How to Improve Soil Health in Agricultural Systems

Here at Zylem, we walk, talk, live and breathe soil health. But what’s the big fuss about? Read on to learn more about soil health, why it is so important, and how we can improve soil health in agricultural systems in South Africa. 

In this post: 

What is soil health? A soil health definition:

The significant role of soil

The characteristics of healthy soil

The importance of a healthy soil

What are the 5 principles of soil health?

How can I rebuild my soil?

How do you check soil health?

South Africa’s soil health solution

What is soil health? A soil health definition:

Soil health is most often defined as the “capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health”. As such, soil health is fundamentally linked to land productivity and environmental sustainability.

The significant role of soil

Along with water and sunlight, soil provides the basis for all the biodiversity and terrestrial life around us, including the field crops that we harvest for food and fibre, and animal products (such as meat, milk, eggs, wool). It sustains plants, animals and humans by: 

• Enabling plant growth
• Providing ecosystem services
• Resisting erosion
• Retaining nutrients
• Storing water
• Acting as an environmental buffer in the landscape

However, soil can only perform these functions effectively if it is in a healthy state. 

The characteristics of healthy soil 

What makes good soil? Physical and chemical characteristics like friability and acidity? Sufficient nutrients in appropriate ratios constitute fertility? Soil organic matter? 

Increasingly, scientists are looking to the role soil biodiversity plays in supporting plant life. We know that many of the critical services provided by soils depend on the build-up of organic matter. 

Since the chemical, physical and biological characteristics of a healthy soil vary depending on the inherent qualities of the array of soils that exist on earth, it’s impossible to classify a soil as ‘healthy’ based on these factors.

However, soil can be described as ‘healthy’ if it demonstrates most (if not all) of the characteristics below: 

• Allows water to infiltrate freely
• Supplies water, nutrients and oxygen for healthy plant growth
• Stores water
• Retains nutrients
• Resists erosion and disease 
• Exchanges gasses with the atmosphere readily 
• Contains a diverse population of soil biota
• Is not acidifying
• Is not salinising
• Has a range of pore spaces to house nutrients, water and organisms

What we know about earthworms

When it comes to soil health in agricultural systems, earthworms are the ‘chief engineers’ of soil structure. They consume leaves and other plant material, and their excretions undergo finer decomposition by other microbes. They are also a vital food source for reptiles, amphibians, birds and mammals, further increasing the biodiversity of the ecosystem. 

The presence of worms in the soil is also an indicator of the health of the soil, as they are affected by tillage, rotation, organic matter management, compaction, waterlogging and acidity. Damage to the soil generally means a decrease in its earthworm population. In the UK, farmers are even encouraged to count the number of earthworms found in 20cm cubes of soil in order to assess its quality. 

Minerals in the soil 

Minerals are a vital source of energy for plants. They can be seen as the ‘essential vitamins’ or ‘dietary supplements’ that help crops thrive – helping them grow faster, produce high yields and resist pests and diseases. 

The key to achieving excellent quality crops with very high yields is to have minerals ready in the soil for plant uptake. Plants and all biology do best when given full-spectrum nutrition, including major minerals, secondary minerals, trace minerals and rare earth elements. Good soil quality makes this possible. 

For successful growth, plants require specific chemicals derived from different sources, such as:

• Oxygen from the air
• Hydrogen from water

The other minerals are found in the soil. They are:

• Nitrogen – boosts leaves and general growth
• Phosphorus – beneficial for the root system and the development of buds and seeds
• Potassium –  metabolism and resistance to pathogens

Minor minerals include:

• Magnesium – a chlorophyll component vital for photosynthesis
• Calcium – acts as a building material for cells and a toxic neutraliser
• Sulphur – part of proteins and enzymes.

Along with the minerals already mentioned, plants also use small amounts of boron, copper, manganese, chlorine, zinc, iron and silicone.

