The traditional definition of resilience is a paddock that is functional and able to withstand adverse conditions.
For those seeking tangible evidence of when resilience exists, it is the ability of a paddock to generate carbon flows from rain i.e. how well the pasture responds to rain. Perhaps the best test of resilience is the ability of paddocks to respond to isolated small falls of rain during a dry period.
A paddock that has the capacity to successfully produce carbon flows is one that is also well equipped to better withstand extreme events, be they drought, heat or heavy rain.
LINKING RESILIENCE TO DIFFERENT PADDOCK RESPONSES TO RAIN
The fence line comparison above is a good starting point for discussing what underpins resilience.
The right hand side of the fence is a grazing paddock, not a farming paddock. Look at the surface water right up to the fence and nothing on the other side. This outcome is more than just different soil structure, as will be discussed.
Add some slope and the right hand side of the fence is at risk to erosion.
These two pictures show the productive capacity of each side of the fence at a later date i.e. the paddock’s inherent ability to produce carbon flows. The top photo is the left hand side of the fence and the bottom one the right hand side of the fence. The resilience of each side of the fence is very different. Stating the obvious, resilience and water use efficiency go hand in hand.
THE TWO COMPONENTS OF PADDOCK RESILIENCE
Paddock resilience has two components, plant resilience and soil resilience, and both rely on carbon flows.
Maintaining plant resilience relies on good animal management. Animal management that does not let plants grow to their potential after rain, reduces the flow of carbon into them.
Allowing carbon to flow into plants increases their resilience by increasing internal energy reserves for them to call upon and increases their root volume.
The perennial grass plant above is what a plant lacking resilience looks like. It is struggling to come out of dormancy after good rain because it is short of stored energy. Energy reserves in plants are short term carbon brought in by carbon flows. In perennial grasses they are stored in the roots and also in the crown. These reserves are the energy source prior to green leaves collecting energy.This plant is generating no carbon flows to feed soil life, which is responsible for restructuring the soil and making it more fertile.
It is also not going to produce any ground cover. Ground cover increases water use efficiency by reducing evaporation in two ways, lifting the wind off the soil and keeping the sun off the soil.
Increasing carbon flows into plants produces a more extensive and deeper root system to allow them to source more water and nutrients i.e. become more resilient. Roots are 45% carbon.
Roots act as wicks to take water down through the soil profile, especially important with harder soils. The water travels down beside the roots. The pooling in the fence line photo was not just due to poor soil structure, it was also due to a lack of roots in the paddock.
One aspect of soil resilience is how well water enters and how well the soil is able to retain moisture over time to promote plant growth.
Think of the soil as a construction site. If plants do not supply carbon compounds to all the life in the soil that are responsible for keeping it well structured and fertile, then they die.
Carbon flows into plants are the true source of soil organic matter which is about 58% carbon (short term carbon). Organic matter is the raw material for humus which is long term soil carbon. Humus is the undigested portions of organic matter.
Because humus is highly charged, it will aggregate many soil particles into stable aggregates. This leads to better soil structure and it is the resultant pores that hold extra water containing the soluble nutrients like nitrate nitrogen.
Humus changes the pH of the soil and so buffers against any toxic elements present.
Humus is smaller than clay particles, which is why it has a higher water holding capacity than clay i.e. it has a higher surface area to volume than clay.
Organic matter changes the bulk density of soil, which adds to water storage capacity.It also stores nutrients ready for soil life to mineralise them into the inorganic form which is plant available.
Flowing short term carbon also feeds the soil biology responsible for creating macro-pores in the soil. Macro-pores enhance air and water movement. These macro-pores will still be there after this fast moving carbon is back up in the atmosphere.
For every 1% increase in organic carbon, to a depth of 30 cm (12 inches), the soil is able to store an extra 144,000 litres of water per hectare. This is in addition to the water holding capacity of the soil itself.
With poor management, plant resilience reduces first, then soil resilience reduces. This highlights that your animal management affects the soil, by affecting plants first.
SHORT AND LONG TERM RESILIENCE
The fast moving short term carbon (plant energy reserves, root volume, organic matter and ground cover) supplies short term resilience. On the other hand, the slow moving long term carbon (humus) supplies long term resilience. It protects the long term survival of the system. Humus will slowly decline without good management of carbon flows.
Maintaining short term resilience helps maintain long term resilience.
INCREASING THE PATHWAYS FOR CARBON INFLOW
Because resilience relies on carbon flows, there is a need to increase the pathways for carbon to enter the paddock i.e. increase the mix of plants to cover all circumstances.
A production system based on perennials is more resilient than one based on annuals, simply because perennials generate more carbon flows over time, especially in marginal years.
FEEDBACK LOOP WITH CARBON FLOWS
The discussion to this point, highlights that current carbon flows are influenced by previous management of carbon flows. This is why water use efficiency over time is linked to management of carbon flows.
Just as money makes money, carbon also makes carbon i.e. carbon flows lead to more carbon flows.
Both plant resilience and soil resilience rely on carbon flows.
With a resilient paddock, more water leaves the paddock via transpiration (creating carbon flows) instead of as run off or evaporation.
Resilient paddocks are more profitable and looking at the bigger picture, they supply better environmental outcomes for the rest of society.
The only time you can build paddock resilience is in the short period after rain.