Frozen Forage Crops

The first hard frost of the winter has arrived in some parts of Scotland this week, resulting in this alert as a reminder of the possibility of high nitrate levels in brassica crops.

High nitrate levels in leafy crops occur when the plants uptake more nitrogen from the soil than the plant can utilise through its roots, meaning the surplus is stored in the leaves.  When rapid growing crops such as brassicas are affected by stress such as cold frosty weather, then the high levels of nitrates can be found in the plant.

Some tips on feeding brassicas in frosty weather:

• Ensure animals are not hungry when offered the crop, to prevent gorging on the nitrate high leaves. This can be achieved by ensuring a good accessible supply of fresh hay or silage is available to the animals.
• Avoid feeding frozen crops, moving the electric fence or break after the crop has thawed through the day.
• Offer less brassica and more hay or silage during periods of frost so that a lower percentage of intake is from the frozen crop thus reducing high nitrate intake.

Kirsten Williams, kirsten.williams@sac.co.uk