Spatio-temporal analysis of nitrogen variations in an irrigation distribution network using reclaimed water for irrigating olive trees

Abstract

Fertigation management of olive grove is highly complex, especially when reclaimed water is used for irrigation. Nitrogen (N) is the main nutrient component of olive trees which, traditionally, has led to an excessive use in fertilization programs. This problem can be exacerbated if reclaimed water is used since it already contains N. For this reason, water quality must be considered in the fertilization plan. Both total content and N form arriving to the trees have implications in olive tree nutrient requirements as well as the environment. If reclaimed water particularities and the length of the pipes of water distribution networks are considered, the form and total concentration of N can change over space and time. In this work, both spatial and temporal analysis of the N content and form in a water distribution network using reclaimed water for irrigating olive trees was performed. This study proved that changes in N were evident both over time and across the irrigation water distribution network. Seasonally, N content was reduced during the summer period. Spatially, a clear nitrification occurred from the pumping station to the farms. These variations demonstrate the importance of a continuous water quality control in order to adjust the fertilization plan according to the N content in water.