Corn silage and grain yield responses to plant densities

Many corn (Zea mays L.) producers in New York harvest fields for either silage or grain, depending upon growing conditions, storage space, and grain prices. Corn producers, who plant corn for dual purposes require more information on silage and grain yield responses of modern hybrids to plant density. Silage and grain yield responses of seven commercial hybrids were evaluated at harvest densities from 12 000 to 36 000 plants/acre on a well-drained soil in a wet (1992) and dry (1993) year to compare optimum plant densities among hybrids with recommendations by seed companies and Cornell Cooperative Extension. When averaged across hybrids, optimum densities for corn silage exceeded 36 000 plants/acre in 1992 and averaged 35 231 in 1993. When averaged across hybrids, optimum densities for grain exceeded 36 000 plants/acre in 1992 and averaged 30 452 in 1993. Apparently, plant densities should average about 7.5% higher for silage than for grain on well-drained soils in New York Hybrid responses to plant density varied most in the dry year when optimum silage and grain densities ranged from about 27 500 to above 36 000 plants/acre. Optimum silage and grain yield densities did not vary much among hybrids with fixed, flex, and semi-prolific ear types. Optimum grain densities in this study exceeded the 1992 recommendations of seed companies and Cornell Cooperative Extension by more than 6000 plants/acre. Seed companies and Cooperative Extension should periodically evaluate plant density responses of newly released hybrids in specific growing regions to accurately adjust plant density recommendations.