Starter fertilizer has become common place in today’s row crop production systems. This approach of applying fertility at planting takes many forms–with the seed, 2’’ by 2’’, 2” to the side on the surface or simply on the ground behind the press wheel. The goal is to provide vital nutrients to young plants to overcome cool soils or low fertility. Starter fertilizer is not a replacement for a good overall approach to fertility. Rather, starters are a management choice to ensure even emergence and solid early crop growth.
Questions about Starter Fertilizer
The most common questions surrounding starters are always focused on rates and what nutrients can be applied. To answer these questions, we often turn to salt index. In general phosphate fertilizers will have lower salt indices with nitrogen and potassium fertilizers having higher indices. It is always important to remember that thiosulfate can be very toxic to seedlings and should not be used unless the starter is placed well away from the seed trench. For corn production, Ward Laboratories has always used a factor of 8 pounds of N plus K2O as a limit of fertilizer that can be applied with the seed on 30-inch rows. For producers using narrower rows this rate can be elevated to 12 pounds. Those that are on 36-inch operations should keep these rates to 6 pounds or less.
Other factors to consider when finalizing rates are soil moisture, texture and organic matter. Purdue University recommends dropping the 8-pound rule to 5 pounds when dealing with sandy soils with CEC less than 7. It may also be necessary to reduce rates in abnormally dry soils.
Ward Laboratories, Inc. is here to support all your crop production fertility management decisions. Soil and fertilizer analysis goes hand in hand. We have soil scientists and agronomists on staff to help with recommendations based on sampling.
Originally printed in April 2020 Ward Letter.