Biologically Enhanced Agricultural Management

by Stephen Shafer on March 11, 2019

 

                                      Biologically Enhanced Agricultural Management (BEAM)                               

Summary: Views of a regenerative grazier and climate hawk  on  Biologically Enhanced Agricultural Management,  a system to boost soil organic carbon and  improve soil health without chemical inputs. BEAM  uses  a unique low-tech composting method  (static yet aerobic) the product of which  sequesters carbon in  soil by inoculating roots in  ground  with  beneficial microbes (fungi > bacteria)  rather than delivering carbon as would biochar.   Comparing the mass of  feedstock  input to composting to the mass of carbon sequestered  in  treated soil, BEAM  is  several hundred times more efficacious than standard composting.  It is 20-25 times as efficacious in carbon sequestration as most modes of  “conservation agriculture”  or  improved grazing surveyed in meta-analyses of peer-reviewed studies.  150  million tonnes of vegetal and animal waste  put  through BEAM  into the soil of  all 150 million hectares (371 million acres) of  U.S. cropland over twenty years could improve the soil greatly and by  2040  be drawing  down 1.6 Gt C ( 5.9  Gt CO2)/yr,  more than   all  U.S.A. annual CO2 emissions now.  If  BEAM  proves as good as trials indicate, this country and the world would get a  triple  win   by  a WW II-mode home front project to compost clean waste and inoculate soil with the product: improved soil,  more profit for  farmers and substantial carbon drawdown.   The  project  could begin on a small portion of US agricultural land and be incremented yearly.  The  methods could readily extend to a similar, ever-growing,  proportion of global agricultural  lands.

           

Introduction   Prof.  David C. Johnson, a molecular biologist  at  New Mexico State University,  has  a composting variant known as   Biologically Enhanced Agricultural Management (BEAM) .  The finished product, which he calls “inoculant,”   is a crumbly solid  with a high ratio of  fungi to bacteria.  Applied in small amounts,  material  like  this can  after a couple of years enable sequestration of  far more carbon in soil per mass of  raw material input than any  other means of soil-tending except the peerless grazing + cropping program of  Gabe Brown .           

            Johnson’s method  is not the only way to make fertilizer that  embeds or recruits mycorrhizal fungi to build carbon in soil.    I  have no data  to  compare  its potential for  carbon sequestration (hereafter, C-seq )  to that of  one  commercially-available counterpart (“MF”™  ) sold in the US.   A  U.S. – based  maker  of  devices  to  prepare compost that stimulates microbial activity in soil  reports that their  solid product can be spread at a ton per 1-2 acres, about the same intensity  as  BEAM  moist inoculant.  A “tea” from the Aeromaster TE-500™ extractor (mfg Midwest Bio-Systems, Tampico IL)  can turn that ton into a spray to  treat 650 acres.  What rate of C-seq or crop yield improvement either of these   returns   I don’t know.  Nor do I know  how the final product of  BEAM  compares in  microbial populations to an Australian MF product (Nutri-Life Platform ™,  YLAD Living Soils, NSW AU)  also made with the Aeromaster.  

            So far as I can tell,  commercial operations in AU and USA that make a bioactive soil amendment to  mobilize mycorrhizal fungi in soil all turn their compost to keep it aerobic.  It sounds as if  some  add  a  dash  of mycorrhizal fungi to their inoculant just before it is to be applied to seeds or soil.   Knowing  today  more  about  BEAM ‘s workings and performance  than  that of  similar microbe-deploying processes I will confine my  discussion to BEAM.   Its low-tech  management of  clean  waste  makes BEAM  potentially applicable at  low cost  to  millions of  acres worldwide  to  save soil  and draw down carbon.

            I can’t claim to  understand  BEAM  fully,  probably have some things wrong.  Yet   I believe it  is monumentally important to soil and atmosphere health  and  am  a voice for it.

