The link between soil health, carbon and healthy plants
We’ve always stressed how important soil health is to plant health, but our friends at Madumbi are the experts so we asked them to give us a more in-depth understanding of carbon.
Fact: The nutrient content of a plant’s tissues is directly related to the nutrient content of the soil, and its ability to exchange nutrients and water with plant roots. (FAO – Food & Agriculture Organization of the United Nations fao.org/ soils-2015)
In simpler terms, plant health and soil health go hand-in-hand. South African gardens are made up of a wide range of different soil types, each with their own properties, benefits and challenges. Soil is the foundation of a good garden and as our understanding of soil health grows so too does the priority of building soil.
What do we mean by building soil?
To build a house you need bricks, cement and a team of builders. We all understand that – but how do we as gardeners go about building soil?
At Madumbi, our reference point starts with nature, where soil is formed primarily in two ways:
Physical and chemical: The weathering of rocks, into smaller and smaller fragments that ultimately lead to soil formation.
Biological: The decay of dead plant and animal material to form organic matter.
These processes have been taking place for millions of years, and will continue to do so. However, as the global population grows, so does the pressure for healthy food production and healthy soils. The natural soil-forming processes simply cannot sustain our growing planet – we need to do our bit by protecting our soils and building soil in our individual capacities, whether in the garden, on the farm or in nature.
The importance of carbon in soil
The carbon cycle is a fundamental part of life on earth. See above.
CO2 is probably the form of carbon we are most familiar with, but this only makes up a small portion of the gases in our atmosphere (0.04%). Significantly more carbon is stored in soils as ‘soil organic carbon’ (SOC), which is more commonly understood by gardeners as soil organic matter (plant and animal matter in various stages of decay).
Soil carbon is the backbone of soil fertility. The more carbon in the soil, the healthier the soil, and as a result the healthier the plant growth will be.
What are humates and humic substances?
EcoBuz HumiGro is a carbon-based soil conditioner made from humate granules. Humic substances make up the major organic component of the Earth’s soils and sediments, created from decayed biomatter. After plants die, their organic biomatter is degraded by microorganisms in soil to eventually produce humus. Humus-rich soils form the basis of healthy plant growth. Humates are the active ingredient in humic substances.
Adding humates to the soil adds carbon to the soil. In nature, nothing happens in isolation, and the additional carbon promotes existing microbes, enhancing microbial population growth, which results in improved microbial activity and decay (supporting the biological processes needed to build soil).
Humates have the following key benefits:
Feed beneficial micro-organisms (provides energy and nutrition).
Increase root respiration and formation.
Enhance nutrient absorption.
Improve soil aeration and water retention.
Decrease water loss and reduce leaching.
Enhance the performance of fertilisers.
Act as a buffer to harmful substances in the soil.
Think of humates as a concentrated version of compost that forms part of a holistic approach to soil health management.
Humates and compost contribute to the building of soil but because HumiGro is a more concentrated version it has a significant impact on the rate that soil and organic matter is improved.
Soils need to be viewed as a living, symbiotic ecosystem. While this article focuses on the importance of carbon, the basis of soil fertility, it is important to remember that carbon is just one cog in a highly complex system.
By understanding how soil works, we can see the benefits of understanding that soil is an ecosystem that needs as much attention as the plants planted in it.
Think of soil as the ocean. You can’t see much on the surface, but once you go below, as you would in an aquarium, you see all sorts of life teaming beneath the waves. These soils are alive with billions of bacteria, fungi, and other microbes as well as macrobial organisms like earthworms and insects. All play an important role in enriching and aerating the soil, processing organic matter and feeding the plants.
Advantages:
Anchors plants and promotes strong root growth;
Holds water and makes it accessible to plant roots;
Holds air so that roots and soil microbes can breathe;
Holds nutrients and makes these available to the roots.
Tests to find out your soil type Before planting up a new bed, garden or veggie patch, make time to get to ‘know’ your soil. There are many different soil types, and there may be great variation between different areas of your garden. Soil is broadly classified into loam, clay and sandy soils. There are two simple tests that can be done to help you determine what is what:
1. The sausage test
Wet an area of soil, then collect a handful and roll it into a sausage shape and gently bend.
If it is very crumbly and breaks before bending it means your soil is sandy.
If it holds its shape and then breaks slightly when bending then it’s loamy soil (ideal).
If it bends and holds its shape (without breaking), it means your soil is clay.
2. The ball test
Wet an area of soil, collect a handful and roll it into a ball.
If the soil particles won’t bind together, the soil is sandy.
If the soil moulds to a loose ball but breaks easily then its loamy soil (ideal).
If the soil retains its shape after moulding, it’s a clay soil.
Working with your soil type
Once you have established what soil type you have, you will be able to implement a suitable plan of action for its improvement or sustainable management. Even loamy soil needs continuous enhancement and nutrition to support optimal root and plant growth. The EcoBuz range offers a holistic, balanced approach to soil health.
Loam soil
This soil consists of a combination of clay and sand particles that results in:
A workable soil with good colour that holds its shape.
A balance of large and small soil particles, with mixed pore spaces.
Good water-holding capacity.
Medium porosity – allowing water and nutrients to be absorbed while the excess can drain away.
Good aeration – allowing oxygen to penetrate into the soil to sustain life.
A soil that can hold onto nutrients for use by plants and keep the soil pH balanced.
Sandy soil
The problem:
Sandy soil has the following characteristics:
Coarse and gritty to touch.
Has large particle sizes with large pore spaces.
Has a low water-holding capacity.
Drains easily.
Well-aerated.
Poor in nutrients.
