soil fertility

5 Key Factors in Soil Fertility – Fertile Soil

5 Key Factors in Soil Fertility – Fertile Soil

Soil fertility is generally defined as the ability to sustain plant growth. I think I’ll take it a bit further and define soil fertility as the ability to sustain a healthy, soil ecosystem, both above and below ground.

Fertile soil is easy to recognize. It has plant growth above ground and, if you were to check it out, it has abundant microbial life below ground. However, good organic soil is not as easy to define. So we’ll try here to talk about the key factors that all healthy soils have.

5 Key Factors in Soil Fertility

  • Nutrients and Water supply
  • Soil Structure
  • Soil pH
  • Absence of Toxins
  • Soil Microbes

Let’s discuss each factor in a little more depth.

Nutrients and Water Supply

For soils to be able to support plant and microbial life, they need several key nutrients and of course water. Along with N, P, K (Nitrogen, Phosphorus, and Potassium) Calcium, Magnesium and Sulphur are all considered major nutrients. These elements must not only be present they must be in a chemical form that is usable by the plant.

Other key elements are Carbon (from CO2 in the air), hydrogen and oxygen (both from water).

In addition to these elements, there are another 8 elements that are considered micro or trace elements. There are some great articles that discuss these nutrients further, so I won’t go into any more detail here.

Suffice it to say, that for soil to be considered fertile all of the above nutrients must be inĀ  the soil.

A quick additional word about water. Water carries nutrients into and through the plant. That’s why water solubility is such a key factor for nutrients.

Too much water can be very harmful to the soil. It can clog up the small pores in the soil that allow oxygen transfer. Saturated soils really affect the microbial populations as well. Anaerobic bacteria abound when the soil has too much water. These organisms don’t help soil fertility.

Soil Structure and Soil Fertility

Here’s a good definition of Soil Structure.

Soil structure refers to the grouping of soil particles (sand, silt, clay, organic matter, and fertilizers) into porous compounds. These are called aggregates. Soil structure also refers to the arrangement of these aggregates separated by pores and cracks.

Good soil structure allows for easy movement of water and has numerous pores for gas (think Oxygen and Carbon Dioxide mainly).

Without good soil structure soil fertility is impossible.

Soil pH

PH is the measure of acidity or alkalinity in soils. The range is from 1-14 with 1 being the most acidic and 14 being the most basic. In practice, most soils are between 3.5 and 10.0.

For most crops a pH value of between 6.5 and 7.5 is ideal. pH values outside of this range can inhibit nutrient solubilization. Nutrients must be able to move through the soil in a soluble manner to help the plant.

Should you have plants that are not responding to the addition of chemical nutrients and fertilizers, it may be worthwhile to investigate the soil pH.

Absence of Soil Toxins Increases Soil Fertility

The absence of soil toxins is not a subject that is often discussed, but in today’s environment it is vital. Soil toxins come in a number of forms including form toxic rain, hydrocarbon spills, heavy metal poisoning, pesticides, herbicides, and too much fertilizers.

These toxins can kill or greatly reduce the native microbial populations. They also can get into the plant, injuring or killing any plant life.

The absence of soil toxins is vital to healthy, organic soils.

Soil Microbes Need to be Present in Sufficient Numbers and Variety

Soil microbes are vital for plant growth. They must be present in sufficient numbers and in sufficient variety in healthy, fertile soils.

Soil microbes come in a variety of shapes, sizes, and species. But ultimately, many of them form a synergistic relationship with plants. Current though is that the microorganisms and the plants evolved together.

The plant provides nutrients in the form of sugars to the microbes and the microbes provide growth hormones and convert many nutrients into a form that can be utilized by the plant.

Without soil microbes, you cannot have healthy, productive soil.

BioAg Products

BioAg products is here to help you with your soil fertility issues. Contact us at for more information.

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