A GIS-based tool for integrated management of clogging risk and nitrogen fertilization in drip irrigation

Precipitation of insoluble compounds poses a relevant concern in the management of drip irrigation. This risk is controlled by acidification of irrigation water. The main objective of this work was the development of a GIS-based tool to control drip clogging risk in drip irrigation by nitric acid injection in irrigation water. The study was performed in the province of Jaen (south Spain) focused on the irrigation of olive orchards. The GIS-based model was developed incorporating climate and water data in order to identify zones with different risks of drip clogging which require different rates of acid injection in the irrigation water. Volume of nitric acid injected increased with irrigation frequency and acid injection time. The model provided information on the total amount of N supplied with acidulated irrigation water; e.g. with 30 min injection time in daily irrigations, more than 10 kg N ha−1 were applied in 47% of land potentially irrigated with surface water, meanwhile this percentage was around 60% of that potentially irrigated with underground water. This means that N supply with acid injections to reduce clogging risk may account for a relevant portion of N fertilization requirements in olive orchards. Consequently, this supply should be integrated in fertilization programs to avoid agronomic and environmental constraints. The GIS-based tool proposed was able to provide complementary technical solutions to the clogging problem in drip irrigation. For each alternative released, a precise estimation of N supply to be considered in accurate N fertilizer management was provided. The tool also supplied graphical visualization of information and functionality of handling geographic data with an easy update. All this is necessary in planning and decision making at regional scale with changing properties in irrigation water.