Project : USDA ARS

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Research Project: Developing and Evaluating Strategies to Protect and Conserve Water and Environmental Resources While Maintaining Productivity in Agronomic Systems

Location: Soil and Water Management Research

2025 Annual Report

Objectives
Objective 1: Quantify the transport and fate of nutrients, agrochemicals, and contaminants in managed landscapes and investigate controlling mechanisms. Sub-objective 1A: Determine the persistence and degradation of agricultural inputs and environmental contaminants and factors that control availability to biotic or abiotic (i.e., soil mineral interaction, soil temperature, moisture, and oxidation) processes. Sub-objective 1B: Measure and model the occurrence, export, and transport of agricultural inputs and environmental contaminants to and within surface water and ground water resources. Objective 2: Develop management approaches to reduce adverse impacts of agronomic practices on water quality and quantity. Sub-objective 2A: Examine conventional (BAU) and aspirational (ASP) management practices and investigate new technologies and approaches that will enhance food production while protecting water resources. Sub-objective 2B: Investigate the ecosystem services of turf.

Approach
The challenge we face with a growing world population is to increase agricultural production to meet demands while maintaining environmental quality. Critical to this challenge is protecting the integrity of water resources, which is the foundation of our project’s objectives that quantify the transport and fate of agricultural inputs and contaminants in managed landscapes (objective 1) and develop management approaches to reduce adverse impacts of agronomic practices on water quality and quantity (objective 2). Laboratory, plot level, and watershed-scale investigations will encompass one or more of three over-arching approaches that include: (1) measurements to identify occurrence of contaminants and their sources; (2) management to mitigate contaminants; and (3) modeling to evaluate broader impacts of contaminants and effectiveness of conservation practices or mitigation strategies. Research addressing the first objective will measure the persistence and degradation of agricultural inputs and environmental contaminants and factors that control their availability (subobjective 1a). This includes improving our understanding of biochar aging mechanisms that impact agrochemical sorption and degradation (goal 1a.1), and characterizing contaminants in urban agricultural systems and reducing contaminant availability with management practices (goal 1a.2). In addition, we will measure and model the occurrence, export, and transport of agricultural inputs and environmental contaminants to and within surface water and ground water resources (subobjective 1B). This includes mapping sources and sinks of contaminants in agricultural watersheds to evaluate the mitigation efficacy of management practices (goal 1b.1), and characterizing pesticide sorption to agricultural microplastics (goal 1b.2). Research addressing the second objective will examine conventional and aspirational management practices and investigate new technologies and approaches that will enhance food production while protecting water resources (subobjective 2a). This includes the evaluation of perennial and annual cover crop management practices to reduce negative impacts of row crop production on water quality (goal 2a.1), community-scale denitrifying bioreactor for mitigating nutrient and sediment losses from subsurface tile drained landscapes (goal 2a.2), and synergistic benefits of additives with optimized nitrogen management to reduce loss of soluble nitrogen from cropping systems to ground and surface waters (hypothesis 2a.3). We will also investigate the ecosystem services of turfgrass (subobjective 2b), one of the largest crops grown in the United States, to measure its effectiveness to mitigate transport of roadside contaminants to surface waters (goal 2b.1) and to evaluate the effect of soil moisture and grass species on N-cycling (goal 2b.2). Results of this research will formulate guidelines to enhance the sustainability of agriculture and protect water quality, thus improving water resource security and safeguarding the environment and human and animal health. Data from this project plan will also contribute to Long-Term Agroecosystem Research.

Progress Report
In agricultural landscapes, intense agricultural production is often accompanied by decreased water quality resulting from movement of sediment and nutrients from farm fields into receiving waterways. Growing suites of conservation practices are available to help farmers maintain productivity while also protecting water quality. However, it remains uncertain where to most effectively locate conservation practices to improve water quality in the larger context of watershed channel networks. In support of Objective 1B.1, scientists from St. Paul, Minnesota, are developing new approaches to make water quality maps from small inflatable boats called packrafts. For the current reporting period, we continued packraft-based sampling of High Island Creek watershed in addition to Crane Creek Watershed and Rice Creek watershed. Additional fixed-point monitoring locations have been established in High Island Creek watershed during ice-free conditions. Monitoring data continue to be used to develop nutrient loads for watershed-scale nitrogen export. New approaches are being developed to provide a framework for interpreting spatially-resolved data that are produced by packraft-based sampling. Results from this research demonstrate that different regions of watershed can exhibit varying behaviors when exporting nutrients and stream channels in some watershed locations can be sites of nutrient removal. These results benefit farmers, conservation professionals, and stream restoration professionals seeking to maintain agricultural productivity while also protecting water quality. Results from this work have been published in the journal Water Resources Research (LOG NO. 416764) and presented at the 2024 annual fall meeting of the American Geophysical Union. In cultivated fields in the U.S. Corn Belt, environmental harm from sediment and nutrient runoff often occurs during bare soil conditions in the spring and fall. Winter cover crops help alleviate this problem, but it can be challenging for farmers to find time for additional field operations, especially in the northern Corn Belt where winter snow cover can persist into the late spring. In support of Objective 2A.1, ARS scientists in St. Paul, Minnesota are working to develop management guidelines for growing corn and soybeans in a perennial living mulch of kura clover, thus eliminating the need for additional fall and spring field operations needed for winter cover crops. During the current reporting period, we collaborated with graduate students and faculty at the University of Minnesota study the impact of management practices on performance of corn in a kura clover living mulch system. Biomass and grain yield samples and data from the 2024 growing season are being processed and interpreted. Preliminary results from this experiment have been presented at the Midwest Cover Crops Council meeting (2024), Soil Science Society of America meeting (2024) and the University of Minnesota Forever Green Initiative (2025). Preliminary modeling results about the water quality outcomes of switching to a perennial living cover system were presented at the 2024 annual fall meeting of the American Geophysical Union. This research benefits farmers and conservation professionals who aim to reduce the environmental impacts of cultivated fields by increasing the adoption of perennial living cover in agricultural landscapes.

Accomplishments

U.S. DEPARTMENT OF AGRICULTURE

Soil and Water Management Research: St. Paul, MN