Best management irrigation practices assessed by a GIS-based decision tool for reducing salinization risks in olive orchards

Abstract

Sustainable irrigation should rely on the efficient use of water while avoiding soil degradation. To this end, decision tools for assessing best management practices are necessary. There is, however, little evidence of efficient tools to assess best irrigation practices at regional scale taking into account water quality to avoid soil degradation and negative impacts on crop yields. The objective of this work was the performance of a GIS-based decision tool to assess best irrigation management practices aimed at reducing the negative effect of salts in irrigation water in olive orchards. The approach in this tool involved first the blending of two sources of available waters, surface and underground, and when necessary, the application of leaching fractions (LF). We tested this tool in the province of Jaen (south Spain) as representative area of olive cultivation in Mediterranean environments.

In 82.4% of the study area, the use of one of both water sources with electrical conductivity (ECw) below the defined threshold (1.8 dS m−1) was possible without blending. Water blending for achieving optimal irrigation water quality was possible in 16% of the irrigated land. In other 9.8% of the irrigated land, leaching fraction was required to achieve the defined salinity threshold. In the area where water blending was possible, this strategy resulted in the best irrigation water efficiency (IWE) estimated for the province. With water blending and LF when necessary, the annual gross income in the province can be increased by 80 mill €.

The proposed GIS-base decision tool is easy to update for different crops and regions. It is able to transform and combine geographical data and value judgments for decision making in irrigation at a regional scale with a view of achieving the most efficient irrigation water use while avoiding negative effects on crop and soil due to water salinity.