                            Acronyms and  notations   used in text

BEAM            Biologically Enhanced Agricultural Management

EtOH              Ethanol

F:B                  ratio of fungi to bacteria

MCP                Marin Carbon Project

MF                  Mycorrhizal fungi

NRCS             Natural Resource and Conservation Service

SBD                Soil bulk density

SOC                Soil organic carbon content as % of soil

SOM               Soil organic matter as % of soil

E+ 6                * 10 to the power of 6 ( = 1 million) = * 10^6

Gt                    billion metric tonnes = petagram (Pg)

M mt               million metric tonnes = teragram (Tg)

mt                    metric ton = tonne = megagram (Mg)                          

                         Acronyms used in text
 

BEAM materials and methods   For a year since Don Wilkin told me about it  I’ve  admired David  Johnson’s work from afar and exchanged   e-mails and calls  with him. For an introduction, click  here to see Dr J. presenting in 2018;  here to read an in-depth interview; here for an earlier interview; here  to see a slide show; or here for a preprint of  a report posted in 2015 citation David Johnson, Joe Ellington, Wesley Eaton  Development of soil microbial communities for promoting sustainability in agriculture and a global carbon fix.

            I see BEAM   as  two steps.  First,  prepare  finished  product  (hereafter called BEAM inoculant) in a  Johnson-Su bioreactor    .  Click here for pdf manual.  One can be built for about $50 US  of materials.  Note: earthworms are necessary.  Second, get  BEAM  inoculant, by one of a variety of methods described  below,   into soil that’s already growing plants,  is being seeded, or has very recently been seeded.      

Bioreactor

            BEAM   needs  no  electricity or fuel combustion.  It   uses little water.  Composting time, depending on location and season is 6-12 months, twelve preferred.  It can be done  on  every continent but  Antarctica.   It can use manure (mixed with other waste) ,   pre or post-consumer food waste, waste from gardens and  fields,  tree leaves, barn litter, even wood chips (if small).  BEAM   does  not  demand  “organic” inputs,  though such must be preferable. Toxins like heavy metals and residual biocides (e.g. glyphosate) should be avoided, although many biocides are degraded by the microbes.  Some feedstock (e.g. big leaves, spoiled hay)  may  need to be shredded or chopped.   Earthworms are essential for the composting period after the early thermophilic phase.      

            BEAM is not on patent.   The finished product  is cheap to make.  The Haggertys in Western Australia  added  10  tonnes  C /ha to their previously carbon-poor very dry soils with a one-time application of a seed coating for  $30/ha.  Their natural fertilizer was not made by Dr Johnson himself,   but sounds to be on similar lines.  I surmise they used product from Rhonda and Bill   Daly, the founders of  YLAD  in New South Wales..   Click  to view a  microbial analysis  on the YLAD  “living compost” .   In case that link does not work I have copied screen shots in the appendix.   Remember, this analysis is not of Johnson’s inoculant, but of  that made by a company in Australia with roughly similar methods and possibly similar output.      

           

 

Dr Johnson reports  C-seq rates from BEAM of  10.27 tonnes C/ha/yr when used on initially very  low-SOC soil.  This is 20-25  times higher than the  mean rates of  0.4 to 0.5 tonnes C /ha/yr  tabulated  in  two meta-analyses of “improved management”  (Conant RT et al 2001;    Garnett T  et al 2017).  It is 19 x the mean rate of 0.57 tonnes C/ ha/yr  that  West and Post  ascertained from 67 long-term agricultural experiments around the world. (West and  Post 2002.     

            Raw materials to  fill  Johnson-Su bioreactors  are scarce in some dry places.   One of the many advantages of   BEAM,  though,  is that the final product, especially when diluted,  is much more portable than traditional  compost.  How much more,  is discussed below.  Thus BEAM  inoculant  can be made where raw materials are abundant and shifted  by small vehicle.  From what  the Haggertys described,  a pickup truck (“ute”) can carry all the composting product  that’s  needed  when  mixed with  water   to significantly enhance carbon in the top 30 cm of  1500 acres. For the rest of this essay, however,  I will be more conservative and  say  that  400 lb/acre of inoculant  is needed to add  4.3 tonnes C to the soil of 1 acre 30 cms deep (Johnson, personal communication May 2018).  That’s 1 lb/100 sf,  a mere pinch as fertilizers usually go.  To treat a hundred acres, however, needs twenty tons of  INOCULANT. (800 fifty- pound bags) if the solid form is used..           

