Farmer Focus: Cover crops bring big benefits after harvest

We have started to harvest our soya beans and while the yield isn’t great, I am very grateful for what we are getting.

There was a point in January when I questioned whether the combine would go in at all.

Following the combine is a no-till drill, planting an eight-species cover crop mix. Winter is traditionally our dry, fallow period, so planting anything in autumn is hit and miss.

The reason I try is because I feel the potential benefits far outweigh the risks. Cover crops improve the organic matter content of the soil and live roots in the soil give off root exudates (sugars), which feed a whole host of microbes.

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These microbes add to the biological activity of the soil, improving its health. Each species of plant is host to its own spectrum of microbiology. Therefore a multispecies cover crop broadens the soil’s biological activity.

With a summer cash crop, you only have live roots in the soil for about five months of the year. But by adding a winter cover crop, you can extend that live-root window by another four or five months.

These cover crops can also “recycle” residual fertility from the previous cash crop, with each species having its own element-gleaning spectrum. This has environmental and financial benefits and the advantage of at least one legume in the mix is obvious.

Another reason I like many different species in my mix is that every plant type prefers different growing conditions. This is a way of spreading my risk, as I don’t know what the season will bring.

Over and above all these soil benefits, I can also get some much-needed fodder for my cattle. Some criticise this as they say I am detsroying the cover and therefore negating the benefits.

While I cannot argue against this, I try not to graze too hard and there are still plenty of roots left in the soil. Next month I will discuss the principles of species selection and how I calculate seeding rate.

Bruce Shepherd farms in KwaZulu-Natal, South Africa. He plants 320ha of rain-fed summer crops. He also runs 2,200 weaner oxen on pastures, finishing them in a feedlot with maize grown on the farm.

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