Pasture legumes differ in herbage production and quality throughout spring, impacting their potential role in fodder conservation and animal production

Abstract

Grazing systems in global Mediterranean and temperate environments rely on natural rangeland plants to support livestock production. However, livestock production can be constrained in these environments during periods when herbage availability is limited and/or herbage quality is sub-optimal. In Mediterranean-type environments, herbage supply and herbage quality gaps are common over summer and into autumn. These pastures are usually dominated by annual plants that germinate in autumn and complete their lifecycle prior to the onset of low moisture-high temperature conditions experienced in summer (Cocks & Thomson, 1988; Moore et al., 1997). In temperate environments, where there is a greater prevalence of perennial plants, inadequate herbage availability in winter often limits livestock production, as pasture growth is constrained by low temperatures (Barrett et al., 2005; Kemp, 1988; Moore et al., 1997). In both Mediterranean and temperate environments of Australia, the timing of opening season rainfall and rainfall received throughout the growing season are the major factors impacting herbage production (Black, 1964; Chapman et al., 2009). Recent modelling has shown increasing variability in autumn rainfall, declining growing season rainfall and tripling (from 20 to 60 days) in the number of spring moisture stress days in the period 2002-2015 compared to 1988-2001 for medium rainfall areas of southeastern Australia (Perera et al., 2020). Despite variability in seasonal conditions, a common feature of both Mediterranean and temperate environments in extensive livestock production systems, such as those in southern Australia, is an excess of spring production relative to

“Summer sowing”: A successful innovation to increase the adoption of key species of annual forage legumes for agriculture in Mediterranean and temperate environments

“…Additional research could also focus upon optimising benefits achievable from summer sowing in areas of potential increased nitrogen supply for following crops (associated with greatly increased biomass), increased weed suppression offered by more vigorous growth in the establishment year, and conservation of excess feed from summer-sown forage legumes as silage and/or hay (see Hackney et al, 2021).…”

A Comparison of Cereal and Cereal/Vetch Crops for Fodder Conservation

“…Consequently, the capacity to support livestock production will become more difficult as annual pasture regeneration becomes less reliable and the impacts of moisture stress (drought) on persistence of perennial pasture species become more severe [4,5]. Maintaining current levels of livestock production under future climate scenarios will require an increase in the use of stored fodder, including conserved forages, to cover deficits in the quantity and quality of pasture available [6]. Similarly, fodder conservation can be used to remove grazing pressure and the risk of overgrazing, particularly under adverse climatic events such as drought, that can lead to adverse effects on soil and other plant species.…”

Growth rates and persistence of annual and perennial clovers

“…However, these impressive growth rates resulted from stands left to seed. Allowing full seed set meant the two top flowering species were unavailable for grazing and feed quality declined (Hackney et al 2021) before it could be used. The consequent residual herbage was difficult to 'clean-up' over summer (Macfarlane et al 2015).…”