How can soil health increase resilience to heavy rain?
With extreme weather events becoming the norm, building up the necessary resilience to heavy rainfall events is a must for every farmer.
In this article, Northumberland beef, sheep and arable farmer Stuart Johnson explains how healthy soil can help prevent flooding, waterlogging and soil runoff.
Beef, arable and sheep farmer Stuart Johnson is also a member of our mentoring team.
Rainfall events
“Over recent years rainfall events have become more volatile and unpredictable,” says Stuart, 2023 Soil Farmer of the Year and a member of our mentoring team.
“Aside from the obvious issue of seeing dirty water running down roads into our water courses and drinking sources, we also need to consider the impacts of water runoff.
“Runoff is taking nutrition away from the soil profile, as well as inputs we may well have utilised. This not only costs the farmer money in lost nutrition, but also the wider public in the form of contaminated water entering the environment.
“Building the ability of our land to handle these deluges will not only improve our financial performance, but also our environmental footprint (and reduce our stress levels!)
“So, how do we do it?
It’s all about aggregation
“The fundamental goal of using regenerative farming practices is to improve soil health, which in turn enhances business resilience.
“Building a healthy soil is the foundation for many other benefits, whether that is cutting costs, improving livestock and crop performance or increasing resilience to extreme weather.
“One of the key improvements in soil health is building soil aggregates which provide the conditions for life and nutrient soil cycling whilst also providing more infiltration capacity.
“Building a healthy soil is the foundation for many other benefits, whether that is cutting costs, improving livestock and crop performance or increasing resilience to extreme weather.”
“Through exchanges from root exudates, fungi and many soil organisms, organic matter and biotic glues bind the soil particles together into a structurally sound aggregate.
“These aggregates have structural pores; small ones that can hold moisture for when it’s needed, and (more relevant recently!) larger pores that allow water to quickly infiltrate through soils.
“So, on a very simple level, if we build aggregates we manage our water cycle better.”
Leaf architecture: The first line of defence
“One of the key principles for improving soil health is to keep it armoured as much as possible, ideally with a diversity of plants with living roots in the ground.
“The leaves of grass and other plants act as a huge buffer when the rain comes down.
“The leaves catch and hold water, which either reaches the soil more slowly or may even evaporate away when the sun comes out. They also break up water droplets and slow them down before they hit the earth.
“All of this can help protect the soil from becoming overwhelmed by heavy rain and reduce the compaction effect which a heavy downpour can have on bare ground.
“The leaves of grass and other plants act as a huge buffer when the rain comes down.”
“As soon as you get that armour on the soil, you're going to see benefits nearly immediately.
“Keeping living roots in the soil is also key in maintaining soil aggregation.
“Living roots feed life-giving carbon to the soil microbiology that builds soil aggregates. Without a reliable flow of carbon from living roots we will rapidly start to see a breakdown of aggregates and therefore soil health and function.
“Diversity is also absolutely crucial in building and maintaining aggregate formation. We need diversity in rooting structures to help break up compacted and anaerobic soils and avoid a lack of infiltration.
“It also provides different root depths and mineral gathering capabilities, which in turn provide a diversity of carbon root exudates and a diversity of microbiology within the soil - further enhancing soil function and resilience to stresses.
Minimising disturbance
“Alongside keeping the soil covered with a diversity of plants, another key principle of building soil health is to minimise disturbance, for example, with the use of ploughing or tillage.
“Disturbing the soil simultaneously breaks up the aggregates and exposes it to the elements, whilst destroying the biology that is actually helping to bind it together.
“There may well be contexts where some form of tillage may be a preferred option to achieve your goal. However, the more you can reduce it the more it will help your soil become resilient to heavy rainfall events.
Let the soil soak it up
“Building soil aggregation is a much slower process than growing the leaf cover, but it will pay dividends over the years as your land becomes more resilient to heavy rain and, for that matter, periods of drought.
“As the soil becomes more aggregated it is able to soak up water like a sponge with a higher infiltration rate.
“A one per cent increase in organic matter (organic matter is on average 50% carbon) can increase the water holding capacity by upwards of 70,000 litres per acre.
“This will help hold onto water for longer, giving the plants the opportunity to make full use of it. It will also slow its entry into water courses which can have a huge impact on flooding further downstream.
“If the soil can absorb the water, or let it infiltrate through (especially without taking a whole host of costly nutrition with it) it will be less liable to waterlogging, flooding and being washed away in heavy rain.
Management is key for any soil
“Of course, the type of soil will vary from farm to farm depending on how much sand, silt or clay it contains.
“Often farmers can perceive this as the limiting factor in how resilient it is to heavy rain.
“However, no matter what type of soil you have, it is possible to improve its structure and aggregation with the right kind of management.”
Mentoring in soil health for farmers at no upfront cost
Regenerate Outcomes provides mentoring in soil health to build profitable, resilient farms and improve livestock and crop performance.
We also baseline and measure soil carbon to generate carbon credits which our members can retain or sell for additional income.
There is no cost to join and no cost to leave.
Download our Programme Handbook now to find out more.