Pasture type and management for year-round growth in focus

Traditionally a lot of NSW was regarded as a mainly winter rainfall climate. Growing up on a farm in this environment, it was often thought summer rain only grew weeds like Bathurst burr and was of little pasture use.

The main pasture species was sub clover combined with annual grasses like brome, barley and ryegrass. Yet as like now, summer rains were common and potentially could add to the feed supply.

However, rotations have dramatically changed, commonly now being continuous cropping with zero till and stubble retention. Pastures are often more long-term and in arable areas, often more restricted to lighter or other soils less capable of storing a lot of subsoil moisture.

Lucerne, while perhaps restricted to around 1 million hectares, is great at supplying quality feed all year, plus building soil nitrogen. But it is restricted because of factors like short life, and it doesn't like acid or poorly drained soils.

Temperate perennials that are the most drought tolerant, especially in off-tableland environments, tend to be summer dormant types. These don't help much in supplying summer feed.

In higher elevation and higher rainfall areas, temperate perennials can be quite persistent and at least reasonable summer growers, plus good winter growers and combine with winter legumes.

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Native grasses can coexist with winter legumes and can grow well in summer, as well as winter/spring if well managed and if soil fertility is good. In many respects, tropical grasses, combined with winter legumes are similar to native grasses but for most areas, are far more productive, especially in late spring, summer and autumn.

Adding tropical perennial grasses as partners to winter legumes adds to the feed supply when so-called "out of season" rain occurs.

For example, winter annual legumes like sub clover generally seed down and stop growing as spring warms up and soil moisture declines. They don't begin to re-establish normally until the following autumn, or all too often, in winter before the break occurs.

When dry early springs occur, species like sub clover commonly shut down from mid-September onwards. They then often fail to use late spring as well as summer rains. And often rain in early autumn, especially if there is no follow-up rain, fail to establish winter legumes.

Therefore rain from mid-September to April, seven months of the year, fails to be adequately used in winter species-only pasture.

Even in southern NSW areas, around 40 per cent of annual rainfall on average falls in the period when winter only pastures are not growing, or not growing much. Adding a long-term persistent perennial tropical grass can easily double the average yearly feed supply. That added feed supply can be high quality if soil fertility is good quality.

Pasture management is an important part of ensuring pastures containing winter legumes, and tropical gasses (including native species) coexist well.

A key grazing management aspect is when a late wet summer occurs, or a wet spring occurs. In these situations, a dense summer mass of grasses coming into autumn, or a dense mass of clovers coming into spring, can totally shade out their respective partners at the time they should be beginning their main growth cycle.

Grazing management that may include some paddocks being cut for hay or silage, which helps ensure, in the case of autumn, clovers and, in spring, tropical grasses, are not smothered, is important. In general terms, it means keeping drymatter at these key times below 3t/ha, which should help ensure their timely commencement of growth.

A further aspect of ensuring good all-year growth can include preparation for timely sowing of winter fodder or dual-purpose crops. Timely sowing of these on fallows with good subsoil moisture helps ensure good winter feed, especially critical in years with late autumn breaks.

Next week: Wheat varieties with greater heat tolerance.