October 1, 2003 | By: Laura Skillman

Before planting this year’s winter wheat crop, farmers may want to spend some time with their computer reviewing a spreadsheet first developed by a Shelby County farmer and enhanced by a University of Kentucky Cooperative Extension Service specialist.

The spreadsheet originally was developed by Mike Ellis, a no-till farmer, to facilitate drill calibration for different varieties. UK Extension Agricultural Engineer Sam McNeill expanded the spreadsheet to include seed costs and other useful information.

The spreadsheet can be used to compare varieties on a cost per acre basis, which can considerably vary depending on seed size and quality. Since wheat seed is sold by the pound and seeding rates are based on a specified number of seeds per unit area, the smaller seed of good quality is a better buy, provided it has the same yield potential as other varieties being compared.

By simply changing the target population on the spreadsheet, the total amount of seed and its cost for a given operation can be quickly calculated. This is a useful feature that helps farmers select profitable target populations, McNeill said.

To illustrate this point, consider the impact of different seeding rates on a 500-acre operation with four varieties of varying maturity for a typical range of desired plant populations.

A difference of 50 plants per square yard changes the total seed cost by $1,705 or $3.40 per acre.

Seeding rates typically are increased as the planting season progresses. Therefore, the difference becomes even greater when comparing timely planting and late planting rates and can approach $3,410 or $6.80 per acre.

Another factor that comes into play in seeding rates is the amount and condition of residue encountered at planting time in no-till fields.

The economic impact of treating seed before planting also can be evaluated with the spreadsheet. For example, suppose one variety was found to have a 70 percent germination rate, yet when treated with a fungicide the quality improved to a 90 percent germination rate.  As a result, the seeding rate for a target plant population will range from 101 to 130 pound per acre for the 90 percent and 70 percent germination, respectively. As a result, the $1 or less cost of the seed treatment is readily recovered because less seed is needed, McNeill said.

All this information will be for naught, however, if producers don’t take the time to calibrate their drills.

Drill calibration is a key factor toward attaining optimal yield potential. Selecting and achieving the optimum seeding rate during planting requires that grain drills be calibrated for each seed variety/lot that is used, McNeill said.

One study shows that seed metering/delivery units on drills can vary by more than 10 percent above or below the target seeding rate, which affects costs proportionately. Collecting from three to five drop tubes across the length of the drill during calibration is the best way to obtain an accurate measure of seeding rate.

This spreadsheet is provided at no cost and is accessible by the UK Biosystems and Agricultural Engineering department’s Web site at www.bae.uky.edu or through your county Cooperative Extension office.                        -30-                                 


Writer: Laura Skillman 270-365-7541 ext. 278
Source: Sam McNeill, 270-365-7541 ext. 213