Precision agriculture is a way of thinking abouthow to improve productionand get more from existing resources.It often involves the use of technology.An example found mostly in wealthier countriesis a computer-guided tractor.The computer does most of the driving.It uses signals from satellitesin the Global Positioning System.GPS technology helps the tractor cut rows in straight linesand put the right amount of fertilizer in the right place.Jimmy Messick is a farmer in northern Virginia,not far from Washington.He says the GPS guidance system makes it easy to come back laterand plant the seed in his fields of maize, or corn.JIMMY MESSICK: "Because the tractor that's pulling the planteralso has the same auto-guidance system in it as the tractorthat applied the fertilizer and did this tillage,it will come back and put the seed right on top of these marks."Because of the GPS guidance,Mr. Messick now pays half what he once did for fertilizer.Bruce Erickson is an agronomist at Purdue University in Indiana.He says saving even a little bit of seed,pesticide or fertilizer "computes directly to cost savingsand less environmental damage."Raj Khosla is an agronomist at Colorado State University.He says farmers in the developing worldcan use precision agriculture even without high-tech tractors.RAJ KHOSLA: "We do not necessarily have to have complex,large machinery to practice what could be doneas as using bottle caps."The idea is to use a bottle cap to pour a measured amountof fertilizer right next to each plant.It takes more work than simply throwinghandfuls of fertilizer across a field.But Mr. Khosla says researchers taughtthis bottle cap method to farmers in sub-Saharan Africa.They discovered that it was worth the extra effortif they could only afford a small amount of fertilizer.RAJ KHOSLA: "There was a huge difference:more than double, in terms of productivity."Of course, new technology is not always so cheap.But Mr. Khosla says farmers could form a cooperativeor combine their resources to pay for new equipment.He and other researchers worked with a farmer in Indiato precision-level his irrigated wheat fields.That kept the fields from developing wet and dry areasthat reduced productivity.The farmer also added better fertilizers and insect control.As a result, he was able to grow almost three timesas much wheat on the same amount of land.Mr. Khosla says with the extra money the farmer made,and a small loan, he bought his own precision leveler.And now, for a fee, he offers that as a serviceto his neighbors and other farmers.And that's the VOA Special English Agriculture Report.