A Three‐Dimensional View of Nutrient Hotspots in a Sierra Nevada Forest Soil. Issue Volume 78:Issue Supplement 1(2014) (30th May 2014)

• Record Type: Journal Article
• Authors: Johnson, D.W.; Woodward, C.; Meadows, M.W.
• Is Part Of: Soil Science Society of America Journal. Volume 78:Issue Supplement 1(2014)
• Page Start: S225
• Page End: S236
• Publication Date: 2014-05-30
• Subjects: Soils -- United States -- Periodicals; Soil science -- Periodicals; Periodicals; 631.4973
• DOI: 10.2136/sssaj2013.08.0348nafsc
• Languages: English
• ISSNs: 0361-5995

Abstract

Abstract : Soil nutrient hotspots have important influences on both plant nutrition and water quality that are obscured by averaging values and eliminating outliers from data sets. An investigation of soil nutrient hotspots and hot moments was conducted in a Sierra Nevada forest soil using a matrix of resin capsules placed at various depths and collected at two times (first precipitation in autumn, Mediterranean climate, and post‐snowmelt in spring). Fluxes of Ca 2+ and Mg 2+ in the mineral soil were much greater in the spring than in the autumn samples, suggesting that soil water flux was a major factor. The reverse was true for NH4 + and Na +, for which most total fluxes occurred during the first precipitation in autumn. Fluxes of NH4 +, NO3 −, and ortho‐P declined with depth in most cases, whereas the patterns in average fluxes of Na +, Ca 2+, and Mg 2+ with depth were inconsistent. More than 85% of hotspots for NH4 +, NO3 −, ortho‐P, Na +, and Ca 2+ were also hot moments (varied spatially with time). Most hotspots for Mg 2+ were spatially co‐located with time (fewer hot moments), perhaps indicating local variations in soil Mg or preferential flow paths. Hotspots were more common for NH4 + and NO3 − than for Ca 2+, as noted in most previous studies at this site. Whether the latter reflects fundamental differences between C and N or the relative abundance of these ions in the soil remains to be determined.