URBAN FARMER:Well-fed soil gives healthy crops but which food is best?

‘FEED the soil, not the plant” has always been the cardinal rule of organic gardening, in the belief that healthy soil produces crops that are both healthy and health-enhancing. The only problem with this, as OPW gardeners Meeda Downey and Brian Quinn have discovered, is that it’s all too easy to run out of provisions, especially when you’re feeding the ever-hungry maw of an intensively-cultivated, two-and-a-half acre walled kitchen garden.

Thus, having spent much of November toiling away on the garden’s enormous, double herbaceous border (cutting back, dividing and weeding), the OPW gardeners have now used up what remained of their year-old hoard of well-rotted farmyard manure, which was spread as a thick, soil-enriching mulch along the full length and width of the flower beds.

The OPW gardeners used cow manure, which is rich in both nutrients and organic matter but is difficult to work with, demanding strong arms and a sturdy back. “It’s very heavy to fork and you have to break up the clods as you go along, which takes a bit of effort. But at least it’s nice warm work,” says Brian cheerily.

Over the next six months, and without any further “nice warm work” on Meeda or Brian’s part (such as digging or forking it in), this rich layer of organic matter will gradually become incorporated into the soil, protecting and improving both its structure and fertility levels.

The result should be a magnificently healthy and colourful herbaceous border. The downside, however, is that the gardeners have now got almost nothing left to mulch the many fruit and vegetable beds in the garden.

“We didn’t really have much of a choice – the border needed manuring badly,” explains Meeda resignedly. “And we’ve been promised more manure early next spring, so at least the rest of the garden will get some then.”

But what makes the shortage of farmyard manure especially worrying for the OPW gardeners is the fact that they’d already decided not to grow any green manures this autumn, which now leaves the soil in some parts of the walled garden without any form of winter protection.

“We’ve grown a lot of different green manures over the past few years, but not this autumn,” Meeda says firmly. “One reason is the difficulty we had, because of this year’s very late and very cold spring, in digging any green manures back into the soil in time for them to rot down before the growing season began. The thing is, by the time the ground was any way workable, it was already too late in the season. We just couldn’t afford to wait and lose another six weeks.

“The other problem was the particular green manure that we used, an Italian rye mix that came strongly recommended. It turned into a really annoying weed, growing right through the box hedging and appearing everywhere, so that we spent the whole summer pulling it out. So we decided that this autumn we’d give green manures a miss.”

But even without farmyard manure and green manures, there are plenty of alternatives for the OPW gardeners to consider, including horse and poultry manure, garden compost, leaf mould, spent mushroom compost, and even straw or hay. If required, other possible soil feeds could also include wood ash (for potash), rock phosphate (for phosporous), or even fish, blood and bone meal (both nitrogen and phosporous). Other enterprising gardeners have even used pond mud, while many a seaside garden has been enriched by a thick mulch of seaweed, scavenged from beaches where it’s washed up after a storm (just remember that you should ask permission from the relevant authority before taking it).

In fact, according to Jonathan Bell and Mervyn Watson, the authors of A History of Irish Farming 1750-1950, Irish gardeners have a long history of being resourceful when it comes to the business of feeding and improving their soils. The authors write that, “clay and earth, dug elsewhere, were . . . commonly spread on cultivated land to increase fertility.

“The soil was sometimes spread straight onto the ground, or might first be mixed with farmyard manure. Arthur Young records frequent instances of earth being taken from ditches to form composts, by both landlords and small farmers”.

These same Irish gardeners, Bell and Watson, go on to explain, used seaweed in abundance, even sometimes going so far as to establish “kelp beds”, marked out by stones and extending far out to sea.

They also used Peruvian guano, the name for the collected droppings of seabirds such as the Guanay Cormorant and the Peruvian Booby, and a popular fertiliser that was once commonly available. Yet another traditional Irish soil enricher, according to Bell and Watson, was shell marl, a thick, lime-rich clay which was dredged up from the bottom of both the Shannon and Waterford harbours.

Back in 21st-century Ireland, the author and organic vegetable gardening expert Klaus Laitenberger swears by another type of soil enricher, this time a composted mix of waste produced by a Donegal waste-recycling company called Envirogrind (envirogrindltd.com).

Made from a mix of garden waste, food waste and fish waste (all organic-only) and with added grit for porosity, it’s a wonderful soil-conditioner with a perfect balance of plant nutrients.

According to Envirogrind’s managing director, Martin Eves, the feedback from both private gardeners and landscapers has been phenomenal. At only €25 per cubic metre, it’s also very affordable in comparison to equivalent garden-centre bagged products.

Envirogrind is one of several similar companies around the country that are listed on the website of CRÉ, the composting association of Ireland (cre.ie).

Alternatively, Dublin gardeners will be interested to know that Dublin City Council occasionally supplies some of the smaller Bring Centres around the city with compost produced from its brown bin collection service. Details of availability are posted on the website (the latest news section) of Dublin Waste, dublinwaste.ie .

Whichever one of these mulches you do decide to use (and a mixture of several is often the best solution), between now and next spring is the ideal time to spread them (ideally during a milder spell of weather).

Added to even the poorest, most compacted and undernourished of soils, they have a transformative effect – the ground becomes workable, any subsequent weeds become pullable and the yield of fruit and vegetables quickly increases.

So perhaps that famous saying could be reworked with GYO in mind. “Feed the soil to feed the gardener” – it has a nice ring to it, don’t you think?

** The OPW’s Victorian walled kitchen garden is in the grounds of the Phoenix Park Visitor Centre, beside the Phoenix Park Café and Ashtown Castle. The gardens are open daily from 10am to 4pm

** Next week Urban Farmer in Property will cover allotments

** Fionnuala Fallon is a garden designer and writer

WHAT TO: sow, plant and do now

Sow(under cover, with heat of 55-60ºF/13-16ºC to then plant in polytunnel once germinated) : kale (Ragged Jack), peas (Kelvedon Wonder), Swiss chard, spinach.

Plant: (in polytunnels): kale, peas (Kelvedon Wonder), Swiss chard, spinach, garlic.

Do: Clear, weed and mulch/manure beds when possible, spread and peg down black polythene sheeting to kill perennial weeds on previously uncultivated ground, order fruit trees.