Responses of residual and recommended N, P, K, S nutrients and crops to six annual soil test-based fertilizer rates and seeding systems

Abstract

Responses of residual and recommended nitrogen (N), phosphorus (P), potassium (K), sulfur (S) nutrient amounts and crops (yield, emergence, and height) to 0, 60, 100, and 140% soil test-based fertilizer rate applications on the same plots for six years under minimum tillage and direct seeding systems were assessed. Higher fertilizer rates increased residual nitrate (NO₃)-N, extractable K, and sulfate (SO₄)-S amounts after a low crop yield year, particularly NO₃-N, without temporal trend. Increase in residual available P level at higher fertilizer rates showed a positive temporal trend. Lower N, P, and S fertilizer rates were recommended to crops after higher residual NO₃-N, available P, and SO₄-S levels. Crops effectively used the residual nutrients. Compared to 0%, the relative seed yields at 60, 100, and 140% rates increased with years of fertilization. There were no clear responses of measured soil and crop parameters to seeding systems. Testing residual nutrients can optimize fertilizer use and crop yields.

Keywords:

• canola
• emergence
• temporal trend
• yield

Acknowledgments

Sincere thanks are due to the Gauthier Farms Ltd. for providing land for the trial, St. Albert co-operative (Falher) for donating fertilizers, and A&L Laboratory for discount on sample analyses. All the help from staff of SARDA Ag research is appreciated. Thank you to Dr. Tom Jensen and Dr. S.S. Malhi for excellent reviews and suggestions. Very valuable suggestions from anonymous reviewer have substantially improved the manuscript.

Additional information

Funding

Thank you to the Alberta Canola Producers Commission (ACPC), the Alberta Pulse Growers (APG), the Alberta Barley Commission (ABC), the Government of Alberta (Agricultural Opportunity Fund), and the municipal governments of Smoky River, Big lakes, Greenview and Northern Sunrise for funding the project.