Air & Water Are Critical To Garden Soil Fertility Management

Healthy garden soil is well colonized by microorganisms that, in turn, maintain and release nutrients to the plants above. Air and water are central to this important balance.

by Zach Loeks
PHOTO: Dylan de Jonge/Unsplash

When it comes to soil fertility management for gardens and market gardens, I like to divide it into three groupings.  These three groupings follow the stages of preparing land for garden using tools, two-wheel tractors or 4-wheel tractors. 

  • In essence, the primary land preparation is when we first turn field or lawn into new plots.
  • Secondary land preparation, then, occurs when we form and finish new garden beds.
  • Finally, we subsequently refinish as we seasonally recreate gardens for succession planting. 

In this article and the following two, we will explore the types of fertility that can be used at different stages. We’ll also look at why and how to apply them.

We will also look in more detail at the final stage, as this is the steady-state land management phase. At this point, the garden is finished and we are in mode of operation, planting and maintaining garden space over many years.  In this stage, the management of fertility is much more linked to the crops we grow in rotation.

This is opposed to what we in the first two stages, when fertility management is more greatly linked to the initial formation of garden soil (stage one) and the fine-tuning of quality top soil (stage two).

Read more: What is soil, and how does it actually grow plants?

How Does Soil Work?

Before we get into the discussion of the stages of soil fertility management, let’s review how soil works. This is, after all, the foundation of fertility management. 

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It is important to understand soil holistically, as it is a mixed composition of:

  • 45 percent mineral material (sand, silt and clay particles)
  • Approximately 5 percent organic material (rotten, decomposed plant and animal residue and manure)
  • 25 percent air
  • 25 percent water  

When we look closely at a pie chart of soil with these percentages, we can see an interesting fact. Soil is about 50 percent pore space! 

That 25 percent air and 25 percent water require 50 percent of the soil to possess a porosity that it can fill. Water mostly fills what is termed “macro pores”, and air in what is termed “micro pores.” 

The significance of soil porosity to hold air and water is best understood from the point of view of the fifth component of soil, which has no percentage for it moves freely through all the element of the pedosphere. 

What’s this fifth component? Soil life!

Air & Water Feed & Sustain Beneficial Microorganisms

Air and water are consumed by living organisms. They act as a transport network them as well. 

Air and water are essential ingredients into the decomposition process that soil creatures contribute to, as well. This is true for larger arthropods that help shred leaf litter and vegetable plant debris. It’s also true for nitrogen-fixing bacteria that bring nitrogen into the soil to help balance with carbon and to micro-compost below the surface. 

Air allows aerobic (oxygen-requiring) organisms to survive. That’s important, because many of these organisms are essential for healthy soil to function. 

Water, in turn, moves nutrients around so they can be taken up by plants.  Indeed, plants receive nutrients not in their solid mineral form, but rather as part of a soil water solution where the nutrients are dissolved. (Think about salt in a cup of warm water.) 

As such, the soil is in a constant dance. Microorganisms build new pore space through tunneling. They contribute to decomposition rates. And they fix, cycle, store and release nutrients to the plants above. 

As such, the quality of the soil is as much a factor of a welcoming habitat for soil life as a product of a healthy soil ecosystem.  

Read more: Build your soil naturally with probiotic farming. Here’s how to start.

Making Good Soil Means Building Soil Life

What this all comes down to is a a pair of simple statements.

  1. When we start to build new gardens (in the primary and secondary stages), we want to initially improve soil so it can be actively colonized by soil life.
  2. And then, in the third stage, we want to keep feeding the soil so the soil ecosystem can actively maintain quality soil for our garden plants. 

The goal is to create good aggregation in the soil. This way, the soil has a healthy composition of mineral, organic matter, air and water.

Well-balanced soil serves as a good home for arthropods, bacteria, fungi and other beneficials.

Grow on,


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