Initiation Date and Nitrogen Rate for Stockpiling Smooth Bromegrass in the North-Central USA

Increasing costs associated with winter feeding have renewed interest in extending the grazing season in the North-Central USA. A factorial design with three N treatments was applied to existing smooth bromegrass (Bromus inermis Leyss.) pastures to evaluate initiation dates and N fertilization rates for stockpiling forage. Stockpile initiation dates were 1 June, 15 June, 1 July, 15 July, 1 August, and 15 August. Nitrogen fertilization treatments were 0, 56, or 112 kg ha-1. Data collected included forage mass in October, residual forage mass the subsequent April, leaf concentration, and forage nutritive value. October forage availability was generally greater from earlier stockpile initiation dates (2.58, 2.44, 1.98, 1.28, 0.78, and 0.65 Mg dry matter ha-1 for 1 June, 15 June, 1 July, 15 July, 1 August, and 15 August stockpile initiation dates, respectively; LSD at 0.05 = 0.19). Leaf mass available in October was similar through the 15 July stockpile initiation date. October forage mass was greater with 56 kg N ha-1 than with 0 N fertilization, averaging 1.26, 1.75, and 1.85 Mg ha-1 (LSD at 0.05 = 0.14) for 0, 56, and 112 kg N ha-1, respectively, when averaged across stockpile initiation dates and years. Trends in April forage mass for stockpile initiation date and N fertilization tended to be similar to October. Crude protein tended to increase and acid detergent fiber and neutral detergent fiber tended to decrease as stockpile initiation was later in the season. These results indicate that initiating stockpiling of smooth bromegrass-dominated pastures about 1 July with 56 kg N ha-1 optimizes stockpiled smooth bromegrass in the North-Central region.