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Crops and Conservation Tillage Glean Carbon for the Land

By Don Comis
March 9, 2001

Parking the plow can build new topsoil and keep atmospheric carbon dioxide levels down, Agricultural Research Service scientist Don Reicosky reported today at the 27th annual Mid-Atlantic No-Till Conference in Delaware.

Reicosky, a soil scientist in Morris, Minn., has found that tillage releases carbon into the atmosphere in sudden rushes or “burps” of CO2 as soil is opened up. CO2 is one of the greenhouse gases that may be causing global warming.

Reicosky described how he measures CO2 losses by placing a large portable chamber on the soil shortly after plowing. He has found that when wheat fields were plowed, as much carbon escapes in the form of CO2 as was added the previous season by leaving unharvested wheat straw on the field.

Since the 1970s, farmers have increasingly been leaving a third or more of their fields’ surfaces covered with unharvested crop stalks and leaves--after planting--to protect soil from erosion, in a practice known as conservation tillage. Conservation tillage includes a range of tillages, with no-till being the one that disturbs soil the least. Farmers are also planting cover crops for more residue, especially after crops with low amounts of residue.

Reicosky talked about defining the various tillage options by the amount of CO2 each releases. He discussed how keeping carbon in the soil leads to many economic and environmental benefits, such as better yields with less chemicals, keeping waterways clean by preventing erosion and speeding the breakdown of chemicals.

Reicosky shared center stage with Carlos Crovetto Lemarca, an internationally recognized no-till farmer-author from Chile. Reicosky has spent several days on Lemarca’s two farms in Chile, where Lemarca’s soil-building techniques have added an inch of new topsoil in less than a quarter century--twenty times faster than Nature’s process of building soil by weathering rocks.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Scientific contact: Don Reicosky, ARS North Central Soil Conservation Research Laboratory, Morris, Minn., phone (320) 589-3411, fax (320) 589-3787,