Hands up those who don’t get their fertiliser spreader tray tested each season
Hands up those who don’t get their fertiliser spreader tray tested each season? If that’s you, then you are not alone, but read on and find out why a simple test could help save money each year when applying fertiliser to your crops, writes Dominic Kilburn.A simple fertiliser spreader tray test carried out at least once a year could ensure better yielding crops and make significant financial savings.Poorly set up fertiliser spreaders could be costing wheat and oilseed rape growers around 35 per hectare when applying recommended rates of fertiliser to their crops. However, a simple test carried out at least once a year could ensure better yielding crops and make significant financial savings.That’s according to a fertiliser and crop nutrition specialist who questions whether the recommended fertiliser application rates provided, such as in RB209, are always right in on-farm situations where fertiliser can be spread unevenly. “A lot of recommendations can come to grief if the fertiliser is not applied properly,” says Suffolk-based Ecopt consultant, Dr Ian Richards (left). “All trials carried out for recommendations are done in small plot situations where the fertiliser is able to be spread very evenly. However, in reality, throwing a 2-4mm sized particle accurately up to 24m in an on-farm situation is asking a lot of machinery,” he points out.Dr Richards says that anything from disc speed; machine angle; bout width matching; fertiliser quality and wind can have a negative effect on the accuracy of application. But he believes there are two areas of accuracy that farmers have to focus on; the first is calibration of the fertiliser spreader which he says farmers generally do very well; and the second is getting the machine tray tested at least once a year. The latter, critical to accuracy over large spread widths, is not carried out by enough farmers, he highlights.According to the annually-produced British Survey of Fertiliser Practice, which asks growers about their frequency of spread pattern checks, about 40 per cent of farmers are reporting inadequate tray testing of their spreaders each year. In fact, the 2012 survey found that 27 per cent claimed that they never performed a tray test, 8 per cent said that they did it less than once a year and some (7 per cent) said that their machines hadn’t been tray tested since they left the factory.”It’s important to be cautious when considering survey statistics but it does seem that a large percentage of farmers are reporting inadequate tray testing of spreaders,” he adds.
With RB209 recommendations based on a zero per cent spread pattern coefficient of variation (CV) – when fertiliser is applied ‘perfectly’ even – Dr Richards explains that recommended fertiliser rates remain valid if farmers can maintain a required level of accuracy. “Provided growers can keep the CV within the 10 per cent range then there is little effect on yields using the RB209 optimum rate when applying fertiliser to winter wheat and oilseed rape. However, as the CV increases to between 15-30 per cent, crop yields in both wheat and oilseed rape start to go down.”The higher the CV, the lower the yield,” he continues, “and, at 30 per cent CV, RB209 recommendations are not appropriate as the optimum application rate falls by 10kg N/ha,” he adds.
According to Dr Richards, very often spreader calibration companies find spreaders at 30 per cent CV due to inappropriate set up and the general condition of the machine. And that doesn’t take into account any operator errors.This, he points out, can lead to a significant financial loss to the wheat and oilseed rape grower. “A CV of 10 per cent can result in a 4-5/ha loss of yield compared with a ‘perfect zero’ CV; a 20 per cent CV can equate to a 15/ha loss while a 30 per cent CV can result in a significant 35/ha loss.
“It’s a big financial incentive to get the CV down,” he adds.
“The answer to this is to get the spreader set up correctly by tray testing at least annually. This will give farmers more confidence in RB209,” he suggests.Testing times
SCS Spreader & Sprayer Testing’s Rob Foxall (left) agrees that not nearly enough growers are having their fertiliser spreaders tray tested. He says that his company tray tests in the region of 2,500 spreaders a year, and about 1,000 more are tested by other companies. “If you consider that NSTS is testing about 15,000 sprayers a year, then you would assume there are a similar number of spreaders on arable farms. Add to that the spreaders on livestock farms then you begin to see the full picture in terms of what is not being tray tested.”Rob stresses that until growers actually put a set of trays under their spreader, then it’s very hard to know if things are going wrong with their fertiliser applications. “When applying nitrogen you don’t see any striping in the field when the CV is between 10-20 per cent.
“Indeed, when applying P&K; considering the cost of up to 4,000 in soil testing for a 200ha farm, plus the extra paid for a GPS-controlled variable rate spreader, it pays to invest just 210 to check the fertiliser is actually being applied precisely,” he says.Web-based tool
Dr Richards has developed a web-based Excel tool for wheat and oilseed rape fertiliser applications whereby given a recommended rate for nitrogen, growers can input the crop type, the price of N and crop value/t and the optimum rate is given for zero per cent CV.
In addition, the tool will provide the optimum application rate when the CV varies, as well as expected yield (t/ha) with the optimum kg/ha of N applied.The tool is available to FACTS-qualified advisers on the FACTS website; www.factsinfo.org.uk
“Applying fertiliser within the target 10 per cent CV is key and puts growers within a range where recommended rates can be applied without a problem.”Getting the fertiliser application right will cover the cost of a spreader tray test after about only 5ha’s use and so, as a matter of course, growers should be getting their machines tested at least once a year if efficiency gains are to made,” he concludes.