Regenerating Soil Helps Tackle Water Crisis, Experts Say

In recent years, fre­quent and long-last­ing droughts have caused severe water short­ages and threat­ened farm­ing pro­duc­tion.

This occurred in the com­plex con­text of cli­mate change and its effects, in which the water cri­sis plays a key role.

Experts com­mit­ted to restor­ing the affected ecosys­tems are work­ing quickly to find solu­tions for sus­tain­able water man­age­ment while rais­ing aware­ness among peo­ple and insti­tu­tions.

“In the cur­rent cli­mate cri­sis with its many facets, one of the most press­ing issues is water avail­abil­ity,” said Massimiliano Pasqui, a physi­cist at the Institute for BioEconomy of the National Research Council (IBE-CNR).

“Generally, in the Mediterranean area, we observed increased win­ter tem­per­a­tures and very hot tem­per­a­tures not only at the peak of sum­mer but also in spring or fall,” he added. ​“In this frame­work, when we should have the great­est rain­fall amounts in fall and win­ter, a decline in pre­cip­i­ta­tion is emerg­ing.”

Dry peri­ods are some­times inter­rupted by abun­dant but intense rain­fall where most water runs off. These events may cause flood­ing while fail­ing to alle­vi­ate drought.

The IBE-CNR Drought Observatory noted that water scarcity neg­a­tively impacts agri­cul­tural yield and qual­ity and trig­gers soil degra­da­tion and deser­ti­fi­ca­tion, influ­enc­ing plants’ car­bon seques­tra­tion capac­ity.

“In sev­eral Mediterranean regions, the inci­dence of severe drought has risen,” Pasqui said. ​“This can affect the work of farm­ers, with reper­cus­sions on pro­duc­tion costs and mar­ket trends.”

“Overall, the water cri­sis has a major envi­ron­men­tal and social impact,” he added. ​“Hence, there is a need to raise col­lec­tive aware­ness and, on the prac­ti­cal side, imple­ment appro­pri­ate agro­nomic prac­tices.”

While each cit­i­zen can play an impor­tant part in imple­ment­ing these swift changes, experts broadly agree that a wide range of actions should be under­taken col­lec­tively to tackle the water cri­sis effec­tively.

“There is not a sin­gle solu­tion, but a set of mea­sures that should be planned and imple­mented at a com­mu­nity level, given the seri­ous­ness of the water sit­u­a­tion glob­ally,” said Matteo Mancini.

As an agron­o­mist, he coor­di­nates the tech­ni­cal area of the non-profit and non-gov­ern­men­tal orga­ni­za­tion Deafal, which sup­ports farm­ers by apply­ing agroe­col­ogy and regen­er­a­tive agri­cul­ture tools.

“The Mediterranean basin is one of the cli­mate change hotspots, and the olive tree is among the crops that are suf­fer­ing the most and poten­tially most at risk in this area,” he said. ​“When it comes to pro­duc­ing oil, this plant needs an ade­quate water quan­tity, from around 350 to 800 mil­lime­ters per year.”

“Note that the annual rain­fall of an area with lim­ited pre­cip­i­ta­tion, such as the Mediterranean, can range between 400 and 800 mil­li­liters, but there is a risk of fur­ther decrease,” Mancini added. ​“Hence, we should develop solu­tions whereby rain­wa­ter is retained as much as pos­si­ble in the ground. Soil regen­er­a­tion can be piv­otal to achiev­ing this in the short term.”

Research has demon­strated that healthy soil is key to tack­ling the inter­locked cli­mate and water cri­sis, so major inter­na­tional orga­ni­za­tions are call­ing on gov­ern­ments to take action on this issue.

The United Nations has esti­mated that one cubic meter of soil can store more than 250 liters of water and remarked that, after the oceans, soil is the largest active car­bon store.

Yet, it could cap­ture and store more if human activ­i­ties did not degrade it. Therefore, its restora­tion is cru­cial since it pro­duces rapid results, is inex­pen­sive, cre­ates jobs and enables peo­ple to ensure food secu­rity.

“Regenerating soil ben­e­fits not only the agri­cul­ture sec­tor but the whole com­mu­nity,” Mancini said. ​“Every farmer can imme­di­ately start doing it by imple­ment­ing a real agro­nomic plan.”

Mancini believes that improv­ing soil’s organic fer­til­ity by increas­ing its organic mat­ter con­tent is a fun­da­men­tal step in start­ing a regen­er­a­tive project.

“Organic mat­ter con­sists in the degra­da­tion prod­uct of plant and ani­mal com­po­nents that come from out­side the soil, like ani­mal manure, stub­bles and plant residues, olive leaves, twigs and more,” he explained.

“Microorganisms degrade this mat­ter, trans­form­ing a small part of it into some­thing extremely valu­able called humus,” Mancini added. ​“The lit­er­a­ture says that one kilo­gram of humus may retain 20 liters of water.”

According to data from CNR and the National Association of Consortia for Land and Irrigation Water Management and Protection, the organic mat­ter con­tent in most Italian soils is two per­cent, below which a process of deser­ti­fi­ca­tion may start.

Moreover, the E.U. Joint Research Center warned that ​“a stag­ger­ing 61 per­cent” of European soils are in an unhealthy state, sub­ject to sev­eral types of degra­da­tion, includ­ing loss of organic car­bon.