A healthy soil will be home to these minerals in adequate ratios as required by specific plants. 

The importance of a healthy soil 

Soil depletion in Africa remains a significant problem. It affects yields, and threatens domestic food security and revenues derived from export crops. According to a 2016 report from the UN Food and Agriculture Organisation (FAO), 40% of African soils were suffering from some form of degradation, including nutrient loss and erosion.

An FAO article reports that the world has been put on a heightened famine alert. In this article is a new report, Early Warning Analysis of Acute Food Insecurity Hotspots, which includes a stark warning that four countries contain areas that could soon slip into famine if conditions continue to worsen. These areas are: Burkina Faso in West Africa’s Sahel region, northeastern Nigeria, South Sudan and Yemen. The report notes that acute food insecurity levels are reaching new highs globally, and that another 16 countries are at high risk of rising levels of acute hunger.

Despite food shortages in some areas, Africa’s population continues to expand; it is forecast to rise by almost 1 billion to reach 2.2 billion people by 2050. Yet food production is already failing to keep pace with rapid population growth. Although Africa has 60% of the world’s uncultivated arable land and agriculture accounts for 60% of the labour force, the continent imports an average of $72 billion in food per year.

What is the most common soil health problem in South Africa? 

In South Africa, some of the most common health problems include damage related to expansive soils and collapsible soils. Soil erosion is a major environmental problem confronting resources in South Africa. Although soil erosion is a natural process, it is often accelerated by human activities such as poor farming practices, clearing of vegetation, soil tillage or overgrazing. Prolonged erosion causes irreversible soil loss over time, since soil is essentially a non-renewable resource.

In South Africa, it’s often said we lose an average of 13 tons of topsoil per hectare of maize harvested, a number that can go up to 25 tons in some of the more fragile areas.

Addressing soil deficiencies and improving the productivity of African lands is critical

A healthy soil is the foundation of a productive farming system, food and nutrition security, the improvement of livelihoods, and the alleviation of poverty on the continent and in our world.

In many African countries, soils have become unhealthy due to years of crop nutrient mining and limited organic or inorganic resupply. In their current state, these soils are not able to provide adequate nutrition; when a soil is degraded, yield drops dramatically. 

The soil structure needs to be able to support an extensive network of roots, microbe biodiversity and water retention by having an appropriate balance of water, air, minerals and organic matter.

Too often, however, soil health in agricultural systems has been degraded and is moderately to severely lacking when it comes to having the optimal physical structure to provide the correct amount of minerals, air, humus and water. Until these basic foundational requirements are met, the crops grown in that soil won’t be able to achieve top yields and quality. 

Rich soil is abundant in the macro and micro-elements needed for healthy plants to grow, which is why maintaining a fertile soil is vital to all farmers. High-quality, high-yielding crops start in the soil. 

A healthy soil:

• sustains biological productivity
• maintains environmental quality
• promotes plant and animal health

A healthy soil is thus productive, sustainable and profitable.

Healthy soil for farming

A soil that is biologically active and contains high levels of organic matter is an essential component of successful and sustainable farming. When soil is in a healthy condition, it’s able to make better use of nutrients, is more resistant to weather extremes and prevents nutrient loss, all of which typically lead to higher yields. 

The principles for promoting good soil health management for agriculture include: 

• Causing as little soil disturbance as possible 
• Diversity in crop rotations 
• Maintaining a living plant throughout as much of the year as possible
• Maintaining surface residues

Healthy soil for the environment

A healthy soil has better water-holding capacity than an unhealthy soil, which leads to less erosion and landscape destruction. Farmers with healthy soils also have less reliance on harmful chemicals, preventing these from being leached into the natural environment. 

Healthy soil for society 

Healthy soil allows farming to become more sustainable. Passing productive and profitable farms on to the next generation helps secure the future of the world’s food supply. 

What are the 5 principles of soil health? 

