Effects of Nitrogen Fertilization Rate, Stockpiling Initiation Date, and Harvest Date on Canopy Height and Dry Matter Yield of Autumn‐Stockpiled Bermudagrass

Autumn stockpiling is a management technique in which forage is allowed to accumulate throughout the late summer and early fall for subsequent grazing throughout the late fall and winter. Well‐established stands of common and ‘Tifton 44’ bermudagrass [Cynodon dactylon (L.) Pers.] located at Fayetteville and Batesville, AR, respectively, were chosen to evaluate the effects of stockpiling initiation date (August or September) and N fertilization rate (0, 37, 74, or 111 kg N ha−1) on the canopy height and dry matter (DM) yield potential of autumn‐stockpiled bermudagrass forage. Within year, DM yield increased linearly (P ≤ 0.008) with N fertilization rate at Fayetteville in 2001 and in Batesville during both years. For August initiation dates, DM yield declined linearly (P ≤ 0.007) with harvest date at both sites during both years; however, cubic responses (P ≤ 0.024) also were observed at both sites in 2000 but not (P ≥ 0.076) in 2001. For September initiation dates, DM yield exhibited less consistent patterns over harvest dates, but responses were cubic (P ≤ 0.053) over time for all four site‐years. Tests of homogeneity for regressions of DM yield on canopy height for individual site‐years indicated there were differences for the intercepts (P < 0.001) and linear coefficients (P < 0.001) and a tendency for the quadratic coefficients (P = 0.063) to differ. Quadratic equations are not suitable for producer use; therefore, a combined linear model for all data (N = 512) was determined, Y = 146X − 838 (P < 0.001; r2 = 0.762), which may address the need for a quick estimator of available forage.