“Organic mat­ter, or car­bon, has a fun­da­men­tal role,” Mancini under­lined. ​“It is full of life, as it con­tains organ­isms like fungi, bac­te­ria, actin­o­mycetes and more; it retains min­eral ele­ments respon­si­ble for chem­i­cal fer­til­ity, namely food for plants; and it holds water. The lit­er­a­ture says that a one per­cent increase in organic mat­ter is enough to make a hectare of land hold 300,000 liters more water.”

There are mul­ti­ple ways to increase organic mat­ter on a farm. Mancini sug­gested that one is to min­i­mize tillage.

“Tillage oxi­dizes car­bon, result­ing in greater soil res­pi­ra­tion,” Mancini said. ​“Respiration is a nat­ural process of releas­ing car­bon diox­ide from the soil to the atmos­phere.”

“Yet, increased oxi­da­tion trans­lates into greater car­bon loss and, there­fore, fer­til­ity in the long term,” he added. ​“Reducing tillage in an orchard helps to pre­serve and grad­u­ally increase its organic car­bon con­tent.”

Mancini observed that in some areas, grass­less olive orchards are eas­ily found plowed in depth by farm­ers to avoid com­pe­ti­tion for water between the roots of olive trees and those of weeds.

“We must con­sider that organic mat­ter accu­mu­lates in the upper top­soil, called in pedol­ogy ​‘O hori­zon,’ where ​‘O’ is for ​‘organic,’” he said. ​“Although com­pe­ti­tion may occur, with­out grassy cover, this is exposed to air, light, wind and water, and sub­ject to degra­da­tion.”

“Therefore, to avoid com­pe­ti­tion while main­tain­ing pro­tec­tion, a strip tillage can be use­ful, con­sist­ing in nar­row strips of land, even in alter­nat­ing rows in the case of an olive grove, which should be lightly tilled,” Mancini added.

According to Mancini, another way to increase organic mat­ter is to let spon­ta­neous plants grow or plant cover crops.

Different species and fam­i­lies are used to fix nitro­gen – legumes are the most com­mon – one of the most essen­tial ele­ments for the olive tree and gram­i­na­ceous plants. After choos­ing the most suit­able types, they can be grown in rota­tion with other crops, where nec­es­sary.

“These crops must be prop­erly man­aged to obtain the best results,” Mancini said. ​“Research found that the method applied by many farm­ers, which con­sists of cut­ting the cover crops and plow­ing into the ground, is not help­ful since the organic mat­ter accu­mu­lated dur­ing the plant growth is min­er­al­ized and lost imme­di­ately once in the soil.”

“In the last decade, Deafal and other orga­ni­za­tions have pro­moted a dif­fer­ent tech­nique that helps to retain more mois­ture and car­bon,” he added. ​“It con­sists of flat­ten­ing the cover crops down with a roller-crimper so that they slowly die and dehy­drate, act­ing as nat­ural mulching.”

Mancini added that fer­til­iza­tion is another way to bring organic mat­ter into a plot from out­side.

“In the past, farm­ers used ani­mal manure, which is still a great option,” Mancini said. ​“Today, we can also use com­post, which is avail­able in large quan­ti­ties and can be self-pro­duced and diges­tate.”

“Among recently devel­oped prod­ucts, biochar is a very sta­ble form of car­bon that enhances soil’s struc­ture,” he added. ​“If appro­pri­ately used, all these prod­ucts help to improve the soil health sig­nif­i­cantly.”

With the IESS project, Deafal and CNR-IBE are assess­ing the pos­i­tive impacts of graz­ing lay­ing hens in the olive grove.

Both rumi­nants, such as cows and sheep, and poul­try are help­ful in the orchard, sig­nif­i­cantly con­tribut­ing to the soil health with their manure.

Based on the study of the sward and bear­ing capac­ity, this research orga­nizes ratio­nal graz­ing plans to max­i­mize the pos­i­tive effects of this agroe­co­log­i­cal prac­tice.

“An impor­tant phase to con­sider is plan­ning a new orchard,” Mancini said. ​“Applying the key­line design can be a use­ful strat­egy to mit­i­gate drought and ero­sion.”

Deafal and CNR-IBE stud­ied the ben­e­fits of this hydraulic agri­cul­ture sys­tem. It har­nesses the force of grav­ity of slight slopes to slow down the water runoff and dis­trib­ute it from areas with a higher ero­sion risk towards those suf­fer­ing from low water per­ma­nence.

After a topo­graph­i­cal sur­vey, a cul­ti­va­tion pat­tern is designed accord­ing to the key­lines, which inter­cept the water flow with proper agro­nomic man­age­ment.

“Many farm­ers and agro-tech­ni­cians report water and fer­til­ity improve­ments with this sys­tem,” Mancini said. ​“However, these results can only be achieved by com­bin­ing them with fur­ther soil man­age­ment prac­tices pre­vi­ously men­tioned.”

“We must be aware that this is a com­plex cri­sis, and there is a need for sev­eral inte­grated inter­ven­tions, com­bin­ing var­i­ous dis­ci­plines and skills,” he added. ​“There is not a unique response to the chal­lenges posed. The water cri­sis must be addressed at var­i­ous lev­els, and the whole pro­duc­tion sys­tem, start­ing from pol­i­cy­mak­ers, must become more aware and orga­nized to tackle it effec­tively.”

• United Nations