Holistic Management Educator, John
King argues pasture regeneration and longevity is due to animal behaviour,
a factor controlled solely by the farmer.
Part 1: Natural History has Clues for Grazing
With the possibility of greater seasonal variations, maybe looking at
natural history gives some clues about changing grazing patterns to buffer
droughts.
Scientists now understand with greater clarity that animals, grasslands,
and soils develop together, not as three separate entities. It is
the movement of animals across grasslands that simultaneously determine the
plant species that survive there and the soil structure that supports them.
Around the world the best evidence of this relationship comes from herding
animals in highly seasonal rainfall environments. We think of the
great herds of Africa and North America. Testimonies from explorers
to these continents record the size of the herds that roamed. In South
Africa, early Dutch explorers report springbok and antelope migrations that
are estimated at between 18-20 million. The Bison herds of pre-European
North America are estimated at around 60 million. Yet despite these
huge animal numbers in these highly seasonal rainfall environments there
are few, if any, recorded observations of overgrazing whatever the rainfall
pattern.
The herding behaviour of grazing animals sustains grasslands in these
environments despite large herd sizes. Prior to electric fence and
shepherds, grazing rotations were determined by the presence of a specie’s
own dung. Predation encourages grazing animals to bunch together
as protection resulting in high concentrations of dung and urine on the
ground. When bunched at high concentrations, wild animals avoid grazing
over their own dung at almost any means. They will only return to
re-graze an area once their dung has worn off.
This avoidance behaviour allows severely bitten plants to fully recover
and totally replenish their root reserves ready for another severe grazing.
The high concentrations of dung and the trampling of plants and leaves return
organic matter, especially carbon, back to the soil to complete the decay
process. Further, these actions help cover the soil to prevent evaporation.
Reducing soil moisture loss increases the productivity of plants and the
life they support thereby extending the grazing season.
Part 2: Strong Root Systems Key to Plant Recovery
What determined the rotation of grazing areas prior to humans inventing
shepherds and electric fences? Simply, the presence of a specie’s
own dung. In high concentrations, wild herding animals avoid grazing
over their own dung. This behaviour results in the huge migrations
we see in Africa on the television.
How does this natural behaviour differ from what is currently practiced
in pastoral farming? Set stocking does little to mimic what happens
in nature. By reducing the animal density, more plant selectivity
occurs. This is great for animal performance but often means the same
plants are grazed time and time again. A shift to mob stocking and
strip grazing allows greater utilisation of the pasture by concentrating
animals. It allows animals to move off their own dung everyday and
onto fresh pasture.
Many farmers argue their grazing rotations utilise pasture efficiently.
However, the question is how do they determine their rotation? Conventional
grazing rotations are determined by plant growth rates, not plant recovery
rates. This means severely grazed plants are seldom allowed to fully
recover. To fully recover, a plant needs to replenish its root reserves.
A weakened root system reduces a plant’s ability to perform. If it
dies the space created provides the right conditions for weeds and natives
to establish.
So how do you know your plants are fully recovered? Many farmers
use grass height as a guide to their pasture management. Yet grasses
grow at different speeds and to different heights throughout the year.
Using the four leaf methods is better. If one leaf has died and is
returning to the soil, you know the plant roots have recovered from any
severe grazing it has experienced.
There will be many farmers this spring grazing plants that are already
stressed. Smaller plants with tiny roots reduce the effectiveness
of the soil to retain moisture and fertiliser, thereby shortening the growing
season of the pasture. Such paddocks will suffer drought problems
whatever the rainfall. Incorporating pasture fallowing could provide
long term benefits to tired pastures if properly planned. Otherwise
farmers will be reseeding pasture, at a time and cost that places pressure
on their business and lifestyle.
Part 3: Feeding the Soil Key to Pasture Survival
By utilising common sense, Holistic Management® practitioners understand
the relevance of the animal/plant/soil relationship in their business.
They know that changing the grazing behaviour of their animals can not only
ensure good animal performance, but also regenerate and sustain pasture
production.
Many farmers are often unaware of the benefits of using their grazing
regimes to feed the soil. While they pour on the fertiliser, crank
up their stocking rates, and increase pasture utilisation, they steer themselves
to pasture burn out. Pasture not only provides feed for the animal,
but must also supply carbon to the soil. Increasing pasture litter
or trash increases water holding capacity, improves drainage, and reduces
pugging, all of which lengthens the grazing season and overall productivity
of paddocks. Furthermore, carbon hangs on to the elemental minerals
preventing leaching from the soil.
Farmers are very familiar with the grazing role of animals, the removing
of vegetation to maintain pasture quality. But there is another role
they are less familiar with, animal impact. Animal impact involves
the other activities animals do that enhance the functioning of land.
Firstly, in eating grass they convert it into dung to help with the cycling
of carbon and nutrients. Secondly to trample grass to the soil surface
so it can decompose and add to the carbon pool. Animal create soil
through their grazing behaviour.
Farmers struggle with this concept and talk of their pastures going
to seed and losing their vegetative state. This observation arises
from the fact many New Zealand pastures are dominated by ryegrass, a species
that does shut down after producing seed. On the other hand, many farmers
complain they cannot maintain ryegrass in their pastures either. Whatever
the case, the costs of renovating pasture often puts more pressure on a business
trying to rebuild when that money could be invested elsewhere.
Animals are not just income generating commodities, they can be used
as tools to create sustainable landscapes. With planning, their behaviour
can be used to ensure pastures remain productive. Understanding how
animals behave creates opportunities to reduce production costs, improve
the effectiveness of rainfall, and increase profitability.
Published in Nelson/Marlborough Farming summer 2001/2002
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