Allowing pastures to persist

It was an issue, Tasmanian-based farm business advisory and pasture specialist Basil Doonan addressed during a farm walk on Nick McRae's property Yeronga near Mangoplah and organised by Riverina Local Land Services.

A partner at Pinion Advisory, Mr Doonan said the cost of pasture establishment makes persistency the number one issue when breakeven can be up to ten years.

"If you aren't getting your pastures to persist then it is a very high cost to the business and they don't persist then you are probably better off not to worry about pasture improvement," Mr Doonan said.

"But if you manage your pasture to persist then at the same time you are presenting it to your animals in as good as it could be nutritionally."

Mr Doonan explained the preferred grazing regime of the landholder has a big bearing on pasture persistence.

"I would say to anyone who wants to use the set stocking methodology which is entirely appropriate, I wouldn't bother improving pastures," he said.

"They will really battle under a set stocking regime."

But if you want to rotationally graze, Mr Doonan pointed out it is a methodology which allows landholders to do the best by the plant.

"There are lots of research papers available which say there is little or no benefit in rotational grazing but that is generally because they compare a set stocking scenario with a fixed rest period," he said.

He went on further to note that rest period might by for four or six weeks, but the plants read time by temperature and the amount of available moisture.

"We base our management on morphology which in simple terms is leaf stage," Mr Doonan said.

"We do have clients who set stock on certain pastures - the lower the potential productivity, the larger the scale, the lower the rainfall, the lighter the soil, the lower the soil fertility, and drinking water limitations the more we will gravitate to a set stocked or periodic rest system.

"But even under the set stocking, the pastures will generally get a break at some stage."

Recognising that Phalaris is a major component of southern improved pastures, Mr Doonan explained the growing stages of the plant post grazing.

"Phalaris is a four to five leaf plant, so when it gets to that growth stage it is ready for grazing," he said.

"It has gone through a process where the first thing it has done post grazing is put out a small amount of leaf from its stored energy reserves to capture sunlight and by the time it is at two or three leaves it is starting to recharge it's energy reserves and can be grazed without damage.

"By the time it is around four leaves, it has produced a daughter tiller and the next thing is that it will fully charge its energy levels."

Mr Doonan explained that the daughter tillers are critical in extending the life of the pasture.

"Once the parent tiller starts to go to seed it is going to die and those daughter tillers have to replace it," he said.

"And in a set stocking system, where the growth is continually being grazed, the stored energy reserves of the plant are run down."

Mr Doonan said not all the plants will die, but the density of the pasture will generally become thin over time.

"The stocking rate then has to be low enough to match the feed available," he said.

"Hopefully the amount of feed meets the stocking rate in spring and seed sprinkles is produced and germinate."

Mr Doonan does not recommend 'shotgun' pasture mixes because the various plants species have different leaf growth stage preferences for grazing which can be a challenge when assessing the rest periods for the paddock and ultimately favouring one species over another.

"Having more than one grass species in the mix means the grazing regime will eventually favour one species," he said.

"Sowing a 'shotgun' mix of say five species and only ending up with one species after five years is not a good use of resources.

"Legumes, on the other hand are a perfect companion for grass as they provide nitrogen and survive very well at the appropriate defoliation interval of grasses because they are not shaded for extended periods of time."

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