All you want to know about soil health

Whether you call it soil, mud, dirt, earth, or sand, the ground we walk on is full of organisms crucial for nature. Besides water, it is where life on earth starts. When you want to restore nature, you must start improving soil quality as the soil serves as a building block for organism survival in every habitat. As such, we must deliberate efforts to ensure the soil is healthy.

The ecological system should be sustained rather than overexploited, destroyed, or wiped out. The negative trends in the environment have called for environmental sustainability. The major players in achieving this are green plants in the form of trees and shrubs. However, certain conditions must be made available for these organisms (that is, plants) to survive and perform their ecological function. The most hidden yet vital among them is the quality of the soil.

The quality of soils is crucial in determining species richness and diversity in every ecosystem. Soils with good ‘grades’ favor the existence and abundance of diverse organisms, both micro and macro. Healthy soils promote plants’ growth, reducing direct exposure of the soil surface to heat from sunlight, thereby creating favorable conditions supporting various life forms. In other words, good soils support plant growth which also favors the ability of the soil to retain and improve those good properties. Research has revealed the interdependence of organisms in their natural ecosystem for survival; the major determining factor of this survival is the quality of soils. Soil health should be checked when discussing food availability, environmental sustainability, and human survival.

What is soil exactly?

Let’s start at the beginning with understanding what soil is. As it has been established that biodiversity in every ecological system is highly dependent on soil, we must therefore understand all that is there to know about the soil.

“The fine earth which covers land surfaces as a result of the in-situ weathering of rock materials or the accumulation of mineral matter transported by water, wind or ice.”

Nortcliff et al. (2006)

As stated in Nortcliff’s definition, two major processes contribute to the formation of soil: the breakdown of rock materials and the accumulation of mineral matter.

The soil comprises some key components: organic material or matter, mineral elements, air, and water. The proportion of these components brings about differences in soil properties and the ability of the soil to support plant life and the survival of other organisms. Some physical properties of the soil that bring about differences in soil include soil texture, structure, and porosity. Likewise, soils’ chemical and biological properties also contribute to the differences in soils and their ability to support biodiversity. This inherent ability of the soil to support life and the extent to which this is done determines the health of the soil.

The six most common soil types

All soil types have peculiarities in their properties. These properties determine their suitability for any project. An agroforestry project aims to increase biodiversity; hence, the soil type available must support the survival of organisms. Certain qualities of soils, such as their water-holding capacity, are vital for plant growth. However, the extent to which various soils hold water differs across soil types.

What determines healthy soil?

The Food and Agricultural Organization (FAO), in her 2015 International Year of Soil report, stated that an estimated 95% of our food is directly or indirectly produced on our soils. The report also defines healthy soil as a living, dynamic ecological system teeming with macro- and microorganisms that carry out several vital functions. Soil health is a major determining factor in global food availability as plants rely on available nutrients in the soil to grow and reproduce. These nutrients are products of microbial actions that ensure the breakdown of organic material into simple elements that these plants can utilize. We can say that soil health is determined by the degree to which the soil supports life. 

Several environmental factors play key roles in promoting or limiting biological activities in the soil. These include temperature, pH, moisture, and light. When these factors are favorable, beneficial microorganisms and higher organisms begin to act on available organic matter, thus causing rapid decomposition and ensuring nutrient availability to plants. However, unfavorable conditions destroy these organisms, thus affecting nutrient availability and plant uptake. One major step to reverse this trend is a conscious and deliberate approach toward planting and nursing trees to create an enabling habitat for these organisms to thrive and carry out their ecological functions. Organizations like reNature have taken it as a responsibility to rebuild the soil ecosystem via regenerative agriculture and agroforestry.

Idowu et al. (2019) from New Mexico State University, also defined soil health as the sustained ability of a soil to provide services, such as the production of crops and other agricultural products, retention, and filtration of water, serving as a habitat for several organisms and nutrients recycling. However, the ability of soil to carry out these functions cannot be verified except through proper soil health analysis. The soil test ensures that before any field project is carried out, the soil has been proven to have all the necessary qualities. For instance, soil intended for an agroforestry project will be tested to ensure its nutrient availability, water entry, retention capacity, degree of acidity or alkalinity, bulk density, and so on. All these qualities differ in proportion based on the soil types, and a simple glance at the soil cannot determine these.

How to measure soil health?

The major factor in determining soil health is the level of biological activity in the soil. Biological activities in the soil take place mostly in the topsoil and are carried out by microorganisms. These organisms perform multiple functions in the soil, such as decomposing organic matter, making nutrients available in usable forms for plants, breaking down toxic substances in the soil, establishing a symbiotic relationship with plant roots, and playing certain roles in the weathering process. Macro organisms such as earthworms and nematodes are also vital in improving soil properties such as aeration, water penetration, etc. They, therefore, matter in assessing soil health as well.

The amount of organic matter in the soil, to a large extent, determines the biological activities in the soil. These substances help nourish these organisms even as they depend on one another for survival. Their feeding process helps break down the organic matter into the simplest form that plants can take up, thus ensuring a cycle of dependence among organisms in an ecosystem.

Taking topsoil samples for analysis should not be taken lightly.

Sampling makes it easy to have a quick laboratory test of soil quality and its ability to support any project. However, taking samples without basic knowledge of it defeats the essence of the whole exercise. In one of his reports, Walworth stated that soil analysis can only be as good as the sample sent to the laboratory. Therefore, it is important that professionals do soil sampling properly as the outcome of any agricultural project is highly dependent on results from the samples taken. Soil samples are usually taken from the topsoil due to the expected high level of organic matter in the topsoil. The topsoil is usually between 5cm to 20cm in depth and contains most of the ground’s nutrients and fertility.

Samples taken are used to estimate the general properties of the entire soil. Certain considerations such as where samples must be taken from, when they must be taken, how often they must be taken, and how they should be handled guide the professionals’ decisions to ensure accuracy in sampling and laboratory soil analysis. Several sampling designs have been developed over the years to eliminate biases in sampling, which could lead to errors in the data taken. The European Soil Data Center (ESDAC) stated in its report that the determination of any physical and chemical property of the soil can be subject to uncertainties because of the sampling method. Therefore, knowing the appropriate sampling method or design is key to taking accurate data and implementing the right managerial action to ensure the soil performs to its full potential.

New and improved methodologies for soil sampling

To ensure the quality of our soil health analysis, reNature has partnered with groundbreaking agtech companies, including Biome Makers, Biotrex, and Regen Aglab. These partnerships aim to help individual farmers, corporate farms, governments, and non-governmental organizations working on regenerative agricultural projects to carry out soil health analysis and provide appropriate solutions needed to restore the soil.

Main Photo by Nicolas Postiglioni