SCIENCE WADES IN

Financial Mail - - FEATURE - Alis­tair Anderson an­der­sona@busi­nesslive.co.za

SA’S fre­quent pe­ri­ods of water short­age have drawn the at­ten­tion of re­searchers, who have of­fered in­no­va­tive so­lu­tions to mit­i­gate the ef­fects of drought

Unisa sci­en­tist Neil Stacey has de­vel­oped a tech­nol­ogy to re­duce global water usage dras­ti­cally by ap­proach­ing the mat­ter from an un­usual an­gle: he looked at where water ends up.

Two of Stacey’s re­search ar­ti­cles, pub­lished in in­ter­na­tional sci­en­tific jour­nals, have shown that more than 90% of the water used in agri­cul­ture is lost to evap­o­ra­tion. And since 70% of global water usage is for agri­cul­ture, those evap­o­ra­tive losses ex­ceed losses from all other forms of water usage put to­gether.

Stacey and his team set out to find ways to min­imise these losses. By us­ing a green­house as a model they demon­strated that there is a limit to the re­duc­tions that are achiev­able through con­ven­tional means.

Plants re­quire car­bon diox­ide, which they ob­tain from the air. Huge air­flows are needed to sup­ply enough of the cru­cial CO², as it is highly di­lute in air at just 400 parts per mil­lion. That air­flow drives evap­o­ra­tion, be­cause all that air has to be brought to the warm, hu­mid con­di­tions that plants re­quire.

Stacey’s pro­posed so­lu­tion is to use CO² en­rich­ment to de­crease the flow of air needed to sup­ply enough of the cru­cial car­bon, thereby cut­ting down evap­o­ra­tion and po­ten­tially re­duc­ing water usage to a frac­tion of present lev­els. Stacey’s pre­ferred method of CO² en­rich­ment is by us­ing in­or­ganic sil­ica mem­branes to sep­a­rate a high-co² stream from the open air. It is a mod­u­lar ap­proach that can be im­ple­mented on any scale.

Farm­ers could po­ten­tially boost rev­enue with this method as well; op­er­at­ing at higher lev­els of CO² re­sults in faster plant growth

and in­creased crop yields.

In the case of some pop­u­lar crops, the yield in­crease is over 20%. So a farmer can ex­pect a rev­enue boost along with the water sav­ings.

Still in its early stages, the project has nonethe­less gone be­yond just the sci­en­tific; Stacey’s busi­ness model is in the run­ning to be one of the top 50 projects se­lected by the El­se­vier Foun­da­tion Green & Sus­tain­able Chem­istry Chal­lenge. El­se­vier is the world’s largest sci­en­tific pub­lisher. Each year it se­lects the most com­mer­cially promis­ing, sus­tain­able chem­istry projects, of­fer­ing prizes of €50,000 and €25,000 to those in first and sec­ond place re­spec­tively.

What it means: Agri­cul­tural groups say they are aware of the ex­tent of their water usage and have been putting mea­sures in place to re­duce it

De­spite the ap­par­ent com­mer­cial po­ten­tial of CO² en­rich­ment, Stacey’s team has placed the con­cept in the public do­main rather than hold­ing on to a patent, choos­ing in­stead to fo­cus on com­mer­cial­is­ing the prac­ti­cal as­pects of the tech­nol­ogy.

Stacey (31), a re­searcher at the Unisa Science Cam­pus, is no stranger to in­no­va­tive think­ing; just over a year ago he was in the news for break­throughs in bio­fu­els pro­duc­tion. He is also over­see­ing a project aim­ing to re­place the coal used in iron ore re­duc­tion with en­vi­ron­men­tally friendly al­ter­na­tives, in­clud­ing biomass and waste plas­tics.

SA’S ur­gent need for tech­nol­ogy to im­prove agri­cul­tural water ef­fi­ciency is well known, with agri­cul­tural groups say­ing they are well aware of the ex­tent of their water usage and have for a while been putting var­i­ous mea­sures in place to re­duce it.

Niël Jou­bert, a di­rec­tor at Vin­pro and or­gan­ised busi­ness group Agri SA, and who farms with wine grapes and stone fruit, says wine­mak­ers have var­i­ous water-sav­ing strate­gies in place.

“Fruit and wine farms are, and have al­ways been, acutely aware of their de­pen­dence on sus­tain­able water re­sources to be able to pro­duce a good-qual­ity prod­uct and in the process cre­ate jobs, not only on farms but also in the value chain — right up to the shelves of chain stores and even [the stands of] in­for­mal hawk­ers who earn a liv­ing by sell­ing farm pro­duce,” says Jou­bert. “Fur­ther­more [many] ru­ral towns [de­pend on] re­spon­si­ble farm­ing and water usage.”

Drought con­di­tions have been present in the Western Cape for a third con­sec­u­tive sea­son. Most pro­duc­ers de­pend on water from ir­ri­ga­tion schemes, and this water has been ra­tioned since early in the 2017 grow­ing sea­son. Quo­tas have been cut by 50%-80%.

The Oli­fants River re­gion is worst af­fected by the drought. Pro­duc­ers in this re­gion have been al­lo­cated less than 17% of their usual water quota from the Clan­william Dam. The Orange River re­gion is the only wine re­gion not ex­pe­ri­enc­ing water short­ages.

Over the years ma­jor changes have taken place in tech­nol­ogy.

Jou­bert says ir­ri­ga­tion prac­tices have changed from sprin­klers and mi­cro-ir­ri­ga­tion to vari­a­tions of drip tech­nol­ogy, de­pend­ing on where the farm is. Water stress lev­els are mon­i­tored by so­phis­ti­cated equip­ment to al­low pre­cise sched­ul­ing of wa­ter­ing hours and vol­umes in in­di­vid­ual blocks ac­cord­ing to soil type, canopy size and wine style.

The sci­en­tific ap­proach ex­tends to ev­ery de­ci­sion, from soil prepa­ra­tion and the choice of root­stock and cul­ti­var for a spe­cific ter­roir to the cover crops that are used.

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