The objective of this on-farm study was to determine the effects of corn planting population on forage yield, plant phosphorus (P) concentration, and P removal from the soil. The study was performed on a 200-cow dairy farm located in Virginia. In 2 cornfields, 2 corn hybrids (conventional and BMR) were planted in plots at a theoretical seeding rate of 60,000, 80,000, and 100,000 seeds/ha (LOW, MID, and HIGH, respectively). Each seeding rate had 4 replicates within each cornfield. Corn was planted with a 6-row no-till planter. Plots were 3 (3) 30.5-m long rows separated by 76 cm. Pre-planting fertilization included 112 kg N/ha. The resulting populations were 64,000, 75,000, and 87,000 plants/ha for LOW, MID, and HIGH, respectively. At V6, half of each plot was fertilized with 51 kg N/ha and the other half was fertilized with 102 kg N/ha. At early-dent stage of maturity, 10 plants from each plot were cut by hand (15 cm above ground), weighed, chopped, mixed, and analyzed for DM and P concentrations. Data were analyzed as a split-plot in a completely randomized design. The model included the fixed effects of field, hybrid, planting density, fertilization, and all their interactions, and the random effects of whole and split-plot errors. Dry matter yield tended to differ among planting populations (P < 0.06), being greatest for LOW and HIGH (19.2 Mg/ha) and lowest for MID (17.8 Mg/ha). Dry matter yield was greater (P < 0.01) for the conventional than for the BMR hybrid (20.6 and 16.9 Mg/ha, respectively). Doubling N fertilization at V6 increased DM yield (P < 0.03) from 18.2 to 19.3 Mg/ha. No interaction was observed between planting population and N fertilization (P > 0.22). The concentration of P in the forage differed among planting populations (P < 0.01), being greatest for LOW (0.249% DM) and lowest for MID and HIGH (0.226% DM). Total P removed differed among planting populations (P < 0.01), being greatest for LOW and HIGH (46 kg P/ha) and lowest for MID (40 kg P/ha). In conclusion, under the conditions of this study, high corn planting population resulted in similar DM yields and P removals to those obtained with low planting population, and the concentration of P was reduced at high planting populations.