            The extraordinary potency  of  BEAM   on a mass basis in  boosting  soil carbon is due to  the  high  numbers of  living micro-organisms (especially  fungi)  in the  BEAM inoculant  The  BEAM  composting process  — relatively slow,  static,  passively aerated and high-moisture –  promotes extensive fungal hyphae formation that is disrupted by conventional turning.  In the  video made at Chico State in 2018 at about minute 103  Johnson jokes that in the bio reactor the fungi  “don’t find their furniture on the sidewalk.”    Mycorrhizal fungi are not plentiful in the  inoculant as it goes into the soil, though other fungi are, far out-populating bacteria.  Once in the soil interacting with growing  roots  the inoculant makes mycorrhizal fungi proliferate.  In  the soil,  the microbiota concentrated in the inoculant  start  sequestering carbon underground from CO2 captured above ground.  The carbon in the inoculant  itself  is almost trivial     

            The role of mycorrhizal fungi in promoting plant health, stepping up photosynthesis and thus carbon sequestration in soil has been recognized for decades.  One can buy bags  of  “MF” at  Home Depot to use in the garden.  This preparation has added minerals, it’s not pure compost. At retail price, it would cost $4000/ton.  What I see as distinctive about Johnson’s BEAM system is that it’s simple enough to be  do  it yourself,   but deployed on a grand scale would revolutionize agriculture.  It is quite suitable to the developing world.      

            The amendment can  be done in several ways.  One is by scattering moist crumbles on   soil surface at  400 lbs/acre. This can be done by hand on a small area.  For a larger area, a slurry can be splattered; or,  inoculant can be mixed with powdered biochar as a slurry then splattered.   A  larger  area can be treated with a given quantity of inoculant   by  beating  a chunk of it   in water (1 kg/70 L water) , then  straining the suspension.    The extract is sprayed on foliage or  dripped  into a furrow with seeds.  Another  method  is to  bathe  the seeds in a slurry,  then plant them dry or wet-coated.  Increased yield of above-ground plant matter is seen after only one year of BEAM.

BEAM effect                                                      Cautions

            Caution 1: Dr Johnson’s figures assume that all biomass grown (successive diverse- species legume-rich cover crops twice a year)  is tilled back into the top few inches  of soil for four years.  Once  BEAM  has been in place for 4-5  years, tilling should cease for good.   Every year or two  foliar spray is applied at about 1 lb inoculant/acre diluted in the needed volume of water .  Thus,  for  three or four years no cash crop from BEAM-treated ground can be harvested for take-away.  This limits what proportion of  her total cropland a farmer can commit to  BEAM at any one time  without expecting  a temporary drop in cash crop yield.

            On the other hand, most conventional farmers and ranchers have to buy synthetic fertilizer and biocides to get their usual yield.  By starting  BEAM  on a piece of land, the operator forgoes  the  net profit on it, which is for most hardly enough  and for many, in a bad year,  a  red  negative unless salvaged by crop insurance.  Furthermore,  most farmers and ranchers will choose to treat their worst soil with BEAM   before their better; there’s less that way   to lose by not harvesting and a better marginal return on investment.  Finally, when BEAM has matured on the ground  held out of cash-cropping, yields should be so much better  and  input costs so much lower that the investment will pay off  handsomely. The transition years remain a problem.

           

 

Caution  2 :  The fungi and bacteria in the BEAM inoculant  must interact with  living roots.  If  ground  is wholly bare, the inoculant  should go in with seeds and at least a little water  by each seed or should be injected into an already seeded furrow.  The inoculant takes best when  watered  in  by rain or irrigation.  

Caution 3:  Even when the mass of carbon in a volume of soil is increased substantially, say from x  tonnes/ acre  to 30 cm depth   to 1.25x tonnes/acre t, the arithmetic difference year to year  in  measured SOC  may  be  too small to be discernible  given sampling variability    The effect  of  BEAM  should be validated by measuring above-ground mass of the crop year to year.   This may need  in the near future   to be controlled for  “CO2 fertilization.”                               

