It was just after midmorning as the high-clearance sprayer made its way through the field. The farmer was applying foliar fertilizer containing sulfur and other nutrients in corn at about the 12-leaf stage. He was using Y-Drops with undercover nozzles to spray near the top of the corn plants. When asked after harvest, he said he felt the application paid. He skipped one pass as a check. Yield was definitely lower on that pass, he noted.
Why is it important to indicate what time of day the farmer sprayed in this description? Although he didn’t know it at the time, it turns out that when foliar nutrient applications are made in corn may affect the size of the yield response from the application.
After hearing theories, Beck’s staff members decided to include a study in their Practical Farm Research program at the Atlanta, Ind., location to test what sounds like an odd theory. Could when you apply foliar fertilizer really make a difference in how effective it is at helping the crop?
Ryan McAlllister heads up Beck’s PFR program. The 2016 Beck’s Practical Farm Research book contains a summary of a trial set up to test the theory. One quart per acre of a foliar product, Versa Max Corn, was applied over V5 corn. Two hybrids were included in the study, and applications were made at two different times: 8 a.m. and 3:30 p.m.
The yield boost for making that single change — time of application of foliar fertilizer during the day — averaged 4.2 bushels per acre over both hybrids. The yield increase was 6 bushels per acre for one hybrid and 2.4 bushels for the other.
It’s just one year of data. Most agronomists warn people to be very cautious in making decisions based on one year of data. However, if this observation proves to be accurate, it means you can increase yield just by changing timing of application. It wouldn’t cost more unless you have so many acres to cover that you can’t make timely applications only running in the mornings.
Sulfur soil test levels were low where Beck’s conducted this trial. Joe Nester of Nester Ag, Bryan, Ohio, says he’s seeing more low sulfur tests. The nutrient is no longer free in the air, thanks to the Clean Air Act, he notes.
Tissue test results helped Beck’s determine that 28% more of the phosphorus applied and 18% more of the nitrogen applied made it into the plant during the morning application compared to the afternoon application. Adequate sulfur levels help deliver better N-use efficiency.
Temperature may be the determining factor, as noted in the Beck’s report. The temperature was 70 degrees F during the morning and 88 degrees in the afternoon. As heat stress increases, plants close the stomata on leaves to conserve moisture. When this happens, plants are less productive.