Abstract
Freshwater nitrogen (N) pollution is a significant sustainability concern in agriculture. In the U.S. Midwest, large precipitation events during winter and spring are a major driver of N losses. Uncertainty about the fate of applied N early in the growing season can prompt farmers to make additional N applications, increasing the risk of environmental N losses. New tools are needed to provide real-time estimates of soil inorganic N status for corn (Zea mays L.) production, especially considering projected increases in precipitation and N losses due to climate change. In this study, we describe the initial stages of developing an online tool for tracking soil N, which included, (i) implementing a network of field trials to monitor changes in soil N concentration during the winter and early growing season, (ii) calibrating and validating a process-based model for soil and crop N cycling, and (iii) developing a user-friendly and publicly available online decision support tool that could potentially assist N fertilizer management. The online tool can estimate real-time soil N availability by simulating corn growth, crop N uptake, soil organic matter mineralization, and N losses from assimilated soil data (from USDA gSSURGO soil database), hourly weather data (from National Weather Service Real-Time Mesoscale Analysis), and user-entered crop management information that is readily available for farmers. The assimilated data have a resolution of 2.5 km. Given limitations in prediction accuracy, however, we acknowledge that further work is needed to improve model performance, which is also critical for enabling adoption by potential users, such as agricultural producers, fertilizer industry, and researchers. We discuss the strengths and limitations of attempting to provide rapid and cost-effective estimates of soil N availability to support in-season N management decisions, specifically related to the need for supplemental N application. If barriers to adoption are overcome to facilitate broader use by farmers, such tools could balance the need for ensuring sufficient soil N supply while decreasing the risk of N losses, and helping increase N use efficiency, reduce pollution, and increase profits.
Highlights
IntroductionNutrient losses from agriculture are a significant concern from tile-drained landscapes in the U.S Midwest [1,2]
Introduction conditions of the Creative CommonsNutrient losses from agriculture are a significant concern from tile-drained landscapes in the U.S Midwest [1,2]
Of specific relevance to the present work was the sensitivity of model predictions to increasing cumulative rainfall amounts across the 49 on-farm study sites. We investigated this by running model simulations and comparing SMN concentration 60 days after corn planting at sites experiencing moderate versus high precipitation
Summary
Nutrient losses from agriculture are a significant concern from tile-drained landscapes in the U.S Midwest [1,2]. Building on the work and recommendations of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force over the past two decades. Changes in N management are important because of the combined influence on crop yields and water quality. Compared to other practices, there is potential for immediate impact through voluntary adoption because changes in N management can result in cost savings and have relatively greater stackability (the ability to pair management practices) and trackability (the ability to track practice implementation) [3].
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