spatially explicit investigation of phosphorus sorption and related soil properties in two riparian wetlands

• Published in: Journal of environmental quality 2004-03, Vol.33 (2), p.785-794
• Main Authors: Bruland, G.L, Richardson, C.J
• Format: Article
• Language: English
• Subjects: Accounting; Adsorption; Agronomy. Soil science and plant productions; Aluminum; Applied sciences; Autocorrelation; Biological and medical sciences; Bulk density; Chemical Phenomena; Chemistry, Physical; Clay (material); coastal plain soils; Correlation; Earth sciences; Earth, ocean, space; Ecosystem; Engineering and environment geology. Geothermics; Environmental Monitoring; Exact sciences and technology; forest soils; Fundamental and applied biological sciences. Psychology; geostatistics; Iron; Kriging; lowland forests; Models, Theoretical; Moisture; Organic matter; Phosphorus; Phosphorus - analysis; Phosphorus - chemistry; Pollution; Pollution, environment geology; riparian areas; riparian forests; Sampling; Sand; Scale (corrosion); Soil; Soil (material); Soil adsorption; Soil organic matter; Soil properties; soil texture; soil water content; Sorption; spatial variation; Surface layer; Texture; Trees; wetland soils; Wetlands
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2004.0785

Soils of riparian wetlands are highly effective at phosphorus (P) sorption. However, these soils exhibit extreme spatial variability across riparian zones. We used a spatially explicit sampling design in two riparian wetlands in North Carolina to better understand the relationships among P sorption, soil properties, and spatial variability. Our objectives were to quantify patterns of spatial variability of P sorption and related soil properties, and to determine which soil properties best explained the variability in P sorption after accounting for the effects of spatial autocorrelation. We measured bulk density, moisture, pH, soil organic matter (SOM), texture (percent clay, silt, and sand), oxalate extractable aluminum (Al(ox)), iron (Fe(ox)), and the phosphorus sorption index (PSI). Due to differences in texture, Al(ox), and Fe(ox), the two sites had substantially different mean PSIs. At each site, we found considerable differences in the spatial variability of soil properties. For example, semivariance analysis and kriging illustrated that soil properties at Site 1 varied at smaller scales than those at Site 2. At both sites, after accounting for the effects of spatial autocorrelation and all other soil properties, we determined that Al(ox) had the highest Mantel correlation with PSI. We believe this geostatistic and Mantel approach is robust and could serve as a model for research on other biogeochemical processes such as denitrification.