Wheat is considered a highly responsive crop to band-applied fertilizers, particularly phosphorus (P). Application of P as starter fertilizer can be an effective method for part or all the P needs. Wheat plants typically show a significant increase in fall tillers and better root development with the use of starter fertilizer (P and N). Winterkill can also be reduced with the use of starter fertilizers, particularly in low P testing soils.
Phosphorus fertilizer application can be done through the drill with the seed. In-furrow fertilizer can be applied, depending on the soil test and recommended application rate, either in addition to or instead of, any pre-plant P applications. The use of dry fertilizer sources with air seeders is a very popular and practical option. However, other P sources (including liquid) are agronomically equivalent and decisions should be based on cost and adaptability for each operation.
When applying fertilizer with the seed, rates should be limited to avoid potential toxicity to the seedling. When placing 11-52-0 or 10-34-0 fertilizer in direct contact with wheat seed, producers should use the guidelines in the table below, assuming there is no added potassium K20.
Air seeders that place the starter fertilizer and seed in a 1- to 2-inch band, rather than a narrow seed slot, provide some margin of safety because the concentration of the fertilizer and seed is lower in these diffuse bands. In this scenario, adding a little extra N fertilizer to the starter is less likely to injure the seed - but it is still a risk.
Certain types of fertilizers should never be applied with the seed, even at low rates. No urea-containing fertilizer (urea, UAN solution) should be placed in direct seed contact. The hydrolysis of urea to ammonia can result in ammonia toxicity to seedlings.
Stacy Campbell is a Crop Production agent in the Cottonwood District (which includes Barton and Ellis counties) for K-State Research and Extension. You can contact him by e-mail at [email protected] or calling 785-628-9430.