Silage and hay for weed control - crops and pastures
Hay and silage are options that can be used in crops and pastures where excessive numbers of weeds have survived previous weed control tactics.
Silage production and hay making reduces the viable seed set of target weeds and removes viable weed seeds so that they are not added to the soil seedbank. These weed control tactics are best suited to farms with a livestock enterprise. Hay is much more portable than silage and so hay is preferable when the product must be transported to market.
Issues to consider when using hay or silage production for weed control
Timing the cut
Timing is critical for hay and silage production to be successful as weed control tactics. Cutting too early will allow any subsequent regrowth to set viable seed and contribute to the weed seedbank. Cutting too late means that mature weed seed is likely to have already been shed, adding to the weed seedbank in the paddock.
Weed regrowth can produce enough seed to keep the seed bank topped up
It is necessary to cut early to remove weed seeds before they shed, but regrowth monitoring is very important. Bill Roy (York, 2005) showed that where paraquat was not used to control regrowth, and hay was cut 2-3 weeks after the silage production, almost no reduction in annual ryegrass numbers resulted. A knockdown herbicide or intensive grazing used after an early cut is a reliable way of controlling weed regrowth.
Is the use of hay or silage spreading weed seeds?
Hay may contain viable weed seeds, especially if the crop is cut late. Most seeds are no longer viable once they have been ensiled, but a few may survive depending on the weed species in question. Therefore, hay or silage have the potential to introduce weed seeds. Consider feeding out in dedicated areas to allow control of any weeds introduced in the feed.
| Issue | Hay | Silage |
|---|---|---|
| Prevention of viable seed addition to the weed seedbank in the paddock | Similarly effective, assuming no target weed seed production occurs before the cut and regrowth is controlled to prevent further weed seed production | Similarly effective, assuming no target weed seed production occurs before the cut and regrowth is controlled to prevent further weed seed production |
| Potential for weed seeds to be spread to other areas during feed out | Moderate to high | Low if properly ensiled |
| Potential for regrowth | Depends on growth stage of weed at time of cut | Depends on growth stage of weed at time of cut |
| Feasibility | Depends on the scale of the operation, livestock enterprises within the business, distance to end-use point and demand for the product | Depends on the scale of the operation, livestock enterprises within the business, distance to end-use point and demand for the product |