Annual pastures usually enter the 'vegetative' pasture growth phase during winter. In this phase, plants have become established and are mature enough to withstand being grazed and defoliated by animals. While pastures are in vegetative growth and actively growing, stocking rates can be maximised. However, it is important to remember that:
- Over-grazing can result in insufficient leaf area for maximum pasture growth.
- Small plants with poor root development may be susceptible to cold stress during this period.
A minimum feed on offer (FOO) of 1000 kilograms of dry matter per hectare (kg DM/ha) is recommended going into winter. However, the optimum pasture growth of clover dominant annual pastures occurs at about 1400kg DM/ha.
The general rule: higher FOO = higher leaf area = faster pasture growth.
Grazing during the vegetative pasture phase in winter is important to:
- encourage plant tillering in grasses and branching in clovers
- assist in weed control
- maintain palatability by promoting young shoot growth.
Grazing management through the vegetative phase should aim to meet animal production needs, while being sensitive to the productivity and sustainability of the pasture. Tactics to increase pasture utilisation and profitability include:
- strip grazing
- intensive grazing
- use of nitrogen.
As spring progresses, annual pastures move into the 'reproductive' pasture growth phase, which is characterised by flowering and seed set. Pasture growth rates are often at their highest and many paddocks grow faster than the stock can eat, leaving excess pasture. Dealing with this excess pasture is key in managing issues such as grass seed contamination, feed conservation for summer and effective seed set for the following year.
Grazing during this period can have an influence on seed production. Overgrazing during flowering will reduce seed production due to removal of flowering parts. This may affect annual grasses more than prostrate species such as sub clover which buries its seed.
Grazing management during spring can influence pasture composition in both the current year and following season. It is also the time of the year where preparations should be made to manage the potential summer feed gap and summer grazing issues.
- Manage pasture pests such as red legged earthmite.
- Consider pasture topping to control grass seed set.
- Manage pastures for maximising clover seed set.