Project : USDA ARS

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Research Project: Improving Understanding of Soil Processes for Making More Informed Agricultural Management Decisions that Increase Agricultural Sustainability in the Central U.S.

Location: National Soil Erosion Research Laboratory

2025 Annual Report

Objectives
Objective 1: Enhance and develop best management practices that optimize crop nutrition and ecosystem services related to soil health, water quality, and crop production efficiency for Central U.S. cropping systems. Subobjective 1.A: Develop relationships that describe how soil properties partly control soil P dynamics and kinetics in the context of crop uptake. Subobjective 1.B: Assess the impact of combined conservation practices on soil health indicators, including soil organic C dynamics (SOC) and physical properties. Subobjective 1.C: Quantify phosphorus uptake efficiency and timing in corn towards formulating more efficient nutrient application strategies. Subobjective 1.D: Evaluate the effect of soil phosphorus drawdown on crop yield and water quality in tile-drained fields among three different regions of Indiana (Northeast, Central, and Eastern). Objective 2: Enhance, develop, integrate, and support soil erosion prediction tools to enable and inform policy-maker decisions on soil conservation practices and improve communication on the impact of erosion on sediment, nutrient, and carbon budgets. Subobjective 2.A: Improve USDA-ARS soil erosion model functionality and performance. Sub-objective 2.B: Enhance prediction of Soil erosion and redistribution in agricultural landscapes under climate and land use change. Objective 3: Improve functionality and resilience of agricultural systems in the Central U.S. to drought and extreme weather through the expansion, development, integration, and deployment of hydrological modeling across coordinated Long-Term Agroecosystem Research (LTAR) network sites. Subobjective 3.A: Evaluate the impact of management on resilience of soil health to extreme weather of depression watersheds. Subobjective 3.B: Assess the propagation of drought through the hydrological system in the Western Lake Erie Basin. Subobjective 3.C: Systems/community resilience and natural resource sustainability at the agriculture-environment-society nexus.

Approach
Approach Objective 1: Laboratory and field crop growth experiments will be used to study nutrient uptake at several scales for improving fertility recommendations as well as assessing how various management practices impact soil organic matter stability and water quality. Approach Objective 2: This research will expand and improve sediment transport knowledge, equations, and logic used within process-based soil erosion prediction technologies. Paired no-till vs. tilled soils will be subjected to simulated rainfall in the laboratory, as well as inflow water to measure interrill and rill detachment rates and determine baseline erodibility parameters. Existing public web services from NRCS (https://data.nal.usda.gov/dataset/soil-data-access-web-service), U.S. Geological Service (USGS) (https://www.mrlc.gov/data-services-page), National Oceanic and Atmospheric Administration (NOAA) and NASA (https://daymet.ornl.gov/) and National Agricultural Statistical Service (NASS) (https://www.nass.usda.gov/Research_and_Science/Cropland/sarsfaqs2.php) will be used with data transformation algorithms developed to integrate these datasets of different scales in dynamic mapping applications related to soil erosion at a specific scale (e.g. pixel size, field size and shapes). Approach Objective 3: Historic and additional soil samples within depression watersheds will be analyzed to better understand long- and short-term soil redistribution dynamics of spatial and temporal pattern within depression watersheds. Long-term datasets of precipitation, soil moisture, and discharge across spatial scales ranging from individual fields to large watersheds will be leveraged to quantify how anomalous meteorological conditions transition into hydrological drought.

