Why our topsoil should be our top priority

It is incred­i­ble how almost all of life on Earth is anchored to the less than a feet thin top lay­er of the soil. The top­soil is home to most of the microor­gan­isms, and large amounts of organ­ic mat­ter. It is where most of the action hap­pens, which makes life on Earth pos­si­ble. For cen­turies, agri­cul­ture and food pro­duc­tion had been based on the prin­ci­ple of healthy soils pro­duc­ing healthy plants. The incep­tion of indus­tri­al and chem­i­cal-based agri­cul­ture saw strip­ping the soil of its microor­gan­isms and nutri­ents, over­load­ing the soil with chem­i­cals, lead­ing to a loss in soil fer­til­i­ty.

In the last 150 years, the Earth has lost over half of its top­soil due to inten­sive chem­i­cal-based agri­cul­ture and oth­er rea­sons. A stag­ger­ing 24 bil­lion tonnes of fer­tile or 12 mil­lion hectares top­soil are lost along with 27,000 bio species every year. Once lost, regen­er­at­ing the top­soil, would take many years, and experts warn of the end of agri­cul­ture if we con­tin­ue at the cur­rent rate. With­out healthy and alive top­soil, the Earth’s capac­i­ty to sequester car­bon, fil­ter water, improve pol­li­na­tor habi­tat and pro­duce food would go plum­met­ing down mak­ing it a mat­ter of grave con­cern as it would direct­ly impact food and water secu­ri­ty. Pro­longed land degra­da­tion which even­tu­al­ly leads to deser­ti­fi­ca­tion, has in the past led to the col­lapse of major civ­i­liza­tions, includ­ing the Harap­pan civ­i­liza­tion. Accord­ing to the Assess­ment on Land degra­da­tion and Restora­tion report by the Inter­gov­ern­men­tal Sci­ence-Pol­i­cy Plat­form on Bio­di­ver­si­ty and Ecosys­tems (IPBES), “Cur­rent­ly, degra­da­tion of the Earth’s land sur­face through human activ­i­ties is neg­a­tive­ly impact­ing the well-being of at least 3.2 bil­lion peo­ple, push­ing the plan­et towards a sixth mass species extinc­tion, and cost­ing more than 10 per cent of the annu­al glob­al gross prod­uct in loss of bio­di­ver­si­ty and ecosys­tem ser­vices.”

Rec­og­niz­ing this, the Unit­ed Nations Con­ven­tion to Com­bat Deser­ti­fi­ca­tion (UNCCD) was estab­lished in 1994 and is the only legal­ly bind­ing inter­na­tion­al agree­ment address­ing land degra­da­tion, its effects and link­ing it with sus­tain­able land man­age­ment (SLM). Fight­ing deser­ti­fi­ca­tion is also among the tar­gets under the Sus­tain­able Devel­op­ment Goal 15: Life on Land — To pro­tect, restore and pro­mote sus­tain­able use of ter­res­tri­al ecosys­tems, sus­tain­ably man­age forests, com­bat deser­ti­fi­ca­tion, and halt and reverse land degra­da­tion and halt bio­di­ver­si­ty loss.

SDG 15 : Life on Land

15.3 — End Deser­ti­fi­ca­tion and Restore Degrad­ed Land

By 2030, com­bat deser­ti­fi­ca­tion, restore degrad­ed land and soil, includ­ing land affect­ed by deser­ti­fi­ca­tion, drought and floods, and strive to achieve a land degra­da­tion-neu­tral world.

What caus­es land degra­da­tion? Land degra­da­tion is caused by sev­er­al fac­tors, some nat­ur­al, some direct and some are under­ly­ing. Some main fac­tors are : ● Exces­sive use of chem­i­cal fer­til­iz­ers and pes­ti­cides ● Defor­esta­tion and land clear­ing ● Over­graz­ing ● Ero­sion by water and wind ● Urban expan­sion There are sev­er­al oth­er fac­tors such as unsus­tain­able farm­ing prac­tices, over usage of ground­wa­ter, mono­cul­ture, sali­na­tion, inva­sive species, land­slides, etc. “The prin­ci­ple glob­al dri­ver of land degra­da­tion is the expan­sion and unsus­tain­able man­age­ment of agri­cul­ture, fuelled by unprece­dent­ed lev­els of con­sump­tion in an increas­ing­ly glob­al­ized econ­o­my.” says the report by IPBES.

