Clover content and yield of swards on organic farms - maintenance and estimation

Summary

Grassland production based on legumes is an essential part of the productivity and economy of the organic farming systems. The clover content is an important factor in organic grassland management to optimize the yield, feed value and pre-crop effect of ley.
The ley yield and clover content of one-, two- and three-year-old leys were determined on eight organic farms in 1998. Two-year-old leys produced the highest (6500 kg/ha dm) and three-year-old leys (4900 kg/ha dm) the lowest yields, with no significant differences between one- and two-year-old leys. The clover content (20-80 % of dm) diminished to the same extent as the yields.
Because the ley samples from the organic farms gave strong evidence of decreasing yield level and clover content in the 3-year-old leys, we started to develop a technique to maintain the ley productivity in older swards. This technique includes oversowing of clover in the spring of the second ley year and utilization of lime-pelleted, pre-inoculated seed. Lime-pelleted, pre-inoculated clover seed oversown at different times in spring were compared with the aim of developing an oversowing method for Finnish conditions. The preliminary results do not show any differences, but studies are ongoing.