Making the move to regenerative farming methods can seem overwhelming to many farmers. Where to start? And how to remain profitable? When it comes down to it, regenerative agriculture is grounded in soil health. 

What is regenerative agriculture? 

Regenerative agriculture is defined by Terra Genesis International as “a system of farming principles and practices that increases biodiversity, enriches soils, improves watersheds, and enhances ecosystem services. It aims to capture carbon in the soil and above-ground biomass (plants), reversing current global trends of atmospheric accumulation and climate change. At the same time, it offers increased yields, resilience to climate instability, and higher health and vitality for farming and ranching communities.”

Basically, what this means is farming in a way that both protects and enhances the soil. In an Eco Farming Daily article, Savory Institute Field Professional and regenerative farmer Spencer Smith outlines five simple soil health principles to transform farms of all scope and sizes into regenerative businesses. Using these five core principles can enhance your soil, store carbon, and increase your farm’s health and productivity. 

Principle 1: Soil Armour

Keeping litter on the soil acts as a soil ‘armour’, which has many benefits when it comes to soil health. Essentially, covered soil increases the habitat for soil biology. Greater soil biology means better nutrient cycling, a great aggregate structure to accept and hold more water, as well as mitigation of soil temperature variations and protection against erosion. 

Principle 2: Diversity  

Increase diversity wherever possible on your farm – in fields, fencelines and pastures. Just like eating a varied diet provides a range of different nutrients for human health, so does plant diversity increase the available nutrients in the soil. Different plants mineralise different nutrients, so the more diversity of plants and rooting structures in the soil, the healthier the farm and its harvest.

Principle 3: Continual Live Plant/Root

Regenerative farmers aim to maximise the time that they have living roots interacting with the rhizosphere. Having green, photosynthesising plants in a field means continual capture of carbon from the atmosphere. This carbon helps to feed the soil and grow healthy plants. Having live plants also builds soil aggregates and mobilises nutrients for current and subsequent crops.

Principle 4: Livestock Integration

Adding livestock to the previous principles of covered soil, greater soil diversity and having living plants growing through the year creates compounding and cascading benefits. Here’s why:

• You can use livestock to break capped soils and lay armour on top of the soil
• This increases the soil’s gaseous exchange and allows for soil biology to flourish
• Livestock function as walking composters
• Animals disperse seeds and bring biology and fertility back to poor soils
• Plants experience health and growth benefits when enzymes in saliva are left on the plants.

Principle 5: Minimising Soil Disturbance

The increased biology and diversity added to the soil while adhering to the previous principles is maintained by minimising soil disturbance. This means reduced or no tillage. In fact, all the efforts to improve your soil health can be undone with heavy tillage. Another disturbance that can harm soil health is adding synthetic fertilisers, which are damaging to soil biology.  

To till or not to till?

Over the past few years, farmers have begun to drill seeds directly into the soil to limit or eliminate the need for tilling or ploughing. But a new debate has sprung up around whether tilling improves or degrades soil health. Minimising tillage increases biodiversity (and thus soil health and crop productivity) in the upper layer of the soil as organic material builds up. 

Although there’s an increase in carbon in the topsoil when there is no tilling, there can be a decrease in carbon further down in the soil in the long term due to lower soil disturbance and carbon redistribution.

How can I rebuild my soil? 

In the past, soil fertility improvement efforts have generally focused on the use of inorganic fertiliser as the primary mechanism for temporarily improving soil fertility as well as crop yields. However, under conditions in which soils are largely degraded (with limited organic matter), using inorganic fertilisers alone has shown limited success in improving soil fertility. 

That’s why the continent needs to move towards a sustainable soil management regime that involves measures to protect soil from erosion and other threats, and preserves the soil’s ability to retain water. Some ways of doing this include:

• maintaining vegetation cover
• minimising tillage
• avoiding monocultures through crop rotation and inclusion of livestock

These longer-term solutions help build organic matter and organic nutrient pools in the soil; an essential component to achieving sustainable soil fertility. 

