KEY PRACTICE: In the seed row is the best time and place for the first 15 to 20 lb./ac. of phosphate — which is the amount most likely to produce an economic return in the year of application. However, this rate is not enough to match crop removal, which may lead to phosphorus shortages over time.
KEY RESEARCH: Grant, C.A., Agriculture and Agri-Food Canada (AAFC), et al. “The importance of early season phosphorus nutrition,” 2001, Canadian Journal of Plant Science, 81(2): 211-224.
M. Nyborg and A.M.F. Hennig, AAFC. “Field experiments with different placements of fertilizers for barley, flax and rapeseed,” 1969, Can. J. Soil Sci. 49: 79-88.
Phosphate applied in the seed row at rates of 15 to 20 lb./ac. (equivalent to 30 to 40 lb./ac. of monoammonium phosphate) should give each seed equal access to a droplet or prill without compromising seed safety. Seed safety, even at these rates, can be at risk in sandy soils using drills with very low seedbed utilization.
Nyborg and Hennig’s 1969 paper showed plant stand and yield benefits from seed-placed rates around 10 lb./ac. compared to no seed-placed phosphate. However, they also found that yield and plant stand started to fall at seed-placed rates above 20 lb./ac.Open the PDF to read the entire research summary from the 2014 Science Issue of Canola Digest
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