Do your vegetables taste bland? Don't blame the cook. The problem could be rooted in the soil.
Soil can make a significant difference to the flavour of produce. Just ask David Cohlmeyer.
The farmer turned sustainable food consultant noticed in the 1990s that the taste of the vegetables he grew near Thornton, Ont., depended on how he treated the earth. When he was gentler on the soil – if he set aside his Rototiller and grew a cover crop, such as rye and hairy vetch, over the winter – he found that the next year's carrots and beets tasted sweeter and more complex.
"Pretty well across the board, just about everything" tasted better, Mr. Cohlmeyer says. "Kind of like with a good wine. You know, it's not just one taste, you get an assortment of tastes."
It wasn't just his imagination. Chefs who used his produce also noticed the difference.
Tests of his vegetables confirmed elevated Brix levels, or sugars, in their juices. A carrot that would normally be 8 degrees Brix now measured 12 degrees Brix. And, perhaps more important, his vegetables had higher levels of diffusion, a measurement of the amount of dissolved solids, including flavour components, nutrients and aromas, for which he credits their robust and complicated flavour. Root vegetables, in particular, also tended to last longer in storage. (Certain varieties of vegetables do yield higher Brix levels, but Mr. Cohlmeyer found these varying levels between the same strains grown in different soil.)
Around 2005, with the support of a government research program, Mr. Cohlmeyer began conducting his own research based on his suspicion that soil life – the universe of insects and micro-organisms in the ground , including bacteria, fungi, yeasts and protozoa – could be a key factor in developing tasty produce.
Last fall, he has been working with scientists at the University of Guelph to further examine how to improve soil to enhance flavour and naturally prolong shelf life. They plan to test how different amendments to soil, such as adding compost or compost tea, affects various crops such as carrots, beets, squash, winter radishes and potatoes. The aim is to identify what is increasing the Brix and diffusion levels of the vegetables. The team is now seeking funding for its research.
When it comes to wine, no one bats an eye at the mention of terroir, the notion that flavour is tied to the soil and climate of a region. Terroir affects the taste of other crops as well, says Antony John, owner of the Soiled Reputation Farm in Sebringville, Ont.
"The exact same principles apply to vegetables as they do to grapes," Mr. John says, noting that eating locally grown food isn't just a feel-good philosophy; it tastes distinctive too. "In Europe, this is understood that olives grown in one part of the region will taste different than [those grown in another]"
At his farm in fertile Perth County, the soil of the region naturally contains a good mix of calcium, sand, clay, humus and other rich organic matter, which makes it ideal for growing vegetables, Mr. John says. Home gardeners can create a similar soil composition in their own backyards, he adds.
So what's the recipe for good soil? Here are a few elements that can potentially alter the taste of your vegetables:
Calcium: Calcium is important as it is involved in the formation of sugars in root vegetables and encourages bud formation in flowering vegetables, Mr. John says. Home gardeners can pick up bone meal or limestone at gardening stores to add calcium carbonate to their soil. Mr. John recommends stone dust containing limestone, which also increases the porosity of the soil. You don't need much. A two-pound (900-gram) bag of any store-bought garden product that contains calcium will be sufficient for a typical home garden, he says.
Clay: Vegetables grown in heavy clay soils generally taste better than those grown in sandy soil, Mr. Cohlmeyer says. Clay has a higher cation-exchange capacity, which means it is able to hold more positively charged mineral ions, such as potassium and magnesium, making them more readily available to plants. But clay can be tricky. It tends to dry out, making it hard for plants to germinate and for growers to harvest roots. If your soil lacks clay, adding compost will also increase its cation-exchange capacity, Mr. Cohlmeyer says.
Peat moss and compost: Across Canada, soil degradation, particularly the depletion of organic matter, has become a concern for farmers. Vegetables thrive in soil that is rich in organic matter, which retains moisture and has an abundance of bacterial and fungal activity. But a muck soil, which is extremely rich in organic matter, doesn't hold onto nutrients well and can alter the flavour profile, Mr. John says.
For most home gardens, though, it's generally a good idea to add some quality compost, Mr. Cohlmeyer says. After all, he says, having a healthy amount of organic matter in soil is what organic farming is all about. "If you have good organic matter, high enough organic matter, in the soil, you don't need these herbicides and pesticides," he says. "It's not that you choose not to use them, you don't have any need for them."
How to brew compost tea
Through his experiments to produce tastier vegetables, David Cohlmeyer has come up with a formula for compost tea to promote soil life:
Mix a small amount of quality compost (make sure it's free of harmful E. coli, which can be present in manure) with some molasses and a sprinkling of oats to boost fungal activity. Let the mixture sit for a few days, keeping it moist. Add water, and insert a fish-tank bubbler to aerate it for about 24 hours, encouraging the growth of aerobic bacteria and fungi. (Mr. Cohlmeyer uses a shovelful of compost for every 45 gallons, or 170 litres of water, enough for an entire acre, so home gardeners should scale down accordingly.) Spray the compost tea over damp soil.
"With a compost tea, we were able to get a similar increase in the biological activity in the soil as putting on compost, so you can get similar effects with less compost," he says.