The Effects of Throughfall Manipulation on Soil Leaching in a Deciduous Forest

• Published in: Journal of environmental quality Vol. 31; no. 1; pp. 204 - 216
• Main Authors: Johnson, D.W., Hanson, P.J., Todd, D.E.
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01-01-2002; Crop Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cations; Chemical, physicochemical, biochemical and biological properties; Deciduous forests; Environmental Monitoring; ENVIRONMENTAL SCIENCES; FORESTS; Fundamental and applied biological sciences. Psychology; LEACHING; Lysimeters; Mineral components. Ionic and exchange properties; Nitrogen - analysis; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant Leaves - chemistry; Rain; Soil erosion, conservation, land management and development; Soil Pollutants - analysis; Soil science; Soil solution; SOILS; Sprinklers; THROUGHFALL; Trees; Water Movements; United States; North America; Tennessee; America; Substance loss; Soil quality; Environmental factor; Phosphorus; Forest soil; Nitrogen; Wet deposition; Leaching; Dry deposition; Runoff; Soil horizons; Nutrient; Hardwood forest tree; Chemical composition; Atmospheric precipitation; Canopy(vegetation)
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2002.2040

ABSTRACT
The effects of changing precipitation on soil leaching in a deciduous forest were examined by experimentally manipulating throughfall fluxes in the field. In addition to an ambient treatment (AMB), throughfall fluxes were reduced by 33% (DRY treatment) and increased by 33% (WET treatment) using a system of rain gutters and sprinklers on Walker Branch Watershed, Tennessee. Soil leaching was measured with resin lysimeters in the O horizons and with ceramic cup lysimeters in the E (25 cm) and Bt (70 cm) horizons. Large and statistically significant treatment effects on N fluxes were found in the O horizons (lower N fluxes in the DRY and higher N fluxes in the WET treatment). Together with the greater O horizon N content observed in the DRY treatment, this suggested that N was being immobilized at a greater rate in the DRY treatment than in the AMB or WET treatments. No statistically significant treatment effects on soil solution were found in the E horizons with the exception of (Ca2+ + Mg2+) to K+ ratio. Statistically significant treatment effects on electrical conductivity (EC), pH, Ca2+, Mg2+, K+, Na+, SO2−4, and Cl− were found in the Bt horizons due to differences between the DRY and other treatments. Despite this, calculated fluxes of Ca2+, Mg2+, K+, Na+, SO2−4, and Cl− were lowest in the DRY treatment. These results suggest that lower precipitation will cause temporary N immobilization in litter and long‐term enrichment in soil base cations whereas increased precipitation will cause long‐term depletion of soil base cations.