UC Riverside

Furrow irrigation and fertigation systems should be designed and managed to optimize the availability of water and fertilizer to plants and minimize their losses through evaporation, deep drainage and leaching. We developed a furrow irrigation submodule for HYDRUS (2D/3D) and used it to evaluate the effects of different furrow soil surface treatments and different timings of fertigation on root water and solute uptake, deep drainage and solute leaching in a loamy soil. Numerical simulations showed that more water was available for transpiration in the treatments with plastic placed at the furrow bottom compared to the control treatments. However, more water was lost due to evaporation and less water was drained from the soil profile for these treatments. The highest and lowest root solute uptake was achieved when fertigation was applied in the middle and at the beginning of the irrigation cycle, respectively. The least amount of solute was leached from the soil profile for treatments with the plastic bottom and when fertigation was applied at the end of the irrigation cycle. The scenarios with plastic and irrigation in alternate furrows showed a reduction in transpiration and yield, more water loss due to deep drainage, and less water lost due to evaporation. However, similar crop yields were obtained for this alternate furrow strategy as for the control furrow surface treatments. When only half the water was used for irrigation in this scenario, the reduction in yield was less than 20 % compared to the control treatments, producing higher water-use efficiency.