Organic market gardening examined

Press, 18 May 1984, Page 17

Organic market gardening examined

Both the theory of organic husbandry, as it is being tested at Lincoln College, and the practice of it, as applied on a commercial scale on a Marshland vegetable farm, were to the fore at the week-end, when members of the Soil Association from many parts of New Zealand met in Christchurch for their annual conference.

During a field day on Sunday, delegates to the conference — and a scattering of interested members of the public — visited a private garden in Christchurch as well as the Lincoln research plots and the Marshland farm.

The Lincoln plots are managed by Mr R. Crowder, senior lecturer in horticulture at the college, as part of a research scheme begun in 1976.

Since the scheme began, the area available for Mr Crowder’s research into biological husbandry — the cultivation of crops without the use of fertilisers or sprays — has been increased from o.2ha to sha, and he hopes soon that the facility will be extended to lOha.

It is the only such research facility in New Zealand, but its expansion has been hampered by shortages of funds, and the Soil Association has launched an appeal for money to help the project. A primary aim of biological husbandry, according to Mr Crowder, is the creation of a “balanced environment” made up of a wide variety of plants which can provide a home for the predators of insect pests.

In his experimental plots at Lincoln he has a broadbased mix of vegetation, including fruit, berries, culinary herbs, flowering shrubs, trees, and garden flowers as well as vegetables. The fruit trees in the unsprayed experimental garden are underplanted with a mixture of* herbs, with the aim, he says, not only of providing a home for predators but of suppressing grasses, which are undesirable in orchards. Ideally, he says, the “ground-floor” herbage in an orchard should be win-

By

DERRICK ROONEY

ter-green and dormant in summer, when the dead tops provide a mulch. Useful plants for this purpose include some which most people regarded as weeds — such as onion flowers. Grape hyacinths, comfrey, foxgloves, and daffodils are other useful, as well as attractive, companions for fruit trees, he says.

This winter some of the trees in the experimental plots, after the unusually wet and humid summer, are showing signs of serious damage by insects or disease, but Mr Crowder says this may be because the organic system is not yet working fully. A period of at least four years is required for the transition from conventional to fully organic farming. Also, the fruit trees may not have adapted to the “nospray” regime. All were grown from stocks that were used to conventional management, and it may well be that some varieties can never adapt to a “nospray” system. On the other hand, some are showing encouraging resistance to pests.

The ultimate aim of biological husbandry, he says, is to develop a balanced system in which no pollutants are added to the environment and food is produced simply by using waste.

The starting point in the transition is pasture. “If you’re on a farm, look at your herbage,” Mr Crowder says. A balanced greensward — which he calls a “mixed herb ley” — should contain a variety of grasses, legumes, and deeprooting plants, such as chicory, giving a spread of rooting depths from which the plants can bring up nutrients to the important surface layer.

One such area in the Lincoln trial is now in its third year. Hay has been taken from it for compostmaking, but otherwise it has been left untended.

Tests show that in that time there has been a buildup of magnesium, phosphate, and other elements important to fertility, and the area is now ready to grow crops, he says. The difficulty is in deciding how to “move out of the herb ley and into crops.” Options being considered included minimal tillage and mulching.

Extensive use of compost — made from a mixture of hay from the trial area, vegetable refuse, straw from the college farm, and sheepyard manure — is an important part of the system. The compost is applied at the rate of about 40 tonnes to the hectare, and lightly rotovated in. Little

or no other cultivation is done, and most crops are mulched in summer with straw or hay. No mulch is applied in winter, because a winter mulch renders crops much more liable to frost damage. Though there have been, and are, problems to be solved in the system excellent yields have been obtained from some crops, in the small plots, Mr Crowder says. The onion harvest was at the rate of about 50 tonnes to the hectare, and garlic yielded about 30 tonnes to the hectare.

However, he says, “we are not happy with brassicas.” Some brassica crops failed, for reasons not yet clear. Special seed strains suitable for organic husbandry may have to be sought out. “Or we may have been too light with the compost,” he said.

