Why mix and match?

Cover crop mixture

Multi-species mixtures have become a popular approach to “cover cropping”. The question arises: What is the benefit in this approach?

  • According to research by Penn State University, planting a multi-species crop, as opposed to a mono-culture, provides multifunctionality. If you only have one plant, you only get one benefit. Combining species enables you to tick multiple boxes.

  • Multiple species improve the soil’s biological activities as they feed beneficial organisms.

  • Difference in plant size, type and growing behavior encourages better growth. The greatest competitor for a plant is another of the same plant – as they compete for the same space, nutrients, sunlight and moisture. With a mix of species – with plants vary in their requirements. These plants may grow at varying heights – absorbing sunlight at different levels. Their root systems may reach different depths – gathering water and nutrients. Further to this, different plant types may be able to benefit each other – for instance, some plants fix Nitrogen which is beneficial to a neighboring plant.

  • The majority of studies performed view plants in a monocrop scenario - and insights are drawn on the way they behave in isolation. However, when you view plants in mixes you see that they behave in a totally different manner.

On the other side of the coin, planting a mix requires some careful consideration and planning.

  • Certain species may not be complementary. Where plants compete for the same resources there is always a winner and a loser. Consider both the plant type and seed count in your planning.

  • Seeding multiple species (especially when faced with varying seed size) may result only one species being planted optimally. Here consider the machinery available to you, or a mix that includes similar seed sizes.

Andre McGuire, of the US Centre of Agriculture & Sustainable Resources, cautions that polycultures “aren’t the silver bullet”. When considering a cover crop, both monocrops and polycrops should be considered – each has its place, and this depends on your objectives.

#mixes #covercrops #greenmanure #soilheath