The importance of grazing management

Wiltipoll sheep being rotationally grazed using portable electric fencing in the olive grove at Manna Hill Estate

Agriculture is a major use of land. Half of the world’s habitable land is used for agriculture. Of this, nearly 80% is used for grazing – so grazing management is one of the key levers in moving to a more sustainable earth. This extensive land use has a major impact on the earth’s environment as it reduces wilderness and threatens biodiversity and is a significant driver of climate change. Increasing the productivity of land, producing food with much smaller inputs, reducing the impact on the environment, and sequestering carbon in the soil all have very dramatic benefits given the huge scale of grazing on the planet

Managed rotational grazing on the left, set stocking (and desertification) on the right. Source: Savory Institute

There are many different grazing methods currently in use today - but why is this important? Depending on the approach grazing management can either be a deleterious activity by increasing land degradation and desertification, reducing soil carbon, and reducing species diversity – above and below ground.  Conversely good grazing management can reverse many of these issues – reducing land degradation, increasing soil carbon and increasing species diversity above and below the ground

Wiltipoll sheep rotationally grazed amongst the olive grove (and munching on some olive tree prunings) at Manna Hill Estate

It can be very confusing when confronted with the large range of apparent grazing methods (e.g. set-stocking, rotational grazing, strip grazing, cell grazing, timed grazing, deferred grazing, Holistic Planned grazing, etc, etc.). All of these grazing methods fall on a continuum between the two extremes.  At one end you have set-stocking (sometimes called continuous grazing) and at the other, intensive rotational grazing.

Under (strict) set-stocking, animals remain in one paddock for the whole year and the pasture receives no rest. Few producers use this grazing method in its strictest sense (though you do seem to see this approach used with horse paddocks!) but most do leave stock in the same paddock for long periods, especially during the growing season.

In contrast, rotational or adaptive multi-paddock grazing involves the frequent (sometimes more than daily) movement of stock through a series of paddocks (often using portable electric fencing). Historically, set-stocking was the only grazing method used with annual pastures and, somewhat unfortunately, is still the predominant grazing method in Australia today.

Seedling density under managed rotational grazing (left) versus set stocking (right). Source: Victoria Department of Agriculture

So what are the downsides of set-stocking

·        Set-stocking enables the animal to control where, when and which plants it eats.  This often results in the more beneficial grass species being grazed out, leaving the less palatable, less nutritious species which then predominate in the pasture resulting in lower productivity and less species diversity

·        Set stocking often leads to bare patches of ground and overgrazing as animals continually revisit preferred areas of pasture and around troughs and trees.  This can result in increased soil erosion during wind and high rainfall events.

·        The pasture density decreases - a number of studies have demonstrated that the density of perennial pastures declines rapidly under set-stocking

·        Set stocking results in pastures with much shallower root systems – making them less resilient to droughts, unable to access nutrients in the deeper subsoil and building less soil carbon.  The Department of Agriculture in Victoria found that under set stocking, over 95 per cent of the total root biomass was in the 0–20 cm soil profile, and less than five per cent was within 20–60 cm profile.

·        Typically, it has been found that set stocking results in lower stocking rates (by 25 to 50%) and that herbage production under set stocking was decreased by 19–50% compared with AMPG. 

The upside of set stocking is that it is less management intensive and requires less infrastructure in terms of fencing and stock water systems.

Conversely Rotational Grazing or Adaptive Multi-Paddock Grazing (AMPG) if managed appropriately may generate the following benefits: -

·        Greater pasture productivity and increased stocking rates – in some cases by 100% or more

·        Pasture quality retained for longer

·        Better persistence of sown species

·        Easier stock surveillance

·        More even dung distribution

·        Higher soil carbon levels

·        More drought resistant pastures with profound increases in root biomass deeper in the soil profile

·        Typically, reduced concentrates, fertilisers and requirement to provide additional feed.

·        Longer grazing season

·        Better soil health

·        Better animal health

However, APMG usually requires more infrastructure (fencing / water – even if temporary / portable) and significantly more management focus.  Given the comprehensive benefits of APMG it is surprising that it is not utilized more widely across the Australian farming landscape.