What cover crop mixture should I plant?
The secret to the perfect mix lies with the individual farmer.
Cover crops are a hot topic in modern farming today, with more and more of them being used in all disciplines of regenerative agriculture. The number of farmers who recognise the benefits of planting mixed species to protect and build their soils is growing and more and more hectares are being covered each year, a recurring question which is posed is – “What mix should I plant?”
The recipe and formulation of the perfect cover crop mix lies with each individual farmer.
It is relatively simple to formulate the mix with a bit of original thought, reasoning and planning. As each farm and farmer is unique in what they produce, how they produce it and where they produce it – so too is each cover crop mix distinctive in its formulation, application and purpose.
Identifying the reasons for the planting the cover crop is the place to start. The farmer has to be clear in his personal reasons for wanting to adopt this approach. If he decides to plant one just because his neighbour is doing it or because he went to a field day and saw what other farmers plant, then he is wasting his time, effort and money.
A cover crop should be treated in exactly the same way that an income producing enterprise is handled, with careful thought and meticulous planning. The main purpose of any cover crop is to improve and build long term soil health and fertility. The proof that cover cropping works lies with farmers who have been utilising the technique for a number of seasons and who now use the technique as a regular tool in their farming operation.
A multi-species mix - aimed at breaking the monocropping cycle of sugarcane in this field. The plant selection takes into account plant types suitable for grazing. A dual purpose cover crop!
So where does the farmer start when he wants to make the perfect cover crop mix?
The farmer must have a close look at his soils and know the potential that those soil types are capable of. If they are performing at a level lower than their potential, then he has to identify why and what are the limiting factors. Once the farmer has targeted the limitations the mix can be constructed.
The seed company should listen to the farmer and guide him in the offerings available to hit his specified targets. A seed should not be in the mix if it does not fulfil its potential.
There are factors which need to be considered, which if ignored can affect the success of the cover crop.
Plant architecture is one of these. As far as possible the plant shapes in a mix should be similar. There will be limited success in mixing a tall erect, fast growing plant with a short, squat creeping plant. The absence of light for the shorter plant will inhibit its growth and it will not fulfil its potential or role in the recipe.
Seed size is another critical consideration. To get good germination the seed needs to be planted at the correct depth. If the seed size differs markedly this can be a problematic.
Planting method must be deliberated. If a precision planter is to be used then the seed must be graded into small, medium and large and placed in the various seed bins for accurate placement. If the mix is to be broadcast and then covered, seed size is more important. For example covering a Fava bean to the correct depth may place some of the smaller seeds, like clover too deep.
The number of plants per hectare should be a studied point when formulating the mix. Bush type plants can be around three hundred and fifty thousand per hectare. Tall, single stem, erect type plants can be as high as one point two million plants per hectare.
Other considerations such as soil type, slope, aspect, rainfall, seed availability and importantly cost are reasons specific to the individual farmer and are unique to each mix.