The LTAR Cropland Common Experiment at Platte River/High Plains Aquifer

The Platte River/High Plains Aquifer (PR/HPA) region is characterized by cropland, pastures, and grasslands that are faced with changing climatic conditions and agricultural intensification. The PR/HPA Long-Term Agroecosystem Research (LTAR) site is located in Eastern Nebraska with the goal of improving resilience, sustainability, and profitability of agroecosystems through enhancing ecosystem services and environmental quality, developing strategies for efficient agricultural production, and mitigating and adapting to climate change. To meet this goal, a common experiment and five ancillary experiments have been developed to evaluate prevailing regional practices in grain crop production systems compared to alternative practices in rainfed and irrigated systems. These experiments reflect different geographic regions and cropping systems within PR/HPA. The common experiment is at a plot scale under sub-drip irrigation. The prevailing practice is a corn-soybean rotation with a fixed N fertilizer rate. The alternative practice is a corn-winter wheat-relay cropped soybean rotation with temporally variable N rates using fertigation. There is also an auxiliary alternative practice, a corn-soybean rotation with temporally variable N rates using fertigation with fall manure application after soybean harvest. This document describes the regional characteristics, cropland LTAR experiments, stakeholder engagement, and future plans for the PR/HPA cropland experiments. Agriculture is the dominant land use in the Platte River/High Plains Aquifer (PR/HPA) Long-Term Agroecosystem Research (LTAR) region. Cropland agriculture in the PR/HPA region includes both rainfed and irrigated systems. The PR/HPA LTAR site cropland common experiment contrasts prevailing and alternative practices at both plot and field scales. The goal of PR/HPA LTAR is to develop resilient integrated agriculture systems for the region. The Long-Term Agroecosystem Research (LTAR) Network consists of cropland, grazing land, and integrated research sites in the contiguous US. The Platte River/High Plains Aquifer (PR/HPA) region is comprised of six states in the central U.S. and is dominated by agricultural land characterized by cropland, pastures, and grasslands. Cropland agriculture in the PR/HPA region is primarily rainfed in the east, while irrigated systems are dominant in the west. Grasslands in PR/HPA tend to be native warm-season grasses, while pastures are largely introduced cool-season grasses. The purpose of PR/HPA LTAR is to evaluate and develop resilient integrated agriculture systems.