Are livestock producers ground cover obsessed at the expense of soil health?

Ag Advice - May 2022

Phil Cranney, Senior Land Services Officer, Pastures

GroundCover magazine is the primary hard copy communication vehicle for GRDC. It contains case studies and research updates. Why “Ground Cover” title for cropping enterprises? Because they are putting their soil most at risk of erosion through soil disturbance and annual crops.

Annual crops, by definition, are plants that live and die within one year. Matt Newell, NSW DPI researcher based at Cowra, is one of the only scientists in Australia looking into the ability of wheat to be a viable perennial option for farmers. You can hear from Matt at the research update on Friday May 27 on farm at “Sunny Downs” 250 Burnt Yards Road, Mandurama.

So, are livestock producers on the Central Tablelands overly obsessed with maintaining ground cover at the detriment to soil health? The answer is - “I don’t know.”

I do know that Cook 1992 found that perennial grasses had larger root systems and a longer growing season than annuals, which should point towards their ability to reduce ground water recharge. I also know that most government funded NRM incentives and agricultural extension advice has some component of “maximising groundcover” as an overall objective.

The key principle of maintaining ground cover is based on research conducted by RD Lang over several different experiments in NSW from 1979 to 1995. I do not debate the importance and validity of this research. I merely ask that we lift the covers, pun intended, and consider what is happening beneath the soil surface.

Obviously, any land management practice that reduces erosion is a good thing for the environment, the farmer’s business, and the community – a sound triple bottom line strategy. However, the pursuit of one main goal over all others, for any business, is fraught with risks.

The potential risks of pursuing maximum ground cover over all other farm productivity and environmental measures are as follows:

  • Poor utilisation of pasture, due to conservative stocking rates
  • Lost profit opportunity due to not matching stocking rate with pasture production
  • High proportion of poor-quality grass (stalky) pastures
  • Poor legume growth due to shading of emerging annual clover
  • Poor livestock performance and greater risk of livestock disease due to the lower proportion of legume in the diet
  • Lower levels of fixed nitrogen from legumes
  • Slow growth of the high-quality annual species caused from shading
  • High soil carbon to nitrogen ratio, depleting soil nitrogen levels
  • Long grazing rest periods can favour perennial weeds

The above issues are common amongst farmers on the Central Tablelands over the past two years.

So how should we adjust our management and priorities?

It would be sensible to first understand and subsequently rate each paddock’s erosion risk. This is determined by the soil type and the degree of slope. It is also determined by the pasture type. Annual dominant pastures will be more susceptible to erosion than a perennial pasture.

The more mature narrative is to recognise “ground cover” as one of the base building blocks to a profitable and environmentally sustainable farming system. Now, let us start to move this triple bottom line narrative forward.

“Productive Perennial Grasses and Lucious Legumes” should be the more nuanced mantra for livestock producers, especially in the Central Tablelands area. It is time to admit that simple “silver bullet” solutions are not effective in solving complex problems.

We should acknowledge and celebrate the beauty of our complex farming systems. There is much to be learnt by looking under the (soil’s) surface.

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