Science: Weedkillers from outer space: Satellite signals will soon enable farmers to be more economical with herbicides. Mike Williams reports

They are gathering in the harvest, down in Suffolk. Like mechanical insects, the combine harvesters are marching up and down the fields reaping the crops and separating grain from straw.

But this year, the high technology which has long replaced the traditional activities of the harvest is even more hi-tech. Some of these combine harvesters are eavesdropping on signals from outer space.

The result is likely to be a reduction in the amount of weedkilling chemicals sprayed on our fields each year.

The 24 satellites which form the Global Positioning System (GPS) were originally funded by American taxpayers so that their armed forces would know, with pinpoint accuracy, exactly where they were anywhere in the world. Vehicles, ships and aircraft with equipment to receive and process the signals can identify their position with an accuracy of less than two metres, a valuable asset when the Americans and their allies were fighting among featureless sand dunes during the Desert Storm campaign in Kuwait.

If tanks can listen in to the satellites, then so too can combine harvesters. Outwardly, those fitted with satellite receivers look little different from normal, apart from an additional small console in the driver's cab. Most modern combine harvesters have equipment to measure grain yield continously as the crop is harvested. Adding a GPS receiver to a harvester allows the production and position to be correlated and so yields can be plotted on a map of the field, held in a computer. Yields often vary by a factor of two, and a threefold difference between the best and worst yields in one field is not uncommon.

The problem may be an area of compacted soil or poor drainage, but a frequent cause of grain loss is competition from weeds. Most problem weeds grow in patches, and these can be indicated on the field map.

The final stage, once this year's harvest has been brought in, is to go over the fields with a special crop sprayer also equipped with its own GPS link and a computer to 'read' the weed data on field maps. The map and the satellite signals trigger the control system to switch the sprayer on as it passes over a weed patch and off, or to a low precautionary dose level, for weed-free areas.

Compared with conventional spraying, which applies a uniform dose of weedkiller over the whole field, the selective technique can achieve a significant reduction in herbicide application. This is attractive to the farmer, because spray chemicals are expensive, and there is an environmental pay-off also.

Equipment for the map-making stage is already available. It was developed by Massey-Ferguson - one of the world's leading farm machinery companies - and their Danish partner, Dronningborg. A prototype version was demonstrated in 1991 and this year about 30 farms in Britain have combine harvesters with GPS equipment. This number is likely to increase rapidly as more farmers are attracted by the opportunity to increase production from low yielding areas and reduce expenditure on weed-control chemicals.

Equipment to use the maps for selective spraying is still being developed. The first experimental sprayer with its own satellite link, known as the 'patch sprayer', has been working at the Silsoe Research Institute near Bedford, a Biotechnology and Biological Sciences Research Council centre. It is one of the Institute's major projects, attracting finance from several sources including the Ministry of Agriculture and the EU.

Dr John Stafford and Mark Paice of the Chemical Application Group at Silsoe, say their tests show that patch spraying often reduces herbicide application levels by 30 to 50 per cent, and up to 80 per cent has been recorded.

A further refinement in GPS weed control is to identify the principal weed varieties in each patch and include this information on the map. This would allow the sprayer control system to select appropriate specific weedkillers instead of a more expensive herbicide cocktail.

One approach developed by RDS, a company specialising in electronic equipment for agriculture, is to fit a control unit in the combine harvester cab with a push button for each of the most important weed species. Pressing the appropriate buttons adds the information to the map while the harvester is working.

The Silsoe research team is also developing techniques to provide more detailed information for the sprayer. One method is for the farmer to walk across each field with a GPS receiver and a hand-held computer. Details of patches and species are entered on a map displayed on the computer screen while GPS signals record the location.

(Photograph omitted)

