October 14, 1999 6(26):157-158

Joe Lauer, Corn Agronomist

The relationship between corn grain yield and silage yield is important for determining Loan Deficiency Payments. The current method for calculating this relationship first appeared in 1972 (Table 1). Much progress has been made in breeding adapted high yielding hybrids that are more resistant to biotic and abiotic stresses. Does the old relationship between grain and silage yield still hold?

To describe the relationship between grain and silage yield, data were used where plots had been split with half of the plot harvested for silage yield and the other half harvested later for grain yield. Treatments applied to these plots included various plant density, planting date and row spacing factors. Numerous locations, hybrids and yield levels were obtained over the 1997 and 1998 growing seasons (n = 253).

The relationship between grain and silage yield for current hybrids is described in Figure 1. Grain equivalents at two silage moistures are shown in Table 2. Current hybrids produce grain yield equivalents greater than that of 1972 levels, by 1.0 to 2.0 bushels of grain per ton of silage at 65% moisture. Using the relationship developed in 1972 would under estimate grain yields for calculating Loan Deficiency Payments using modern day hybrids. Further investigation is required to properly describe this relationship.