Effect of phosphorus fertilization on bromegrass hay yield

A field experiment was conducted on a Black Chernosemic silt loam soil at Lacombe in central Alberta to determine the effect of P applications on dry matter yield and concentration of protein and N03‐N of smooth bromegrass (Bromus inermis Leyss.). Treble superphosphate was applied annually for 5 years at 0, 10, 20, 30, 40, and 60 kg P/ha, and once initially at 60, 120, and 180 kg P/ha. The P fertilizer was incorporated into soil before seeding bromegrass for the initial applications, and the subsequent annual applications were spread on the soil surface. The total dry matter yield (TDMY = cut 1 + cut 2) increased with P rate, but the yield response was proportionately greatest at 10 kg P/ha. The P fertilizer did not affect protein or NO3‐N concentration in hay. The residual effect of P on TDMY lasted for at least 5 years.