Assessing soluble organic nitrogen pools in horticultural soils: a case study in the suburbs of Shanghai (China)

Abstract Soil soluble organic nitrogen plays a significantly important role in nitrogen biogeochemical cycling. The aim of this study was to investigate the amount of soluble organic and inorganic nitrogen pools extracted by water, salt solutions, and centrifugal-drainage technique from different horticultural management system soils. Approximately 5.4–16.6, 4.4–46.5, 7.1–18.2, 8.8–27.8, 1.8–5.6, and 1.7–4.4 mg kg − 1 soluble organic nitrogen were obtained by 1M KCl, 0.5M K2SO4, 10 mM CaCl2, 1/15 mM phosphate buffer (pH 7.0), water, and centrifugal-drainage technique, respectively, in the 0–20 cm horticultural soils. Large variation in soluble organic nitrogen pools was observed across the sites in the present study and the volumes of soluble organic nitrogen pools generally followed the order: organic production system soil > conventional production system soil > transitional production system soil. In relative contrast to soluble organic nitrogen, organic management, known primarily for the absence of a...