Most meteorologists say 1988`s drought isn`t nearly as devastating as the infamous Dust Bowl drought of 1934 that destroyed most Midwestern crops. But there`s another big difference, and it could make 1988 simply a poor crop year instead of a very bad one:
Crops handle drought a lot better than they used to.
The advances take many forms. Agricultural researchers breed strains of corn, soybeans and other crops that conserve water and mature faster. Farmers plant and harvest in ways that save every drop of moisture. And genetic engineers probe the inner workings of plant cells in a quest to build better plants.
These are bold attempts to buck nature`s odds, and the progress is slow. But there is little doubt that farmers today have less to fear from drought than their predecessors.
``It has been a sum total of small changes, but our crops are able to make it through these droughts better,`` said Emerson Nofziger, an agronomist with the University of Illinois extension service.
To create new strains of crops, scientists look for two different plants with traits they`d like to combine. With corn, for instance, one plant may have deep roots to reach water in a drought; the other may have large, plentiful ears.
The scientists cross-breed the plants, making a hybrid that shares both traits. But getting the best mix of traits requires sorting through hundreds of hybrids, a process that can take 10 to 15 years.
With each decade representing just another small step, science is still a long way from creating truly drought-resistant plants.
``You almost never gain something from nothing,`` said Nofziger. ``If you make a corn plant more drought resistant, you usually have to give up some yield.``
Deep roots alone do not make a plant more drought resistant. Researchers also try to change the shapes of leaves, the amount of water lost during photosynthesis and the rate at which plants grow and pollinate.
``During droughts, the silks on the ears come out later than the tassels, so the corn doesn`t get pollinated,`` said breeder Tony Cavalieri of Pioneer Hi-Bred International in Des Moines. ``But we`ve developed hybrids that silk and tassle more closely together in dry conditions.``
Cavalieri said breeders have raised corn yields about 1 percent each year, while also making the plants slightly more drought resistant.
Matching plants to growing conditions in dry areas leads to the best drought-resistant crops. For example, researchers have developed strains of wheat, black-eyed beans, sorghum and millet for Africa`s semi-arid Sahel region that mature in the short 70-day growing season there.
Some of these plants have shown tolerance for U.S. drought conditions. They enable farmers to harvest earlier, avoiding the late summer dog days that used to damage many crops.
``These plants have deeper root systems, they`re smaller, and they yield very high-quality grain as well,`` said Timothy Schilling of the International Sorghum and Millet Program at the University of Nebraska. ``They`re very good in drought years. But if it rains at the end of the season and the plants have already matured, you run into problems.``
Those problems, such as overripening and mold, illustrate a major concern of U.S. plant breeders: Droughts do not happen frequently here, so plants that do well in dry years might not thrive in normal years.
So researchers also devise farming techniques that preserve precious water.
``The key is to conserve water and keep it on the land,`` said James Parr of the Agricultural Research Service, a branch of the U.S. Department of Agriculture in Beltsville, Md. ``Then you bring the breeder back and develop the plants for those conditions.``
The best crop management techniques include:
- Ridge till planting, or planting crops on the same ridges for two or three years in a row. This keeps weeds low, leaving more water for the plants. - Furrow dikes, or ridges of soil every few feet that catch and hold water from heavy rainfalls.
- Conservation bench terraces, or alternating steep and flat sections on a hill that prevent water from running off.
- Minimum tillage, or leaving the residue from past crops at harvest time. This holds water in the ground and prevents topsoil from blowing off.
``I`m not saying another Dust Bowl isn`t possible, but today`s farmers are pretty savvy,`` said Parr.
Farmers may soon get help from genetic engineers as well. These cellular surgeons have already taken single genes from bacteria and put them into plants like tomato and tobacco, making them less susceptible to some insects and herbicides.
Certain plants can control how much water they use with a special hormone. During droughts, the hormone makes the plant shut down. Other drought-resistant plants have thick, fleshy leaves to hold more water, or very deep taproots to seek water far below the surface.
If scientists can find the genes that control these features, they may be able to transplant them into commercial crops. But there are probably many such genes, and finding them all will be difficult.
``It`s a very complex problem,`` said Philip Filner, director of molecular biology at Sungene in San Jose, Calif. ``Right now, we don`t have enough knowledge of the genetics of plant cells.``
Scientists have recently put ``model genes`` into rice, corn and rye plants, showing that it may be possible to genetically alter those crops.
``Things have been moving so fast in the last decade, I`m still stunned by it,`` Filner said. ``And the pace is accelerating every year.``