Ten years of data collected in practical farm research by Beck's Hybrids, Atlanta, Ind., near the home plant point to the same conclusion. Earlier-planted corn tends to yield more than late-planted corn, even if later-planted corn has higher harvested population than the very earliest-planted corn. That result verified itself again in 2007, as reported in Beck's latest Practical Farm Research Summary booklet.

What's early and what's late needs some explanation and definition. And that's where some variation comes in year to year, the report notes. The earliest planting dates in '07, March 30 and April 7, had lower populations, and thus lower yields than April 19, 30 or May 10. However, the yields were still above 200 bushels per acre at all of those dates! Yield peaked at 231.6 bushels per acre, for an average of two hybrids, on April 30. The highest individual yield came for a single hybrid planted May 10, at 261.7 bushels per acre. The same hybrid planted April 30 yielded 252.9.

Yield was still above 200 bushels per acre, but lower than any of the previous planting dates, for corn planted on May 24. Yields on June 6 planting declined considerably, averaging 172.4 bushels per acre.

Lower populations on the earliest-planted corn is a consistent trend, and shows up as such in the 10-year average. However, yields for late March and April-planted corn on the 10-year average are still slightly higher than anything planted May 1 or after! The booklet contains a bar graph, prepared by comparing average yield over the 10 years at each planting date to the overall average. Yield doesn't drop below the overall average until planting dates of May 14 or later. It falls drastically for corn planted May 29 or later, even though harvest populations are still much higher than for the plots planted in late March or very early April.

There were differences observed in the two hybrids in the study in how they performed in '07, the report observes. Actually, the hybrid that emerged fastest wound up yielding considerably less. Beck's personnel contribute it to the excellent yield potential of the second hybrid. However, the earlier-emerging hybrid was 2% drier in grain moisture at harvest.

Grain moisture for the first three planting dates was 18% or less. The April 30 planting date averaged 20%, and the May 10 planting date was 25%. Moisture content actually dropped for the last two planting dates. The plot was harvested on September 19.