What is in this article?:
- Odd field patterns help identify yield variation at plant level
- Plant height variation losses
- Mirrors old Purdue research
- Aerial images that show visual patterns in a field can be the first step in discovering problems that affect yields. Follow that up with detailed plant-by-plant analysis on the ground to verify the impact of the problem in yields and more objectively zero in on the problem.
- Aerial photos early or late in the day produce shadows that point out subtle plant height variations; plant height within a field correlates with ear size and yield.
- A close look at plant spacing and projected yields from single ears in a 17-foot, 5-inch span (1/1,000 acre in 30-inch rows) vividly shows planter skips and barren plants are yield killers.
Mirrors old Purdue research
Bob Recker’s plant-by-plant findings confirm long-term research by Purdue University that plant-to-plant variability matters in corn yields, especially in no-till continuous corn. A 14-year study there from 1981 to 1994 showed greater plant height variability at week 4, especially in no-till continuous corn, was associated with yield drops. In that study, increases of 23% to 30% variations in plant height were associated with 6-bushel to 41-bushel per acre drops in yield. No-till continuous corn had the greatest plant height variability and lowest yield (see table).
“We now know that the variation in final plant yield has very little to do with small differences in seedling emergence time or even plant spacing,” says Purdue Agronomy Professor Tony Vyn, who led research in this area. “Plant-yield variability has a lot more to do with variation in flowering times and stalk diameter near flowering stage. Plant heights are one indicator of a plant’s competitiveness, but stalk diameter and the time between pollen shed and silk emergence is another,” Vyn adds.
“Another really important story is that plant-to-plant variation really increases with plant stress in the season resulting from things like high plant density or low N fertility. ”
His research recommends paying close attention to management practices that reduce variability that include 1) distribute residue evenly, 2) avoid soil compaction, 3) place seed with consistent spacing and depth, and 4) apply N precisely and consistently at a safe distance from each plant in the row. For more information see http://bit.ly/uniformPurdue
For more reading on the importance of plant uniformity, see http://bit.ly/QControl.