There’s a lot to like about undersowing. It’s fast, it’s relatively cheap, you can cover a big area of ground, and you don’t lose much feed in the process. But it can also be a waste of money if it doesn’t go to plan. The single biggest key to success? Timing.
Autumn is often a busy season for undersowing, and this year is no exception, especially in regions which incurred significant pasture damage during the very wet spring. Many farmers in this situation weren’t able to repair those paddocks because of the weather, and now they are looking worse for wear, as are paddocks in areas which have suffered a dry summer.
Fast establishing pasture cultivars like Shogun hybrid ryegrass are ideal for undersowing, because they rocket out of the ground, produce a big bulk of high quality feed and are ready for grazing before winter.
The only way Shogun can achieve this performance for you, however, is if it has room to grow! For it to reach its potential, which is significant, it must be sown before existing weed seeds in the soil have time to germinate and fill the gaps in paddocks that need to be undersown.
Weeds will take hold faster than many people realise; you may only have 3-4 weeks to beat them. After that, the gains from undersowing are usually much less, and you may be best to spray herbicide before drilling.
The diagram below illustrates just how quickly the situation can change, as the balance of plant species in a damaged paddock tips from sown ryegrass and clover to weeds.
For best results: undersow after hard grazing; use treated seed and sow at 50-75% of the normal rate (using more seed in thinner pastures). Graze normally, to prevent seedlings from being shaded.
Annual ryegrass like Hogan is ideal for undersowing paddocks which will be cropped in spring; Shogun will last 2-3 years.