Yield and quality responses of irrigated timothy to fertilizer application in southern Alberta

Abstract

Timothy (Phleum pratense L.) hay production for export markets has expanded considerably in western Canada during the past decade. Fertilization practices for optimum yield and quality of irrigated timothy were investigated for 4 yr at two locations in southern Alberta. The efficacy of spring-broadcast urea and ammonium nitrate (AN) were similar and greater than that of controlled-release urea. The optimum N rate for dry matter yield was approximately 130 kg N ha-1 for the first cut and 110 kg N ha-1 for the second cut, depending on crop and fertilizer prices. Both green colour and brown leaf ratings increased with N rate, with optimum colour for the first cut obtained with 100 to 150 kg N ha-1. Digestibility was unaffected by N rate except when crops were very deficient in N. At the location where timothy was responsive to P fertilization, yields were similar with annual broadcast applications of 13 kg P ha-1 or one pre-seeding application of 86 kg P ha-1. Timothy yield and quality were not responsive to K fertilization, although high K removal rates may shorten the period until K deficiencies develop. High yields of timothy hay (average 11 Mg ha-1 yr-1) were consistently obtained with adequate N and P fertilization. Key words: Phleum pratense, controlled-release urea, ammonium nitrate, phosphorus, digestibility