Corn and soybean yield can be estimated in the field by calculating the number of grains in 1/1000th of an acre. Select several locations in the field and count the number of corn ears or soybean plants in 1/1000th of an acre. When the crop is planted in 30-inch rows, count the number of ears/plants in 17 feet 5 inches of row. When it is planted in 15-inch rows count 34 feet 10 inches of row. For 7-inch rows count 74 feet 8 inches of row.
To estimate corn yield, count the number of ears in 1/1000th of an acre. Then count how many rows there are on the ear of corn and the number of kernels per row. Multiply the number of rows by the number of kernels per row to determine the number of kernels per ear. Select five ears and average the kernel count. Multiply the average number of kernels per ear by the number of ears in 1/1000th of an acre. On average, there are 85,000 kernels of corn per bushel. Divide the number of kernels in 1/1000th of an acre by 85 to estimate corn yield. Do this in several locations in the field to get an average grain yield.
Estimate soybean yield by counting the number of plants in 1/1000th of an acre. Count the number of pods on 10 to 15 plants and average that number. On average there are 2.5 seeds per pod. Multiply plants per 1/1000th of an acre by pods per plant by 2.5 seeds per pod and divide by 162. There are approximately 162,000 seeds in one bushel of soybean.
For more information contact Valerie Tate, Field Specialist in Agronomy for University of Missouri Extension in Linn County by email at firstname.lastname@example.org or call 660-895-5123. MU Extension programs are open to all.