Managing soil water in an effective way is a key condition for developing agriculture capable of meeting global demand under the scenario of climate change, FAO notes
by Matteo Cavallito
There has always been a deep relationship between water and soil that forms “the foundation of our agrifood systems, our environment, and our very existence.” So said FAO Director-General Qu Dongyu at the opening of the proceedings of the latest Global Symposium on Soils and Water, held in recent days.
A nexus, that between the two “elements,” that underlies an extensive debate involving land degradation, pollution and fires. But also retention capacity, natural resource management and conservation, and much more.
Salinity affects 1 billion hectares of soil
Effectively managing soil moisture levels is a must for developing agriculture capable of meeting global demand in the climate change scenario, FAO notes. Water and soil, in particular, also form the foundation of healthy ecosystems. To protect these, therefore, it becomes necessary, not surprisingly, to take safeguard and mitigation measures to minimize problems such as erosion and compaction.
These phenomena compromise the soil’s ability to store, drain and filter water by increasing the risk of floods, landslides and sand or dust storms.
Today, the FAO recalls, “more than one billion hectares of soil are impacted by salinity and sodicity, mainly because of poor irrigation and drainage practices, and almost three times as much are at risk globally.”
The nexus of soil, water and health
In this context, promoting the sustainable use of agricultural inputs, using appropriate irrigation methods, improving drainage systems and monitoring salinity levels provide an effective response to the climate crisis. Indeed, healthy soils act as a carbon sink, sequestering the element from the atmosphere. In addition, “soil organic matter can retain about 20 times its weight in water, as in saying that one cubic meter of soil can enclose more than 250 kilograms of it. Damaged and compacted soil, on the other hand, loses almost half of its retention capacity.”
In agricultural systems based on the irrigation contribution of rain, it is the ability of soils to retain water that is crucial in providing adequate yields.
The Planet’s soils, the U.N. organization says, filter and clean large amounts of water, supporting human health and thus completing a broader nexus of the various factors involved. Soil health, in particular, “is key to the One Health approach, which wraps together issues such as safety thresholds for contaminants and their impact on biodiversity, food quality and safety, as well as the nutritional value of the food we eat.”
In order to improve soil and water resource management, it also becomes necessary to harness the potential of new techniques and technologies such as precision agriculture, remote sensing and big data analysis. Among the examples quoted at the Symposium and during the parallel event of the 2nd Rome Water Dialogue is the WaPOR or Water Productivity through Open access of Remotely sensed derived data system, whose new version was launched these days.
WaPOR, the U.N. organization explained, is a portal that “offers users near real-time satellite data to track actual water consumption in cropping fields, irrigation applications and the economic value-addition that an extra drop can offer, doing so with seasonal nuance and high-spatial resolution.”
The system, in particular, measures evapotranspiration, or the natural dispersion of freshwater from the soil to the atmosphere. In this way, explains Lifeng LI, director of the FAO’s Land and Water Division, “the platform can render, in pixelated maps, a picture of how much biomass and crop yield is produced per cubic meter of water consumed,” allowing for calculation of its productivity.”