|Peairs, Frank -|
|Hansen, Neil -|
|Westfall, Dwayne -|
|Peterson, Gary -|
|Herman, Justin -|
|Shaver, T -|
|Randolph, T -|
|Rudolph, J -|
Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: February 1, 2013
Publication Date: March 1, 2013
Citation: Peairs, F.B., Hansen, N.C., Poss, D.J., Westfall, D.G., Peterson, G.G., Herman, J.C., Sherrod, L.A., Shaver, T.M., Randolph, T., Rudolph, J. 2013. Agronomic & entomological results from 7 years of dryland cropping systems research at Briggsdale, Colorado. Experiment Station Bulletins. Technical Bulletin 13-01 CSU. Interpretive Summary: The Briggsdale cropping system study goal was to determine what type of intensive cropping system might be sustainable in this water stressed environment. Through seven years of experimentation with alternative crops at Briggsdale, corn, soybean, sunflower, grain sorghum and forage soybean were eliminated as alternative options. The forage crops foxtail millet and Austrian winter peas may succeed in this environment if proper management techniques are used. Mixing the foxtail with forage sorghum showed promise in recent years. Examination of the rotations, based on wheat grain yield, indicated that the six-year system was too exhaustive of soil moisture and was not sustainable. There was no difference in wheat grain yield for the WF and WMF rotations, implying that the primary crop for the rotation (wheat) is not significantly affected by intensifying the rotation from a two year system to a three year system as both wheat crops are following a summer fallow. It is extremely difficult and risky to grow and crop in a water stressed environment like Briggsdale Colorado during an exceptional drought period. Seven years of late spring freezes and/or severe summer drought provided an inhospitable environment for insects, and none reached levels of economic concern.
Technical Abstract: Dryland crop production in the semi-arid Great Plains is limited by both the quantity and timing of precipitation. Sustainable dryland cropping systems maximize precipitation use efficiency by managing precipitation capture, storage, and use. Pest management approaches are also critical for efficient crop production in water limited environments. The primary purpose of this long-term study was to determine if the stressful environment in the Briggsdale, CO area would support intensified cropping systems. The objectives of this research were to evaluate productivity and insect dynamics for different no-till crop rotations in an environment with less than 15 inches of annual precipitation. More specifically, objectives were to study integrated pest management tactics to control Russian wheat aphid (RWA) and to evaluate beneficial insect population abundance within more intensive cropping systems. Another objective was to evaluate alternative crops for this environment. The project was established in 1998 and was discontinued in 2005. The study compared four no-till crop rotations ranging from summer fallow every other year to continuous cropping with no summer fallow. During this period the annual precipitation averaged 13.7 inches which was below the long term average and therefore led to many crop failures and low grain yields. The dry conditions did not sustain insect pest populations large enough to be of economic concern. Reductions of wheat yields of 11-78% were observed in the most intense rotations as compared to the traditional 2-year system. Crops such as corn, sunflower, soybean, grain sorghum, Austrian winter pea, and forage soybean, which were all used at least once in the 6-year cropping system, had low yields and were found to be too risky for dryland production in this water stressed environment. These results indicate that the environment coupled with intense cropping systems had a negative impact on the potential production for this location. The most suitable cropping systems found were those with fallow every other year or every third year (2-3 year systems). Well adapted annual forage crops may be a reasonable choice for rotation in winter wheat-based systems.