Plant density and hybrid influence on corn forage yield and quality

Corn (Zea mays L.) hybrid selection and plant density are important management considerations for successful forage production in dairy and livestock operations. The objectives of this study were (i) to determine the effect of plant density on high- and low-quality corn hybrids and (ii) to describe the economic trade-off between plant density and forage yield and quality. Two adapted hybrids selected for high and low quality characteristics were grown in the field at five plant densities ranging from 44 500 to 104 500 plants ha(-1) at six locations in Wisconsin during 1994, 1995, and 1996. Forage quality response among hybrids was similar across the range of plant densities evaluated. As plant density increased, dry matter yield increased 1.7 to 4.1 Rig ha(-1), depending on location. Maximum dry matter yields were observed at 97 300 to 102 200 harvested plants ha(-1). In vitro true digestibility decreased 16 to 23 g kg(-1) as plant density increased. Crude protein decreased 6 to 8 g kg(-1) as plant density increased. Neutral-detergent fiber increased 20 to 35 g kg(-1), and acid-detergent fiber increased 19 to 29 g kg(-1) with increasing plant density. A tradeoff exists between yield and quality for corn forage, Milk Mg-1 decreased 98 to 143 kg milk Mg-1 with increasing plant densities, but milk ha(-1) increased 926 to 2176 kg milk ha(-1) until about 75 000 to 85 000 harvested plants ha(-1), and did not change with higher plant densities.