title: Transformations, transport, and potential unintended consequences of high sulfur inputs to Napa Valley vineyards.
abstract: Unintended anthropogenic deposition of sulfur (S) to forest ecosystems has a range of negative consequences, identified through decades of research. There has been far less study of purposeful S use in agricultural systems around the world, including the application of elemental sulfur (S(0)) as a quick-reacting fungicide to prevent damage to crops. Here we report results from a three-year study of the transformations and flows of applied S(0) in soils, vegetation, and hydrologic export pathways of Napa Valley, CA vineyards, documenting that all applied S is lost from the vineyard ecosystem on an annual basis. We found that S(0) oxidizes rapidly to sulfate ( ) on the soil surface where it then accumulates over the course of the growing season. Leaf and grape tissues accounted for only 7-13% of applied S whereas dormant season cover crops accounted for 4-10% of applications. Soil S inventories were largely and ester-bonded sulfates; they decreased from 1,623 ± 354 kg ha(-1) during the dry growing season to 981 ± 526 kg ha(-1) (0-0.5 m) during the dormant wet season. Nearly all S applied to the vineyard soils is transported offsite in dissolved oxidized forms during dormant season rainstorms. Thus, the residence time of reactive S is brief in these systems, and largely driven by hydrology. Our results provide new insight into how S use in vineyards constitutes a substantial perturbation of the S cycle in Northern California winegrowing regions and points to the unintended consequences that agricultural S use may have at larger scales.
authors.affiliation: Department of Geological and Environmental Sciences, Stanford University, 450 Serra Mall, Stanford, CA 94305-2115, USA. eve.hinckley@colorado.edu
authors.forename: Eve-Lyn S
authors.initials: EL
authors.lastname: Hinckley
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Matson
mesh_terms: D002140:California; D007553:Isotope Labeling; D009038:Motion; D012987:Soil / Q000737:chemistry; D013431:Sulfates / Q000032:analysis; D013455:Sulfur / Q000032:analysis* / Q000737:chemistry*; D013997:Time Factors; D027843:Vitis / Q000737:chemistry*
chemical_list: D012987:Soil; D013431:Sulfates; D013455:Sulfur