Monday, 2 December 2013

Manure for the garden: a fundamental matter

Not quite seven in the morning, and I’m on site to make preparations for an early delivery. The faintest glimmer of daylight fringes the trees bordering the fields of the stud farm opposite, but nearer to hand the tarpaulin laid out over the drive bounces the harsh brightness of the security lights about the garden. A slightly surreal, not-quite-half-light time of the day and on the chillier side of mild and dry – which is very good news. As with most garden tasks it’s possible to do this job in the wet, but a day without rain makes for a distinctly more pleasant experience. All is set; I pour myself a large mug of tea from my flask and walk across to the lane outside to await the arrival of the tipper.

Ten minutes, a mug of tea and sixty quid later, I have what I came for – a significant heap of chocolate brown horse manure, shrouded in a haze of steadily rising steam, and a warming morning’s work ahead of me. There’s about three cubic metres of manure to move, roughly two and half tonnes depending on the water content. Experience tells me that it will take three to four hours to shift it, depending on how far it has to be barrowed, and longer if it’s to be immediately used to mulch borders already stocked with plants. This lot is destined for a temporary location between the compost heaps and the bonfire.

The going is soft, if not sodden, and I wear a trench in the turf as I go. This part of the lawn will need some remedial treatment, aerating and topdressing in order to relieve some of the compaction caused by repeated trips made by a stout gardener and his heavily laden wheelbarrow. But that’s a job for another day. This is lovely stuff from I source that I trust – well rotted, mainly crumbly with the odd pocket of really rich gloop every few shovels fulls – let’s not be coy, we are talking about horse shit here, but it doesn’t smell, as indeed it shouldn’t. Given a horse’s largely hay-based diet there’s little if anything to be squeamish about; just processed, rotted down vegetable matter that will do the garden a world of good. Wheeling each successive load past the borders it is pleasing to think how much the garden will benefit from a generous helping of the gardeners’ black gold.

I use an annual dressing of a manure for two main purposes. Firstly as a mulch, which suppresses weeds, both warming and insulating the soil and having a pleasing aesthetic effect of providing an even dark tone against which the plants can stand out. Secondly, I add manure as a conditioner for the soil. Not as a fertiliser – the nutrient content of well rotted manure is rather low (slightly higher for horse than cow manure, not nearly as rich as bird guano which is a phenomenally good, natural fertiliser) – but as a material rich in organic matter which the soil flora will process in short measure, turning it into rich humus, aiding the ability of the soil to retain moisture in dry spells whilst also creating a favourable soil structure with the kind of friable texture envied by those whose unmanaged clay flip-flops from waterlogged in winter to rock hard in summer.

If I’ve managed to convince you of the benefits of manure for your garden, you may have a few further questions, which I'll endeavour to answer. Do please use the comments section below this post if you have any queries which aren’t covered.

Where can I get hold of manure for my garden? 
The most obvious place is probably your local DIY shed or garden centre, most of which sell well rotted farmyard manure in large bags. This is probably the most expensive source.

Should you have the time and the inclination, many stables and horse owners are only too keen to get rid of their manure for free, and a phone call from a gardener in need is often met with a positive response. It is highly likely that you’ll be welcomed in to help yourself, meaning you’ll have to shovel, bag and transport it to your garden yourself (bring bags and tools). For anything other than small quantities, this can be very time consuming, though the benefit of an unlimited supply of free mulch and soil conditioner may outweigh the inconvenience. Some kind owners even bag the manure themselves and leave it for collection, for a small fee – look out at the roadsides when driving through Kent; we’re not short of stables.

If you have the space and the cash, the best option is to find someone who will deliver a load for you. I found my supplier through the supremely uncomplicated approach of a google search. It often works out more affordable if you can find a local farmer or stables who will deliver, rather than opting for one of the commercial ‘bulk bag’ operations. This tends to be good stuff, but not the cheapest.

Should the manure smell?
Well rotted manure, which is what you want, should not smell at all. If it does have a whiff, then the process of decomposition is still going on and you will need to leave it in a heap until this has finished, or else it will rob your plants of valuable nutrients and possibly cause plant tissue to burn (rotting involves an exothermic i.e. heat generating process).

Should my manure contain straw?
A small percentage of rotted down straw is acceptable, and indeed inevitable when dealing with the product of mucking out, but you don’t want too much. Any lumps which have yet to finish decomposing I leave in a heap or put on the compost. Undigested carbon, which is what straw consists of, causes essential nutrients such as nitrogen to be ‘locked up’ by the microbes involved in decomposition, making them unavailable to your plants.

Should my manure contain a stirrup/random bits of tack?
Not really, though it’s happened to me more than once!

What equipment do I need?
A good shovel is essential. Don't try to do the job with a spade, they are about half the size of a shovel and have no sides so stuff falls off the edges. Buy a lightweight shovel, you don’t want to add to the weight of what you’re lifting with the weight of the tool.

A wheelbarrow, likewise, is an obvious requirement. One with a big tub, preferably made out of composite (plastic) material rather than metal, which is lighter and just as strong. A pneumatic tyre, suitably inflated, will relieve stress on the joints, too.

A tarpaulin is a very good idea if you are having the manure delivered. It can be spread over your drive or lawn where the heap is to be tipped, and makes clearing up afterwards so much easier. Get the biggest size you can, it’s frustrating when the footprint of the pile turns out to be larger than the tarp.

A lightweight, long-tined compost fork is great for spreading the mulch out when you’ve got it to the final location.

How should I shovel?
This is important, albeit a bit of a nag. Keep your back straight, bend your knees, and keep your core (stomach) muscles engaged i.e. tight. It sounds silly, but try to move gracefully and in a flowing motion, and watch out for obstacles that might catch the shovel and cause jarring to your body. Sloppy shovelling, as with lifting, can cause you painful persistent back and joint problems. Of course, the best way to shovel anything is to get someone else to do it.

How thickly should I mulch?
There is little point in doing things by half. To be effective, mulch needs to be applied at a thickness of no less than three inches, preferably four inches (10 centimetres) or more.

Other mulches, and a warning for dog owners
There are of course other materials that you can use for mulching, many of which will eventually rot down to become incorporated in the soil, although only garden compost will do this with anything like the speed at which manure decomposes; this might be a benefit or a drawback depending on your point of view. In fact, compost generated from the garden is the most desirable material for mulching, being free, and having the benefit of returning to the ground much of what has been removed, although many if not most gardens are unable to produce it in sufficient volume to be used to without adding to it from external sources. The various other mulching options could form a blog post of their own, but I will just say there is one material I absolutely won’t use as a mulch on any garden – cocoa shells, which in spite of its eco-credentials as a by product of the food industry contains dangerous levels of theobromine, potentially fatal to dogs in reasonably small doses. Even in homes without dogs, you can never be sure if friends will visit with the family pet, so I would rather err on the side of caution.

 1 the foundation of basis of something
 2 formal or humorous a person’s buttocks or anus
Oxford Dictionary of English