This is an adapted version of an article published in the journal Soil & Tillage Research (2020)
With an increase of high-profile projects in various countries, the effects of AQUA4D® technology on irrigation water are being increasingly studied. However, despite the ample first-hand evidence in the field there has been no standalone study looking at its effect on soil structure.
In order to quantify pore changes due to AQUA4D® on cultivated soil, a study was set up by INRGREF agronomy research institute in Tunisia, in collaboration with INRAE in France.
Soil structure regulates many ecological functions, such as water retention and infiltration, gaseous exchanges, soil organic matter and nutrient dynamics, root development and susceptibility to erosion. It also has strong effects on plant development, soil water balance and soil workability. Soil porosity is strongly related to soil structure and is responsible for soil aeration, water infiltration and solute transportation which contribute to nutrient supply and plant root growth.
Soil porosity can be greatly altered by a variety of factors, frequently due to human activities associated with land use. Changes in the structure and pore formation of surface soil layers result from physical forces. These changes can be due to natural or human causes such as climate, soil tillage, irrigation practices, and soil biological activity. In this study, the researchers examined the effects of one of these factors, irrigation, on soil structure when irrigation water was treated by AQUA4D®.
As a great many growers have observed positive effects on salinity and soil the researchers hypothesized that soil structure, via its porosity – which strongly influences water flow – is modified. Changes in porosity can influence hydraulic conductivity and increase the intensity of exchange processes.
The soil was rich in calcium carbonate (25 %) due to its limestone parent material and was poor in organic matter (ca. 1 %). Half were irrigated using AQUA4D®-treated water, and half were not. Soil sample images were analyzed using Visilog software at two spatial resolutions (micro- and macromorphological) to quantify pores classified according to size and shape at each scale.
Detailed analysis found that AQUA4D® had a strong effect on porosity, which on average increased from 8.8–11.4 % to 11.9–14.8 % at the macroscopic scale and from 13.1–14.2 % to 20.6–22.7 % at the microscopic scale. At the macroscopic scale, pores of all morphological types increased after AQUA4D® treatment. At the microscopic scale, packing pores increased the most after AQUA4D® treatment. The results suggest that AQUA4D® acts on soil structure by fragmenting soil material at a fine scale and creating abundant interstitial porosity between aggregates.
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“This is the first study showing the effect of AQUA4D treated water on soil porosity and pore size and shape at two spatial scales,” says company CTO, Charles-Henri Faure. “The improvement in micro porosity of the soil explains an increased water retention and availability in the root zone that allows to lengthen the time between 2 irrigations. The improvement in macro porosity of the soil explains an increased drainage of water that allows irrigation with saline water”.
The results quantify what growers in more than 40 countries have experienced for over a decade: moister soils requiring less intense irrigation, and even irrigation with saline water. The changes to irrigation management enabled by AQUA4D® sustainably improve soil health and can play a key role in a new regenerative agriculture.
“AQUA4D® can improve soil properties greatly by increasing soil porosity at two scales,” says Malak Moussa, who co-authored the study. “Through this porosity, water, solutes and gases can diffuse through the ground, thus increasing exchange processes. These changes modify the soil as a habitat and thus improve the biological activity of soil flora and fauna.”
Archive of Scientific Studies involving AQUA4D
Animation: The effects of AQUA4D® water treatment: