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Stretching your winter pasture?

Winter pasture growth can be encouraged with good soil fertility and gibberrellic acid.  Photo J. Powells

As we head further into winter many land managers are considering how to meet their animals’ feed requirements, especially in another tight season. Purchasing fodder and grain or growing forage crops such as winter cereals or brassica are ways to address feed gaps however, we often get asked, “what can I do to get more from my existing pasture during winter?”

First of all, our tropical or “summer active” pasture species such as red grass, paspalum, lovegrass and kikuyu are dormant during winter. These species typically enter this dormancy period as the temperature drops (<13OC) and the days shorten and then break their dormancy in mid to late spring. Whilst being dormant in winter, these grasses have the ability to actively grow in high summer temperatures (up to 32OC) when other species cannot.

Our temperate or “winter active” species such as phalaris, cocksfoot, weeping grass, ryegrass and many more can typically grow between 5 and 27 OC. These are the grasses that have the ability to grow during winter (when conditions allow them to) and typically become dormant during the heat of summer.

The first and most sensible way to promote pasture growth is through adequate soil nutrition and this applies to both native and introduced pastures. There is an extensive body of research work that demonstrates that pasture plants are more resilient to grazing when they are supported with good soil nutrition. Pastures with adequate soil fertility also have more capacity to continue growing herbage heading into winter, as well as, dry periods and these pastures are also the first and fastest to respond once conditions improve. A soil test can quickly identify which key nutrients may be limiting growth in your pastures.

Promoting additional plant growth during winter can also be achieved using targeted applications of nitrogen and/ or gibberellic acid. Gibberellic acid is a naturally occurring plant hormone that was identified back in the early to mid-1900s and when applied to pasture can stimulate plant growth through the elongation or “stretching” of plant leaves and stems.

Early research using gibberellic acid on pastures questioned the economic value of its use however, the product was used at extremely high rates (>250g/ha) compared to today’s recommended application rates (2.5 - 20g/ha). Research into the product and its effects continues to this day, particularly by our Kiwi neighbours who have been conducting numerous trials looking at the combined effects of gibberellic acid and nitrogen fertilisers.

Pasture growth can be encouraged during the cooler months with good soil fertility and careful management. Photo J. Powells

Gibberellic acid application has been shown across numerous trials to significantly increase herbage mass (the weight of pasture) and is most effective when used in combination with a nitrogen fertiliser. This additional pasture “growth” is achieved by the plant drawing on its nutritional reserves and increasing the size and density of its tillers (the stem produced by grass plants). This is best achieved using an established pasture (older than 1 year), typically ryegrass or phalaris, and one with solid soil nutrition to help support the extra plant growth. There also needs to be sufficient soil moisture – so assess conditions on ground before you invest.

When feed is especially tight some of our annual grasses such as barley grass and volunteer ryegrass, which in some situations we may treat as weeds, can also provide high quality feed for livestock when they are in a vegetative growth phase. It’s best to utilise these grasses while they are short and green.

At the end of the day, the challenge always remains to best match our stocking rates to our feed availability. Winter can be an especially tricky time to achieve this especially with calving and lambing commencing and the nutritional requirements of stock changing, however, with a bit of planning, winter feed gaps can be sustainably managed.

For more information about livestock feed requirements visit the NSW DPI’s DroughtHub or speak to your local advisor or Local Land Services staff.


Media contact: Jo Powells, South East Local Land Services, 0429 785 986