Corn Response to Starter Fertilizer
Greg Roth
Department of Crop and Soil Sciences
Penn State
March 1999
What benefit do you get from the use of a starter fertilizer? Does the particular hybrid you are planting make a difference in your answer to the previous questions? Unfortunately there is no simple answer to these questions. You may be surprised at the results of two separate university trials which address these issues.
From 1995-97 a study evaluating the effectiveness of starter fertilizer applications to 12 different varieties of corn was conducted at the Kansas State University Agricultural Experiment Station. This particular trial evaluated the response of 12 hybrids to the application of a 30-30-0 (lbs per acre N-P2O5-K2O respectively) liquid starter fertilizer on soils with high available phosphorus. The starter was a blend of UAN and 10-34-0. Seven of the 12 hybrids had a significant increase in 3 year average yield. The hybrids were chosen from 5 different seed companies and all but one company had at least one variety which responded to the starter fertilizer.
At the 6-leaf stage of growth, whole plant dry weight, phosphorus uptake, and nitrogen uptake was recorded for the 12 hybrids. All hybrids showed an increased growth response to starter but this translated into a yield benefit for only 7 of the hybrids. Most of the hybrids that responded to the starter fertilizer required fewer days to midsilk where a starter was used and the researchers feel that factors that promote earliness are also associated with higher yields.
They have also found that altering the starter blend did not influence the responsiveness to starter fertilizer. The Kansas researcher have found the same trend on grain sorghum hybrids.
We conducted a similar experiment in Pennsylvania in 1998. In this trial, 6 hybrids were evaluated for their response to the application of a starter application of 14-28-28 (lb. per acre N-P-K respectively. The field used in this trial was deficient in P and K, so one would assume that that all six hybrids would have a significant increase in yield due to the starter fertilizer. However, although all six hybrids showed an early season growth response to starter fertilizer, only three of the six hybrids showed a significant increase in final yield. As with the Kansas State study, the Pennsylvania study concluded that the choice of hybrid has an impact whether or not the final yield is influenced by starter fertilizer.
The results of these experiments indicate that response to starter fertilizers are apparently influenced by genetics. Understanding this better could help us figure out where and when and if starter fertilizers are justified on high testing P and K soils.