Soil scientist Don Howard says farmers should think of starter fertilizer as being just like any other tool — one they only use when needed and when they can best fit it into their management systems.
“One thing farmers should realize is that they should not expect to get a yield increase from a starter fertilizer every year,” he said. “Some growers have evaluated it one year, didn't get a response and discontinued using it.”
Speaking at the National Conservation Tillage Conference in Tunica, Miss., Howard said that, in general, starter fertilizers provide a yield response when soils are cold. “That's when you want to use a starter. You can push that window of planting time just a little earlier than you normally would.
“Once you get on up into the planting season and soils begin to warm up, you should eliminate that starter fertilizer because it probably will not work as efficiently as it did earlier in the year.”
Howard, professor emeritus with the University of Tennessee, also cautioned growers to make starter fertilizers fit their management schemes.
“Don't put out a rate of starter fertilizer that will require you to stop and fill up the fertilizer tank before you have to fill up the seed hopper,” he noted. “Planting is the most important and costly thing you do, and you don't need to slow down that planter.”
In tests in no-till corn, starter fertilizers applied in-furrow increased yields an average of 10 bushels per acre over a three-year period in west Tennessee, according to Howard, who retired from the University of Tennessee's West Tennessee Experiment Station at the end of 2001.
The UT- Milan Experiment Station and the West Tennessee Station in Jackson were responsible for much of the pioneering work in no-till crop production systems in the South over the last two decades.
“We really didn't have any choice about going to no-till,” Howard told farmers attending the Fifth Annual National Tillage Conservation Conference. “From our rolling soils in west Tennessee, we were losing an average of 40 tons of soil per year to erosion. With no-till, we've reduced that to an average of eight tons per year.”
Howard said starter fertilizers can be important in no-till because soils frequently are cold and wet when farmers normally begin planting corn. It's not that they're any colder than conventionally tilled soils, however, he notes.
“Most people will tell you that no-till soils are colder than conventional soils,” he said. “There are situations in which they are reversed. When it's cold in the spring and raining, conventionally tilled soils are colder by one-half degree to a degree than no-till because they're holding moisture. The no-till soils let the moisture go on through the profile.”
Nevertheless, soils can be cold when they are planted no-till because farmers don't have to delay planting while waiting for soils to dry enough for conventional tillage equipment.
Howard said in-furrow applications of up to 30 pounds of nitrogen per acre increased corn yields without reducing plant population in the loess-derived soils of west Tennessee. Adding phosphorus or potassium to the starter fertilizer application did not appear to increase yields.
“Some people say that if you keep phosphorus and potassium at medium soil tests, you reduce the need for a starter fertilizer,” he noted. “Our studies show that if you broadcast apply P and K, the yields are just as high as if you band them behind the planter or inject them.
“Again, just broadcast the P and K and be done with it. Don't slow down the planter to band or inject those nutrients under or beside the row.”
In his paper, Howard said other studies have indicated that in-furrow starter applications were also safe on medium-textured soils and increased yields.
“However, research conducted on coarse-textured soils showed that in-furrow applications reduced plant populations and should not be considered as a starter application.”
In-furrow applications of 10 pounds of nitrogen per acre on the medium-textured or silt loams or silty clay loams increased no-till corn yields, he said.