WEST BROOKLYN, Ill. (AP) _ The sounds of chain saws and combines are part of the country music, as thousands of farmers journey to a 1,400-acre stretch of northern Illinois for an agricultural exposition billed as the world's largest.

''My fear was that they would be in a real down mood because of the drought and poor yields, but they seem to be optimistic,'' said Don Nichols, one of the 340 commercial exhibitors at the event, which wraps up tonight.

For Nichols and other exhibitors, the idea is to attract the attention of an estimated 200,000 farmers from as near as Indiana and Iowa and as far as New York.

They do it with displays like balloons, wagons stacked five high, sculptors carving with chain saws, and antique tractors.

''We're here to show them our products and, hopefully, write orders,'' said Nichols, a salesman for J. M. Schultz Seed Co.

As farmers stroll away from the 60-acre midway, they are surrounded by test plots with 400 varieties of corn and 260 varieties of soybeans, as well as information on herbicides, new machinery, and farming tips.

''I come here to get ideas,'' said Lowell McCollough of Bourbon, Ind., who farms 276 acres and carried a plastic bag full of product brochures and microwave popcorn samples.

One insurance company offers a bingo game to entertain visitors, while a university offers advice and testing on the impact of agricultural noise on farmers' hearing.

Some show visitors gathered to welcome Vice President George Bush when he visited the area Wednesday, while barkers from the food tents strolled the exhibit area soliciting customers.

''If you eat at Tent 5, it'll keep you alive,'' said Alberta Strasser of nearby Creston, wearing a red-and-white clown suit and a black hat with a yellow flower.

''There is a lot of competition - there are five food tents. But, business is tremendous,'' she said.

At one of the exhibits, Frank Bretthauer put on his goggles and guided his chain saw into the wood, turning a rough log into a carved bear as a crowd gathered to watch.

''The idea is to stop them as they walk by, and the carving is the big crowd-pleaser,'' said Bretthauer, a chain saw salesman from Tonganoxie, Kan. ''It's well worth being at this shows - our sales in the state always go up 15 percent.''

Carving the wood is not as easy as some people think, and cutting even a simple square can be tricky.

''You start off to make a bear,'' Bretthauer said. ''You cut the nose too short, so you do a coyote. My first carvings became firewood.''

Manager Tom Budd said the farm show began as a one-day event in 1953, and expanded to a three-day show in 1960. It moves from Illinois to Indiana to Iowa, sponsored by Prairie Farmer Magazine.

''We wanted to bring advertisers and farmers together to see the latest advances in science and technology, and see machinery operate under normal field conditions,'' Budd said. ''The idea clicked.''

The show is held on the land of five families who farm around this Lee County community, about 75 miles southwest of Chicago.

''At first, we didn't know if we wanted to get involved,'' said Duane Ackland, one of the host farmers. ''But, it benefits the community, and it makes you feel good to do something for the future.''