Evaluation of seed placed fertilizer rates
Questions that now remain unanswered are urea impacts on calcareous soils and the role that ammonium sulphate might play in various mixes with urea and what the safe rates of combined N,P,K and S fertilizers might be.
IPNI-1995-CAN-SK13
30 Aug 2001
Justification
- Across western Canada, there is a significant trend towards one pass seeding systems in which seeding and fertilizing can be accomplished in one field operation. This movement has resulted in a sharp increase in the demand for information regarding safe rates of fertilizer that can be placed with the seed. Urea is the major nitrogen source where seedling damage might be expected so a significant amount of field and growth chamber work has been done on urea in the past five years. In Saskatchewan, this work has culminated in the production of recommendations and a bulletin providing guidelines for safe rates of seedplaced urea in consideration of modern air seeder equipment with a variety of openers for placement of seed and fertilizer. That bulletin has been in very high demand and went through three printings in the first edition. A revised edition is now in distribution.
Questions that now remain unanswered are urea impacts on calcareous soils and the role that ammonium sulphate might play in various mixes with urea and what the safe rates of combined N,P,K and S fertilizers might be. Attempts to use literature values and salt index considerations for other fertilizer elements have proven ineffective. If we are to provide farmers with meaningful recommendations about N,P,KS blends applied with the seed at high rates, more research must be done.