Both natural and man-made causes can result in soil damage or loss of soil. If you’ve struggled with poorer crop yields, one of your first investigations will be to dig into the quality of your soils. Discover the common causes of poor soil health and how to improve it in our guide. We’re going into detail about the preventative and reactive steps you can take to improve the quality of your soil—namely, its ability to retain nutrients.
What Causes Soil Damage & Loss?
Physical
Soil Compaction: There are various ways compaction occurs, including heavy traffic and sillage equipment across wet ground. Soil compaction can increase the amount of standing water due to poorer drainage. This can also lead to a loss of nutrients and nitrogen, which in turn depletes the health of the soil. This is due to bacteria using nitrate for oxygen.
A simple preventative measure is to ensure tractors and farm vehicles have the right tyre settings. Farmers can also monitor the density of their livestock.
Erosion
Water & Wind: There will always be erosion—it’s a natural process. Whether the result of wind or water run-off, soil erosion is an increasing issue for agricultural land. Rainfall, overland flow and rill formation are the most common causes of soil erosion in Europe. The impact is soil degradation, which results in a loss of fertile land as well as an increased flood risk.
However, there are actions land managers can take to minimise the risk of erosion:
- Use cover crops: Apply cover crops to soil year-round and in winter.
- Add organic matter: Make sure organic matter levels are appropriate, particularly for heavy soils. Adding this can improve soil structure and act as a good binding agent to reduce soil run-off. The best way to calculate your organic matter is to get a soil sample test. If it’s low, there are a number of options to increase the amount. This includes adding animal manures, purpose-grown cover crops, compost and even by-products from food processing.
- Avoid over-cultivating: This is especially true of light or wet soils in the autumn, as this makes them prone to erosion.
- Improve the water solubility: If water can’t penetrate the soil, it runs off. This is particularly true for hilly areas. It’s recommended that you keep stock off land when it’s wet.
Chemical: Nutrient Composition
The chemical composition and nutrients of your soil are also important. From phosphate to nitrogen, discover effective ways to measure your soil to ensure it has healthy amounts of each nutrient.
Dry or waterlogged conditions can be a cause of nutrient depletion, as these conditions make it more difficult for roots to absorb the nutrients. If your soil is deficient, this can have adverse effects, including stunted crop growth or yellowing leaves, resulting in lower crop yield or poorer quality produce.
How do you measure your nutrients?
There are different measurements used in England and Scotland to calculate the nutrient and chemical composition of arable soil.
- In England, soils for phosphate, magnesium, and potash are measured in indices. The target is 2 or 2- for phosphate for arable crops and grassland.
- In Scotland, soil nutrients are measured on a scale of low, intermediate or moderate. The aim is to achieve a moderate level of nutrients.
- For nitrogen levels, this is slightly different. The same guidance applies throughout the UK. Recommendations are outlined in the Nitrogen Guide RB209, which is free to access. It’s important to make sure you do not exceed crop requirements. Measured by soil analysis every 3–5 years is a requirement for all farmers in England. You can also use a fertiliser sensor.
The Soil N Supply Index, also known as the SNS Index, provides tables to estimate nitrogen amounts. You can have a sample taken, which needs to be done professionally with lab analysis. Both methods should give the same estimate.
Biological: Organic Matter
Is soil depleted of life? Is there plenty of active organic matter? Most soils want a level of 4% organic matter to be healthy. Some soils have 10% naturally, but lighter soils can struggle. Too little organic matter can be a sign of poor water retention. A lack of organic matter can also affect the physical structure of the soil.
The good news is that organic matter can be adjusted by applying compost and manure.
Other ways to improve the biology of your soil:
When it comes to improving the biology of your soil, ensuring a healthy population of earthworms and having the right sort of fungi present can make a significant difference. Mycorrhizal fungi associate with plant roots. They penetrate the roots, which makes them larger and better able to exploit the soil for nutrients. This is particularly good for phosphate.
- Keep the soil aerated: Beneficial bacteria are aerobic, and damaging ones are anaerobic. Bacteria and microorganisms that break down organic matter release ammonium and nitrate into crops.
- Apply organic matter that’s not fully decomposed: It’s not just the amount of organic matter you add, but the quality. Manure offers a rich source of food and energy for microorganisms. That being said, compost is a good way to raise the organic content of the soil, as it doesn’t get decomposed. But if you want to improve soil quality, apply manure, as organisms are more likely to feed off it.
The key takeaway is that organic matter is crucial for the health of your soil.
If you would like to stay up-to-date with all the latest best practices and trends to keep agricultural soil in good condition and mitigate the effects of common challenges, such as erosion and nutrient depletion, browse our soil management courses.