Crops thriving under the organic regime include rhubarb, peas and beans, globe artichokes, and asparagus. A crop being investigated this winter is a plot of autumn-sown onions for harvest in November, and if these are successful they will give a good return at the time of year when onions are most scarce, he says. The plot is also being used for a study, by the first masterate student in organic husbandry, of the possibility of controlling weeds among onions without resorting to the use of chemicals.

Onions, which are very vulnerable to suppression by weeds, have proved to be a difficult crop to manage under the organic system. Conference delegates saw evidence of this on Mr Tony Mallard’s Marshland property, where part of a block of young onions, which had been hand weeded, was growing strongly, while an unweeded segment of the block was disappearing under a sward of stinging nettle and other weeds. But Mr Mallard’s market garden, on the low-lying peaty Marshland loam, is a very different proposition from the free-draining trial area at Lincoln. Because of the severe problems presented by a combination of heavy soil, a high water table, and a layer of impeded drainage about 50cm beneath the surface, the maintenance, of a loose, open-textured topsoil is a key part of Mr Mallard’s organic management regime.

He makes compost in huge quantities, carting in many truckloads of sawdust and poultry litter every year; he uses no fertiliser, and sprays nothing against pests or diseases. As far as possible, Mr Mallard avoids going on t© cultivated areas, and for the minimal tillage necessary to work in the scm layer of

compost that he spreads each year and to make his seed-beds he uses a crawler tractor, because the spread of weight over its tracks means that it causes less compaction than does a wheeled vehicle. The crawler is also used to spread the compost, from heaps made alongside the perimeter track. The farm truck is never driven on to the cultivated area. When he went to the property 12 years ago, Mr Mallard says, the soil was impoverished from decades of conventional farming, and the first year was a bitter disappointment, with one crop after another failing. Lack of capital forced him to adopt conventional methods in his second year, but as soon as possible he moved towards a wholly organic type of farming. Initially, he used mainly chicken manure, spread directly on to the paddocks, but while this promoted excellent growth its benefits were short term. Compost, as he now applies it, has better long-term effects, and at the same time the fertility of his soil is increasing steadily. Phosphate levels, for instance, have risen more than 2000 per cent.

The “no chemicals, no fertilisers” rule is applied

strictly on Mr Mallard’s, property — to the extent that he’ abjures even that great farmer's standby, lime.

Lime, says Mr Mallard, is just not necessary. With the use of compost, the pH of his soil has come up steadily to a healthy 6.5 — fairly close to the ideal for the majority of crops. The increase in fertility through compost and the improvement in soil texture have not occurred without penalties, one of which is vigorous growth of weeds, such as the stinging nettle among the onions. The organic system has another drawback — it is very labour intensive. Throughout the growing season Mr Mallard works from dawn to dusk, and a bit longer. For these reasons, he says, he doubts whether it is economic for him to grow crops such as onions, which require very intensive management if no sprays are used.

He has had some problems with brassicas, too, particularly brussels sprouts, which are difficult to grow to market standards by organic means. However, he is on the way to overcoming this by planting small plots, by timing his plantings to avoid the peak periods of pest activ-

ity, and by selecting varieties compatible with or-ganic-farming methods; and he now grows a full range of both leaf and root vegetables.

Yields? Very satisfactory, he says. Because of his system of growing numerous small plots, he says it is difficult to compare his yields directly with those of his neighbours who farm by conventional methods. But he does know that none of them can match his potato crop. There is a difficulty here, too. Because he uses no sprays, his potatoes may quickly become infected by virus disease, and he finds it necessary to buy fresh seed every year, while his neighbours, who spray their crops, can get as many as three seasons from a batch of seed. The reduced costs of his method of growing potatoes, and his high yield, compensate for this, he says. His farm is, unlike most of the surrounding properties, free of the potato cyst nematode, and he hopes to keep it that way.