Knowing the factors that impact soil fertility can help maintain and improve agricultural production, or figure out why a certain soil isn’t yielding much.
In this short guide, we outline the different factors that impact soil fertility.
Summary Of Factors That Can Impact Soil Fertility
- Nutrient Supply In The Soil (Macro, & Micro Nutrients)
- pH Of The Soil
- Parent Material Under The Soil
- Clay Content, & Cation Exchange Capacity Of The Soil
- Bulk Density (Compaction Or Looseness Soil)
- Moisture & Water Content In The Soil
- Other Direct, & External Factors
Different Factors That Can Impact Soil Fertility (Explained)
- Nutrients Supply In The Soil (Macro, & Micro Nutrients)
Nutrients are important to supply to the plants or crops growing in the soil, and both macro and micro nutrients are required in fertile soil.
The amount of nutrients available in soil depends on soil properties, soil biology (organisms living in the soil that break down organic matter into nutrients), organic matter available (that can be broken down into nutrients), soil water (water in soil pores carries the nutrients to plant roots), and amount of fertiliser applied (fertilizers contain nitrogen and other nutrients).
Balancing nutrients in soil is important as nutrients can be both added or lost over time.
Loss can occur through soil erosion, runoff, leaching, burning of crop residues, and gaseous loss.
Addition of nutrients often occurs through fertilizer, but too much nutrients can lead to pollution of water via run off (amongst other environmental issues).
Read more about these macro and micro nutrients at https://www.qld.gov.au/environment/land/management/soil/soil-properties/fertility
- pH Of The Soil
Availability of nutrients is affected by the pH of the soil. Simple soil tests can be done to determine the pH of the soil, or, the plants or crops growing in the soil can be tested to determine soil pH.
Different countries and regions have different naturally occurring pH levels in their soil.
Different plants and crops are going to grow better in different pH soils.
Agricultural lime or dolomite might be applied to acidic soil to make it more alkaline, whilst mulches, compost mixes and manure might be applied to alkaline soil to make it more acidic.
- Parent Material
The parent material is the underlying layer of material (usually bedrock) from which soil forms.
Soils inherit a large amount of their nutrients, structure and other characteristics from parent material.
This material can be different in different locations, which is why you can get different types of soils in different locations.
- Clay Content, & Cation Exchange Capacity
The CEC influences the soil’s ability to hold onto essential nutrients and provides a buffer against soil acidification.
As plants and crops grow, they come into contact with cations and nutrient supply occurs.
Low CEC indicates the possibility of easily losing nutrients by leaching – so, soils with a higher CEC tend to have more nutrients present.
The CEC varies according the clay %, the type of clay, soil pH and amount of organic matter.
Read more about CEC at http://www.soilquality.org.au/factsheets/cation-exchange-capacity
- Bulk Density
Compacted soil is not desirable.
Looser soil is preferred as it allows plant and crop roots to penetrate the soil and reach nutrients in the soil.
- Moisture & Water Content
The soil solution is different to the solid soil matrix.
The soil solution is impacted by the moisture and water content in the soil.
Gases, organic matter, and minerals are all found in the soil solution – so it’s important the moisture/water content of the soil is right.
- Other Factors
These factors are separate factors, or factors mentioned within the above factors:
- Soil Structure
- Presence Of Life In The Soil Such As Micro-organisms
- Presence Of Organic Matter In The Soil, & Content Of The Organic Matter
- Nutrient Release Capability Of The Soil
- How Well The Soil Retains/Holds Water
- How Well The Soil Allows Water To Infiltrate It
- How Well The Soil Allows Excess Water To Drain From It
- Groundwater (presense of ground water, and whether the groundwater is saline or not)
- Usable/Exploitable Depth Of The Soil
Furthermore, these are some external factors that can affect soil fertility:
- Climate (rainfall, temperature etc.)
- Geographic Location and Topography (sloping land, sloppy land etc)
Factors Outside Of Soil Fertility That Can Impact How Productive A Soil Might Be, Or How High Of A Yield A Soil Might Produce
- Soil Health – read more in this guide
- Soil Quality – read more in this guide
- … the presence of weeds and even certain farming methods (sstinfolab.com).
- [pests and diseases should also be considered]