VEGETABLE gardeners can prevent erosion by growing a cover crop and digginh it under in the spring.

Recent advances in agricultural science and technology are beginning to supply vegetable gardeners with new, practical systems for controlling soil erosion and restoring marginal land on farms and gardens.

Conservation tillage is one of these systems, according to Henry Becker III of the USDA Agricultural Research Service (ARS). In conservation tillage, the land is left unplowed while using crop residues to control erosion. Field plot tests showed in one instance that crop residues reduced soil-erosion loss 85 percent.

Minimum and no-till systems also have been effective in reducing soil erosion. ARS research findings show that in one case where no-till was practiced on soybeans, only 0.13 tons per acre of soil eroded as compared with 12.92 tons from tilled soil.

Water runoff can be noticeably reduced by new furrow systems, Becker says. New grasses are being developed to withstand drought and hold soil in place, and other techniques such as improved cropping sequences are being introduced.

Slotting fields is one of the newest approaches to control of soil erosion, according to research being conducted at Washington State University by ARS scientists Keith Saxton, Donald McCool and Richard Papendick.

By slotting hilly fields with straw-filled trenches 18 to 24 feet apart, farmers can let water drop into the soil profile, even when the soil surface is puddled or frozen, Saxton says.

"One of the beauties of the slotted field approach is that it not only eliminates, or drastically reduces, erosion, but it may increase the amount of water available to grow crops -- thus resulting in additional yields and additional profits," he says.

Saxton says lack of water limits crop production in the state of Washington's Palouse County, where the average loss is 17 tons of soil per acre. Up to a third of the annual precipitation in higher rainfall areas may be lost as runoff. Where fall-seeded wheat had been planted, four or more inches of water were lost because of runoff.

Agricultural engineers are designing equipment to make the slots and automatically stuff them with straw. Saxton says research has shown it is essential that straw be pushed all the way to the bottom of the trenches and that it fills out the top. Uniform density in the middle apparently is not critical.

In the closing days of the year, it is apparent that soil erosion from farms and vegetable gardens is our nation's most serious problem, according to Becker. Each year we are losing about 5.5 billion tons of topsoil, he says.

"Enough soil erodes from the land into the Mississippi River alone in one year to build an island one mile long, a quarter-mile wide, and 200 feet high," Becker says.

"Evidence indicates that we could be running out of land for increased food and fiber production. If soil losses from erosion remain unchecked, our physical capacity to produce food and fiber at reasonable costs is severely threatened," he says.

"The soil is invaluable to the economic development and prosperity of the United States. Even in the 1930s, researchers and farmers overcame the ravages of the Dust Bowl and proved that the United States could grow all the food and fiber needed to feed the people of the world.

"Today we export the harvest from one out of every three acres planted. Each year, agricultural exports become more important to the country's trade balance."