Roadside DSC09078

Maintaining groundcover, but not the bulk!

The balancing act of maintaining at least 70% groundcover in your pastures is recommended to protect soils from erosion by summer thunderstorms; but too much ground cover remaining at the autumn break reduces subsequent growth and will result in reduced nutritive value of feed in both perennial grasses and annual legumes.

The amount of biomass grown after this long-wet spring will make removal challenging.  Summer rain will reduce quality further and stimulate growth of green pick which stock will preferentially graze over the mature grass.

The more fragile material, like leaves can degrade unaided and blow away. Stock will graze seedheads which have higher starting feed quality (digestibility 80%) but ignore the poorer quality stems with lower digestibility (65%). Nutritive quality of leaf blades and seed heads declines rapidly for about three weeks after flowering before steadying.  Therefore, the window for utilising feed while it still has moderate feed quality is about three weeks after flowering.

Dry mature feed by January may contain as little as 4 to 6% crude protein, digestibility of 50 to 55% and a low energy content of 7 to 8 mega joules of metabolisable energy per kilogram of dry matter.

Farmers may have maximised spring utilisation using spring lambing or calving, agisting additional stock, and conserving fodder or reduced excessive spring growth, by sowing fodder crops or even spray-topping annual grasses which can reduce biomass by 20%.

However, excess herbage mass is still likely to be an issue and rather than lose control on all paddocks, decisions need to be made on which ones to concentrate grazing on. Priority paddocks for grazing are high growth pasture paddocks and paddocks destined for lambing or calving. Un-grazed paddocks can be grazed during winter when other paddocks are rested.

In years of big spring surpluses, slashing or burning are sometimes tactics used to remove litter, but the preference is always to try and utilise feed grown. Slashing is best done earlier, to allow regrowth if there is summer rainfall and when there is low fire risk.

Grazing methods which minimise selective grazing are needed. Use high stock numbers (at least 100 DSE/ha) in short intensive grazing periods of three to seven days. Use cattle in preference to sheep, as they do a better job of litter removal and are less selective grazers and use dry stock or non-lactating stock, but avoid using weaners.

More information is available from the new MLA factsheet called How do I remove excess mature reproductive pasture?, written by SFS.

Photo: Roadside in autumn provides an example of cut phalaris with new growth (left) and uncut phalaris (right) shading new growth with its excessive bulk dry feed.
Credit: L Miller, SFS

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