The solution:
Start building the soil to negate the problematic characteristics as discussed above. By adding compost, you promote soil aggregation and improve water-holding capacity, while also adding nutrients. Other good practices like mulching, planting cover crops that can be used as green manures, and adding plenty of organic material into the soil will eventually turn the soil around and give you and your plants the benefits of a healthier soil.
Clay soil
The problem:
Clay soils are not ideal for gardening, as the small clay particles prevent the free flow of water, oxygen and nutrients. These soils are prone to water-logging and crusting, and are easily compacted.
Clay soil has the following characteristics:
Soft and powdery to touch.
Very fine particle size with minimal pore spaces.
High water-holding capacity.
Poor drainage.
Poor aeration.
Nutrient content is usually pretty high, but unavailable for uptake.
The solution:
Start building the soil as with sandy soil. Adding compost to clay soil makes it easier to work, and over time compost improves soil aggregation, aeration and enhances nutrient uptake. Compost builds and contributes to soil structure. A healthy soil is the key to a healthy garden. The journey to garden wellness starts with soil that’s healthy and HumiGro, a carbon-based soil conditioner with a complex list of nutritional elements that form the basis of soil fertility. Think of it as a highly concentrated form of compost. Adding HumiGro:
A potato farmer from Harrismith is changing the way we look
at soil.
Potatoes – just add butter and you have the perfect side dish, whether they are boiled, mashed or fried. We all eat potatoes, and in most households no meal is complete without this starchy tuberous crop. But, and here’s cause for concern, do you know where your humble potato comes from, and what it contains? Has it been grown in clean soil? After all, we are always told that we are what we eat.
James Leslie, a progressive farmer from Harrismith in the Free
State, knew where his potatoes were coming from and where they were going, and
decided to make what some farmers might call a radical change to his approach
to farming.
James’s company, Sesisonke Farming, was founded in 2005, and
the name is particularly apt. ‘Sonke’ means ‘all of us’ in Zulu, a description
that encompasses who the company is and why they are doing what they are doing.
So what are they doing? Essentially, Sesisonke Farming is trying to grow
cleaner food using cleaner soil, which obviously benefits all of us.
James started questioning their methods of farming after
taking his young son to the fields with him one morning. As children do, he was
playing in the soil and eating it, and James had to stop him because of the
poisons in the soil from the pest control products he was using at the time.
When the soil is poisonous it’s time for change. It was then that James decided
to plant in virgin soil (virgin soil is soil that has never been cultivated
before). As you’d expect, he was apprehensive about his yield, especially
relative to the yield from his conventionally farmed lands.
But after harvesting and finding that the ‘virgin soil’
potato yield was higher than the previously planted fields, James knew the
future was in balanced soil. He started to learn, discovering that soil health
is not just about adding nutrients but feeding living organisms such as
bacteria and fungi living within it. According to this new theory, soil should
be seen as a functional whole, an ecosystem. After returning from a seminar
hosted by Graeme Sait, a world leader in the knowledge of healthy soil and the
direct impact it has on our health and planet, James started implementing the
principles to attain a healthy crop while building soil health.
In the last few years, we as consumers have been made aware
of words like organic, sustainable, wholesome, nonchemical and natural. The
perception is that a farmer has to go to great lengths to attain these labels,
but even if they do, do we as consumers even understand these global demands?
When he delved deeper, James was surprised as to the lack of
knowledge available on how soil functions in a healthy environment. He did,
however, bump into likeminded people during his research, like those at Madumbi
Sustainable Agriculture. They found a common purpose to challenge and change
traditional ways of practising agriculture and revolutionise the farming
industry with the goal being to produce nutritious, uncompromised food for the
nation.
By focusing on conditioning and building the soil over more
than a decade, James now plants in a humus-rich biosystem. This results in
softer, more fertile soil, and softer soil equates to less tilling. Less
tilling means that the microbes don’t get disturbed and destroyed, and microbes
add to the health of crops. Healthy crops are in turn less prone to disease,
and that means less chemical applications are required.
“Over the past two decades, human health care has evolved from reactively reaching for medication and anti-biotics to proactively improving overall health, wellness and fitness. It’s time to do the same in your garden.”
To further build the soil, James plants as many cover crops
as possible, after harvesting his main crop. These crops are then incorporated
into the soil as green manures adding valuable organic matter into the cycle.
Keeping living roots in the soil guarantees that the microbes are fed, and by
bringing animals to eat these green crops he ensures that the fodder is
recycled and the nutrients are put back in the soil by the excrement of the
grazing feeders
On my visit to James, he explained the life of soil so well.
He said, “It’s like looking at the ocean’s surface. All you see is blue and
waves, but once you go to an aquarium and submerge yourself you realise the
enormity of life below the surface. It is the same with soil – under a
microscope you can see the millions of functioning microorganisms that inhabit
that space below the surface. They all have a role to play.”
Every time James plants a crop, every hectare is planted
with compost, to boost the levels of organic matter or humus (partially
decomposed organic matter). The humus retains moisture and keeps soil
temperatures moderate. This is also big-scale worm farming, as James uses
vermitea (worm ‘wee’) as an additional fertiliser. Thanks to these practices,
James has maintained a steady yield even through Harrismith’s drier years,
mostly due to his healthy soil and its humus content.
By understanding what the soil needs to function as an
ecological community and the impact good soil has on food production, James and
the Sesisonke team, with the help of Madumbi, have guaranteed good health, for
the soil and for you.
Our Team is ready to answer any questions or concerns that you may have. Feel free to get in touch!
Office Hours: 8:00am – 16:00pm
If we are not available then email us and we will get back to you as soon as possible. hello@tanyavisser.com
1. The sausage test 
2. The ball test 
Sandy soil has the following characteristics:
Clay soils are not ideal for gardening, as the small clay particles prevent the free flow of water, oxygen and nutrients. These soils are prone to water-logging and crusting, and are easily compacted.
