Mother Nature didn't play be the rules last year. And the yields produced last year compared to planting dates were nothing short of amazing. However, crop consultants warn that one of the biggest mistakes in farming can be basing what you do this year on what happened the previous season.
The chart in the Purdue University Corn & Soybean Field Guide shows that the best you could expect on corn planted May 30 with a perfect stand would be 80% of the original potential in that field. If you were expecting 200 bushels per acre if you could plant on time, then you would expect 160 bushels per acre.
So how did some fields planted that late yield 220 bushels per acre last year? Does that mean they would have yielded 275 bushels per acre planted on May 1? Probably not, although there's no way to prove it.
Weather experts note that last year was unusual with one of the coolest July's on record. There was also ample moisture in most places. Corn likes cool, moist weather at pollination time. The weather pattern that persisted a year ago made for tremendous yields, although it also made for a very late fall with high moisture content in grain. That necessitated firing up dryers that hadn't been used extensively in a couple of seasons.
Results from the long-term Beck's Hybrids Practical Farm Research plots at Atlanta, Ind., make the point about last year vs. most years. This demonstration is referenced in the May issue of Indiana Prairie Farmer. However, some of the numbers were incorrect in that story. We apologize for any inconvenience. Here are the proper numbers for the long-term average and for last year.
Averaged from 1998 through 2009, highest corn yield in the Beck's study occurred at March 21 to April 3 and April 15 to April 30 planting dates. Yields were above the trend line average for the trial in those two time slots. Corn planted April 4 through April 14 and May 1 through May 13 were just about at trend, or 100% of average for the entire period. Yields were slightly below 100% for May 14 to May 28 plantings, and just above 80% of the average for corn planted May 29 through June 9.
The tables were flipped last year, however. In 2009, the highest yield, 246 bushels per acre, came for corn planted May 11. Yields for May 20, May 27, June 5 , March 21 and April 24, respectively, were 242, 240, 224, 177 and 212 bushels per acre. Corn planted June 5 yielded 12 bushels per acre more than corn planted April 25.
That's why good research covers more than one year, experts say. You can base planting decisions the rest of this season on last year's numbers and hope this year is just like last year, or you can be guided by 12 –year averages, which include last year, and arrive at an entirely different conclusion. The choice is yours.