Understanding the nutrient content of cover crops can be challenging because it depends on many different factors. Grasping everything that could affect the nutrient value of cover crops can be like trying to drink from a fire hose, says No-Till Innovator Jim Hoorman, but there are ways to simplify and understand how to determine what nutrients cover crops deliver to cash crops. Hoorman says microbes and cover crops are the main keys to making all nutrients more plant-available

“Each microbe is just a soluble bag of fertilizer,” Hoorman says. “Get as many microbes in your soil as possible. The way to do that is by having a living root in the soil year-round to help feed microbes and mycorrhizae.”

Relative Plant Concentration of Nutrients

Hoorman has been studying soil health for more than 40 years. Formerly a soil health specialist with Ohio State University Extension as well as the USDA-NRCS, he currently operates his own soil health research group, Hoorman Soil Health Services. 

Hoorman says carbon and oxygen make up roughly 90% of the nutrient content of a plant followed by hydrogen, which is typically 5-6%. After that, it gets a bit more complex. Nitrogen (N) and potassium (K) are usually the next highest concentrated nutrients — each about 1-1.5%. 

But Hoorman says one of the most important nutrients to monitor is calcium, because although it only makes up roughly .5% of the plant’s nutrients, it can activate 146 different enzymes in the plant — which helps with photosynthesis and…