Location: Northwest Irrigation and Soils ResearchTitle: Regression modeling weather and biosolids effects on dryland on dryland wheat yields in Eastern Colorado, 2011-2012) Author
Submitted to: Colorado State University Technical Report
Publication Type: Experiment Station
Publication Acceptance Date: 12/4/2013
Publication Date: 12/4/2013
Citation: Barbarick, K., Ippolito, J.A., McDaniel, J., Hansen, N., Peterson, G. 2013. Regression modeling weather and biosolids effects on dryland on dryland wheat yields in Eastern Colorado, 2011-2012. Colorado State University Agricultural Experiment Station Technical Bulletin. TB13-3:1-20. Interpretive Summary: In the western Great Plains, climate dictates dryland wheat and corn production; municipalities also use this region to recycle sewage biosolids. We used several multiple regression models to study whether biosolids applications to western Great Plains dryland agroecosystems interact with weather to affect wheat production. The common parameters found in our models were October mean temperature and May precipitation, while biosolids did not appear in any of the final models. A positive result of these analyses is that biosolids did not harm crop yields and, therefore, can be recycled at agronomic rates on dryland agroecosystems.
Technical Abstract: In the western Great Plains, climate dictates dryland wheat (Triticum aestivum, L) and corn (Zea mays, L.) production. Municipalities also use this region to recycle sewage biosolids. Will biosolids (from the Littleton/Englewood, CO Wastewater Treatment Plant) applications to western Great Plains dryland agroecosystems interact with weather to affect wheat production? To this end, we regressed crop yields on weather variables from 2000 through 2011 at a site about 20 kilometers north of Bennett, CO (North Bennett) and at a site about 40 kilometers east of Byers, CO (Byers). We used SAS (Proc Reg) to develop several multiple regression models to predict crop yields. Our models of choice included two weather parameters for North Bennett and four weather parameters for Byers wheat production. Regression variables included monthly mean temperatures and monthly and critical grain-filling-period precipitation. Biosolids or nitrogen fertilizer application did not appear in any of our chosen models. We validated the wheat models using weather data and yields from the Colorado State University (CSU) Crops Testing Program from Akron, Burlington, Lamar, and Yuma, CO. According to t-tests comparing mean observed and predicted yields, the Byers model was the superior yield predictor. Neither of the models exhibited accuracy to predict individual year yields. A positive result of these analyses is that biosolids did not harm crop yields from 2001 through 2011 and, therefore, can be recycled at agronomic rates on dryland agroecosystems.