Improving and Understanding Soil Health

There are countless reasons to consider the health of your soil and invest time in improving its biology. Here at RCS, we get asked many valuable questions about soil health, such as what techniques to use for improvement and how to measure and analyse your success. Here we share up the advice we give based on decades of experiment, learning and sharing knowledge within our agriculture community.

What is Soil Health?

Before trying to achieve good soil health, it’s important to understand what good soil health truly is. It’s more technical than just soil that does the job and looks good. For soil to be in good health it needs to have:

  • Great soil structure (50% air) and be crumbly.
  • Adequate macro and micro mineral availability.
  • A fungi:bacteria ratio of 1:1.
  • Microbial activity – bacteria, fungi, nematodes, protozoa.
  • Increasing carbon – improving water holding capacity.
  • High water infiltration rates.
  • Diverse living root systems.
Hands holing soil with worms

What is Soil Biology?

Soil biology refers to the living organisms in the soil including bacteria, fungi, nematodes and protozoa. One teaspoon of healthy soil contains more living organisms than there are people in the world. Soil biology is partially formed when organic matter dies, in a process called necromass.

This relationship soil has with plants allows soil biology to bring plants the minerals they require. The plant feeds the biology sugars in exchange for this service, using quorum sensing to talk to each other.

Canola Field near Wallendbeen NSW

How can I Improve Soil Health on my Agriculture Farm?

To achieve good soil health, you need to have a diverse range of pastures or crops photosynthesising for as long as possible with large root biomass. In livestock operations, introduce rest for all pastures and match Stocking Rate to Carrying Capacity to ensure optimal ground cover and pasture diversity.

Another integral part of soil health is biodiversity, which can be promoted via flora and fauna in all trophic levels. Carbon levels in the soil should be improved to increase water holding capacity, improving water infiltration rates.

Aim for a fungi to bacteria ratio of 1:1 and increase nutrient cycling from stock by increasing stocking density and increasing rest. Lastly, think regeneratively by increasing organic matter and avoiding the use of chemicals or practices that harm the soil structure and microbial life. Do all this and you’ll be well on your way to good soil health.

How do you Measure and Analyse Soil Health?

Once you’re dedicated to improved soil health, you’ll be eager to measure and analyse it to see how it’s tracking. Remember: below the ground is reflected above the ground. Here are a few tests and tools available:

  • Soil tests for macro/micro minerals and ratios
  • Soil organic carbon / soil organic matter levels
  • Water infiltration tests
  • Penetrometer to asses compaction 
  • Soil structure tests
  • Clay percentage
  • Pasture transects – monitoring sites of plant species basal areas over time
  • Photo monitoring sights
  • Ground cover percentage
  • Tree canopy cover

Frequently Asked Questions

Taking the time to improve soil health in pastures has endless benefits. Tips for improvement evolved on decades of RCS experience and knowledge sharing are as follows: 

  • Match rest period for each paddock to the growth rates of the desirable species.
  • Match Stocking Rate to Carrying Capacity.
  • Promote ground cover, which provides armour as protection for the soil.
  • Promote biodiversity of flora and fauna throughout the food chain.
  • Ensure optimal tree coverage for land type and ecosystem.
  • Increase stock density to increase nutrient cycling and pasture utilisation.
  • Introduce legumes or promote legumes that are already established.
  • Have green leaf growing for the maximum amount of time, keeping plants in phase two to optimise photosynthesis.
  • Use fungi-based composts like the Johnson-Su bioreactor.
  • Use high quality vermicasts

 

As with any inputs however, we recommend first doing a financial analysis on the expected production returns and comparing that to the direct costs before purchasing or applying any of the above options. If you want to learn more about the principles and concepts mentioned above, we recommend our Grazing Clinic or GrazingforProfit® program.

Healthy soil is required for healthy pastures and crops. And healthy pastures are required for healthy livestock. And healthy livestock and crops are required for increased production to increase gross product! There is a strong and obvious link between soil health and production that should be honoured within your approach to agriculture. Learn more about this link at our Farming & GrazingforProfit program.

Start by increasing the organic matter in your soil. This promotes soil biology and increases the soil’s resilience, in turn increasing the resilience of your pastures. 

In wet years you can maintain soil structure and hold on to minerals within the soils, and in dry years you can pull on root reserves to access moisture from a larger profile. Plants will also respond to small or variable rainfall and increased infiltration rates will ensure rainfall utilisation is high.

Extensive ground cover and perennial root systems will minimise runoff and the loss of topsoil, while deep rooted plants will improve the access of moisture and minerals from deep in the soil profile. To ensure different species respond at different times of the year, create diversity in your pastures.

To ensure your soil is rich in organic matter, first promote biodiversity, such as grasses, legumes, chenopods, cereals and brassica. 

You should always have living roots in the soil and green leaf to promote photosynthesis. Provide soil protection like armour through plants and litter and ensure optimal tree canopy cover. Stock densities can be used to increase nutrient cycling at a threshold of 60 head/hectare.

It all comes down to building and encouraging biological activity in your soil, especially fungi. We need a fungi to bacteria ratio of 1:1 for our most desirable pastures and row crops. Most agricultural soil is very low in fungi and, just as importantly, humus.

Humus is the substance that is left over after plants and animals have undergone a long process of thorough decomposition done by earthworms, bacteria, fungi, and other microorganisms. It is found in the top few inches of soil. The colour of humus is brown or black, and it has a loose, crumbly, and spongy texture. Humus is a function of soil biological activity.

There are numerous techniques for improving soil function, just make sure the technique you choose focuses on the right area of your soil.

We need to change our thinking from the linear thinking approach to the systems thinking approach. When considering a particular technique, consider the following questions:

  • Do I know what I am trying to achieve?
  • Is this the right technique for what I am trying to achieve?
  • Is it meeting all the RCS Soil Health Principles?
  • How will this technique affect all other areas of my operation in both the short term and long term?

 

Want to know more? We recommend our Regenerative Cropping Workshop.

Mycorrhizal (AM) fungi (found on roots and in soils) produce glomalin which forms the glue that holds soils together and provides soil structure. An increase of 1% organic matter (about 0.5% increase in carbon) can result in the soil being able to hold over 150 000 extra litres of water per hectare. Meanwhile, humus has a positive and negative charge allowing it to hold onto negative and positive compounds. For example, zinc, magnesium, sodium and iron are positive, sulphur, phosphorus and nitrates are negative. 

Ensure you take a holistic approach to your thinking and management of soil health and move away from a linear framework.

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Terry McCosker Founder of RSC Australia and the popular Grazing For Profit School. Terry is picture working with course participants of soil health and farm management principles.

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