Evaluation of the water productivity of cereal crops in arid environments: example in the El Outaya plain
Abstract
Dry lands agriculture faces several challenges such as productivity and sustainability. The
approach that combines analysis of the natural environment and agronomy contributes to sustainable
development in arid regions.
The El Outaya plain is a large endorheic depression in the southern part of the Saharian atlas.
It is crossed from north to south, by the oued Biskra which cuts through a Quaternary alluvial
outwash, the upstream part of which is cultivated. The soils, developed on silty-clay alluvium,
support several agricultural production systems: cereal crops (wheat, barley and corn), fodder
crops (alfalfa, sorghum), pheoniculture and arboriculture.
On the Driss Omer farm site, the study aims to determine the potential of low-permeability
soils on the basis of granulometric, geochemical and mineralogical analyses. The characteristics
of these soils raises the question of their irrigation: a potentially high available water capacity
and a relative impermeability expose them to degradation phenomena such as waterlogging and
runoff, as well as to a risk of salinization and alkalinization. To prevent deterioration due to the
quality of irrigation water (which comes from salt-rich groundwater), it is essential to control
the amount of water required by crops.
The aim of this study is therefore to estimate the actual evapotranspiration (”plant water consumption”)
and water productivity of wheat on plots irrigated with pivotal ramps, by using a
combination of remote sensing data, climatic data and a surface energy balance model. The
methodology applied enables us to understand the spatial variability of actual evapotranspiration
and of water productivity in this crop.