Drilling spring crops into cover crops – Tillage & Soils
Where cover crops have been in place over winter, it is clear that they have protected soils from January deluges for improved water filtration, leaving a better soil structure ...
“Looking forward to drilling spring crops following a cover crop, or drilling into the green, correct cover crop destruction and establishment of the following crop is vital to maximise benefits,” says agronomist Andrew Roberts.
“Whilst it’s true that frosts can do some of the work, most winters (including this one) won’t kill cover crops outright. How yours is destroyed can be as important as what was grown to allow for the best entry into your spring crop. Leaving cover crops in the ground too long before destruction can make establishing the following crop more difficult and/or lock up nutrients, leading to yield losses,” he says.
Careful destruction of the cover crop is essential and the timing and methodology chosen to do this very much depends on the cover crop mix, he points out.
“In the main, if drilling into spring cereals, a cover crop containing cereals should be taken out 6-8 weeks before to allow sufficient time for an effective kill. It also allows the soil surface to dry out and the spring cereal to be direct drilled into it. Cover crops that were cereal free are ideal candidates for drilling into the green.”
Mr Roberts says: “Chemical desiccation is often the easiest option for taking out cover crops. Glyphosate is the obvious choice in most instances, either as a split dose or as one dose if the canopy/weed pressure is not too high.
“If significant crop die-down is required, early application is best as glyphosate takes longer to work in the cooler winter/early spring months. Earlier applications aimed at ‘opening up’ the crop may benefit from the addition of 2,4D.
“Where covers contain radish, or phacelia in particular, then 2,4D would be the recommended chemical to ensure proper kill. However label restrictions mean you should consider the following crop carefully before choosing which chemical and at what timing, he says.
He adds that if the cover crop is going into beet, potatoes or pulses then glyphosate on its own will do the job. “It’s important to match rates to the species being controlled.”
Mr Roberts advises that when crimping is to be used, it really needs to follow a spell of frosts that will have damaged plant cell walls, to be fully effective.
“If topping cover crops, it’s important that the drill can handle the biomass residue. If possible, you want to avoid any additional need to cultivate. Otherwise, all the good that cover crops have contributed to soil structure and microbiology may be lost.
“So think carefully about drill choices. For example a good option could be a disc drill that will chop up and incorporate what biomass remains on the surface.”
As a final point he adds: “Ensure there is sufficient nutrition to establish the spring crop as yield potential is determined very early. So get spring crops going as soon as they are drilled.
“In lower fertility soils or soils with low biological activity, a small increase in total nitrogen maybe needed. Remember it takes two weeks for urea-based fertilisers to be available to the plant.”
Cover crop demo puts direct drills through their paces
With cover cropping and direct drilling becoming increasingly popular growers in Cheshire were given a unique insight into how machines compare when drilling wheat into a range of cover mixes.
When it comes to deciding which drill to buy, or cover crop to sow, there is clearly no one-size-fits-all answer. Every farm, field and soil is different, and everyone has their preferred brand, not to mention budget.
The Hutchinsons/CAS drill demonstration at Aston Grange Farm, near Runcorn kindly hosted by Stephen and Andrew Shaw in September, was never designed to find the ‘best’ direct drill, but to provide a view on the performance of different machines drilling wheat into cover crops and the impact on the subsequent crop establishment.
The 10ha field, previously in potatoes, was divided into sections of just under a hectare each with the three types of cover crop drilled and a range of different drill systems were used across each section.
Established in August these consisted of:
- Maxi Cover – Buckwheat, white mustard and berseem clover – Designed for rapid growth
- Maxi Veg – Linseed, buckwheat, phacelia and crimson clover
- Maxi Impact – Sunflowers, linseed, buckwheat, phacelia, crimson clover and berseem clover
CAS agronomist Andrew Roberts, responsible for the trials, explains the reasoning: “The high rainfall in the north-west is one of the biggest challenges to crop establishment and production. Up here we are looking at average annual rainfall of 900mm.
“It all comes down to being able to get onto the fields to drill in autumn. So we are looking at how cover or catch crops might help to pull moisture out of the ground and help dry up soils to widen the drilling window.
“Wet weather prior to drilling on the open day, created some challenging conditions for all machines on the medium-bodied soil, but we got all the wheat drilled. Crop assessments and plant counts will be taken through the autumn and spring and the plots will be taken to harvest.”
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