Human trans­for­ma­tion of nat­ur­al ecosys­tems and trade-offs among ecosys­tem ser­vices and bio­di­ver­si­ty.

Source: IPBES Land degra­da­tion and Restora­tion

Land degra­da­tion and Cli­mate Change: Soils as Car­bon Sinks Land degra­da­tion is a major dri­ver of cli­mate change. Cli­mate change again speeds land degra­da­tion as it leads to glob­al tem­per­a­ture rise lead­ing to fre­quent peri­ods of droughts. How does land degra­da­tion dri­ve cli­mate change? To under­stand this in more detail, we need to look at the fol­low­ing: Soil Organ­ic Car­bon (SOC) and Soil Organ­ic Mat­ter (SOM) Soil organ­ic car­bon (SOC) refers only to the car­bon com­po­nent of Soil Organ­ic Mat­ter. Soils act as the Earth­’s largest ter­res­tri­al Car­bon sink and reduce green­house gas­es in the atmos­phere. Soil car­bon seques­tra­tion is a process in which CO2 is removed from the atmos­phere and stored in the soil car­bon pool. This process is pri­mar­i­ly medi­at­ed by plants through pho­to­syn­the­sis, with car­bon stored in the form of SOC. The planet’s soils store more car­bon than the planet’s bio­mass and atmos­phere com­bined. Land degra­da­tion caus­es the release of car­bon pre­vi­ous­ly stored in the soil into the atmos­phere. Between 2000 and 2009, it was respon­si­ble for annu­al glob­al emis­sions of up to 4.4 bil­lion tonnes of CO2. The Glob­al Soil Organ­ic Car­bon (GSOC) map is an impor­tant step­ping stone to deep­en our cur­rent under­stand­ing of SOC stock stored beneath our feet from 0 to 30cm and soils’ poten­tial for fur­ther seques­tra­tion.

Source: Glob­al Soil Organ­ic Car­bon Map

Why is the top­soil so impor­tant, and why not the oth­er lay­ers? It is because of the Soil Organ­ic Mat­ter (SOM) that is present in the top­soil. SOM is the organ­ic mat­ter com­po­nent of the soil with microbes, plant and ani­mal detri­tus, nutri­ents, manures, sludges, leaves, stalks, and oth­er sub­stances syn­the­sized by soil microbes. SOM sup­ports key soil func­tions like increas­ing poros­i­ty for stor­ing water and air for plant roots, sta­bi­liza­tion of soil struc­ture, reten­tion and release of plant nutri­ents, and allow­ing water infil­tra­tion and stor­age in soil. SOM, with car­bon as its main com­po­nent, is cru­cial to soil health and fer­til­i­ty, water infil­tra­tion and reten­tion as well as food pro­duc­tion. Sus­tain­able Land Man­age­ment (SLM) The Unit­ed Nations defines sus­tain­able land man­age­ment (SLM) as “the use of land resources, includ­ing soils, water, ani­mals and plants, for the pro­duc­tion of goods to meet chang­ing human needs, while simul­ta­ne­ous­ly ensur­ing the long-term pro­duc­tive poten­tial of these resources and the main­te­nance of their envi­ron­men­tal func­tions”

