In-furrow Fertilizers

Do they impact seed emergence?

Fertilizers when applied in-furrow with peanut seed are not recommended by the University of Georgia and could be the cause behind some germination issues and late emergence of plant stands.

In recent years, there has been a rise in seed germination complaints. However, Scott Monfort, University of Georgia Extension peanut agronomist, discovered in some cases the culprit was the addition of in-furrow fertilizers when applied with seed.

Monfort wants growers to know in-furrow fertilizers have never been recommended by UGA.

“Recently, farmers have used more liquid in-furrow treatments, so it is an easy avenue for growers to try new items such as in-furrow fertilizers,” Monfort adds.

Normally, the skippy stands and late emergence of plants would have been noted as a seed quality issue but once Monfort visited the fi elds, he noticed a diff erence in certain spots within the fi eld.

“There was a row every once in a while, that would come up perfectly fi ne while the rest of the rows would look bad,” Monfort says. “This was all due to a clogged tube in the planter so the infurrow treatments were not going out on the row, and we discovered it was an issue with in-furrow fertilizers.”

Even though UGA did not recommend in-furrow fertilizers, the university did not have any data to show what could happen to the peanut crop. This led to a research project by Monfort and a UGA student where peanuts were grown on the fl oor of a greenhouse with sandy loam soil in Tifton. The greenhouse atmosphere provided a more controlled environment for the research. “We devised a test using a half gallon, 1 gallon, 2 gallons and 3 gallons of in-furrow fertilizers which were applied in-furrow with 7 gallons of water total volume,” Monfort says.

Over the course of 14 days, the untreated check came up fi rst, around 5 to 6 days the plant stand started to crack through the ground. Almost all of those plants came up and started to emerge over the course of 14 days, and 30 to 40 percent emerged within 5-7 days.

“If you looked at the seed treated with in-furrow fertilizers, there was a decrease in the amount of emergence and in how quick those plants came up,” Monfort says. “The half gallon and the 1 gallon did not look as bad and had just about 3 or 4 points on average lower than the untreated control on total amount of plants that came up. Whereas the in-furrow fertilizer rates of 2 and 3 gallons had quite a bit less.”

Approximately 84 percent of the untreated seeds emerged compared to the half gallon and 1 gallon in-furrow fertilizer treatment which resulted in 80 to 81 percent plant stands within 7-9 days. The ones with 2-to-3-gallon rates of in-furrow fertilizers never got above 70 percent plant stand.

“So, we lost quite a bit of seed there that never emerged. They rotted because of injury from the in-furrow fertilizer,” Monfort says. “Farmers may think it looks like the half and 1 gallon looks good so they should be okay to use it.”

However, Monfort says, growers should look at how quick the seeds emerge out of the soil compared to the untreated check. He adds, even though growers may discover at the end of 14 days the plant stands look comparable, it actually took 2-3 more days for the seeds to emerge.

The untreated check came up real quick within 5-6 days while it took 7-9 days before the half gallon and 1 gallon treatment came up and emerged. So, there was about a 2-3 day delay in the emergence rate.

According to Monfort, this becomes important when battling tomato spotted wilt virus and can lead to problems.

“That’s why we think that no matter what rate you put out, you are doing something to the seed that is slowing it down,” Monfort says. “We are trying to encourage growers to be cautious and aware of the risks since Extension is not recommending the use of in-furrow fertilizers.”

Since the greenhouse studies were done in a controlled environment with good warm soil temperatures and good moisture, Monfort is looking to continue the research to see if there are diff erences in hot, dry soils. He will be adding more studies this season in fi eld trials across dryland and irrigated fi elds in South Georgia. 