The overall goal of this project is to evaluate the performance of shallow subsurface drainage systems under Illinois conditions. The specific objective is to test the hypothesis that the use of shallow drainage systems results in an improvement in the water quality of tile effluent, without significant reduction in crop yield.

Four isolated drainage systems will be installed in sections of a 40-acre field in the Upper Embarras River watershed. Two of the systems will conform to Drainage Guide standards, and two will be shallow (2 - 3 ft deep) with drains spaced at half the recommended spacing. The cropping practice will be identical over the entire 40 acres. The owner has agreed to provide the field and to cover most of the tile installation costs. The project will only be responsible for drain installation costs over and above the cost for standard tile installation.

Continuous flow rates will be obtained at the outlet of each system. They will be converted into a digital signal and stored in a data logger. An automatic water sampler will be used to obtain water quality samples from each monitored tile system. The frequency of sampling will be based both on a characteristic flow volume and on the rate of change of flow. Thus, there will be more frequent sampling in periods of high flow or in response to a precipitation event.

The samples will be analyzed for ammonia, nitrate, total nitrogen, and phosphorus. These samples will be analyzed using standard methods outlined by the Environmental Protection Agency . All the analyses will be performed in the Water Quality Laboratory in the Agricultural Engineering Department.

We will use the data from this experiment to calibrate and validate models for nitrate transport in tile systems. Models such as ADAPT  and DRAINMOD-N  have been developed for this purpose, but have not been calibrated for shallow systems under Illinois conditions. These models will allow us to examine the effects on tile water quality of changes in practices. We will be able to simulate the effects of reduced, split, or variable rate application of nitrate fertilizer.

The project report will include a detailed narrative description of the field and laboratory sampling procedures as they relate to the study objectives. There will be a description of the procedures that are used to ensure that field and laboratory equipment are functioning properly and accurately reproducing reference values. Calibration standards, calibration frequency, and calibration procedures will also be included.

The data generated from this study will help to quantify the benefits of shallow tile systems in Illinois. If the reductions in nitrate loads follow the same patterns as are observed in the simulations, there should be little resistance to adopting this practice in Illinois. The results of this research may lead to the implementation of a practice that may help to solve one of the water quality problems most commonly experienced by many Illinois communities.

This work ties in with the proposed work in the tile modeling and mass balance groups The data from this study will also be made available to these researchers. If requested, other constituents can be measured or the sampling frequency adjusted to support these other efforts. Management data and climate data, such as rainfall, temperature, wind speed and direction, and humidity will also be collected to facilitate modeling and mass balance studies.

Nov. - Dec., 1999: Installation of drainage systems and monitoring equipment

Dec. 1999 - Sep., 2002: Collection of water samples

Analysis of water samples

July - Sep., 2002: Preparing final report