Progress Report
Subobjective 1.A: Fertilizer management is critical to agricultural profitability. Different soils can hold on to nutrients at different strengths, and that partly controls crop growth. Soils were collected from throughout the U.S. and used in a laboratory experiment that will provide new information on fertilizer management that can reduce negative cashflow to farmers. Soils were adjusted to different naturally occurring soil acidity levels (pH levels) to simulate a variety of environmental conditions. In a second step, phosphorus (P) fertilizer was added at different amounts. After many days, these soils were tested to see if the P levels changed by using different chemicals that tell us something about how strong the P is held on the soil. Once completed, the analysis of this data set will be helpful for the farmers, to know exactly how much fertilizer to add and improve profit. Subobjective 1 B: Healthy and productive soils are crucial for the economy of rural America. ARS research investigates options to support farmers when choosing from a variety of management options. Soils were collected from two Purdue University farm experiments under different tillage systems that stir the soil up differently. Stirring the soil (tillage) influence microbes and microorganisms that break down organic matter and make nutrients available for plant growth. Researchers took soil samples for analysis, including carbon and nitrogen, which are basic elemental building blocks for the foundation of sustainable and secure food production. The acid and salt levels are also being tested since certain acid and salt can be harmful to a variety of essential soil organisms. In the future, additional samples from Oregon and Colorado will be included in this study. Subobjective 1.C: Developing new corn hybrids enhance the options for farmers to increase profitability. In America, agricultural research developed the first corn hybrids nearly 100 years ago. ARS researchers used several corn hybrids going back to 1932 and grew them under controlled conditions to find out which corn hybrid are the most efficient in using nutrients for max plant growth. After growing the plants to maturity, they were harvested and separated into various parts (roots, stem, leave, and corn) and analyzed for nutrient content so that we can determine which corn hybrids would grow most efficiently. A second experiment was done to determine what growth stages were the best for making phosphorus available to plants. The outcome of this research gives farmers options to decide when to apply fertilizer for optimal corn growth and obtain maximum crop yield. Subobjective 1.D: The ARS continues research on fixing nutrient problems (nitrogen and phosphorus). If nutrients are flushed through surface runoff and underground drainage into lakes and rivers this can cause increased algae growth. This process is called eutrophication in lakes and rivers and has negative impacts on human and animal health (harmful and toxic algae blooms) as well as the fishing and tourism industries. Researchers continued to monitor surface runoff and underground drainage and water quality (nitrogen and phosphorus; daily samples) from two adjacent fields in the St. Joseph River watershed (northeastern Indiana) to understand how phosphorus application rate impacts farm economics (crop yield, fertilizer cost, etc.) and water quality (nutrient loads). This year the ARS researchers made the data collected from these fields available to the public through USDA Ag Data Commons. The dataset includes six fields (two from Indiana, four from Ohio) with accompanying information on precipitation, discharge, nutrient concentration and management practices. Farmers are now able to know how their farming methods affect water quality. ARS scientists are continuing research to find the best and most efficient ways to use gypsum. Gypsum is a by-product (“waste not, want not”) that has benefits to growing crops through improving the way water flows through soil, plus it adds nutrients. Subobjective 2.A: Developing prediction technology for soil erosion enhances the ability of stakeholders to assess sustainable land management strategies and evaluate options. The process-based soil erosion prediction model, WEPP (Water Erosion Prediction Project), was developed with the primary focus of predicting soil erosion and sediment delivery by using process understanding and state-of-the-art techniques. Sediment delivery comes from increased soil erosion at times when bare soil is without or less protective vegetative cover protection during rainstorms. This process also washes away many soil nutrients that feed crops – a loss to the farmers investment in managing natural healthy, productive soil or when adding fertilizers. Overall, this causes increased risks for food security, and food security is of national interest. To provide decision-makers with a modeling tool to assess options, ARS scientists released 2024 WEPP with the latest science. WEPP-2024 has an easy-to-use interface in which users are guided to select inputs to meet their individual field conditions (topography, soil, and management) under historical variable weather conditions. Subobjective 2.B: Soil erosion, sediment transport and deposition in fields redistributes also organic matter, and nutrients. ARS scientists enabled the Water Erosion Prediction Project (WEPP) model to be used within the open-source Quantum GIS (QGIS) software. The QGeoWEPP tool and its software code are freely available for download at the research unit webpage. For the first time the software includes a soil redistribution validation data set for a long-term rangeland watershed. This enables users to make changes to the code assuring that any model changes do not negatively impact on the validity of the software. In an experimental version of the predictive erosion model WEPP-WQ, scientists also tested novel water quality components. This version includes processes of both soil and nutrients losses that can be simulated and predicted. This predictive model will help farmers make decisions that will ensure future crop production. Subobjective 3. A: Water and crops behave differently within low spots, or depressions, common in the midwestern landscape. We are collecting data on water quality among several depressions for the purpose of learning how to make better choices in farming those depressions. We continue to collect automated water samples from several depressions within the Midwest. The processing of data samples is ongoing and should lead to results in the next reporting period. This data is going to be used to make management decisions that will improve water quality in streams and Lake Erie such as preventing toxic and harmful algae blooms that cause public health concerns as well as the fishing and tourism industry in the region. Subobjective 3.B: Farmers are challenged by extreme weather events that make them lose their soil and potentially crops. Too much water, not enough water, or not at the right times. These extreme weather events also wreak havoc on fertilizer losses, and therefore direct loss of investments. ARS is studying how these weather events partly control fertilizer losses in the productive Eastern Corn Belt (parts of Indiana, Ohio, and Michigan). Much progress was made in measuring both groundwater and surface water within one of our long-term tile-drained watersheds (80 ha) in northeastern Indiana. Combined with discharge and water quality measurements from the watershed outlet, these in-field measurements of groundwater and surface water have resulted in an unprecedented dataset of water quantity and quality within tile-drained landscapes. Using this data, we published a peer-reviewed article examining the effect of drought (2020-early-2021) and subsequent rewetting (2021) on water quality in this watershed. Results showed that the combined effect of seasonal precipitation contrasts, extreme events, and phosphorus management practices led to a 2-fold increase in annual flow-weighted mean concentrations of dissolved reactive P (DRP) and total P (TP) in 2021 compared to previous years (2012-2019). Findings highlight how targeted conservation efforts, including optimized application timing and placement, and legacy P mitigation are essential for reducing short- and long-term eutrophication risks associated with precipitation variability. Subobjective 3.C. ARS scientists formulated an initiative called BUSHELs to better communicate environmental indicators supporting sustainable production used by farmers. The BUSHELs acronym stands for Banking and Understanding Sustainable, Healthy, and Enduring Landscapes. That means: Banking land to account for any losses and maximize production; Understanding Processes to find sustainable management and investment options for farmers; support Sustainable and Healthy Soils with improved soil and water quality in field and farm to support crop production); create Enduring communities in rural Landscapes with profitable, quality agricultural products, improved water quality, and drought/flood resiliency). ARS research on process understanding, management options, and technology and decision support tools supports farmers. This indicator framework is a direct result of the ARS scientists’ discussion throughout the series of meetings for the last three years (early February). In the past two years, the meeting with stakeholders also included modeling exercises with the WEPP model to facilitate and learn from the interaction with decision-makers using models for sustainable management. The BUSHELs Initiative motivated the representatives at the 2024 Annual Meeting of the Long-Term Agroecosystem Research (LTAR) Network to accept performance indicators into their national framework. The framework is now based on four dimensions: Environment, Economics, Society, and Production (new).

