Document Type : Research Paper

Authors

• Hedyeh Pouryazdankhah ¹
• Mohammadreza Khaledian ²

¹ M. Sc. student of irrigation and drainage University of Guilan, Iran;

² Assistant professor, University of Guilan, Iran;

Abstract

In most cases, to predict soil moisture status before installing irrigation system, some simulations are performed by mathematical models to achieve a correct design and supply plant water requirement. Furthermore, nowadays, to increase water use efficiency, no-tillage system is being considered by many experts, because of its high water saving potential. In this study, the performance of HYDRUS-2D has been assessed for both systems i.e. conventional and no-tillage systems. Hence, a field under corn crop and irrigated with tape drip irrigation was considered for each system, in south of France in a Mediterranean climate. Soil moisture at different depths was measured by a neutron probe before and after irrigation in the experimental fields and was compared with simulated moisture according to two statistical indices, i.e. RMSE and EF. In the conventional tillage system, considering the temporal variability of soil hydraulic properties before irrigations, the model could not satisfactorily simulate the whole 29-day study period; because ploughing caused increase in pores of the soil and, consequently, increased soil hydraulic conductivity (K_s). After the first irrigation, K_s was reduced because of the compaction of the first layer, which resulted in some discrepancies in model simulations, where accounting temporal variability of soil hydraulic properties improved the simulations of model. But, in no-tillage system, by accounting soil hydraulic properties before irrigations as input, the model could simulate the whole study period, because in this system, structure of the soil and, consequently, soil K_s changed negligibly and, therefore, the model could simulate more realistic results.

Keywords

• Soil hydraulic properties
• Soil hydraulic conductivity
• Irrigation