Tillage Effects on Nitrate Leaching Measured by Pan and Wick Lysimeters

Abstract

No‐till (NT) is a recommended best management practice for reducing erosion in agricultural production. Because of potential increases in infiltration with NT, a better understanding of tillage effects on NO−3–N leaching is required. An experiment was conducted in central Pennsylvania on a Hagerstown silt loam (fine, mixed, semiactive, mesic Typic Hapludalf) to study NO−3–N leaching under chisel‐till and NT and to compare results from zero‐tension pan and passive capillary fiberglass wick lysimeters from May 1995 to April 2001. Pan lysimeters collected greater leachate volumes from NT than from tilled treatments during the growing season, likely due to greater macropore flow in NT soil. When leachate collection efficiency corrected values were used, pan and wick lysimeters collected equivalent masses of NO−3–N. Flow weighted NO−3–N concentrations in leachate in both lysimeter types were also similar. Tillage had no effect on total leachate collected during the 6‐yr experiment by either pan (228 mm yr−1) or wick (558 mm yr−1) lysimeters. Flow‐weighted NO−3–N concentrations and NO−3–N masses in leachate were not significantly different between tilled and NT, but increased with increasing N‐rate (at 0, 100, and 200 kg N ha−1, flow‐weighted NO−3–N concentrations were 3.5, 8.2, and 23.9 mg L−1 and NO−3–N masses were 17, 39, and 112 kg ha−1 yr−1, respectively). The results demonstrate that under our condition NT will not result in more NO−3 leaching than chisel‐tillage over a multiyear period.