Deep-Rooted Safflower Cuts Fertilizer
A field of safflower, Carthamus tinctorius L.
A field of safflower in full bloom casts a beautiful yellow glow across the
western Great Plains. But to farmers, safflowers' best features are
An oilseed, safflower could be a high-value rotation cropa crop
planted every 2 to 4 yearsfor wheat farmers using no-till or conservation
tillage, say Agricultural Research
Service soil scientists Donald Tanaka and Steve Merrill. They work in the
Natural Resources Management Research Unit at Mandan, North Dakota.
No-till farming systems use no tillage, or very reduced amounts, to preserve
the natural organic content of the soil. Wheat growers rely on crop rotation to
disrupt the life cycles of insect pests, weeds, and diseases.
Tanaka says safflower may be a good alternative because its deep roots take
up water and nutrients that are out of reach of other crops.
Safflower has been cultivated on other continents for centuries, but it has
been planted in the United States only since the 1950s. Its seeds can be
processed for cooking oil or sold for high-quality bird food.
Tanaka says farmers began planting more safflower in the western plains in
the early 1980s, but it didn't do well in heavily tilled fields. The switch to
conservation tillage in recent years has encouraged production.
"Safflower is best suited to dry, temperate climates such as those in
North Dakota, Nebraska, eastern Montana, and other areas of the western Great
Plains," Tanaka says.
"It does better in no-till or minimum-till systems because the seeds
can be planted closer to the soil surface. Also, the higher moisture content of
no-till fields favors germination and stand establishment. Safflower is
particularly suited to our area of the country."
Research conducted by Merrill shows that safflower roots descend up to 7
feet and can tap water and nutrients deep underground, in subsoil. "Wheat
and other cereal grains, like oats, can typically reach about 4 feet down into
the soil profile," he says.
And another plus: "Safflower's deeper roots can reach fertilizer that
may have leached below the root zone of other crops," says Merrill.
ARS research shows up to 50 percent less nitrate in the soil in years when
safflower was planted in rotation with wheat. Nitrate is another form of
nitrogen, an important nutrient to crops.
"By using safflower in a crop rotation, you prevent movement of nitrate
into the groundwater because the nitrogen is being used to produce seeds,"
says Tanaka. "And when the plant removes water from the subsoil, lost
nutrients are used by the plant and don't move toward the groundwater."
Safflower also encourages carbon sequestration, a process in which plants
remove carbon dioxide from the atmosphere. More research is needed to learn how
much carbon is absorbed and transferred to the soil.By
Dawn Lyons-Johnson, Agricultural
Research Service Information Staff, 1815 North University Street, Peoria, IL
61604, phone (309) 681-6534.
Donald L. Tanaka and
Stephen D. Merrill are in the
USDA-ARS Natural Resources Management Research Unit, Northern Great Plains Research
Laboratory, P.O. Box 459, Mandan, ND 58554; phone (701) 663-6445, fax (701)
"Deep-Rooted Safflower Cuts Fertilizer Losses" was
published in the April 1998 issue of Agricultural Research magazine.
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