Cropside: Starter fertilizer

IT’S A COMMON question from strip tillers: is there still response to starter fertilizer on the corn planter after delivering good fertility in the strip with the strip tiller? For simplicity, it would be ideal if all potential yield response to fertilizer could be met with strip tiller placement alone. Talking with growers, opinions are mixed. Some suggest not enough response to justify outfitting planters with starter, while others still like some at planting.

In Ontario research, yield response to starter fertilizer on the corn planter in a strip till system has been mixed. Early trials that fall banded phosphorus (P) and potassium (K) fertilizer to the bottom of a shank (6” deep) (Figure 1) with early strip till equipment still demonstrated strong responses to starter fertilizer on the planter (Figure 2) where soil test levels were low.

As Greg Stewart, who conducted many of these trials, suggests, deep shank placement may be hiding fertilizer too far from the seed to provide any early season starter effect. In contrast to fall banding fertilizer, a more recent project compared mixing 30 lb/ac of each N, P2O5, and K2O throughout the strip (Figure 3) in spring with a newer coulter-style strip tiller to applying the same fertilizer as starter in a 2” x 2” band on the planter on an unfertilized strip. Responses were variable, but starter placement appeared to provide some benefit at some locations (Table 1).

On-farm and small plot trials are planned to help answer this question in 2019. If you are delivering fertilizer with a strip tiller and have starter fertilizer capabilities on your corn planter (2” x 2” or in-furrow), we would be interested in more participants in future years. Treatments are simple — randomize four side-by-side strips of starter fertilizer on (treatment 1) and starter fertilizer off (treatment 2) over fertilized strips. Growers are free to use practices of their choice (timing, products, rates, placement) provided we document what they are. Contact me, Ben.Rosser@ontario.ca, if you are interested in participating. •