Practicality of BEAM  compared to typical compost   I did several  sets of calculations about what mass of   “ inoculant”  delivers a specified mass of  C-seq in top 30 cm of soil per unit area. By inoculant   I mean the solid but kneadable  material from the bioreactor after a complete cycle, before it is crumbled or suspended in water.  All rates below are per year.  Two sets are shown.       Table 1  hypothesizes  that  C-seq in soil from  using the liquid extract is 1/100th of 10.7 tonnes C/ha or 0.107 tonnes C/ha.  I have no empiric basis for this number.   Table 2 uses figures gleaned from reading interviews with Dr Johnson and corresponding with him   [Lines 39 and  623 in the preprint read 10.27 tonnes  The  10.7 value in these tables was imputed from  line 468, but I saw no  need to replace it as the results would be hardly different. ]

Table 1  0.107  tonnes C/ha/yr sequestered  in soil  using  strained suspension in which 250 kg finished product  are diluted  so as to treat  250 ha

            0.25 tonnes inoculant applied to 250 ha         sequesters 0.107  tonnes C/ha   

            1 tonne inoculant applied to 1000 ha              sequesters 0.107  tonnes C /ha 

            1 tonne inoculant applied to 2470 ac              sequesters 0.0433  tonnes C/ac  

            0.0004  tonnes inoculant applied to 1 ac        sequesters 0.0433 tonnes C/ac           

C-seq yield of BEAM  inoculant on a mass basis in this hypothetical scenario is .0433 tonnes C/ 0.0004 tonnes inoculant  applied  =  108

Table  2  10.7  tonnes C/ha/yr  sequestered in soil  by  dusting  surface foliage at 450 kg/ha  ( = 400 lb/ac)

            0.45  tonnes inoculant applied to 1 ha            sequesters 10.7  tonnes C/ha    

            0.45 tonne inoculant applied to 1  ha              sequesters 4.3  tonnes C/ac 

            0.45 tonne inoculant  applied to 2.47 ac          sequesters 4.3  tonnes C/ac 

            0.18 tonne inoculant applied to 1 ac               sequesters 4.3  tonnes C/ac 

 C-seq yield of BEAM  inoculant on a mass basis is 4.33 tonnes C/0.18 tonnes v  applied  =  24

 Discussion  A frequent   knock on composting in general  is that the mass of  top dressing needed to cause sequestration of   (say)  0.2 tons  C/acre is so  much it could not be used on millions of acres.   This is true.   A decent  compost  is 15  %  C  by  weight  with a C:N ratio of about 20:1    If  C is 15% (i.e. 300 lb /ton),  just to spread 0.2 t  C/ac requires applying 400/300 = 1.35 tons of top dressing dry weight per acre. Much more would be needed to set the stage for actually sequestering 0.2 t/ac to 30 cm deep in soil.        

            It’s painfully clear, then,  that a great deal of  raw material would be to prepare a compost   that would  boost  soil organic carbon content in a large area even in the most important top four  inches.   The esteemed  Marin Carbon Project  (Ryals and  Silver 2013)   was not designed to measure carbon sequestration in soil but, rather,  to see if compost could  restore degraded grazing land [ Note: it can]   I got  from  Toensmeier’s Appendix C  that 2.1-4.7 t C/ha/yr were sequestered over four years.  [To my dismay I could not understand  from the article how Toensmeier calculated the range of the rate estimate, but that’s my problem.]

            In the MCP finished compost from municipal waste was applied  to  soil at  70 t dm/ha .  It’s a safe bet  that  at least  150  tons  of wet raw material had to be trucked, windrowed  and periodically turned.  The Cornell Waste Management Project composting method, for example, got  about 1 ton of finished compost for every 5 tons of fresh material. (Schwarz and  Bonhotal 2018).    When many tons of finished amendment /ha are needed,  the process cannot be applied  to many millions of acres/year.    

            Let’s  compare the C-seq in soil observed in the MCP  to  that reached by  BEAM  in respect to  mass of final product applied to soil, using  Table 2.  Remember, the MCP figure is a  secondary  finding .  This was not the research objective.

            MCP 28 tonnes of finished compost  applied to 1 acre with plant mass partly ingested,  not all put back into soil sequesters 2.1 to  4.7  tons C/ha/yr = 0.8 to 1.9 t/ac . The mid-range is 1.4  tons C/ac/yr  The  C-seq yield  is   1.4 t / 28 t =  .05  tonnes C sequestered/tonne dm finished product applied/acre (these may be short tons but no matter; it’s the ratio that matters)
            Johnson-Su compost yield with all plant mass put back into soil  is 4.33  tonnes C /0.18 tonne applied   =  23.9  tonnes  C sequestered/ac  /tonne INOCULANT  applied/ac

NB:  The C-seq in soil yield  of  BEAM   is   23.9/0.05 = 478  times greater than MCP weight for weight of product applied. 

