Grazing management - It's a balancing act

Ideal grazing management depends on many factors including seasonal conditions, time of the year, species, as well as changing livestock requirements.

This past mid-summer onwards into winter has been especially noteworthy as it has commonly allowed opportunities to restrengthen drought affected pastures as well as graze to ensure good supply of quality feed into winter, spring, and possibly early summer.

Where summer/autumn rains were good, species like tropical grasses, if previously reasonably managed, grew rapidly. Because of consecutive follow up rains annul grasses like liverseed, arm grass, button grass and the like also commonly grew rapidly, producing good feed to 4.0 t/ha dry matter or more.

Native grasses, while often decimated in density over a drought surprisingly often bounced back.

Because of so much feed on many properties opportunities for pasture upgrading have presented. For example, a tropical grass or native perennial pasture on the thin side, allowed to seed (rested until seed set) often results in future opportunities (next spring/summer) for recruiting of new plants, that can lead to rebuilding density.

In native grass or introduced perennial grass pastures that rapidly exceeded dry matter levels of over 4.0 t/ha, a dense mat of herbage can stop sunlight reaching ground level, a trigger needed for germination of annual legumes like sub clover and serradella. That can lead to a lack of quality feed in winter and into spring.

In our own case to overcome this scenario a range of strategies were instigated. Two paddocks of tropical grass were harvested for hay. They yielded 6.2 t/ha, clearly very dense and not conducive to winter legumes getting established. Since hay removal a good density of serradella and sub clover has occurred.

Strong native grass paddocks, with reasonable native grass populations, plus annual grasses like liverseed, and a mix of broadleaf herbage, have been grazed relatively heavily to open up the pasture so that winter legumes can establish.

Weaker native grass paddocks, where grass cover has not reached 3.0 t/ha, have been prioritised for rebuilding their density (not grazed until seed set) and winter legumes established early and are the best grazing paddocks for high quality winter feed. On our property, they are predominately light acid soils with the main legumes serradella and biserrula. They will be good bloat safe pastures should bloaty conditions occur.

Winter annual legumes tend to perform best when allowed to develop above around 1.0 t/ha dry matter but kept to below around 4.0 t/ha. Not grazing below this level or allowing feed to get above it, regardless of rotating or variable levels of set stocking, are key management aspects for best productivity. Where soil seed levels of these legumes need rebuilding, grazing pressure coming into spring will be important.

Aerial seeding winter legumes like serradella, biserrula, gland or bladder clover, will need careful assessing if seasonal conditions turn dry late winter onwards. If grazed beyond their growing rate seed set can be prevented. In contrast sub clover, for most varieties, can set a lot of its seed close to the soil surface and quickly berry a good level of it. However even grazing it too hard can lead to poor seed set.

Dual purpose winter crops like oats, canola, wheat or the like grow most feed if allowed to firstly accumulate at least 1.5 to 2.0 t/ha dry matter and not more than 4.0 t/ha. Rotating or set stocking is likely not as important as keeping within these guides.

While in a good season we don't think much about keeping minimum groundcover levels, this past drought has shown us repeatedly just how important it is to protect the soil via it. Not only is protecting the soil important for capturing rainfall, but also to prevent wind and water erosion.

Next week: The 2020 Winter Crop Variety guide highlights many new, upgraded varieties.