Manure is one of nature’s best gifts to gardeners, but with the environmental impact of livestock farming under the spotlight, we can’t help but wonder – is there any way we can move away from using manure in the garden?
In this article, we’ll share our favourite manure alternatives, tell you what works and what doesn’t from personal experience, and compare manure to its substitutes – including peat, garden compost, and fresh clippings.
Why would you need a manure alternative?
Manure isn’t vegan
Manure may have its unique benefits and nutrient make-up, but it also has one significant problem: manure isn’t strictly vegan, as it is a by-product of animal farming.
There are dietary vegans and ethical vegans, each for their own reasons, and using manure in the garden can clash with their beliefs on unethical treatment of animals.
Contaminated manures
Manure is a by-product of other industries, so suppliers tend not to think very hard about manure when feeding their livestock, or preparing their fields. Their primary concern is convenience, which can lead to contaminated manure with trace elements of herbicides and antibiotics.
In 2008, there was a widely reported problem across the UK and some parts of the EU when manure was contaminated with aminopyralid, a hormone-type herbicide sold as Milestone and Forefront, which was used by farmers to control weeds on grazing land. The herbicide led to failed crops on allotments and in gardens for the next two years. Aminopyralid is still sold in the UK and USA today.
What are the best manure substitutes?
Humus
Humus is made up of the broken down, stable materials that are the absolute end result of plant and animal matter’s decomposition. Humus takes a minimum of three years’ composting to achieve, if not more.
You may confuse compost with humus, but compost is in a state of continuous decomposition, even when plant materials are no longer identifiable in the compost mix. This is good for slow nutrient release, but true humus isn’t obtained unless a good number of years have passed, and even then, your compost pile might only contain 10% humus, and the rest of 90% active compost.
The richness of humus and its long lasting shelf life (hundreds of years, in fact), make it an invaluable addition to the garden, and an invaluable manure alternative. So choose humus-rich compost blends if you can, to make humus part of your soil.
Mushroom compost
Mushroom compost is the spent compost from mushroom farming. It contains straw, horse manure, chicken manure, corn cobs, peat moss, lime, and gypsum.
Mushroom compost seems like an excellent idea – it’s inexepnsive, eco-friendly and its water retention is exceptional. However, all of its ingredients are still decomposing, and at the same time have limited nutrients left.
Mushroom compost is also high in salt, and more alkaline than average composts so using it to start seeds isn’t such a good idea.
Grass clippings
Grass clippings (or straw/hay) are a good alternative to manure when they are freshly decomposing. They are only good for mulching, and should never be used on vegetable beds in spring or early summer when grass pollen is highest as this will lead to grass seeding itself on your veg bed.
The decomposition of grass clippings provides extra heat and can be used as a brilliant manure alternative for a potato trench, or bean trench.
At the same time, depending on how dry your climate is, mulching with grass clippings is a double win – it holds moisture and allows some nutrients from the decomposing grass to penetrate the soil.
Can I use peat as a manure alternative?
While peat and peat moss are still cheap alternatives, I recommend you move away from using them. Using peat as a seed starter is harmful enough, let alone spreading it on your garden beds as mulch.
Peat is one of the most environmentally devastating garden composts, mulches, and soil conditioners that has ever been harvested by humans. Its harvest wipes out vast carbon stores, and the unique habitats sustained (not to mention the flood barriers peat bogs create) are destroyed.
When and how to use manure alternatives
When to use mushroom compost
Mushroom compost is a great general purpose mulch, but for plants that need acidic soils (most vegetables) be aware that mushroom farming uses lime and gypsum to regulate growing spaces.
This means the mushroom compost produced as a waste product of mushroom farming is alkaline and salty. Gypsum is a natural slug deterrent though, but in such small quantities it won’t be of much help.
In conclusion, use mushroom compost sparingly, or mixed with homemade compost or horse manure.
When to use chicken manure
I use chicken manure pellets lightly over our entire garden. Anywhere we’re not actively growing veg, we add a sprinkling of chicken manure pellets to garden beds to provide a slow-release fertilizer for the following growing season.
