Globe/Mike Surbrugg

Kansas State University Extension Agronomist Gary Kilgore (left) and soil scientist Ray Lamond talked with soybean growers at a recent meeting in Pittsburg, Kan.

Variety selection key to soybean income

By Mike Surbrugg

Globe Farm Editor

PITTSBURG, Kan. - Planting the right variety at the right time will not cost more money and can help soybean income, Kansas State University Extension Agronomist Gary Kilgore said.

Kilgore talked at a soybean profit seminar Jan. 29 in Pittsburg about growing soybeans that cover more than 175,000 acres each year in Cherokee and Crawford counties.

Kilgore said growers review copies of the 2002 crop variety tests held in Southeast Kansas at their county extension offices. The information provides data on yield and other factors for more than one year.

Getting information for as many years as possible is critical because growing conditions are never the same each year, he said.

Even with a multitude of varieties, nothing works without rain, Kilgore said. He said soil conditions in Southeast Kansas make irrigation a "break even at best" proposition because a claypan layer not far below the surface blocks water penetration.

Irrigation in Western Kansas can enable soybeans to yield more than 75 bushels per acre while yields in Southeast Kansas are often at or below 30 bushels per acre.

Farmers can plant a few acres of new varieties, but should put most acres into varieties with two or three years of data, he said.

Varieties are either determinate or indeterminate. Indeterminate varieties flower 35 to 40 days after planting and flower from the ground upward. Determinant varieties flower 40 to 60 days after planting and flower from the top down. Determinant varieties are in full bloom within four days. Indeterminates need 30 days to get to full bloom, Kilgore said.

There are exceptions, but determinant varieties more often have higher yields, he said.

Variety trials in Southeast Kansas are done at research plots in Parsons and Columbus, and on farmers' fields.

Tests evaluate production in upland soil, fields near a river, those with resistance to Roundup herbicide, those resistant to soybean cyst nematodes that can lower yields of vulnerable varieties, and those best suited to plant after wheat is harvested.

Results of tests in each category are in the 2002 soybean performance trial publications at county extension centers.

The tests look at varieties in all categories with different length of time needed to mature. Maturity lengths are measured in Roman Numerals that for this area can extend from II to V. Lower numbers are shorter maturing and most risky, Kilgore said.

Group II soybeans should be planted in late April through the first week of May to mature before summer heat and drought, Kilgore said.

Farmers planting in upland or droughty soil should select a Group IV or V variety, he said. Those planting in bottomland or banking on timely rain in August on other land need a medium Group IV variety, he said.

A lot of area soybean fields last year averaged less than 25 bushels per acre while 12 varieties tested in river-bottom land produced from 35.7 to 41.5 bushels per acre. A six-year average at the river-bottom site is 46.6 bushels per acre.

Kilgore recommends planting Group III and early Group IV varieties from the middle of May into June and most Group IV and Group V varieties in the middle of June into early July.

Growing soybeans in the same field each year will lower yields. Kilgore said. Soybeans should be grown continuously in the same field for no more than two years. The second year's crop should be planted following wheat harvest, he said.

Tests show soybeans seeded with a planter had 72.5 percent plant emergence and 61.5 percent when drill planted, he said.

Farmers planting with a drill should drop 10-20 percent more seeds per acre than if using a planter, the agronomist said.

The number of plants per acre should be the same regardless if drilled with 10 inches between rows or planted 30 inches between rows. Kilgore said most success comes with 60,000 to 104,544 plants per acre.

Fields planted with a drill with eight inches between rows will have 130,614 plants when there are two plants per foot within the row, he said.

Kilgore uses a hula hoop to estimate the number of plants in a field where soybeans were planted with a drill. The hoop with a 33-inch diameter is tossed in different parts of the field to get an average number of plants within the circle. If the field average is eight plants, it will have more than 59,000 plants per acre; four plants, 29,532; 14 plants, 103,362 over the acre, he said.

Spraying a fungicide on soybean foliage last year did not help yields, but caused a sharp increase in seed quality. "Some of the soybeans not treated had such low quality they would have been hard to sell. Seed quality is critical when you are growing seed beans," he said.

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