The effects of different inflow hydrograph shapes on furrow irrigation fertigation

Abstract

Fertilisers are widely applied to agricultural fields using surface fertigation. However, there are still no adequate guidelines for the proper design and management of surface fertigation. The proper management of surface irrigation fertigation is important because of low uniformity of distribution of water in surface irrigation. The efficient application and distribution of water by furrow irrigation is highly dependent on parameters such as inflow rate and inflow hydrograph shape. Some modified furrow inflow hydrograph shapes were introduced, evaluated for field conditions and simulated using modified zero-inertia model for surface irrigation fertigation. An automatic device was designed to apply different furrow inflow hydrograph shapes to the furrows. The one dimensional advection-dispersion model of the overland water and solute flow was used to simulate furrow irrigation fertigation. The results show that the modified inflow hydrograph shapes reduced tailwater runoff significantly. The use of modified increased discharge inflow hydrograph shape resulted in higher solute uniformity. The fertigation model was able to simulate the experimental field data with good accuracy. The fertigation application was highly affected by the shape of furrow inflow hydrograph. Fertiliser losses due to runoff were between 20 and 67% for different inflow hydrograph shapes. The fertiliser losses due to runoff were highest for the constant inflow hydrograph shape and lowest for the modified increased discharge inflow hydrograph shape. The use of correct inflow hydrograph shape can reduce fertiliser losses due to tailwater runoff significantly.