Maintaining soil fertility - The Accidental Smallholder

Posted: Sunday 4 September, 2005

by Dan at 1:05pm in Growing Comments closed

A central tenet of organic growing is the principle of feeding the soil, not the plant. In practise this means keeping your soil in the best possible condition, and not relying on the application of chemical fertilisers to provide the nutrition and trace elements vital to the production of a successful crop. A lot of fruit and vegetables make great demands on your soil, sp it's important that you try to replace as much as possible.

I do three things to try to keep our soil ticking over:

1. Use green manures.

Green manures are short-term crops which are sown, grown and then dug back into the soil, normally before they set seed. They have a number of benefits including: improving soil structure; preventing panning through weathering by protecting the soil from the worst of the elements; suppressing weeds; and in some cases fixing nitrogen.

There are a wide variety of green manures you can grow, with the best choice depending on the time of year, the length of time you want the crop to be in situ, what you intend to grow after the green manure, and your type of soil. This year I'm using winter tares - a winter hardy vetch which will fix nitrogen and provide good protection, but in the past I've also used clovers, buckwheat, phacelia and grazing rye.

There's more information on green manures at the HDRA website, and I'd recommend getting a copy of their booklet (only a quid) which lists a load of different crops you can grow as GMs.

2. Composting

There's no excuse not to compost these days, with most local authorities (in the UK at least) selling bins at a hefty discount, and with the amount of sense it makes. It's not difficult - pretty much all we do is bung all our vegetable waste into our bins and leave them for a few months. The resultant compost is a fantastic soil improver, and it usually comes with a healthy population of beasties and micro-organisms which will contribute to your soil's health once incorporated into it. I tend to use our compost in spring, on beds which weren't manured over winter (see below) but which could do with a wee boost in preparation for the season's sowing or planting.

3. Manure

The only import into our fruit and veg beds is horse manure, dutifully supplied by Smokie and his pals. Since he's out most of the year it means the dung has to be lifted manually, but this year we've established a better routine, with our trailer a permanent fixture outside his field. The manure is brought back home, piled up, covered with black plastic and then left for a couple of months to mature. In the autumn months it's applied to the fruit beds, and to those vegetable beds due to have a crop the following year which will benefit from such a rich additive.

Even if you don't have a horse of your own you should be able to find some quite easily. Most horse yards maintain a large manure heap, and most will be happy for you to take away the odd trailer load, free of charge. Ideally you want manure from horses bedded on straw, since the straw soaks up urine and rots down with the manure to produce a great conditioner. Beware using manure from horses bedded on wood shavings - while the shavings will rot down eventually, it can take many months. It's best not to apply this to beds into which seeds are to be sown, since compounds released by the shavings as they rot down can inhibit seed germination. Fine for use on established fruit beds though.

This might all sound like a lot of work, but in reality it isn't. When you lift a crop in summer think about sowing a green manure - most can be broadcast sown and it only takes a few minutes. Since most GMs are fast-growing you won't need to do much more until it's ready to be dug in. Come late summer think about trying to source some manure - it's a couple of hour's work for me to get our manure back in the trailer, emptied and covered, and in the late autumn another hour or so to spread it on those beds which need it. And it pays dividends - you'll see yields increase, your worm and insect populations swell, and get a sense of satisfaction knowing that your soil is in fine fettle.