GRASS LEYS undersown in a thick cereal-based whole-crop may only produce half the autumn yield of grass undersown in a legume-based whole-crop, according to recent trials.

Autumn yield of grass following an oat-based whole-crop was 1.3t DM/ha (0.5t DM/acre), whereas the yield after a pea whole-crop reached 3.8t DM/ha (1.5t DM/acre), says a report in the British Grassland Society’s Grass Farmer magazine.

Plant breeder DLF Trifolium’s Rod Bonshor says post-harvest ground cover after pea whole-crop was excellent. Grass was suitable for immediate grazing because residual nitrogen helped boost grass growth. But, after thicker cereal and cereal-based mixes, particularly oats, grass establishment was poor, with small plants and less vigorous regrowth.

So when establishing a grass ley under a whole-crop, Mr Bonshor suggests a pea whole-crop or two-thirds pea and one-third barley mix to maximise autumn grass yield.