Comparing Yield Monitors with Weigh Wagons for On-farm Corn Hybrid Evaluation

For many years, on-farm yield evaluations of corn (Zea mays L.) hybrids were done with weigh wagons, handheld moisture testers, and measuring wheels. Today, most combines have continuous flow yield and moisture sensors. Published research results comparing the accuracy of combine-mounted sensor systems with that of weigh wagons are limited for on-farm corn hybrid evaluation. This study examined the accuracy of combine-mounted yield sensors with traditional weigh wagon methodology in on-farm corn hybrid strip trials. Data from combine-mounted sensors for plot weight, moisture percentage, and yield were compared with weigh wagon weight, handheld moisture testers, and calculated yield in six nonreplicated strip trials in 2012, 2013, and 2014 in east-central South Dakota. A total of 195 total entries were compared. Pearson correlation coefficients and linear regressions for weight, moisture percentage, and yield were calculated for each environment and for all environments combined. The Pearson correlation coefficients across all environments were 0.998 for weight of grain in pounds, 0.928 for grain moisture content percentage, and 0.983 for yield in bushels per acre corrected for moisture content. The probability of nonsignificance for weight, moisture percentage, and yield was P \u3c 0.0001. Linear regression models predicting combine-mounted sensor of sample weight, sample moisture, and yield with the traditional system were significant at P \u3c 0.0001 for all three measurements. Yield monitors can be used successfully for on-farm hybrid evaluations, replacing traditional methods that use weigh wagons, measuring wheels, and handheld moisture testers

performance spreadsheet for radial tires.

Lotus-compatible templates were revised from the Zoz (1987) spreadsheets. Performance of two-wheel-drive (2WD) and four-wheel-drive/mechanical-front¬wheel-drive (4WD/MFWD ) tractors were predicted on agricultural soils for radial tractor tires. Comparisons between the predicted and experimental results of 41 tractors using radial tractor tires showed fair agreement. The performance parameters used in the comparisons were wheel slip, drawbar pull and tractive efficiency. The percentage differences were calculated and the acceptable range was set at 20% difference. For wheel slip, 22 out of 41 tractors had percentage differences that fell within the acceptable range. The drawbar pull comparison showed that 35 out of the 41 tractors had percent differences within the acceptable range. The tractive efficiency comparison showed that 27 out of 33 tractors had percentage differences that fell within the 20% range. The predicted drawbar pull and tractive efficiency were higher than the experimental values in most cases of MFWD tractors. Because some input values for the spreadsheet such as available power, cone index and travel speed were not given in the source of data, the predicted results of tractor performance were not in close agreement to experimental results