Larry Cihacek

Extension and Research Soils Scientist

North Dakota State University

Fargo, N.D.

November 1988

The "white" hilltops that can be seen in a lot of summer fall low fields not only indicate signs of erosion. but of lost crop productivity as well.

Larry Cihacek Extension and research soils scientist at North Dakota State University. specializing in soil management, talked of the effects of soil erosion on spring wheat yields at the recent annual meeting here of the American Society of Agronomy.

Cihacek says years of tillage have taken its toll on organic matter.

Erosion has been an evolutionary. geological process for millions of years. according to Cihacek. "A certain amount of erosion can be good. it's a renewing process. Mountains erode away, washing or blowing into the flat lands and becoming productive soil.

"But once the process is accelerated, it becomes destructive end you have a situation where erosion is taking away more than it is adding."

Cihacek says research at NDSU has examined the differences in the soil characteristics of eroded hilltop soils and compared them with areas of adjacent non-eroded soils.

Measurements of grain yields showed that the eroded sites produced 28 percent less grain than the non-eroded sites in 1986 and 10 percent less in 1987.

In 1986. wheat yields in the study were 29.6 bushels an acre on non-eroded soils compared to 21.3 on eroded soils. Protein 16 to 15.4 percent, yield dropped from, 3,200 pounds per acre on uneroded land to 2,300 pounds per acre on eroded land. 5

Research compiled by the U.S. Department of Agriculture-Agricultural Research service at Mandan, N.D. has proven that for even' ton of organic matter lost from the top foot of soil, a third of a bushel In yield is lost.

Cihacek says the Conservation Reserve Program should help reduce erosion and the loss of organic matter.

Cihacek says organic matter is tough to build up once it lis lost. "It hcecomes a vicious cycle. You can't build up organic matter in the soil without leftover crop residue, but without organic matter, you're not going to have much crop residue."

Farmers have tried to. build organic matter up in their fields through manure application. Cihacek says manure will definitely help. but farmers without manure spreaders will often have a problem with even distnributlon.

"If you use a truck and spread with a tractor and blade, distribution wil be spotty end the hill tops may not be treated evenly."

Manure has to be spread every two or three years to maintain an organic level necessary for adequate crop production. Growing green manure crops such as sweetclover, alfalfa, and sorghum-sudan would als- be a sufficient source to build up organic matter on summer fallow.

Cihacek says adding fertilizer won't completely correct the loss of organic matter, and other management falctors will be needed.