Fall Cover Cropping Ensures Long-Term Nutrient Release into Soil

One of the cornerstones of regenerative agriculture is to have plants growing in the soil for as many days of the year as possible. While today’s agronomic practices are predominately based on using annual cash crops, it is an opportunity to get cover cropping into the management fold.

Doing so will help solve some of the reoccurring problems producers face like compaction, erosion, nutrient availability and weeds.

Fall seeding cover crops can be quite challenging. Lack of growing days after harvest, soil moisture availability, labour and time to seed all play against the desire to get started. It does not matter if you are talking about the Peace River region, southern Manitoba, Ontario or Mississippi. The crops we grow are chosen to mature in our growing area, maximizing the number of days the crop can grow, leaving a small window post-harvest. But there are ways around these issues. Why do we want to have plants growing in the fall post-harvest?

Will it use up the soil moisture creating a drought next year? Will it tie up nutrients from the next crop? Will there be enough moisture in the fall to get the cover crop established? All legitimate questions and concerns.

But weeds grow in the fall. Cover cropping allows us to determine what plants are growing and understanding the function of weeds, we can prevent triggering weeds to grow and speed up the soil-building process.

Soil moisture is a typical concern, and growing plants requires water. In the fall, if there is enough moisture to grow weeds, small-seeded cover crops can be grown. For spring moisture, overwintering species can dry the soil out if not managed but can help wet spring conditions. Yearly management needs to be done to ensure maximum results from the cover crop to match environmental conditions.

Nutrients get tied up if plant material has not rotted down. We can influence this by managing the plant stage at freeze-up. More mature plants have more structure tissues like lignin which take a longer time to break down and release nutrients, whereas vegetative plants will rot down quicker, releasing nutrients more quickly the next year.

Key is having a mixture of green plant material and mature plant material, and low and high carbon-nitrogen plant materials. This will extend the time nutrients will be released instead of all getting released all at one time.