High corn seeding rates don’t necessarily mean higher profits
Corn planting will soon begin in earnest. But Iowa Soybean Association (ISA) On-Farm Network replicated strip trials show high seeding rates aren’t always better.
More than 200 corn population trials from 2009-2013 indicate lower seeding rates are economically better than high rates the vast majority of the time, especially in dry years. Monday’s U.S. Department of Agriculture Crops and Weather Report said topsoil moisture is rated 38 percent short or very short statewide, while subsoil is rated 60 percent short or very short.
For most corn population trials, farmers compared a difference of 5,000 seeds, or 2,500 higher and lower than the grower’s typical seeding rate. For example, if the rate is usually 32,500 seeds per acre, the trial compared rates of 30,000 and 35,000 seeds per acre.
According to data from On-Farm Network trials, the average yield difference between low and high rates is only 0.9 bushels per acre. And, higher seeding rates don’t necessarily mean higher profits. Trial data can be found on the On-Farm Network’s Replicated Strip Trial Database.
Using $5 per bushel corn and $18.75 for 5,000 seeds ($300 per bag with 80,000 seeds), the database’s return on investment calculator shows high population rates did not provide a return on investment about 80 percent of the time in on-farm trials.
In dry years, it’s even less. In 2012, higher seeding rates were only more profitable 5 percent of the time. Individual results will vary depending on corn and seed prices entered.
“It was surprising to me that in the majority of planting rate trials over the last five years, yield increases from the higher planting rates did not pay for the extra cost of the seed,” said Pat Reeg, On-Farm Network director. “Based on this research it seems the biggest potential from variable rate planting is in seed savings.”
The goal of this trial, and hundreds conducted by the On-Farm Network each year, is to help farmers become more productive and profitable in a sustainable way.
Reeg said there’s two questions population studies help answer: What is the ideal planting rate from a uniform seeding standpoint? Are there places in fields where it makes sense to plant with variable rate seeding?
“Over the last few years, many have said if we want to increase yield we have to increase population. With the price of seed, it’s important that farmers verify that,” Reeg said.
Productivity often varies within fields for a number of reasons. Some areas have better soil and higher water holding capacity and others don’t.