COMPARISON BETWEEN SUCTION AND FREE-DRAINAGE SOIL SOLUTION SAMPLERS1

In this study we compared the ability of porous ceramic cups and a newly developed pan sampler to monitor chloride movement through the following three soils of diverse texture: a Grossarenic Paleustalf, a Typic Udifluvent, and a Udic Chromustert. Two pan samplers and three suction cups were installed at a depth of 0.6 m in three locations of each soil. Chloride was applied to the soil surface at 305 kg ha−1. Samples were collected weekly from the samplers and porous cups and analyzed for chloride. Both samplers collected sufficient volume to detect and describe the leaching of chloride through the loamy sand and silt loam soils. The pan samplers generally gave larger and more consistent samples than the porous cups at high soil moisture potentials. Porous cup samplers were ineffective in sampling well-structured clay soils, but samples were collected by the pan samplers in the soil. We think this difference is due to rapidly leaching water and chemicals moving through large pores; it bypassed the porous cups, but was intercepted by the larger surface area of the pan samplers. The initial chloride concentration applied to the soil was 500 mg L−1, but the highest measured concentrations in the samplers were 70, 53, and 170 mg L−1 in the loamy sand, silt loam, and clay soils, respectively.