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
Influence of weather and technology on corn and soybean yield trends — Reply
Abstract Corn and soybean yields on Allerton Trust Farms, Piatt County, Illinois for the period 1950–1976 are studied. Statistical analyses indicate that the description of yield increases by linear trend equations could not be significantly improved by use of various non-linear trend formulations. The adequacy of the linear trend description also applied when the effects of weather were taken into account. Thus, on these well-managed farms, the yield patterns do not suggest that a plateau is being reached. Adjusting for weather effect significantly increased the average yield increases, from 0.182 metric tons per hectare per year to 0.207 metric tons per hectare per year for corn and from 0.028 metric tons per hectare per year to 0.034 metric tons per hectare per year for soybeans. Thus, weather factors have depressed yield increases during this period. Assuming that the yield trends represent the effects of technology, a linear trend indicates that the supply of economical technology has become available at a constant (absolute) rate over this period. A comparison of Allerton Trust Farm yields with Piatt County yields shows that Allerton corn yields are 13% higher than Piatt County yields and that soybean yields are 9% higher. Because this ratio has not changed over the period there apparently has been a rather constant stock of economical, but unused, yield-increasing technology.