Set for a showdown

6 October 2001

Set for a showdown

When a Velcourt farm manager pitched his technical proficiency against the best of the latest agronomy research, there were some surprising results. Tom Allen-Stevens reports

HAVE you ever wondered what might happen to your crops if you set a bunch of research scientists loose on them? Instead of farming them according to your standard farm practice, the latest and greenest agronomic research would be the dogma to guide them through the season.

In effect, this is just what Velcourt farm manager Chris Redfearn did when he agreed to take part in the Trials4u2c project last year. "I was keen to confirm that I was following optimum farm practice," he says. A 14ha wheat field at Fonthill Farms in Wiltshire was duly carved up into plots and drilled with two seed rates in mid-October.

The stage was now set for the big showdown: Mr Redfearns years of experience and local knowledge were pitched against research techniques that are in limbo between reaching the end of their period of HGCA-funding and being launched into the commercial arena. These included canopy management nitrogen regimes and new computer decision support program DESSAC.

Root development work and P&K sap testing were also brought into play in the DEFRA-funded work, which was repeated in Lincolnshire. The research scientists behind the individual projects were on standby to advise on inputs and provide technical support, and progress could be followed by anyone via regular updates with photographs posted on a special part of the HGCA website.

Few differences

The plots are now harvested, the results have been processed and its time for Mr Redfearn to face the music. "Theres not a lot between them, which surprises me. I would have expected there to have been more differences."

He cautions not to read too much into the results because they were not replicated trials, but he had viewed with suspicion the input regimes followed under DESSAC and canopy management and had hoped the results would back him up. "These sorts of systems may work well on nice fertile silts in the east, but not on my thin, free-draining hungry soils."

DESSAC is a computer-based system he had to get to grips with. It forecasts disease risk using local weather data, information about the crop, and in-built knowledge on the main cereal diseases – septoria, yellow rust, brown rust and mildew.

"On the flip side, the computer has a list of chemicals with dose response curves and prices so that it can pull out the most cost-effective solution. You also input crop price and yield and it jiggles its recommendations in relation to diseases observed and its in-built models. Its a real virtual agronomist," says Mr Redfearn.

So how did the two disease control strategies compare? "Its been a really interesting test because this year has been a complete one-off disease-wise. There was the normal high septoria risk coming out of the autumn and into the spring. This started to manifest itself and then stopped. The threat just never took off."

Mr Redfearn adjusted his programme to suit the season: 0.4 litres/ha of Opus (epoxiconazole) was applied at GS30/31 and GS37. This was added to 1.2 litres/ha of Twist (trifloxystrobin) at the early timing, which was dropped to 1.0 litre/ha on the flag leaf. The ear was left untreated.

DESSAC went for a very different approach: 0.25 litres/ha of Landmark (epoxiconazole + kresoxim methyl) was applied at GS31/32. This was stepped up to 1.0 litre/ha on the flag. Depending on plant population, 0.5-1.0 litres/ha of Amistar (azoxystrobin), was then advised as the earwash.

"When it came up with the first recommendation I thought that was way too low because there wasnt enough kick-back to mop up the septoria. The flag leaf dose was fine, but I was staggered by the third strob on the ear."


In the end the DESSAC plots yielded about the same as the farm-managed plots. A quirk of the season, says Mr Redfearn: "In a normal year youd never have got away with such a low dose to keep early septoria out – it can decimate the crop. Id never have contravened FRAC guidelines by putting on a third strob, but I think this year the DESSAC system helped the crop stay green through the late damp weather and kept the yield up."

Mr Redfearns verdict is that DESSAC is a good decision support system, but it wont replace agronomic experience: "Its a tool that brings more information out, but this must be interpreted before going back to the crop."

And it has limitations, he says: "It cannot tell if a crop is tender or lush or suffering from drought, that could influence how you spray it." He points out that you can enter in growth stage, but it wont recognise compaction, for example, as a possible reason for a backward crop.

