| Project: COL00639 |
Department: Soil & Crop Sciences |
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PIs: Hansen, NC
; Westfall, DG |
| Title: Crop and Soil Management Systems in Water Limited Agroecosystems |
| Begin Date: 07/01/2007 |
Term Date: 06/30/2012
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Most recent project status:
Revised
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| Objectives: The overall objective of this multi-disciplinary research and outreach project is to advance understanding of biophysical processes in water limited agroecosystems and develop management practices that promote long term sustainability. The project is undertaken across gradients of climate, soil type, and includes dryland and irrigated systems. The specific objectives of the project are: 1. Develop dryland cropping systems that maximize precipitation use efficiency through detailed understanding of crop productivity and individual components of a water mass balance over a range of cropping intensities. 2. Develop irrigated cropping systems that reduce consumptive water use through a systems level study of crop rotation, irrigation management, and soil management approaches. 3. Identify practical means of documenting consumptive water use savings during transition from full irrigation to limited irrigation and dryland cropping systems. 4. Promote long term sustainability of dryland and limited irrigation cropping practices through management of soil carbon and soil erosion control. |
| Approach: The objectives of this project are achieved through detailed field research studies located in Eastern Colorado. The dryland research objectives are evaluated at long-term research locations at Sterling, Stratton, and Walsh, where studies were initiated in 1986. These three sites have similar long term average annual precipitation, but have a wide range in potential evapotranspiration. At each site, there are replicated field strips with differing notill crop rotations, each of which are evaluated spatially as a function of changing soil type. The crop rotations are wheat-corn-fallow, wheat-corn-millet, wheat-wheat-corn-millet, and opportunity cropping. All of the crop rotations are compared to a perennial grass treatment that mimics the native short grass conditions. On-going data collection includes detailed weather monitoring at each stie, soil moisture assessed with a neutron probe, biomass and grain production, and crop residue dynamics. This information is used to determine precipitation use efficiency as well as the economics and risk of different cropping systems. The long term nature of this study provides the ability to evaluate production economcs for years with varying precipitation amounts, including periods of prolonged drough conditions. Detailed assessments of individual components of the water balance include measurement of runoff using automated runoff plots within the strips at Sterling and Stratton and assessment of the dynamics of infiltration and evaporation with continuous recording time domain reflectrometery equipment at Sterling. The irrigated cropping systems research is conducted at two primary locations, a Fort Collins study initiated in 1995 and an Iliff study initiated in 2007. Both of these locations are evaluating cropping practices that reduce consumptive water use during transition from full irrigation practices to limited irrigation or dryland cropping systems. The Fort Collins study compares cropping practices under both furrow and sprinkler irrigation, while the Iliff location uses only sprinkler irrigation. A water balance approach is used to document consumptive water use for a wide range of crop rotations and irrigation management techniques. The limited irrigation systems emphasis growth stage timed irrigation and crop water stress management. Crop water stress is documented with comparisons of crop growth and development, canopy temperature, and biomass and grain yields. On-site weather data is collected and irrigation and soil water are quantified. This information is used to determine irrigation water use efficiency as well as the economics and risk of different cropping systems. At both dryland and limited irrigation studies, sustainability is evaluated from an ecological perspective through evaluation of soil carbon dynamics. Annual soil analysis is performed over soil depth for total carbon and nitrogen. On a less frequent basis, we will compare carbon in pools including particulate organic carbon, mineral associated carbon, and soluble organic carbon. |
| Keywords: dryland cropping systems,
limited irrigation,
soil carbon,
tillage,
water use,
precipitation,
irrigation |
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