Montana State University

Zero-till shines in drought

February 20, 2003


Brad Gregoire checks a crop rotation at the Sustainable Pest Management in Dryland Wheat Project near Havre in this 1998 file photo.   High-Res Available

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Zero-till cropping "shines" when the sun shines a lot.

Zero tillage crop seeding is a one pass operation that places seed and fertilizer into an otherwise undisturbed seedbed and packs the furrow. Such systems are shining when it comes to both better yields and disease control, says Andy Lenssen, a Montana State University - Bozeman entomologist.

Lenssen is project leader for the Sustainable Pest Management in Dryland Wheat study funded by the USDA at Havre, Moore and Froid. The work is unique in its scope and complexity, says Greg Johnson, who initiated the project and is head of MSU's Entomology Department.

The improved yields were even evident in the continuing dry conditions of 2002 at Havre. That year, zero tillage systems produced four bushels per acre more spring wheat across nine crop rotations than reduced tillage system, says Lenssen. The increased yields are probably the result of better moisture retention under no-till, he adds.

Moisture conservation may also be the key to reducing disease, because moisture stressed wheat is more susceptible to infection, says Bill Grey, an MSU plant pathologist. "No-till residue management definitely reduces the incidence of Fusarium crown rot," says Grey. "The impact of this disease on wheat production has largely been overlooked and underestimated due to the difficulties of obtaining yield data on plants that are influenced by drought. We have estimated that in the North Central Region of Montana over 2 million bushels or $4.5 or $9.5 million were lost to this disease in the 2002 growing season."

The large three-site study has been troubled by unusually dry conditions most years since it started in 1998, but Lenssen says, "Even though we've had drought, we're getting very very useful data."

The study also has shown that:
--diverse crop rotations can improve spring wheat yield and quality.
--diverse crop rotations and zero-tillage help manage weed and disease problems in spring wheat production in Montana.
--green foxtail, a weedy grass, can be decreased by including hay barley in rotation with durum wheat.
--diverse crop rotations can be managed with zero tillage to leave enough after-harvest residue to protect the soil from wind and water erosion.

The crop rotations include wheat and alternative crops that vary at the three sites. The work at Havre, the first site to be established under the program, was in its fifth year during the summer of 2002. Moore was in its fourth year and Froid in its third. Researchers hope to take the long-term, practical study through 12 to 15 years, which would be four or five complete rotations. Each site has a rotation system that was devised by the researchers in conjunction with farmers. Each site is being intensely studied, with soil microbes and insects being looked at as intensely as fertilizer regimens and precipitation.

The jury is still out on some of the studies, including how populations of useful insects such as ground beetles increase or decrease under different management. There are 40,000 species of ground beetles worldwide, including some that eat seeds on the ground, including weed seeds, and some that eat other insects. Little is known about the eating preferences of common Montana ground beetles, so Sarah Wallace, a graduate student of Entomologist Sue Blodgett, is studying that. Wallace, a native of Moscow, Idaho, is examining the gut contents of these beetles to find out what they eat, and especially to see whether they prey on aphids.

The Sustainable Pest Management in Dryland Wheat study sites include one on the Mark Peterson Grain and Cattle, Inc. 35 miles north of the MSU Northern Ag Research Center at Havre; one on the Tyler Ranch 10 miles east of the MSU Central Ag Research Center at Moccasin. The third site, owned by the Sheridan and Roosevelt County Conservation Districts, is about 45 miles north of the MSU Eastern Ag Research Center at Sidney. The sites differ from each other in climate and agronomic characteristics, but also represent significant production areas within Montana. Up to 10 different three-year rotations are being done at each site.

The rotations have included spring wheat, winter wheat, durum, barley, organic barley, peas and organic peas, lentils and organic lentils, traditional and Roundup-ready canola, mustard, sunflower, safflower, chickpea and millet.

Under severe drought, Lenssen said a spring wheat then no-till fallow rotation is producing the most consistent crop. However, while low-moisture conditions have so far limited both Montana's traditional grain crops and the potential alternative crops, the results from this large study will help producers quantify some of the more subtle benefits of crop rotations, from decreased weed problems to the population shifts of beneficial insects.

Andy Lenssen (406) 994-7267; Bill Grey (406) 994-5687, Sue Blodgett (406) 994-2402; Greg Johnson (406) 994-3861