Automated N Leachate Measurement in the Field Using Equilibrium Tension Lysimeter.

Loss of residual nitrogen from manured lands occurs rapidly in the fall where accompanied with high rainfall. Assessment of N leaching has been a problematic issue. Most methods for assessing N leachate are not reliable since they either disturb the natural leaching or do not represent normal leaching conditions.  Zero tension lysimeters may only collect saturated soil water flow and suction lysimeters may not represent normal matrix water movement, thus the amount of soil-water collected, as well as the concentration measured in the sample may not be accurate. A low cost yet accurate automated equilibrium tension lysimeter was designed to collect N leaching from plots with no cover crop and cover crop plots planted in September 2007. Sampling began on 09/25/2007 and ended on 11/15/2007. The battery powered controller and data logger performance were able to keep the suction in equilibrium with soil tension, and stored the information about soil and suction plate suction levels. The electronic system seemed to be reliable and showed good performance in the field condition. The programmability of the controller (Basic-like programming language) gives it the flexibility to be reprogrammed for different performance strategies.