Voices
voicesGood for Lana Del Rey for helping kill that myth, writes Grace Dent
Sport
The Pipes and Drums of The Scottish Regiments perform during the Opening Ceremony for the Glasgow 2014 Commonwealth Games at Celtic Park on July 23, 2014 in Glasgow, Scotland.
Commonwealth GamesThe actor encouraged the one billion viewers of the event to donate to the children's charity
Sport
Karen Dunbar performs
Entertainers showcase local wit, talent and irrepressible spirit
Sport
Members of the Scotland deleagtion walk past during the opening ceremony of the 2014 Commonwealth Games at Celtic Park in Glasgow on July 23, 2014.
PROMOTED VIDEO
Arts and Entertainment
The Tour de France peloton rides over a bridge on the Grinton Moor, Yorkshire, earlier this month
film
Life and Style
fashion Designs are part of feminist art project by a British student
News
Very tasty: Vladimir Putin dining alone, perhaps sensibly
news
Life and Style
Listen here: Apple EarPods offer an alternative
techAre custom, 3D printed earbuds the solution?
Arts and Entertainment
Top guns: Cole advised the makers of Second World War film Fury, starring Brad Pitt
filmLt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a uniform
News
The University of California study monitored the reaction of 36 dogs
sciencePets' range of emotions revealed
News
Snoop Dogg pictured at The Hollywood Reporter Nominees' Night in February, 2013
people... says Snoop Dogg
News
ebookA unique anthology of reporting and analysis of a crucial period of history
Arts and Entertainment
A scene from Shakespeare in Love at the Noel Coward Theatre
theatreReview: Shakespeare in Love has moments of sheer stage poetry mixed with effervescent fun
News
Joining forces: young British men feature in an Isis video in which they urge Islamists in the West to join them in Iraq and Syria
newsWill the young Britons fighting in Syria be allowed to return home and resume their lives?
Arts and Entertainment
The nomination of 'The Wake' by Paul Kingsnorth has caused a stir
books
News
i100
Life and Style
food + drinkZebra meat is exotic and lean - but does it taste good?
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

BI Manager - £50,000

£49000 - £55000 per annum + competitive: Progressive Recruitment: My client is...

BI Project Manager - £48,000 - £54,000 - Midlands

£48000 - £54000 per annum + Benefits package: Progressive Recruitment: My clie...

VB.Net Developer

£35000 - £45000 per annum + competitive: Progressive Recruitment: If you're pa...

SAP Business Consultant (SD, MM and FICO), £55,000, Wakefield

£45000 - £55000 per annum + competitive: Progressive Recruitment: SAP Business...

Day In a Page

Screwing your way to the top? Good for Lana Del Rey for helping kill that myth

Screwing your way to the top?

Good for Lana Del Rey for helping kill that myth, says Grace Dent
Will the young Britons fighting in Syria be allowed to return home and resume their lives?

Will Britons fighting in Syria be able to resume their lives?

Tony Blair's Terrorism Act 2006 has made it an offence to take part in military action abroad with a "political, ideological, religious or racial motive"
Beyoncé poses as Rosie the Riveter, the wartime poster girl who became a feminist pin-up

Beyoncé poses as Rosie the Riveter

The wartime poster girl became the ultimate American symbol of female empowerment
The quest to find the perfect pair of earphones: Are custom, 3D printed earbuds the solution?

The quest to find the perfect pair of earphones

Earphones don't fit properly, offer mediocre audio quality and can even be painful. So the quest to design the perfect pair is music to Seth Stevenson's ears
US Army's shooting star: Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform

Meet the US Army's shooting star

Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform
Climate change threatens to make the antarctic fur seal extinct

Take a good look while you can

How climate change could wipe out this seal
Should emergency hospital weddings be made easier for the terminally ill?

Farewell, my lovely

Should emergency hospital weddings be made easier?
Man Booker Prize 2014 longlist: Crowdfunded novel nominated for first time

Crowdfunded novel nominated for Booker Prize

Paul Kingsnorth's 'The Wake' is in contention for the prestigious award
Vladimir Putin employs a full-time food taster to ensure his meals aren't poisoned

Vladimir Putin employs a full-time food taster

John Walsh salutes those brave souls who have, throughout history, put their knives on the line
Tour de France effect brings Hollywood blockbusters to Yorkshire

Tour de France effect brings Hollywood blockbusters to Yorkshire

A $25m thriller starring Sam Worthington to be made in God's Own Country
Will The Minerva Project - the first 'elite' American university to be launched in a century - change the face of higher learning?

Will The Minerva Project change the face of higher learning?

The university has no lecture halls, no debating societies, no sports teams and no fraternities. Instead, the 33 students who have made the cut at Minerva, will travel the world and change the face of higher learning
The 10 best pedicure products

Feet treat: 10 best pedicure products

Bags packed and all prepped for holidays, but feet in a state? Get them flip-flop-ready with our pick of the items for a DIY treatment
Commonwealth Games 2014: Great Scots! Planes and pipers welcome in Glasgow's Games

Commonwealth Games 2014

Great Scots! Planes and pipers welcome in Glasgow's Games
Jack Pitt-Brooke: Manchester City and Patrick Vieira make the right stand on racism

Jack Pitt-Brooke

Manchester City and Patrick Vieira make the right stand on racism
How Terry Newton tragedy made iron men seek help to tackle their psychological demons

How Newton tragedy made iron men seek help to tackle their psychological demons

Over a hundred rugby league players have contacted clinic to deal with mental challenges of game