Living Roots As Often As Possible
by Jay Fuhrer, Bismarck, North Dakota
There are many sources of food in the soil that feed the soil food web, but there is no better food than the sugars exuded by living roots. Our perennial grasslands consist of cool season grasses, warm season grasses, and flowering forbs. Consequently, adaptable plants are able to grow during the cool spring and fall weather, as well as the summer heat, allowing for a continual live plant feeding carbon exudates to the soil food web during the entire growing season. Our cropland systems typically grow cool or warm season annual cash crops, which have a dormant period before planting and/or after harvest.
Soil organisms feed on sugar from living plant roots first. Next, they feed on dead plant roots, followed by above-ground crop residues, such as straw, chaff , husks, stalks, flowers, and leaves. Lastly, they feed on the humic organic matter in the soil. Healthy soil is dependent upon how well the soil food web is fed. Providing plenty of easily accessible food to soil microbes helps them cycle nutrients that plants need to grow.
Cover crops are able to fill in the dormant period and provide the missing live root exudate, which is the primary food source for the soil food web. Cover crops may be incorporated into a cropping system as annuals, biennials, or perennials. Starting on a small acre scale will allow farmers and ranchers to find the best fit for their operation.