Commercial men sit on fence over varied rates
Commercial men sit on fence over varied rates
The technology for using
field maps and a GPS link to
vary seed rates has been
available for at least five
years, but so far there has
been no rush to use the idea
on commercial farms
MOST leading drill manufacturers now offer at least some models which are equipped or can be adapted to vary seed rates automatically. They use basically the same technology as other GPS-linked equipment such as patch sprayers and fertiliser spreaders, with application rates controlled by data on a field map, using GPS signals to link the position in the field with data on the map.
Some of the reasons for varying the application rate of fertilisers and spray chemicals are obvious, including the potential economic and environmental benefits of ensuring that expensive chemical inputs are used more precisely.
The arguments for using variable seed rates may be less obvious, but they could still be important, says York-based agronomist Chris Dawson.
Mr Dawsons interest in precision farming techniques dates from the mid-1980s, long before the use of GPS for yield mapping was commercially available, and he is involved in the development work at Shuttleworth Farms, Old Warden, Biggleswade, Beds, one of the pioneers of precision farming in Britain.
There are nine years of yield map records on some of the fields on the 545ha (1200 acres) Shuttleworth Farms. For the last four years. trial areas of wheat have been drilled with variable seed rates using a Nordsten and, more recently, an Amazone drill linked to Massey Fergusons Fieldstar GPS equipment.
The area covered by the variable drilling rate crops is up to about 20ha (50 acres) per year.
Mr Dawson has analysed the results and says: "The main objective so far was to make sure all the equipment is working properly. It works very well and it enables us to vary the drilling rate with the level of accuracy we require.
"We have only worked with cereals, but there is no reason why variable seed rates should not be used with other crops, and this is something we may consider in the future. It would not be difficult to do."
Drilling rates are varied according to soil type rather than previous yield history, and in one of the trial fields the standard seed rate for Rialto wheat was 175kg/ha, which was increased to 190kg on the heavier soil areas and reduced to 160kg and 140kg on the lighter and sandy soils.
Benefits available from applying precision farming technology to drilling rates may include yield benefits, and there could also be quality benefits from matching the plant population more accurately to the soil type, says Mr Dawson.
"We know plant population influences the amount of tillering and can have a direct affect on yields," he says. "We also know the quality of crops can be influenced by a number of factors – plant population could be one of them.
"The programme is still at an early stage. We are not saying farmers should be varying their seed rate for any crops, but we have recorded an apparent yield benefit where the seed rate was increased in areas where the tilth was not as good."
Sowing more seed where the seed-bed was not as well prepared was part of good management long before the term precision farming was used, but the latest technology means the same job can be done with more accuracy.
Jonathan Scott, the foreman at Shuttleworth Farms, takes a close interest in the use of precision farming techniques on the farm. Although he is enthusiastic about yield mapping and the possibilities for variable rate spray application or patch spraying, he is still keeping an open mind about the value of variable rate seed drilling.
"If I was a commercial farmer I think I would sit back at this stage and see how it develops," he says. "Patch spraying appears to offer real benefits and I think it is possible to make substantial savings by linking herbicide application rates to the level of weed infestation. Patch spraying would certainly be my first priority after yield mapping, and I would put variable rate fertiliser spreading next."
But he believes one of the attractions of precision farming is that once the farm is geared up for it, the cost of adding an extra application, such as variable rate seed drilling, is relatively small.
"The equipment is also easy to use. Im not really a computer person, but I was able to pick up all I needed to know about the computer side of precision farming in about 30 minutes," says Mr Scott.
"And there is no problem to operate the drill using the variable rate facility – you just load a disc with the data into the control unit and off you go. Its as easy as that."