            Another dig against amending soil with  compost made on a farm or ranch (and thus likely using at  least some manure)   to restore C-depleted soils is that it is  robbing Peter to pay Paul, moving carbon from one spot on the earth to another.   This is true  if the soil  out of which the carbon came before composting does not get  it all  back.       

            Say   the herd   ate   a  ton  of  carbon from the herbage of two acres in the  west pasture and  the compost or stockpiled litter  spread back on did  not  return  a ton of  C to the pasture. There  has been a net loss of C  unless improved grazing practice has caused C-seq despite removal of  carbon.  Moreover, flinging  a ton of  C  onto the sward of the west pasture does not put all that C far enough into the soil to be sequestered.

            In BEAM, the transfer of carbon from point A to point B counts for little, because the   active  agent  of carbon sequestration in soil with BEAM  is not carbon but micro-organisms.  This makes it relatively easy to restore by biological activity to a plot or field carbon that was taken from it by harvesting a crop.  Based on figures Dr Johnson gave me in an e-mail in early 2018,  if 1800 lb  (818 kg)  of  wet-weight crop residue  from two acres of cropland are composted,  the inoculant   yield is 700-1000 lb, let’s say 800 lb ( = 364 kg ) .  This is enough  spread at 400 lb ( = 182 kg) /acre on those same two acres,  to sequester 4.33 tonnes C/ac/yr..  Say the dry weight of  the  crop residue is 15%  of  818 kg , of which about 48% is carbon..  Thus about 56 kg of C went  into the reactor from those two acres, while each of the two gains 4.3 tonnes C/yr.  Good return on carbon investment !

Spreading the wealth of BEAM     According to FAO  http://www.fao.org/faostat/ the USA has about 150 million ha of “arable”  land  suitable for cultivation.    The world has about 1.4 billion ha of arable land,  most  of which  could use a higher soil organic carbon level.  To treat all US arable land with a dusting of 400 lb BEAM  inoculant  /ac (= 449 kg/ha)  would take  67.4 million tonnes.  To prepare  that amount would call for  67.4 * (818/364) = 151.5 million tonnes  of  vegetal or animal waste  feedstock   to be collected and    put into about 190  million bioreactors, each  tended with a  minute’s  daily  labor for a year.

            Every hectare treated would have to be put into eight successive two/year  cover crops for four years, with no two exactly alike.  Each  crop  would be  crushed and lightly tilled into the top four inches of soil.   If  ten  per cent of USA  arable land went into the program per year, it would take fourteen years to finish.   This seems a big task,  but compare it to another fairly recent enterprise, corn ethanol.  

          The USA  grows and delivers about 5 billion bu (140 million tons) of shelled corn/year for making ethanol and about an equal  tonnage of associated corn stover not used in that           process.    In 2011 (the figure is probably lower now)  20.9 million acres of cropland were dedicated to corn for ethanol. (Mumm et al, 2014)  The ethanol thus produced  is   about 365 million bbl/yr or 45 million metric tons.     The corn ethanol life cycle is far   from carbon-neutral.  Production facilities   alone in 2014 emitted 18 M mt CO2

         Sequestration to 30 cm depth   of  10.7 tonnes C/ha/yr  on 150 million ha approaches (at 0.26%/yr)   the global 4per1000 initiative objective  for annual SOC  improvement and also draws out of the air 1.605 million tonnes C/yr  = 1.6 Gt C/yr.   See Table 1  col F below.  This is  16 % of  global  carbon emissions for which humans are responsible. [I disdain  the malformed neologism “anthropogenic” though it is now accepted by everyone else.]  It is  more than the annual  CO2 emissions of the USA.  (see Table 2)    

            Figure 1  below compares actual net annual carbon emissions just from facilities that produced corn ethanol (not full life cycle) to potential net annual emissions associated with BEAM on 150 M ha.  The tonnage of raw material is about the same for both, about 150 M mt.  Only shelled corn is counted, which understates the tonnage of corn appropriated for EtOH by about half.  I won’t consider here that distiller’s grain from the process is used as animal feed.    The BEAM value of minus 1,600 M mt is potential, not actual . 