Data input was not too laborious however: apart from entering crop inspections (no more than half a dozen are necessary) it must be updated with daily figures for local temperature and rainfall. But it can fill in any gaps from 10 years-worth of stored average weather data. "Its a good aid if you do your own agronomy, as long as you have plenty of other sources of agronomic information as a balance."

Canopy management was one aspect of the trials that particularly interested Mr Redfearn. This is work that has been carried out primarily by ADAS. The aim is to achieve a specific density of crop material by June – a green area index of around seven. Inputs, most notably seed rate and nitrogen, are manipulated to achieve this. In theory the field should then yield its optimum for minimum cost, but does it beat standard farm nitrogen management?

Mr Redfearns breadth of experience is certainly worthy competition for the new thinking. Apart from the 1,650ha at Fonthill and surrounding farms hes directly responsible for, Mr Redfearn undertakes agronomy work for two other clients totalling 1,200ha. Fully BASIS and FACTS qualified, he has 10 years of experience under his belt and has kept up to date through Velcourt in-house training and trials work.

In truth he is already a part convert to the canopy cause. "Unlike most growers in this area, Im already down the route of low seed rates anyway." He also likes to drill earlier than most and is particularly keen to keep the crop well-fed. "These soils are pretty hungry."

The site came out of the winter with two plant populations, reflecting the two seed rates that were drilled. The high seed rate plots had 339 plants/sq m – an average value for the area and height above sea level (600 ft) – while the low seed rate plots had 268 plants/sq m. This was much nearer to the rate sought for the canopy management programme.

In the farm nitrogen management plots, Mr Redfearn decided to go for a mid-February dose of 70kgN/ha across both plant populations. This was followed up with 105kgN/ha in early April and another 70kgN/ha a month later.

The canopy-managed plots relied on soil reserves until early March, when 40kgN/ha was applied. Two doses of 80kgN/ha each were applied in early April and early May. A fourth late dose in May was advised if the GAI of the crop was less than 7. Another 40kgN/ha was duly applied on 1 June.

Mr Redfearn admits he was uncomfortable with this nitrogen programme. "The crop went yellow early on and lost leaf area – you dont need to try hard to get tiller death around here. I was concerned they hadnt taken soil type and rainfall into account. It greened up once the nitrogen went on, but Id be surprised if it didnt lose yield."

In the end, the results show that it didnt. Yields were neck and neck, apart from in the low plant population plots where the canopy-managed programme won by a whisker. "There was a lot of residual N from the previous pea crop and a history of manure applications. Normally a crop wouldnt withstand being starved to that extent," says a resolute Mr Redfearn.

Sap tests were taken to test P & K levels in May. The idea of these tests is to reinforce soil tests taken in the autumn, or as an alternative if soil tests were missed and the plants are looking stressed. Developed by IACR Rothamsted, there is now an on-farm kit that gives you an immediate result, destined to be commercialised shortly.

The sap tests showed the P & K levels were adequate and not yield-limiting, and that the autumn maintenance dressing could have been omitted without loss of yield. "It told us nothing we didnt already know," says Mr Redfearn. IACRs Bernard Major, who carried out the tests, points out they confirm that Velcourts P & K management strategy keeps the levels high.

Root support

The root development told Mr Redfearn the least, he says. Under this project, steered by Scottish Agricultural Colleges and Harper Adams University, an analysis of the plant roots is undertaken to assess which roots provide more structural support and which are foraging nutrients. The spread and depth of the roots gives an indication of plant health. "Its nice to know whats going on underground, but it didnt alter any of my inputs," says Mr Redfearn.

So has his brush with cutting edge agronomic research taught him anything? "Its given me an insight into whats happening in terms of research. Its told me that HGCA levypayers money is being spent on something useful."

But whether it will change farming practices is another matter. "You cannot have a knee-jerk reaction to one set of trials that have taken place in very unusual circumstances. Im always questioning my practices and this has helped to highlight some areas that may need reviewing, but we would need to carry out further replicated trials before putting any changes into practice as the present farm system has proved too close to optimum."

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