average 0.68 of total yield and differences in the nutritional quality of regrowth were smaller than for primary growth.