Cover crops grown before sugar beet can reduce beet cyst nematode (BCN) numbers and nitrate leaching, improve soil structure and boost yields, according to several years worth of trials by Frontier and the University of East Anglia (UEA).
Benefits
Paul Brown, seed business development manager at Frontier, says: “It became apparent to us about six years ago that sugar beet was the crop which consistently gained the biggest benefits from cover crops.
“We think this is partly because a cover crop can capture nitrogen left over from the previous crop and feed it gradually into the sugar beet crop from July to September. Cover crops will also improve soil structure and aeration, enabling faster root growth and improved water holding capacity.”
Challenge
Looking at radish-based cover mixes, reductions in levels of beet cyst nematode as high as 90 percent were seen in some cases, with BCN being among the major challenges for beet growers across East Anglia.
After working alongside growers to see how cover crops could be used on-farm, it is not a one-size-fits-all scenario, says Brown, but growers are likely to see benefits.
“We chose radish-type cover crops for their trap cropping potential, but what mix crop growers choose is dependent on the rotation and what their main issues are, such as BCN or poor soil structure,” says Brown. “Some of the cover crops we have trialled are pure radish or a radish cereal mixture, or a broad range of two or three different species with the radish.”
In Frontier’s trials, a number of growers saw yield improvements of more than 4 tons per acre in sugarbeets, with UEA’s work seeing some yields increase by 33 percent.
“This is significant, but what we have now moved onto is the concept of allowing farmers to save money on spring cultivations in front of some crops, particularly sugarbeet,” says Brown.
“A number of our growers are direct drilling sugarbeet into cover crops and cutting out all spring cultivations, saving $35 to $40 per acre in cultivation costs and still getting yield increases because the cover crop creates the right soil texture and maximises water retention to enable direct drilling straight into it.”
In the Field
Oliver Scott, farm manager at Thelveton Farms in Suffolk has been trialling a strip-tillage system for three years with the use of radish and radish mixed with oats and rye in a bid to reduce cost of production and increase yields.
In the first year, a yield benefit of 10 tonnes per hectare was seen in sugar beet which had been strip-tilled, compared to conventionally-grown crop, without a previous radish and oat cover crop mix.
However, last year’s challenging summer did not yield the same results, and although ground which was cover cropped still yielded 7-10t/ha over non-covered ground, direct drilled crop performed poorer than conventionally-drilled crop.
Scott says: “We either grow straight radish or a radish mix with winter oats and sometimes winter rye. Oats and rye take pressure off the top moisture and oats give you a big root mass, which is good for the soil. I have found the radish does the work at depth – the root goes down, but it doesn’t draw a lot of moisture from the top, so come spring when you’re wanting to be doing something, it is always a bit tacky on the top.”
Scott says cover cropped land will always be at least 10 days behind ploughed land, which has better travelling conditions because it has dried out on top. However, once in the ground, crops behind cover crops always look better and grow quicker, he adds.
“The radish has enabled deep rooting and broken up subsoils below, so crops always look healthier as they get hold of the nutrients held by the cover crops. To the eye, they’ll always outgrow the neighbouring field without a cover crop.”
Mastering the right cultivation techniques to create the right tilth is proving the biggest challenge for Mr Scott.
“We generally have to pass with two cultivators to get a good enough seedbed before drilling with a conventional drill. We are seeing more dry springs, and land that’s been ploughed does break up better. Land coming out of cover crops can take a little more work, which is what we’re trying to get away from.
“We are trying to find that one pass system because if we are doing multiple passes and putting metal through it to try and get a good tilth, it counteracts what we’re trying to achieve.”