Biology and Fertility of Soils

, Volume 43, Issue 6, pp 641–651

Irrigation practices may affect denitrification more than nitrogen mineralization in warm climatic conditions

Original Paper

DOI: 10.1007/s00374-006-0143-0

Cite this article as:
Valé, M., Mary, B. & Justes, E. Biol Fertil Soils (2007) 43: 641. doi:10.1007/s00374-006-0143-0


Predicting the impact of irrigation practices on soil N mineralization and N balance is an important issue to optimize N fertilization and reduce the N losses towards the environment. The effect of summer irrigation on N dynamics was investigated in two arable fields in Southern France. Net N mineralization was assessed by combining frequent measurements of water and mineral N contents in soil and the use of a calculation model (LIXIM). It was first calculated assuming that denitrification was negligible. This hypothesis led to inconsistent results, apparent net N mineralized being smaller under irrigated than non-irrigated conditions and net mineralization kinetics being erratic. The occurrence of denitrification was confirmed by the use of 15NO3 tracing in an experiment carried out in summer, including three irrigated treatments. The average 15N recovery varied from 45% to 85% and was smallest in the most frequently irrigated treatment. Over the 8-week experiment, the N losses varied from 30 to 38 kg ha−1 in the irrigated treatments. They were satisfactorily simulated by a simple denitrification model (NEMIS). Combining the LIXIM model and the simulated or calculated denitrification allowed to predict satisfactorily the evolution of soil mineral N accounting for the effects of temperature and moisture. The net N mineralized for 8 weeks varied from 34 kg N ha−1 in the un-irrigated to 46 kg N ha−1 in the irrigated treatments. The drying–rewetting cycles did not induce a flush of N mineralization. Our results suggest that denitrification has to be accounted for in irrigated systems, particularly in warm conditions and when the topsoil contains high nitrate contents.


IrrigationNitrogen mineralizationDenitrificationDrying rewettingN balance15N recovery

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.INRA, UMR1248 ARCHE (Agrosystèmes Cultivés et Herbagers)Castanet Tolosan CedexFrance
  2. 2.INRA, Unité d’Agronomie LMRLaon CedexFrance