 

 Figure 1.  Net potential annual CO2 emissions from BEAM on 150 M ha compared to  net actual emissions from facilities that produced corn ethanol. Neither is a complete Life Cycle Assessment. 

 

 

A

B

C

D

E

F

F
 

million  ha

 INOCULANT mt/ha

RM M mt

M mt  INOCULANT  appl

seq Mmt C

seq Gt C

seq Gt CO2e

1

150

0.449

151.5

67.4

1605

1.605

5.89

2

1500

0.449

1515

674

16050

16.05

58.9

 

Table 1.  Amounts of raw material  (RM)  and  BEAM finished product  (INOCULANT) needed to sequester in soil a specified  mass of  C (in gigatons = Gt) on a specified area of land.

Col A  land area to be treated 

Col B  metric tons of finished product BEAM to be applied /ha  

Col C  metric tons RM (raw material)  needed to make the INOCULANT/ha  in col B      C= D *818/364

Col D  total  application of INOCULANT in million metric tons over all hectares   D = A* B

Col E  total carbon  sequestered in soil over all treated hectares in million metric tons  E = A* 10.7

Col F  total  carbon sequestered in soil over all treated hectares in billion metric tons (Gt)

Col G carbon in col F transformed into CO2

Line 1 is USA  cropland area  Line 2 is world

 

 

 

Global Gt/yr

USA Gt/yr

all GHG  Gt CO2-e

50.1

6.5

CO2 only Gt CO2

37.1

5.3

CO2  Gt  C

10.1

1.45

Table 2. Gross (I think) GHG emissions for globe and USA for all GHG and for CO2 only. Guesstimates and predictions for 2018 from various sources

            Different figures can be put into Table 1 to see  new  scenarios.  The BEAM treatment of just 15 M ha of  US arable land (10% of total) would  require composting only about 15 M mt of waste to ultimately  sequester 0.16 Gt C/yr ,  That mass  would almost offset  all  USA ag emissions (aprox 0.18 Gt C/yr ).  Alternatively, more land could be treated.

         If US grazing land, estimated by NRCS  to be 213 million ha,  were encompassed  as well as all arable land,  363 E +6 ha would be available.  This would require 367 M mt raw feedstock but would sequester 3.88 Gt C, more than  half  of  total  US GHG emissions as CO2-e.   Note that the effect of Johnson’s inoculant on perennial grasslands  could  be less than on cropland because the inoculant  might not get as close to roots as fast when scattered or sprayed  as when touching the seed.  Moreover, it would be imprudent to treat all perennial grass and forbs like a succession of cover crops with serial shallow tilling.  On the other hand, spraying  pasture just before a brief rotation of  trampling defecating grazers might be a big plus.  Another unknown.

            A liquid extract of the inoculant coated onto seeds or spot injected by seeds at planting could magnify its  effect so that  only a few  million tonnes,  carefully applied, might over fourteen years  suffice to sequester 10.7 tonnes C/ha/year on 150 M ha .   A liquid  (Nutri-Life Platform™)  made by a  method that resembles Johnson’s is advertised to benefit soil and plants when seed is coated with only 50 grams/ha.   I have no data on C-sequestration attributed specifically to this material, but it may be  the seed coating that  the  Haggertys  stated added 10 tonnes of C to their soil at very low cost/ha ($22 USA).

Conclusions   If  C-seq in soil via bioactive soil amendments like the BEAM  system on  150 M ha did nothing for soil quality, “only” drawing down  16% of global CO2 emissions/yr, it would be cost-effective in materials  and job-creating compared to high-tech CCS methods.   

            If C-seq in soil via via bioactive soil amendments  on 150 M ha did nothing to remove CO2 from the atmosphere, but increased SOC by 0.26%/year,  it would save our soils and  water from impending ruin, remembering that water  is damaged by nitrate runoff .

            Thus, C-seq in soil via via bioactive soil amendments  on 150 M ha has the potential for enormous good on both the  above  fronts without risk of  harm except short rotation  of some land out of  chemically-dependent cash-cropping.  This is a blessing, undisguised  but unrecognized.  Our country sees nothing amiss in processing several hundred million tons of  good  field corn  to make 45 million tons of ethanol  that’s  distilled with energy,  transported by rail and   combusted into CO2.  This is the will of lobbies.         

