Layout & Design
The site is 6.2 ha (15 acres) and supports two replications of tile spacing plots at 5-, 10-, 20-, and 40-meter spacing (16, 33, 66, and 132 ft), with 0.75 m (2.5 ft) nominal tile depth and 0.4 % slope. Huts contain flowmeters and sampling equipment.
With a length of 225 meters (750 ft) and a width of at least 5 meters (16 to 132 ft) the plots are large enough for a tractor with standard equipment to do standard management practices. These plots were under continuous corn for ten years and were then under a corn-soybean rotation. They have recently been converted to a corn-corn-soybean rotation.
Drain tiles were established on the margin of each plot, so that each plot is an isolated sample collection area with automatic surface and/or subsurface samplers controlled by flowmeters. The tiles allow measuring, monitoring, and subsurface sampling as rainfall on the plot flows through the soil. The volume of water and concentration of transported chemicals can be determined for each plot as frequently as desired.
The tiles under the 5-, 10-, and 20- meter plots are connected to tipping bucket flow gauges. The gauges connect to a computer, which acts as a datalogger and also triggers an automatic sampler after a preset amount of flow.