As farmers are preparing for the upcoming planting season, a common question is “What is the maximum amount of fertilizer that can be in-furrow applied with crop seed?” Two references are available to help answer this question.

1. NDSU Extension Service circular EB-62 ‘Fertilizer application with small grain seed at planting’. The publication lists many factors involved with determining small grain seed tolerance to fertilizer placed with the seed. Two tables in the publication show the maximum nitrogen fertilizer rates based on planter spacing, planter type, seedbed utilization and soil texture. For example, the maximum N rate for placement with wheat seed planted with an air seeder with 10-inch row spacing and 4-inch seed spread is 37-48 lb of N/acre. The publication can be found at the website: http://www.extension.umn.edu/agriculture/small-grains/nutrient-management/docs/fertilizer-application-with-small-grain-seed-at-planting.pdf.
2. SDSU has an electronic fertilizer seed decision aid.  The recommendation on maximum amount of fertilizer applied with seed can be determined by choosing numerous crops and fertilizers, plus seed furrow width, row spacing, tolerated stand loss (%), soil texture and soil moisture at planting.  As an example, the maximum rate of 10-34-0 liquid fertilizer for placement with soybean planted in 22-inch rows in medium-textured soil that is moist at planting time is 1.2 gal/acre. The Excel file can be used on your computer or as an app on your mobile device. The website: www.sdstate.edu/ps/extension/soil-fert/fertapp.cfm.

Greg Endres
Area Specialist, Cropping Systems