Source: Ohio State University
By Steve Culman, Anthony Fulford, Laura Lindsey, Douglas Alt, Stuti Sharma and Grace Looker
Ohio farmers often wonder if micronutrient fertilization will increase grain yields. A recent study exhaustively compiled the last 40 years of Ohio State University micronutrient fertilizer trials in corn, soybean and alfalfa. A total of 194 trials (randomized and replicated) were found across 17 Ohio counties. In general, micronutrient fertilization rarely resulted in a statistically significant yield response. Manganese (Mn) fertilization or a blend of Mn with other micronutrients increased soybean yield in 9 out of 144 trials. Boron fertilization had no effect on corn grain yield in 8 out of 9 trials and actually decreased yield in one trial. Micronutrients had effect on alfalfa yields in 17 total trials.
There is a large degree of uncertainty in using soil tests to reliably predict when a crop needs micronutrient fertilization. This is primarily because yield responses to micronutrient fertilization are uncommon, and without yield responses, soil test critical levels are difficult to develop. It is important to keep in mind that the probability of a yield response to micronutrients is much greater in scenarios where deficiencies are known or suspected to be more prevalent, such as in sandy, acidic, or peat soils. When considering micronutrient fertilization, it is always a good idea to leave an unfertilized strip as a check or control. This will allow you to compare areas that received a micronutrient fertilizer versus an area that did not. Yield monitors or weigh wagons can help you determine if the micronutrient fertilization increased yield and provided an economic benefit.