Accomplishments
1. Timing is everything: How proper phosphorus application timing in corn can improve efficiency. When it comes to phosphorus uptake by corn, the timing of uptake makes a big difference in fertilizer efficiency. Fertilizer efficiency is important because fertilizer is expensive and geologic phosphorus deposits are becoming more difficult to extract. ARS researchers in West Lafayette, Indiana, used an indoor grow-room to determine optimal phosphorus uptake timing in corn. Corn plants received either low or high phosphorus at different growth stages. When plants received high phosphorus for only 30 days before moving into reproductive growth, they produced the same grain yield compared to receiving high phosphorus for all 120 days of growth. Ultimately, with the proper timing, the same maximum grain yield can be achieved by applying less phosphorus, which is more cost and resource efficient. These results will help farmers make fertilizer-application decisions that save them money.

2. Developed WEPP-COMPARE: a user-friendly tool to assess soil and water conservation practices. Comparing various management options for crop production and efficient resources use is essential for farmers and land managers. The Water Erosion Prediction Project (WEPP) is a web-based model developed by USDA scientists in West Lafayette, Indianna, that simulates plant growth and water and soil movement in fields and small watersheds. The new WEPP-COMPARE interface stands for WEPP-Comprehensive Operation Management Practice Assessment and Rotation Engine. The WEPP-COMPARE platform is ready to use with all necessary input available such as weather, land use, and soil information. In addition, users only need to have access to the internet without the need to install any professional programs on computers. The second annual workshop for stakeholders in February 2025 resulted in feedback that ARS scientists were able to use to further improve the interface and user experience. This feedback will allow an interface and functionality for U.S. farmers to make better decisions for long-term efficient production.

3. Getting to the “root” of the matter: improving efficiency of corn root measurements. All water and nutrients taken up by plants come through the roots. Being able to measure root characteristics like length, diameter, and surface area is critical to evaluating new corn hybrids and management practices. In addition, knowledge of root parameters allows scientists to create better models that predict how much water and fertilizer is needed. However, measuring roots is extremely difficult, time consuming, and expensive. ARS researchers in West Lafayette, Indiana, developed a new technique for sub-sampling and measuring corn root characteristics. The subsampling technique involved all parts of the roots system and was accurate when compared to measuring the entire root system and required only half of the time. This new technique will allow corn researchers in private industry to achieve higher throughput for analyzing root systems, enabling greater advances in corn genetic development and fertilizer and water use efficiency.

4. Precipitation extremes exacerbate phosphorus loss. Water movement in farm fields often reflects recent rainfall patterns. During dry periods with little rainfall, growing crops use most of the water or it is evaporated. When conditions are wet, water can move across the ground surface or move into groundwater. Differences in rainfall can directly affect water quantity and quality (nutrients and pesticides). ARS scientists in West Lafayette, Indiana examined data from a watershed (2012 to 2023) to understand how rainfall patterns and farm management practices impact water quality. Dry conditions were observed from 2020 to early 2021, which were followed by a period of excess rainfall. Nearly 50% of the phosphorus losses from the watershed occurred during a 9-month window during rewetting. One large rainfall event after fertilizer application resulted in 8% of the total phosphorus lost over 12 years. Findings indicate that targeted conservation efforts, including optimized fertilizer application timing and placement are essential for decreasing nutrient loss associated with rainfall variability.

U.S. DEPARTMENT OF AGRICULTURE

National Soil Erosion Research Laboratory: West Lafayette, IN