The solu­tion could lie in the prob­lem: Soils as a major car­bon stor­age sys­tem, play a cru­cial role in con­serv­ing and restor­ing soils and are essen­tial for both sus­tain­able agri­cul­ture and cli­mate change mit­i­ga­tion. Sci­en­tists say that giv­en the impor­tance of soil’s car­bon absorp­tion and stor­age func­tions, the avoid­ance, reduc­tion and rever­sal of land degra­da­tion could pro­vide more than a third of the most cost-effec­tive green­house gas mit­i­ga­tion activ­i­ties need­ed by 2030 to keep glob­al warm­ing under the 2°C thresh­old tar­get­ed in the Paris Agree­ment on cli­mate change, increase food and water secu­ri­ty, and con­tribute to the avoid­ance of con­flict and migra­tion. Stud­ies have shown that an increase of just 1% of the car­bon stocks in the top meter of soils would be high­er than the amount cor­re­spond­ing to the annu­al anthro­pogenic CO2 emis­sions from fos­sil fuel burn­ing. This is anoth­er rea­son to believe that rich soils can be a potent weapon to com­bat cli­mate change. Ancient ref­er­ences to soil types and soil fer­til­i­ty: In India, for over 10,000 years we have been grow­ing our own food with­out chem­i­cals and with indege­nous and tra­di­tion­al best prac­tices in rhythm with nature and in tune with the soil bio­di­ver­si­ty, we have reaped rich and boun­ti­ful pro­duce each time. Ancient texts such as Krishi Parashara writ­ten by the grand­son of Vashish­ta, Rishi Parashara, Kautilya’s Artha-shas­tra, Tamil Sangam lit­er­a­ture and Surapala’s Vrik­shayurve­da exten­sive­ly deal with agri­cul­ture, hor­ti­cul­ture, soil health and plant bio­di­ver­si­ty. 12 types of lands were men­tioned based on soil type, fer­til­i­ty, and phys­i­cal char­ac­ter­is­tics: 1. urvara (fer­tile) 2. ushara (bar­ren) 3. maru (desert) 4. apra­ha­ta (fal­low) 5. shad­vala (grassy) 6. pankikala (mud­dy) 7. jalaprayah (watery) 8. kachcha­ha (land con­tigu­ous to water) 9. sharkara (full of peb­bles and pieces of lime­stone) 10. sharkar­a­vati (sandy) 11. nadi­ma­tru­ka (land watered from a riv­er) 12. deva­ma­tru­ka (rain­fed)

Soils were fur­ther divid­ed based on the types of crops suit­able for cul­ti­va­tion and the col­or of the soil. Ancient farm­ers most­ly relied on crop residues (to bring the bio­mass back to the soil) manures (as fer­til­iz­ers to replen­ish the nutri­ents) legumes (for fix­ing Nitro­gen) and neem (as a potent pes­ti­cide) for enrich­ing soil fer­til­i­ty. In Krishi — Parashara, it is stat­ed that crops grown with­out manure will not give yield and stressed the impor­tance of manures. Adding manure to the soil will ensure that the nutri­ents and car­bon con­tent that is stripped from the soil dur­ing plant growth are made up for. Now, due to chem­i­cal agri­cul­ture, and heavy mar­ket­ing by chem­i­cal fer­til­iz­ers and pes­ti­cide com­pa­nies, farm­ers have been brain­washed and have almost for­got­ten their intel­li­gent ways of agri­cul­ture prac­ticed by their grand­par­ents for gen­er­a­tions. Sage Parashara also rec­om­mend­ed com­post prepa­ra­tion from cow dung. The dried, pow­dered cow dung is placed in a pit for decom­po­si­tion where weed seeds are destroyed. Today, through Zero Bud­get Nat­ur­al Farm­ing (ZBNF) and oth­er regen­er­a­tive agri­cul­tur­al prac­tices, we are going back to our ancient roots.

The way for­ward The Unit­ed Nations Gen­er­al Assem­bly has declared 2021–2030 as the UN Decade on Ecosys­tem Restora­tion and aims to mas­sive­ly scale up the restora­tion of degrad­ed and destroyed ecosys­tems as a mea­sure to fight the cli­mate cri­sis and enhance food secu­ri­ty, water sup­ply, and bio­di­ver­si­ty. In India, we are using Satel­lite imag­ing and Remote sens­ing by ISRO to map land degra­da­tion and deser­ti­fi­ca­tion and data show alarm­ing rates of the same. Regen­er­at­ing, restor­ing and car­ing for these soils through sus­tain­able soil man­age­ment, includ­ing mulching, plant­i­ng cov­er crops, nat­ur­al fer­til­iza­tion and mod­er­ate irri­ga­tion is what the Earth needs. 🌎🌱

Ref­er­ences 1. https://www.iucn.org/resources/issues-briefs/land-degradation-and-climate-change 2. http://eagri.org/eagri50/AGRO102/lec08.pdf

TAGS: Soil Fer­tilli­tySus­tain­able Agri­cul­tureWorld Soil Day

#SoilFertillity #SustainableAgriculture #WorldSoilDay