How can you tell if your vegetables contain enough nutrients to keep you healthy?
If your garden only augments your diet then it doesn't matter so much, but if it supplies one-third or more of your intake, you'll want to ensure that your vegetables aren't missing out on ingredients essential to your health.
The harvest may taste great but unless you've been adding minerals to replace those lost through erosion and rain, you are not growing the healthiest crops possible.
Seven thousand years ago people of the Mesopotamia Valley developed agriculture, producing food that sustained generations until overharvesting and erosion finally reduced the land to the semi-arid desert it still remains. As populations farmed new land, this same pattern has occurred and populations have continually moved to virgin soils. North America is no different except that we have nowhere else to go.
If we don't figure out how to invigorate our soils, crops grown here will eventually not sustain us. Nutrients get flushed down the toilet and left over animal waste goes into the garbage. Sure we compost vegetation and animal manure and add fertilizers but it's not enough. I got my soil analyzed last year after 10 years of adding well-made compost that included many cartons of used coffee grounds from a café, all the vegetable scraps from the kitchen and garden, alfalfa meal, kelp meal, fish fertilizer and lime. The soil looked friable and my vegetables looked good, but the soil analysis showed a serious lack of most minerals.
I doubt my garden would have sustained us if we ate from it exclusively. Since I'm going to all the bother of growing our food I want to make it as healthy as possible, so I'm following the suggestions from the soil analysis. This includes adding clay, lime and minerals like manganese, rock phosphate and copper, minerals not readily mined on Vancouver Island.
But what if we were cut off from the mainland? Michael Mockler of Thrifty's Foods estimates that the Island would have two days' worth of food, so it behooves us to grow what we can, know how to store it and ensure we grow the healthiest food we can.
We won't be able to import anything so we should plan on amendments we can source from our own back yard, as it were. Wood ash adds an average of 25 per cent calcium, 10 per cent potassium and less than 10 per cent phosphorus and makes a great substitute for lime (Oregon State University Extension Service). Apply at the rate of five to 10 pounds per 100 square feet, only if the soil is acidic, since wood ash will raise the pH.
Milfoil, a huge nuisance here on Bear Lake, provides nitrogen, calcium and trace minerals. The Osoyoos Basin Water Board harvests milfoil every year and offers it free of charge to anyone who wants to haul it away. The Minnesota Landscape Arboretum has been using milfoil from Lake Minnetonka for almost a decade and they love the stuff! Peter Moe, director of operations says that "in addition to supplying a bit of nitrogen, milfoil makes a good amendment because the organic matter helps loosen clay soil, improving its water-holding capacity and fertility." He didn't mention all the lovely trace minerals they also contain from run-off in the feeding tributaries.