The secrets to growing nutrient rich veggies

The plants and techniques to boost the goodness in your crops

Take one teaspoon. Dip it into healthy – organic, no-till – soil, and count the good things you see. Unless you’ve chanced upon an earthworm, you won’t see much, but that teaspoon of soil contains:

■ around 1 billion bacteria;

■ several yards of fungal hyphae (threads or strands);

■ several thousand protozoa*;

■ a few dozen nematodes*.

If you could tally up all the micro-organisms in that teaspoon, it’s more than the number of people on Earth.

New research shows that the complex community of microbes, bacteria, fungi, protozoa, nematodes, and more – known as the soil microbiome – delivers health benefits to the soil, the plants, and people who eat those plants.

The Rodale Institute is an organic agricultural research non-profit in the US. It has been studying organic vs conventional farming systems, side-by-side, since 1981. Its organic system uses cover crops, compost, crop rotation, and reduced or notillage methods.

What they’ve found is organic systems, in comparison to conventional:

■

produce oats, peppers, tomatoes, and carrots containing 18-36% more minerals and antioxidants;

■

improve the nutrient concentration of beta-carotene, lutein, calcium, and phosphorus (in winter squash);

■

increase plant production of bioactive phytochemicals (eg, flavonoids, antioxidants) – when eaten, these compounds are believed to help in the prevention and reversal of diseases including cancer, diabetes, hypertension, heart, and neurodegenerative disease. Plus, organic crops:

■

perform up to 40% better in times of extreme weather, ie drought;

■

use 45% less energy;

■

release 40% fewer carbon emissions;

■

have over three times the water infiltration capacity, leading to less runoff and erosion;

Two important parts of this regenerative approach to growing are cover crops, and no (or reduced) till farming methods. Cover cropping helps to create soil structure, protects it from erosion and nutrient loss, smothers weeds, controls pests and diseases, enhances water availability, and increases garden biodiversity.

No-till means no digging, turning, or soil agitation with mechanical tools, such as ploughs or discs, which destroy fungal networks and soil structure. No-till soil is higher in nutrients, microbial communities, and cycles more nitrogen than tilled soil.

The best cover crops for your garden will depend on your climate, soil type and condition, rainfall, and growing philosophy. Commercial growers use annual crops, such as oats, peas, vetch, and buckwheat for weed prevention and control, to fix nitrogen, and add organic matter to the soil. These crops are usually sprayed out, then ploughed in.

Organic gardeners often use the same crops but cut or crimp them (read more on page 18) to preserve the soil microbiome.

Permaculture gardeners often grow vegetables in between deep-rooting perennial cover crops that stay in place year after year, including herbs, clover, and groundcovers.

13 things a good cover crop needs

The practical considerations include:

■ can be easily killed or knocked back by cutting or rolling (any time of year), or naturally die or have growth suppressed by cold temperatures in winter;

■ grow enough vegetation to form a thick mulch;

■ provide habitat and food (nectar, pollen) for beneficial insects;

■ have a favourable or neutral effect on nitrogen, potassium, and phosphorus in the soil;

■ don’t suppress the crop to follow through allelopathic or microbial effects;

■ don’t get out of control;

■ don’t bring in pests or disease. Organic cover crop expert Dr Elaine Ingham (read more on page 16) recommends organic vegetable gardeners choose perennial cover crops that also fulfil these criteria:

■ fast-growing, creeping, but not weedy;

■ low-growing (foliage 2cm-8cm, flowers stalks can be taller) so it doesn’t shade food crops;

■ deep-rooting;

■ suit soil moisture (eg, wet, dry);

■ waxy-leaved (which respire less water);

■ can be driven or walked on.

The fuzzy white areas in the soil around the roots of this seedling tree are delicate strands of fungal hyphae, known collectively as mycorrhizal fungi.

In soil, the hyphae are dormant until they sense plant roots getting close. This stimulates their growth, and they infect the plant’s roots, then extend out into the soil.

The hyphae can access tiny soil pores and cracks that plant roots can’t. The result is that in healthy soil, there’s a 10-fold increase in the plant’s effective root surface area, which can double or triple its nutrient uptake.

The hyphae also have a significant effect on the soil structure, increasing air and water infiltration, which improves plant growth.

It also prevents disease because well-aerated soil is less likely to be affected by pathogens (which prefer low oxygen environments).

Hyphae from one plant also connect with hyphae on nearby plants, helping them share nutrients, boosting the growth of young plants.

Source: Rodale Institute Farming Systems Trial, 19812020, Dr Elaine Ingham Conventional, tilled dirt Organic, no-till soil This is what nutrient rich soil looks like compared to ‘dirt.’ Soil in a no-till, organic system contains aggregates and organisms that build structure, bind it together, and prevent erosion. Water moves very slowly through it, reducing impurities. The soil can hold up to 70% more water, so plants growing in it do better in drought, and there’s far less runoff. It also contains higher levels of bacteria, fungi, minerals, and nutrients.