Chicken manure is also useful to help fertilize mixed pots and hanging baskets. While garden bulbs don’t need chicken manure, if you have violas or annual bedding in your pot displays, the chicken manure gives them a boost as they come out, and the bulbs are protected from squirrels who don’t like the smell of chicken manure (which is entirely understandable as it is a foul smell).
When to use grass clippings / straw / hay
Grass clippings are better than straw or hay as a manure mulch alternative, but all three work. The biggest benefit of grass is that it is quick to break down, rich in nutrients, and its decomposition generates heat.
Grass can be used to mulch, or in trenches. Either way, the resulting plants will be stronger than if you had left them alone. For young beans, the grass is less likely to burn their stems than manure too, meaning it’s a safer alternative in many ways. Sadly, if you don’t have a lawn, grass can be incredibly hard to get hold of.
Tip: One unique property of straw and hay in the garden is that they drain well in normal conditions, so by mulching with a layer of straw and hay underneath pumpkins, strawberries, or courgettes, you keep the fruit away from the soil so they don’t get overly wet in heavy rain.
When to use compost
Compost is a great general alternative to manure but comes with many of the same problems as manure for ethical-vegan gardeners looking to find sustainable solutions. Despite international laws limiting the sale and farming of peat, most commercial composts still contain around 40-50% peat.
Many composts (and soil improvers) are enriched with manure too, and there are no regulations in most countries that govern manufacturers to reveal the contents.
The solution to this would be to make your own – this way you can control exactly what goes in it and make sure it’s clean, vegan and peat-free.
When to use humus-rich compost
Humus rich compost is almost always 100% plant matter, but by definition, it can contain fully decomposed plant or animal materials.
There is evidence to suggest that humus-rich composts manufactured from agricultural waste might be the future of commercial farming, which is great news for both farmers and domestic gardeners alike who want to move away from the use of manure.
Different types of manure
The most popular alternatives to cow and horse manure are alpaca and chicken manure. Alpaca manure is fairly similar, but richer and with less ammonia, while chicken manure usually comes in dry pellet forms, with much stronger nutrients.
Alpaca manure doesn’t need that long to rot (6-8 months), and horse manure can be used straight away, but is best left to dry for 1-2 months before use.
(A note on horse manure – if it’s show or racing horse stables you source the manure from, be wary that they might be fed treats with a high sugar content, which does affect the strength of manure. If you’re not sure, leave horse manure to dry and stabilise for 2-3 months before use.)
For a more detailed look at different types of manure and their nutrient make-up, read our article comparing compost, fertilizer and manures here.
Where to find manure alternatives
Like all gardening, thrift and creativity are the best ways to source your tools and materials. Chicken manure is far better in pellet form though, so you can buy that online, and humus-rich compost is best bought from DIY stores or garden centres, as it can take an incredibly long time to make your own.
Mushroom compost can be found online (it’s about the same price online and in gardens centres) but grass clippings are more difficult to find. You can get hay from any garden centre or pet store, but fresh grass is pretty reliant on your having a lawn.
If you’re feeling bold though, head to your local park in summer. We used to live with a really small garden with paving throughout, so we went to the park with rubble bags in the car, and asked the groundskeeper if we could have some clippings.
Sure enough, they were happy to give us a few bags of grass clippings from the trailer. We got most of the topsoil for our garden this way when they were planting trees.
Conclusion
Manure is pretty much irreplaceable in the gardening world, but there are some jobs that are better done without it, and in many cases, you can get away with other, less aggressive fertilizers too.
I don’t like to waste the organic matter from my garden so I try to recycle as many garden clippings as possible in the most efficient way. For me, the best alternative to manure is fresh grass: undried, piles high, and left to heat up until winter.
But the best alternative to manure for you is going to be different from me because it depends on what you grow and when you grow it. Overall though, there is no one size fits all alternative to manure, but there are definitely enough manure substitutes to do every job.
