Electrokinetic Restoration of Alkaline & Saline Soils
Land degradation refers to any reduction or loss in the biological or economic productive capacity of the land caused by human activities, exacerbated by natural processes, and often magnified by the impacts of climate change and biodiversity loss (UNCCD 2013). Between 10 – 20 % of drylands are degraded and 24 % of globally usable land on Earth is degraded at an estimated economic loss of USD 490 billion per year. Land is however often undervalued, and the costs of land degradation and benefits of restoring land are not well understood. Land degradation represents a risk to business, not only for the companies from the agriculture sector, but also to the ones that have indirect links to land, e.g. insurance, retail, mining, oil & gas etc. Restoring land can also represent an opportunity for those companies that have understood the materiality of land to their business and that are taking action. The latest world food predictions are that as land degrades and the human population rises inexorably global demand for food will dramatically exceed the growth in supply, and moreover there may be only a limited time in which to increase production to prevent a worldwide food crisis (BBC False fears threaten food supplies 25 August 2009). It is not the first time that this warning is given, but we better make good use of this limited time.
The UN Food and Agriculture Organization (FAO) recently concluded that agricultural production needs to increase "by 70% (nearly 100% in developing countries) by 2050 to cope with a 40% increase in world population and to raise average food consumption to 3,130 calories per person per day by 2050". What science-based innovations are available to humanity to meet these challenges?
There are surprising many – from the use of GM crops, improved fertiliser applications, especially micronutrients to re-afforesting large areas by intercropping trees and crops together.
But unforunately these are not enough. A truly innovative solution is electrokinetic technology. And contrary to what one might think, this is not a solution of the present but a solution already revealed in 1958 by J.P. Collopy, wo patented "a process for the impovement and reclamation of soils", which he called Electro-Reclamation. In this patent the following (summarized) claims were put forward, based on 4 field experiments and several laboratory tests:
- A process for stimulating plant growth and increasing crop yield in soils of agricultural quality, by irrigating the soil with sufficient quantities of water and subject the root zone to electro-osmosis, electrophoresis and electro-chemical reaction (presently known as electro-migration) to reduce the content of harmfull sodium salts, without lessening the calcium content therein, and by contemporaneously applying a direct current electrical potential between anodes and cathodes.
- A process for reclaiming and improving, to crop productive quality, soils of a type suitable for agricultural use, but excessively alkaline or saline in character, by flooding a large area of soil with sufficient quantities of water to reduce the content of harmfull sodium salts, without lessening the calcium content therein, and by contemporaneously applying a direct current electrical potential between anodes and cathodes.
- A method for reclaiming agricultural class alkaline and saline soils to agricultural quality by supplying sufficient quantities of water and by applying a direct current electrical potential between anodes and cathodes to activate and facilitate migration of sodium ions downwardly from the surface to reduce the exchangeable sodium content at the normal root zone without lessening the beneficial calcium content thereof.
- A method for accelerating leaching of alkaline soils for the removal of undesirable allkaline salts and alkali metal ions, particularly from the upper strata thereof, by irrigating the area with sufficient water and subjecting such upper strata to electro-chemical reaction by contemporaneously applying a direct current electrical potential between anodes and cathodes to reduce the sodium content therein by removing exchangeable sodium ions and exchanging the same with calcium ions present in the soil.
At the end of the 1980s Lambda Consult was managing partner of the company Geokinetics BV, which developed and patented electro-reclamation into an in-situ remediation technology to remove heavy metals and other polar contaminants from soil and groundwater. Detailed information on electro-reclamation can be found in our publication "Electro-Reclamation in Practice, experiences with Field Applications of Electrokinetic Remediation".
A treatise of electrokinetic restoration of saline soils, wherein the original field tests of Collopy are analyzed and our present approach of restoring saline and alkaline soils is presented, based upon our experiences with electro-reclamation during the past 25 years.