The Effects of Chloride and Potassium Nutrition on Seed Yield of Annual Canarygrass

The year-to-year variability of seed yield in annual canarygrass (Phalaris canariensis L.) is a major concern among growers. A field experiment was conducted at 13 site-years across Saskatchewan to determine the response of annual canarygrass seed yield to K and Cl, and to provide better recommendations to producers on the use of KCl fertilizer in annual canarygrass based on soil test results. Potassium did not affect the yield or development of annual canarygrass over a range of 155 to 717 kg K ha(-1) in the top 15 cm of soil. Chloride had a large impact on annual canarygrass seed yield; seed yield increased by approximately 24% when Cl was added in the form of KCl or CaCl2 when averaged across all sites. The seed yield increased because the application of Cl increased panicle size (seeds panicle(-1)). The magnitude of the response tended to increase as level of Cl in the soil decreased. Annual canarygrass growers need to measure Cl when using soil tests to determine fertilizer requirements. It is recommended that 9.1 kg Cl ha(-1) in the form of 20 kg ha(-1) of KCl be applied when the Cl level in the surface soil (0-15 cm) is below 70 kg Cl ha(-1). The findings encourage growers to conduct individual field test strips to determine the strength of the Cl response.