Hay and silage each offer the chance to significantly reduce the return of weed seeds to the seedbank. Hay and silage are options that can be used in crops and pastures where excessive numbers of weeds have survived a previous procedure. Both hay and silage strategies are most valuable to growers when the weeds, crop and/or pasture are nutritious.
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. A high proportion of seeds will remain viable if hay is cut late. This has implications both for feeding out of the hay on-farm and for marketing of the product.
Timing the cut and the management of regrowth is critical for hay and silage production to be successful as weed control strategies. Time the hay or silage approach in accordance with the physiological development of the target weed. Timing the cut and the management of regrowth 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.
An understanding of the biological traits of the target weed is important in improving efficacy of hay and silage as a weed control option. Individual species’ responses to cutting, in terms of subsequent growth and seed production, will be determined by the stage of maturation of the weed at the time of defoliation. Understanding species differences allows for more suitable timing and can thereby improve the effectiveness of the hay or silage method.
Seed-set management timed according to stage of weed physiological maturity will deliver far more reliable outcomes than weed management timed by calendar dates, as weed species development will vary with region and year. Control of any weed regrowth after cutting is essential to reduce weed seed entering the soil seedbank. Intensive grazing used after an early cut is a reliable way of controlling weed regrowth.
Spring cutting can also be used to manipulate the existing pasture composition and the future weed seedbank. Following various defoliation methods and timing of cutting, large changes in pasture composition are produced. For instance, wild oats make excellent fodder and can be included in either silage or hay, while the spikelets on barley grass and vulpia, when close to maturity, make them unsuitable for hay or silage. The key is to identify the target weed species and to strike a balance between the problem weeds and other species which contribute to the pasture mix.
Article: CulturalWeedControl180 (permalink) Date: 9 January 2013; 7:58:50 PM AEDT