SIU Watershed Science

Southern Illinois University

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SIU Watershed Science

Current Research Projects:

Modelling and Designing Saturated Buffers for Nitrogen and Phosphorus Mitigation in Illinois

Riparian buffers are edge of the field BMPs where vegetation can reduce sediment and nutrient transport to surface waters and reduce nitrate from shallow groundwater that moves through the buffer. Unfortunately, in tile-drained areas of the Midwest, riparian buffers are not effective because the tile lines bypass the buffer and discharge directly into streams or ditches. A practice that has shown to be a cost-effective method to remove nitrate-nitrogen (NO3-N) from the tile drain water is saturated riparian buffers. Saturated buffers are used in situations where a field is bordered by a vegetated buffer, typically along a waterway or stream, and drained by a tile network. A saturated buffer is incorporated into a riparian buffer where a shallow lateral line intercepts existing tile lines and disperses the water across the buffer vegetation.

This study is monitoring water quality and quantity on two different saturated buffer designs, the pitchfork, with three dispersion lines, and the traditional, with one dispersion line. Sample are taken of water as it enters and leaves the saturated buffers and water from wells established in the field and throughout the buffer.  It is also looking the potential denitrification rates and the changes in deep soil carbon and nitrogen pools in the area surrounding the saturated buffers.

Water and Sediment Control Basins (WASCoBs) Influence on Crop Yields and Water Quality

A WASCoB, or water and sediment control basin, retains water to prevent erosion, especially gully erosion.  An important design of a WASCoB is that the water retention time does not negatively impact crop yields. The objective of this research is to evaluate the performance of WASCoBs with or without cover crops over time for hydrologic modification, nutrient losses, water quality, soil retention, soil health and impacts on crop yields.

The treatments compared are: l) fields that are drained by WASCoBs 2) fields with WASCoBs plus cover crops, 3) fields containing an ephemeral gully without WASCoBs but containing cover crops, and 4) fields containing an ephemeral gully without WASCoBs or cover crops. The performance of WASCoBs over time for agronomic efficiencies are being compared among these treatments in a field in Atterberry, IL.

Water Quality and Agronomic Impacts of Gypsum Applications in Southern Illinois

The goal of this research is to assess whether gypsum can be a tool for southern Illinois farmers to limit phosphate loss from their fields while maintaining or improving yield. Gypsum as a soil amendment has not been studied in Illinois soils. This four year project is being conducted at two scales to effectively answer two questions: What is gypsum’s impact on the water quality of surface runoff and what is gypsum’s impact on grain yields? 

Surface runoff is collected from 12 flumes at the site to test the effects of different gypsum application rates on the water quality.  To assess gypsum’s impact on yield, we added gypsum at the rate of 1 ton/acre and added an equivalent amount of calcium in the form of ag lime and an equivalent sulfur in the form of elemental sulfur on three different fields. Soil chemistry is assessed for phosphorus and the soil physical properties such as infiltration and bulk density are also tested at both scales.

Minimizing Phosphate and Nitrogen Loss in Corn/Soybean Rotation in Southern Illinois: Effects of Legume/Non-Legume Cover Crops, Tillage, and Topography

Nitrogen (N) from corn-soybean production fields in Illinois is lost both through groundwater via leaching and by overland flow through the surface runoff. Cover crops can reduce nutrient leaching and improve soil fertility.  This research looks at the impact of cover crops on nitrate leaching under different tillage practices, the impact of topography on nutrient leaching when cover crops are used and how cover crops affect runoff and stream nutrient loads at the watershed scale.

This long-term study was established in 2015 at two sites on the SIU University Farms. The cover crop by topography site tests the soil water and soil properties at three slope positions in two watersheds, one with cover crops and one with no cover crops.  Stream water is also collected in each of the watersheds. The cover crop by tillage site has strips that are planted with cover crops or no cover crops and either tillage or no till.  Soil water and leachate water plus soil properties are collected in each replicate at the site.