The potential importance of soil denitrification as a major N loss pathway in intensive greenhouse vegetable production systems

Abstract Background About 30 % of vegetables in China are produced intensively managed greenhouses comprising flood irrigation and extreme rates nitrogen fertilizers. Little is known about denitrification N losses. Methods Soil were measured by the acetylene inhibition technique applied to anaerobically incubated soil samples. Four different greenhouse management systems differentiated: Conventional over-fertilization (CIF, 800 kg ha −1 , 460 mm); CIF plus straw incorporation (CIF+S, 889 Drip fertigation with reduced fertilizer application (DIF, 314 190 DIF (DIF+S, 403 mm). was on nine sampling dates during growing season (Feb 2019-May 2019) for top-/ subsoil (0 – 20/ 20- 40 cm) three deep soils (40-60/ 80-100 cm). Data used constrain N-input-output balances vegetable production systems. Results Rates at least one magnitude higher topsoil than sub- soils. Total seasonal losses 0 cm layer ranged from 76 (DIF) 422 (CIF+S). Straw addition stimulated top- subsoil, but not layers. Integrating our data (0-100 additional leaching, 2 O emissions, plant uptake, NH 3 volatilization showed, that average 50 added fertilizers lost due denitrification. Conclusions Denitrification likely dominant environmental loss pathway Reducing while incorporating allows reduction accumulated nitrate.