Suction Lysimeter Method for Estimating Nitrate Leaching Losses In Horticultural Crops.

Environmental concerns and stricter regulations have increased the need to accurately estimate nitrate leaching losses from horticultural crops.   We developed instrumentation to monitor leaching events and estimate NO₃-N loading in commercial vegetable and strawberry fields.   The equipment, consisting of an array of 8 suction lysimeter tubes,   datalogger,  peristaltic pump,  and electronic vacuum gauge,    maintained a constant vacuum pressure for the duration of an irrigation or rain event.   A battery and solar panel permitted the pump to operate continuously for several days.  The pump maintained low vacuum pressures (> -0.02 MPa) so that the lysimeters sampled gravitational pore water.  A flow meter and rain gauge were used to monitor the volume of water applied to the crop, and crop evapotranspiration (ET) was estimated from reference ET data and canopy cover measurements.  Volumetric soil moisture sensors monitored the change in soil moisture storage before and after irrigation and rain events.    The datalogger was interfaced with an internet accessible cell phone so that the equipment could be remotely operated.