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January 23, 2003

Lessons learned during 2002 crop season may aid farmers this year

WEST LAFAYETTE, Ind. As the old saying goes, "Hindsight is 20/20." And for some Hoosier farmers, lessons learned during the 2002 crop season may help them as they prepare for planting this year.

Last year's wet spring kept Indiana farmers out of the field during the optimum planting time; however, Purdue University Extension agronomist Tony Vyn said there was little relationship between planting date and yields in 2002. In west-central Indiana, the optimum planting window for corn is normally April 20 to May 10, but Vyn said some corn planted on June 1 last year still yielded 200 bushels an acre.

"Some farmers rely heavily on completing planting during the optimum planting period," Vyn said. "This is only one of many factors that affect yields. Farmers who overemphasize this window of time will 'panic plant' even if soil conditions are not suitable."

Later planted corn normally has fewer growing degree days, or the amount of thermal time between planting and physiological maturity. However, warmer than normal temperatures during the 2002 summer made up for lost calendar time, Vyn said. Corn moisture at harvest was average, and farmers did not have to endure many extra costs for grain drying.

If farmers plant when it is too wet or when the seedbed has poor tilth, this will put strain on root development that will hinder plants from surviving later season stresses. These factors along with variety choice, rotation practices and nutrient management are often more important than planting date, Vyn said.

After Hoosier farmers struggled with a wet spring, drought-like conditions plagued much of the state during the summer. Due to these conditions in June, July and August, several farmers were disappointed with the yields after the stressful growing season. Vyn said that farmers' discontent prompted more 'revenge tillage' this fall.

"Deeper tillage alone will not restore compacted soil," Vyn said. "Farmers should not expect too much yield compensation through deeper tillage operations or a greater number of tillage passages. Loosening the soil by tillage may not create the optimal rooting environment for next year, either in or below the tilled zone. In fact, corn yields in 2002 were usually highest where farmers planted into stale seedbed conditions instead of into freshly tilled soil."

Farmers also must keep rotation practices in mind, Vyn said. Farmers who typically plant soybean more often than corn and never plant wheat or forage crops on a given field will experience more soil structure problems. Vyn said this is because soybean results in less persistent residue and less bonding strength among soil particles than most other field crops. This causes the soil to dry and crust over sooner.

Since farmers do not know what the 2003 crop season has in store, Vyn said they should implement strategies that will help manage plant stress.

Vyn said one of the most useful short-term strategies for helping plants fight moisture stress is applying potassium. Farmers typically put more emphasis on nitrogen and phosphorus application; however, Vyn said potassium helps plants open and close stomates, the structures that control the amount of moisture a plant exchanges from its leaves with the surrounding air.

"In Indiana, potassium levels in soil samples submitted to commercial laboratories tend to be in the low to medium range; exchangeable potassium is often below 150 parts per million in many fields," Vyn said. "Adequate potassium levels can help plants growing in soils that are too wet as well as too dry. In saturated soils, anaerobic conditions restrict root development and higher available potassium in the soil helps plant cells maintain growth potential. Potassium also helps plants close stomates more effectively during dry conditions to conserve water."

Potassium should be applied based on soil test results, the soil's inherent cation exchange capacity or the soil's chemical characteristics, crop yield potential, and the expected nutrient removal from the field, Vyn said.

Time will tell what this spring has in store for Hoosier farmers, but Vyn said it is important to take several different management factors into account when making planting decisions.

"No single factor will take corn yield from 125 bushels per acre to 200 bushels per acre," he said. "Fertilizer, plant population, hybrid choice, pest control and timing all go into creating the optimum planting season."

Writer: Jennifer Doup, (765) 494-8406, doupj@purdue.edu

Source: Tony Vyn, (765) 496-3757, tvyn@purdue.edu

Related Web site:

Purdue Extension Farming 2003 Web site: http://www.ces.purdue.edu/farming2003

Purdue News Service: (765) 494-2096; purduenews@purdue.edu


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