What are the garden plants you munch on eating from the soil and air? Where does all that compost and mulch you put on your garden beds go? How does ‘feeding your soil’ relate to feeding your own body? It is all connected.
The average shrub, such as a lovely blueberry plant is composed of 44% carbon, 44% oxygen, 6% hydrogen, 1-4% nitrogen and the very important remaining 3-5% has 60-70 different mineral nutrients. Plants get their oxygen and hydrogen from air and water, yum! However, for their carbon, nitrogen and minerals their ‘grocery shopping’ techniques vary greatly.
For the plants we eat to be healthy, defend themselves, and multiply, they need somewhere between 60-70 different nutrient elements. And get this – humans also require these 60-70 elements! When plants are ‘shopping’ for nitrogen and minerals they look in organic matter and mineral soil. Mineral soil is the original soil that was made from crushed rock. Organic matter is found in the mulch we add to our edible landscapes in the form of such materials as fallen leaves and compost. For their carbon, they can make it themselves through the process of photosynthesis and can also obtain it through any decomposed plant matter that is added to the soil.
However, plants do not take up all necessary nutrients on their own. For their nitrogen needs they have interesting partnerships with bacteria that live on their roots which help them take up nitrogen in exchange for carbohydrates. When growing food gardens we can plant ‘nitrogen fixing’ plants (such as peas, lupine, and clover) which are plants that have this association with a bacteria. It’s the bacteria which is fixing the nitrogen into the soil, not the plant. And so again, human health, as well as plant health, depends on the diversity of microbial life in the soil!
Furthermore, as the mushrooms in the forest this time of year come up, we are reminded of another plant partner in the soil food web, fungi! Again, the plant provides carbohydrates to certain species of mycorrhizal fungi in exchange for being connected to the underground food access network. Phosphourous is one nutrient that plants find hard to access and absorb, however with the aid of mycorrhizal fungi, they can get it! The fungal network also connects plant roots to other plant roots, allowing them to share resources. Most plant families need mycorrhizal connections to be healthy.
If our food plants don’t have access to essential nutrients and microbes from the soil they are unhealthy, and in turn our nutrition suffers, too.
The large amount of vitamin and mineral pills in our grocery stores today are an indication of how our agricultural systems are lacking nutrient content. As gardeners who want healthy harvests, we are wise to continue learning about the soil food web, knowing what and how our food is eating will greatly improve our own health and resilience.
Here’s an excellent resource on growing healthier food and soil, available from the Vancouver Island Regional Library:
The Intelligent Gardener: Growing Nutrient-dense Food, by Steve Solomon.
Ceres Edible Landscaping offers organic horticultural services from garden design to maintenance, utilising holistic principles. Book a consultation for ideas on creating new gardens, renovating old ones, or how to increase your food production. Call Nora at 250.748.8506. We’d love to work with you!