2009 Soybean Yield Prospects Improving
The purpose of this brief is to update our previous evaluation of yield potential for soybeans in Illinois, Indiana, and Iowa in 2009. (Irwin, Good, and Tannura, 2009). This update makes use of a crop weather model that estimates the impact of technology (trend), state average monthly weather variables, and portion of the crop planted late on state average yield. Previously, that model was used to evaluate 2009 yield potential based on planting progress, state average precipitation through June 2009, and alternative 2009 July-August weather scenarios. This update incorporates preliminary state average precipitation and temperature for July and alternative weather scenarios for August 2009. The yield forecasts for the three states are then used to project the U.S. average yield. Trend yields for 2009 for each of the three states and the U.S. are also presented. It should be noted at the outset that average July temperatures for 2009 were well below the coldest July in the sample of historical observations used to
2009 Final Corn and Soybean Yield Forecasts
The purpose of this brief is to update our previous evaluation of yield potential for corn and soybeans in Illinois, Indiana, and Iowa in 2009. (Irwin, Good, and Tannura, August 2009c,d). This update makes use of a crop weather model that estimates the impact of technology (trend), state average monthly weather variables, and portion of the crop planted late on state average yield. Previously, that model was used to evaluate 2009 yield potential based on planting progress, state average precipitation through July 2009, and alternative 2009 August weather scenarios. This update incorporates preliminary state average precipitation and temperature for August, the final month used in the model. The yield forecasts for the three states are then used to project the U.S. average yield. Trend yields for 2009 for each of the three states and the U.S. are also presented. It should be noted at the outset that average July temperatures for 2009 were well below the coldest July in the sample of historical observations used to estimate the crop weather model. In addition August temperatures were at the low end of historical experience. These conditions
SOYBEAN SEED YIELD RESPONSE TO PLANTING DATE AND SEEDING RATE IN THE UPPER MIDWEST
Planting date and seeding rate are agronomic decisions that producers can use to maximize soybean [Glycine max (L) Merr.] seed yield and economic return. Current information on the response to planting date and seeding rate may underestimate the yield penalty for delayed planting in northern climates and overestimate the seeding rate required to optimize yield. The objective was to determine the effect of planting date and seeding rate on soybean seed yield at environments with different yield potentials in Iowa. Field experiments were conducted in six locations between 2003 and 2006 for a total of 13 environments. Four seeding rates were planted at four dates between late April and the middle of June. No yield difference existed between the late April and early May planting dates and the yield decline rate between each date was consistent among the six locations. Harvest plant populations were not influenced by planting date indicating that plant establishment does not pose a limitation to late April planting. Harvest plant populations required to reach 95% of the maximum yield were as great as 290,800 or as low as 194,000 plants ha -1 , for locations seeded in 38-cm row spacing and 157,300 to 211,800 plants ha -1 for locations seeded in 76-cm row spacing. Planting in late April or early May increased economic return ha -1 but there was no difference between seeding rates of 185,300 and 556,000 seeds ha -1 , accounting for additional seed costs. In the cool spring climate of the upper Midwest soybean producers can increase yield by planting soybean 1 to 2 wk earlier than current planting dates. These data also suggest that the optimal seeding rate for most locations is less than current seeding rates.