How to Use Manure as Fertiliser: What Works and What to Avoid

Animal manure has been the backbone of garden fertility for thousands of years, and with good reason. Well-rotted manure improves soil structure, feeds the soil ecosystem and delivers a balanced range of nutrients that keep plants growing strongly. But manure used incorrectly — particularly fresh manure applied at the wrong time — can damage plants, contaminate crops and create more problems than it solves.

Which Manures Are Most Useful?

Not all manures are equal. Their nutrient content, ease of use and how long they take to mature varies significantly:

• Horse manure: widely available, good nitrogen and organic matter content, but often contains straw which needs time to break down. Well-rotted horse manure is a classic vegetable garden feed.
• Chicken manure: by far the highest nitrogen content of common manures — roughly three times that of horse. Very effective but must be well composted or used in dried pellet form to avoid burning plants.
• Cow manure: lower in nutrients than horse or chicken but excellent as a soil conditioner. Very safe to use once composted.
• Sheep and goat manure: richer than cow, comparable to horse. Pelletised sheep manure products are a convenient option.
• Pig and human manure (sewage sludge): not recommended for food crops due to pathogen risks.

Fresh vs Well-Rotted: Why It Matters

Fresh manure contains high levels of ammonia which can burn plant roots and stems on contact. It may also carry harmful bacteria (salmonella, E. coli) and weed seeds. Never apply fresh manure directly to growing crops. Well-rotted manure — typically defined as manure that has been stacked and composted for at least six months — is dark, crumbly, relatively odour-free and safe to use around plants. Pathogens and most weed seeds are destroyed in the composting process.

When to Apply Manure

The classic timing is autumn. Apply well-rotted manure as a surface mulch on cleared vegetable beds after the last harvest. Earthworms and rain will work it into the soil over winter, and by spring it will be well incorporated and ready to support the new growing season. Applying in spring is also fine but allow a few weeks between application and planting if possible. Avoid applying manure in late spring or summer around growing crops unless it is very well composted or in pellet form.

Application Rates

For vegetable beds, a 5–10 cm layer spread over the surface each autumn is generous and effective. For established fruit trees, a 5 cm mulch around (not against) the trunk each spring provides a steady background feed. Chicken manure pellets should be used at the rate stated on the packet — they are concentrated and easy to over-apply.