Focusing on and prioritising sustainable soil fertility efforts should include not just soil productivity, but an inclusive and holistic view of food and nutrition security, poverty reduction and overall wellbeing of communities. Investments in soil fertility improvements should support resilient and sustainable livelihoods, providing both nutrition and economic returns.

How do you check soil health? 

The answer lies in soil testing. The goals of soil testing are to:

1. Assess the current environment for biology
2. Identify and quantify soil constraints 
3. Monitor soil fertility levels
4. Understand the needs of the plants being planted in the soil
5. Enhance soil mineral content through the application of relevant soil amendments and specific nutrients.

Testing the soil and understanding how to interpret the results in terms of actual nutrient needs are the starting requirements for producing healthy, high-yield, nutrient-dense foods and feeds.

Zylem offers growers and consultants technical support via the superior analytical services of Brookside Laboratories Inc. (BLI). The culmination of nearly 20 years of research in soil fertility, BLI’s Soil Health Tool (S019) has revolutionised the effective analysis and amelioration of soil. The test uses an integrated approach that combines chemical and biological test data and is designed to mimic nature’s approach to soil nutrient availability as effectively as possible, in a lab. 

S019 answers some simple questions about the soil:

1. What is the condition of your soil?
2. Is it in balance?
3. What can you do to help your soil?

The business case for improving soil health in agricultural systems

According to the Soil Health Institute, soil health systems increased net income for 85% of farmers growing corn and 88% growing soybean. 

A study conducted by the SHI has found that improving soil health can help farmers:

• Build drought resilience
• Increase nutrient availability
• Suppress diseases
• Reduce erosion and nutrient losses
• Increase economic benefits.

In addition to benefiting farmers and their land, soil health management systems also benefit the wider environment by:

• Storing soil carbon
• Reducing greenhouse gas emissions
• Improving water quality.

Building a business case for soil health

Although many farmers and agricultural businesses are aware that soil health benefits their operations and the broader environment, soil health is just that: an investment. And every investment needs a business case behind it. That’s why the SHI set out to study the economic benefits of adopting soil health practices. The intention was to provide farmers with the economic information they need to make informed business decisions around adopting regenerative soil health systems.

How the study was carried out

Researchers from SHI interviewed 100 farmers across nine states in the United States who adopted soil health systems. The interviews allowed the researchers to acquire production information, such as:

• Tillage practices
• Nutrient management
• Pest management
• Yield changes
• … and more

As part of the research process, SHI Agricultural Economist Dr Archie Flanders then evaluated the on-farm economics using partial budget analysis. He compared the costs and benefits of a soil health system before and after the adoption of that system.

Key findings 

From the analysis and data collection across 100 farms, the SHI study concluded the following about the adoption of soil health management systems: 

• Increased net income for 85% of farmers growing corn
• Increased net income for 88% of farmers growing soybean
• Reduced the average cost to grow corn by $24/acre
• Reduced the average cost to grow soybean by $17/acre
• Increased net farm income by an average of $52/acre for corn
• Increased net farm income by an average of $45/acre for soybean
• 97% of the farmers reported their soil health management system increased crop resilience to extreme weather

The numbers speak for themselves …

As awareness and interest in soil health management grows amongst farmers, they are increasingly looking for a more robust and tangible picture of its long-term benefits. This study by SHI provides additional quantitative evidence to demonstrate the economic benefits of investing in soil health. Although the study was conducted in the United States, our clients at Zylem have also seen the economic benefits of investing in soil health. We know that farmers can become more resilient and profitable – while making a positive impact on the environment.

South Africa’s soil health solution

At Zylem, we believe that understanding, protecting and improving soil health is critical for managing earth’s natural assets. We advise growers throughout the country on the effective use of biological inputs, which are the cornerstone of regenerative farming. Get in touch to find out more about our sustainable services and solutions.