"An innovative leaching solution to the worldwide salinity crisis"

The issue of salt accumulating in soil is as old as agriculture itself. ‘Salinity crises’ resulted in the collapse of ancient civilizations in Mesopotamia, and salinization was one of the catalysts for the invention of the world’s first irrigation systems[1] [2]. These were huge problems on a modest scale, but with soil salinization increasing exponentially across the globe, the impacts are ever greater and the need for a solution more pressing than ever to feed a growing population.

by Chris Thomas

Current figures estimate that over 830 million hectares across all continents is salinized[3], and possibly up to 20% of all cultivated land and 33% of irrigated agricultural land worldwide[4]. Salts are naturally-occurring but salinity concentrations increase after many cycles of irrigation, while additional salts and minerals are also introduced by fertilizers. Crops grown on saline soil suffer “high osmotic stress, nutritional disorders and toxicities, poor soil physical conditions and reduced crop productivity”[5], which can over time turn fruitful fields into deserts. The issue has gained traction in recent decades, especially in arid or semi-arid regions where the problem is most pressing. On the west coast of the US, for example, a 2000 study at the University of California estimated that about 4.5 million acres of irrigated cropland — more than half the state’s total at that time — were affected to some degree by soil salinization.

Soil salinity entails unhealthy levels of harmful mineral ions such as sodium and chlorine, with highly charged water in turn leading to a high level of electrical conductivity (EC) in the soil. Several techniques can be employed to manage salinity. There are hydraulic techniques (irrigation and drainage), physical techniques (leveling the soil), farming techniques (contribution of organic matter) and biological techniques (tolerant plants). A sustainable, long-term solution would have a huge impact on the millions of growers plagued by soil salinity and a huge impact on humanity. Indeed, a United Nations Food and Agriculture Organization (FAO) publication already recognized this 30 years ago, asking: “Can agriculture make use of marginal quality water such as saline water in a way that is technically sound, economically viable and environmentally non-degrading?”[6]

Aqua-4D’s innovative system goes some way to definitively answering this question in the 21st century.

Leaching salts below the rhizosphere 

Michael Cahn at the University of California defines leaching as “the process of percolating water through the soil to move salts below the root zone”[7]. Aqua-4D has a revolutionary way of accomplishing this percolation, by sending a low-level electromagnetic signal through the irrigation water before it is applied to crops. This changes the organization of the water molecules and behaviour of minerals, meaning that plants can absorb what they need and salts are dissolved and transported below the root zone.

This has huge implications for growers in regions with poor quality saline water, but also for growers facing unusable land after several cycles of rising soil salinity. This was the situation faced by Brazil’s Agricola Famosa, the country’s largest fruit producer. Several years of salt accumulation in the soil meant they were faced with ceasing activity on these lands. In the year 2014 they turned to the Aqua-4D system, which had quick results. The way the system breaks down salt molecules so that they’re leached below the roots meant that the company could go back to using this land which they’d thought was a lost cause (see interview with Agricola Famosa agronomist here).

Validated, consistent results

The first study looking specifically at salinization and leaching was conducted at an Aqua-4D customer in Tunisia 2008 growing vegetables (tomato and zucchini) in a greenhouse environment. The water came from a geothermal well, while the soil, which was very sandy and of low organic quality, had a conductivity of 4.43 mS/cm. As the graph shows, soil analysis in 2012 compared with 2008 shows a significant drop in conductivity, at both surface level and up to 2 metres. Continued treatment of the irrigation water with the Aqua-4D system had prevented the accumulation of salts in the soil in both short-term and long-term.

Also based in Tunisia, research published in the Journal of the Saudi Society of Agricultural Sciences looked at the irrigation water and soil salinity of potato growers. The water had a conductivity of 4.0 while the soil was silty clay loam poor in organic matter (1%). The 2011/12 experiment concluded that “the electromagnetic treatment of saline water had a significant effect on EC”[8]. Chemical analysis found notable decreases in the amounts of calcium, sodium and chlorine in the soil which had been irrigated with electromagnetically-treated water:

Meanwhile, in early January 2018 the Center for Irrigation Technology at California State University, Fresno, conducted third-party validation with Aqua-4D. The study looked at eight soil columns in lab conditions, with 40 gallons of water artificially treated with sodium chloride in order to increase conductivity to 2.5 dS/m for the purposes of the research. Half the soil columns were then given water treated by Aqua-4D, and half were not.

Analysis was conducted after 21 days. It showed that 198 mg of salt was leached from the control soil, while 493 mg was leached from the soil which was treated with Aqua-4D water. The authors of the report stated: “It can hence be inferred that the Aqua-4D treated water can potentially leach 2.31 times more ions per ml pf water than the leachate obtained from soil irrigated with the non-treated water.”

Finally, newly-released results from Tonello Soluciones in August 2018, at a large-scale rose grower in Ecuador, reported significant drops in soil conductivity in the space of just 30 days:

Conclusion

The stark reality faced by growers around the world is that a large amount of water used in irrigation is of insufficient quality, leading to the buildup of salts which can, over time, make arable land unfit for purpose. With an innovative, chemical-free and environmentally-friendly leaching effect, Aqua-4D provides a genuine long-term solution which can help make soil salinity a thing of the past, and answer the call of making irrigation with saline water possible.

[1] Salt Of the Earth, New York Times, August 2003: https://www.nytimes.com/2003/08/08/opinion/salt-of-the-earth.html

[2] Irrigation and Soil Salinization, World History, 2015: http://www.worldhistory.biz/ancient-history/62007-irrigation-and-soil-salinization.html

[3] Soil Salinization, Pichu Rengasamy, University of Adelaide, 2016: http://environmentalscience.oxfordre.com/view/10.1093/acrefore/9780199389414.001.0001/acrefore-9780199389414-e-65

[4] Soil salinity: A serious environmental issue, Pooja Shrivastava & Rajesh Kumar, King Saud University, 2015: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336437/

[5] ibid

[6] The use of saline waters for crop production, FAO Irrigation and Drainage, J.D. Rhoades et al, 1992: http://www.fao.org/3/a-t0667e.pdf

[7] Managing salts by leaching, Michael Cahn, University of California ANR, 2015: https://anrcatalog.ucanr.edu/pdf/8550.pdf

[8] Effect of electromagnetic treatment of saline water on soil and crops, M.Hachicha et al, Journal of the Saudi Society of Agricultural Sciences, 2018: https://www.sciencedirect.com/science/article/pii/S1658077X16000023

 

For more information:
Aqua-4D Water Solutions
www.aqua4d.com


Publication date :



Receive the daily newsletter in your email for free | Click here


Other news in this sector:


© HortiDaily.com 2018