Greenhouse Evaluation of Commercial Fertilizer Sources Placed On the Corn Seed In Three Soils.

Fertilizers placed on the seed in corn (Zea mays L.) are commonly used in the Northern Corn Belt due to cool and wet early growing seasons.  A study was conducted to determine the effect of commercially available liquid fertilizer sources placed on the seed for three Minnesota soils. Five liquid fertilizers sources were tested with differing textures of fine sandy loam, silt loam, and clay loam. The fertilizers used were 12-0-0-26, 28-0-0-0, 9-8-7-0, 7-9-6-0, and 10-15-0-0 (N-P-K-S).  Fertilizer was applied as a liquid directly to the seed at six rates according to total N, 0, 1.1, 2.8, 5.6, 11.2, and 22.4 kg N ha-1, equivalent to rates applied with a planter in 79 cm rows. Corn was allowed to grow for fourteen days following the first plant emergence. The plants were observed daily and counted for emergence. At termination, the plants were harvested and height and weight measurements were taken.  Plant emergence, height, and weight decreased as fertilizer rate increased.  Soils differed in all measured factors except for 12-0-0-26.  In most cases the effect of fertilizer source was similar for the silt- and clay loam soils.  Damage potential was greatest for the sand relative to the other soil types.  Depending on the soil type and fertilizer source, corn emergence was maintained near 100% with 0 to 10 kg N ha-1.  Maximum plant weight was achieved from between 0 and 17 kg N ha-1.  In terms of damage potential, 12-0-0-26 caused a high potential for stand loss followed by 28-0-0-0, 9-8-7-0, 10-15-0-0, and 7-9-6-0.  All sources can potentially be used for on seed placement but rates need to be low to minimize stand loss.