Residue management and cover crops

Retaining crop residues and integrating cover crops are key practices that both protect the soil surface and keep living roots in the ground year-round. Both practices have their risks and challenges requiring careful planning and management. Check out the approaches take by Canterbury arable farmers David Birkett and Nigel Greenwood below.

Video description: David Birkett explains how 20 years retaining crop residues has improved soil health and organic matter.

Video description: Nigel explains how cover crops help keep a living root and a solar panel in the ground at all times.

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More on residue management and cover crops

David Birkett: Increasing the speed of soil heath improvements

David has retained 50-100% of his crop residues for over 20 years, generally incorporated with cultivation, with slow but steady gains to soil health and organic matter. However, the addition of cover crops into his system has increased the speed of his soil health improvements, increased grazing income over the winter and benefited his cash crops by recycling nutrients such as phosphate which are then released to the following cash crop.

David’s cover crops:
David’s primary cover crop species are oats, phacelia and buckwheat. Often these are drilled into pea or bean stubble which volunteer and provide a legume component to the cover crop, fixing significant amounts of nitrogen if growing during the warmer months in late summer and early autumn.

David has about 15-20% of the farm in cover crops each autumn/winter depending on what stage of his rotation each paddock is in.

Nigel Greenwood: Maintain a living root and solar panel

According to Nigel, keeping crop residues in the paddock cycles the carbon back through soils and plants and benefits future cash crops. Nigel is also developing a system for sowing cover crops into existing cash crops so that the cover crops are established before harvest.

Nigel’s cover crops:
Examples of Nigel’s standard cover crop mixes are below.

Following cereals going into spring sown crop:
• 10 kg buckwheat (frost sensitive if late sown)
• 1.5 kg berseem clover
• 1.5 kg crimson clover
• 0.5-0.75 kg phacelia
• 3-4 kg sunflowers (included only if sown well before first frost)
• 10 kg vetch
• 30 kg oats

Following peas for autumn sown cereal/rye grass:
• 15 kg buckwheat
• 2.5 kg berseem clover
• 10 kg vetch (not included if next crop is rye grass)
• 0.5-0.75 kg phacelia

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