Like craps, crops can be a gamble.

Weather on the Northern Plains is reliable only in the sense that you can never count on it, and markets always fluctuate.

But farmers, even during a prolonged drought, don't have to wager their future on a roll of the dice. They can attempt to tilt the odds in their favor.

On Tuesday, scientists in Mandan will reveal new data they say farmers can use to increase their profitability and be kinder to their land.

Hardly a magic wand or a crystal ball, the information relies on recent history to forecast the near future. The Crop Sequence Calculator, scientists said, gives farmers a better shot at a successful harvest this year, while also helping them plan for next year and the year after that.

"It's about options - we want to give farmers a lot of alternatives so they can manage for the best use of their land," Jon Hanson, lab director at Mandan's Northern Great Plains Research Laboratory, said. "Our research station is concerned about balancing profitability and protecting and enhancing the environment. We think it's really important that you become pretty aware of the tradeoffs."

The lab put out its first calculator a few years ago, and quickly disseminated 12,000 copies. It now has data on the sequence results of 10 different crops, including corn.

The lab is hosting a conference at the Seven Seas Inn on Tuesday to release results of that latest crop-sequencing study. The study shows that crop diversity is key to yearly success at harvest time. Beyond that, the scientists have determined which crops to plant, and when.

They put the information on their Crop Sequence Calculator - a simple CD-ROM program that allows users to see the effects of planting one crop after another. Some will be available at the conference. Data from that last two studies haven't been uploaded to the calculator yet, but will be available in print format. The conference is open to the public, and starts at 8:30 a.m.

The calculator offers no guarantees, certainly, but does draw conclusions from a wealth of data.

Some of those conclusions: Don't plant flax in the same field in consecutive years; spring wheat yields are 4 bushels per acre higher when planted after canola instead of after another wheat crop; and, despite the possible upsides, it might not be the best idea to plant corn this year.

"There's an unbelievable renewed interest in corn right now," Hanson said. "People are seeing dollar signs because of the biofuels (plants). We're telling them that corn is not sustainable this far west."

The data in the calculator comes from the research station. Since 1998, scientists there have been planting crop plots one over another in matrices to see how residue from one crop affects the soil and the yield of the next crop. They used field-scale equipment and no-till methods (so there were no root crops in the studies).

To determine the economic impact of crop sequences, ag economist Dave Archer added long-term average prices to the matrices. Combined with the yields that the field scientists found, the Crop Sequence Calculator is able to show the probable marketability of specific crops.

Farmers can use the calculator to determine synergies on the land that transfer to the market.

"Farmers are going to plant what they want to plant, but this will show them that some risk factors are higher than others," plant pathologist Joseph Krupinsky said. "In general, it's a good idea to keep diversity in your system."

Monocultures - planting the same crop in the same field, year after year - have been shown to promote plant disease and lower yields. The sequencing studies revealed that in recent years, the vast majority of tested crops fared much better following a dry pea or lentil crop, compared to following itself. In 2004, eight of the 10 tested crops (buckwheat, canola, chickpea, corn, dry pea, grain sorghum, lentil, proso millet, sunflower and spring wheat) experienced their highest seed yield when following dry pea.

The most recent study also showed that dry pea, sunflower and spring wheat may not be as dependent on consistent rain distribution as the other crops. That could be valuable information, heading into a growing season that follows one of the worst droughts in recent history.

"Soil water use and recharge is key," soil scientist Steve Merrill said. "We observed the effects of how one crop affected the next. The effects interact. For instance, sunflower has the ability to mine out water from the subsoil. In a drought year, for plants following sunflower, watch out. There's no water recharge. Corn is also a high water-using crop. Approach it very cautiously."

The scientists started in 1998 with rows of 10 crops, then followed that in 1999 with the same crops planted in the same field, but perpendicular to the initial rows. The result was 100 fields of data. They replicated it four times, and have done the same in subsequent years with different crops.

After all the study, there is one underlying theme.

"It underscores the value of diversity," soil scientist Mark Liebig said. "The data hammers it home."

The Crop Sequence Calculator is intended for a region west of Jamestown and north into Canada. Farmers and scientists from other parts of the country have called the Mandan lab to see how they can get a calculator for their region. Liebig has challenged researchers in other areas to come up with Crop Sequence Calculators, but warned them that it takes a lot of time and preparation, and a great deal of interdisciplinary cooperation.

"This has been a team effort the whole way," Liebig said. "We got the study going and got the information together, and not too far down the road the producers wanted a way to get their hands on it. It evolved into this calculator."

(Reach reporter Tony Spilde at 250-8260 or tony.spilde@bismarcktribune.com.)