1a. Objectives (from AD-416):
1. Develop adaptive management practices and document their benefits to optimize yield and enhance ecosystem services for CGPR dryland agricultural systems most vulnerable to adverse changes in climate. 2. Extend the applicability of adaptive management practices across the CGPR using the development and evaluation of site-specific technologies and process modeling for field scales. 3. Develop and evaluate practices for remediation/restoration of degraded soils in the CGPR.
1b. Approach (from AD-416):
There are 27 million acres of cultivated dryland in the Central Great Plains region (CGPR). The primary limitation for cropping in the CGPR is a variable drought dominated climate. Despite system improvements toward more intensive cropping, 58% of the region’s dryland is still winter wheat-summer fallow (WF). Unfortunately, WF is not economically /environmentally sustainable. Our objective is to develop sustainable dryland systems for the CGPR. A central research theme is adapting the region’s cropping systems to the ever-changing semi-arid climate. The unit works to achieve that objective using a long-term “core experiment,” the Alternative Crop Rotation (ACR) study. This field study compares 23 rotations for their economic, agronomic, and drought-mitigating effects and their effects on soil quality. In support of the core experiment, several satellite experiments evaluate the agronomic and economic potential of alternative crop species; quantify crop water use; evaluate changes in soil quality; develop management for remediating degraded soils; and evaluate nutrient use efficiency in these systems. The combined efforts of the “core” and “satellite” experiments will result in sustainable, climate-adaptive cropping systems for the region and will provide a quantitative knowledge of production limitations of the CGPR to climate change. Introducing biological and market diversity with broadleaf bio-diesel/oilseeds will reduce pest pressures inherent to the current grass-dominated rotations. Economic savings from improved cropping systems, reductions in agri-chemical use, and reductions in soil loss resulting from this research are estimated at $6-$35 per acre annually. Assuming 25% adoption of this technology will result in annual regional savings of $40 -$236 million.
3. Progress Report:
Progress of project approved June, 2011: Sustainable Dryland Cropping Systems for the Central Great Plains. Scientists at the USDA-ARS Central Great Plains Research Station (Akron, CO) with ARS and University Collaborators in several experiments are achieving objectives of the project. Objective 1: Develop adaptive management practices to optimize yield and enhance dryland systems vulnerable to changes in climate. The unit’s publication of the simulation modeling of the adoption of canola for the Central Great Plains is in review. The stripper header management studies are near completion. The four year canola rotation established in 2012 is in its second year with an objective to determine how to fit canola into wheat, corn and millet rotations. The wheat nitrogen use efficiency (NUE) by wheat cultivar experiment established with university (CSU) collaborators is in its third year of data collection. The first year of the grant funded oilseed stress trial was established during the extreme drought of 2012. The 2012 drought precluded the measurement of meaningful differences in cultivars. Scientists monitoring soil water recharge after Sunflowers now have an assessment of how well wheat performs after various summer crops grown under irrigation in 2012. The skip-row sorghum by variety and seeding rate experiment is complete and the graduate student wrote her first draft of a manuscript to submit for publication by August 2013. The 2012 drought precluded the measurement of meaningful differences in the slot tillage experiment established in 2011. Progress was made evaluating soil organic matter quality (measured mid-IR spectroscopy) resulting in a second published manuscript. Scientists made progress in publishing manuscripts evaluating soil organic carbon as influenced by tillage, and organic amendment. The organic wheat rotation experiment established 2011 provided no measurable treatment differences due to drought. Biochar experiments established with USGS collaborators in 2012 are near completion. Objective 2: Extend the applicability of adaptive management practices across the CGPR using site-specific technologies and process modeling for field scales. Progress is still in learning software and purchasing hardware to conduct site specific N management across a landscape. The sequestration cut has made it difficult to move forward with this project simply because we don’t have the technician hours available. Because this is a new effort it has become low priority until additional funding becomes available to hire the additional technical help. Objective 3: Develop and evaluate practices for remediation of degraded soils in the CGPR. Because of the 2012 summer drought no decisions about the direction of the experiment will be made until after the 2013 growing season. Preliminary analyses of yields and soil parameters have been summarized in station annual reports. Two manuscripts have been published. In the fall of 2013 all plots will be sampled to an 8 foot depth (2.4 m) to assess nutrient changes from manure application over the last 6 years and to evaluate other physical/chemical properties in this experiment.
Mikha, M.M., Vigil, M.F., Benjamin, J.G. 2013. Long-term tillage impacts on soil aggregation and carbon dynamics under wheat-fallow in the central Great Plains. Soil Science Society of America Journal. 77:594-605.