            Think back to the line above  “The treatment of just 15 M ha of  US arable land (10% of total) would sequester 0.16 Gt C, almost negating all ag emissions (aprox 0.18 Gt C).”  Compare that to the manufacture of corn ethanol,  which  in  2011 used  8.5 Mha and  has according to USDA  slightly more than  half the GHG intensity of gasoline in its life cycle, no small amount.   Which is a better idea for our country ?   Support  a  biofuel industry  on  5%  of  US arable land   that enables increasing fossil fuel combustion  OR  start  10% of arable land per year  on a low-cost path  that over  10-20 years can restore  failing soils, decrease dependence on  nitrogen fertilizers and almost negate agricultural GHGs?        

            Just asking.

                                                         ________________________

 

End-note about units.  Readers are likely annoyed or bewildered by what seem capricious jumps from metric to standard units even allowing hybrids  like “ tonnes/acre/”  Read carefully, make notes.      Note also that  this entire essay treats elemental carbon, not  CO2.  There are many chances for confusion especially in  memory, when  some writers specify  CO2 and others C.   It’s  easy to read  somewhere  about a  C-seq rate of (say) “ 1.5 tonnes  CO2/ha/yr”  (depth not even specified) and recall it later as  1.5 tons C/ha/yr or worse yet  1.5 tons  C/acre/yr or 1.5 tons CO2/ac/yr . Many permutations.

 

                                References not given as hyperlinks in the text are below

Conant RT, Paustian K  and Elliott ET  Ecol Applications 11 no 2 : 343-355 2001

Garnett Tara et al “Grazed and Confused?” Food Climate Research Network 2017

Johnson, David,  Joe Ellington, Wesley Eaton  Development of soil microbial communities for promoting sustainability in agriculture and a global carbon fix.  https://peerj.com/preprints/789v1.pdf

Ryals R  and  Silver W Ecol Applic 23: no.:46-59 2013

Schwarz M  and  Bonhotal J  Compost Science and Utilization vol 26 issue 2 pp 128-143 2018

West TO and  Post WM.  Soil Science Society of America Journal  vol 66: 1930-1946,  2002

Toensmeier E.  The Carbon Farming Solution. Chelsea Green, 2016

Written by Stephen Q. Shafer MD MA MPH Saugerties NY 12477   Permission to quote is hereby granted so long as the  permalink is cited.  Photos of Dr and Mrs Johnson and of the control and BEAM plots used here are  by permission of Dr Johnson and cannot be reproduced without his permission.

Potential of Different Practices for Carbon Sequestration in Soils

by Stephen Shafer on February 25, 2019

                           Potential of  Different Practices for Carbon Sequestration in Soil   

           This essay starts with  the current loci of carbon sequestration, geological hydrological and biological.  I’ll  then review  some “natural solutions”  for near-term biological C-sequestration, which are mostly through photosynthesis in living organisms.  I will look at  the potential for various of these to contribute to essential carbon dioxide draw-down and  to restoration  of carbon-depleted soils. I point at the end  to  the extraordinary potential for global CO2 draw-down and soil improvement that is  in  low-cost  organic  soil amendments  made from compost  that mobilize soil biota to sequester carbon in ag soils.  One such “inoculant”  leads to sequestration to a 30 cm depth of  10  or more tonnes of carbon /ha/yr .  Treating all 150 Mha of  U.S. arable land with 450 kg/ha (~400 lb/ac) of that inoculant  could,  if small field trials are valid,  sequester 1.6 Gt C ( = 5.86 Gt CO2)  nationally/yr.  This represents more than total yearly US emissions of  CO2 and 16% of global emissions.  It is time to start a healthy low-tech Manhattan Project that puts us in symbiosis with  soil life  instead of thrall to nuclear fission.  The stakes for human survival are just as high or higher  as in 1942.

           Carbon  sequestration  means long-term storage  away from the atmosphere.   What’s   long term is fuzzy; let’s say at least five decades, preferably centuries or eons.  Most of  Earth’s carbon  (see graph) is securely sequestered  in  marine sediments and deep terrestrial rock (lithosphere) or in deep ocean waters.  Three per cent  is  insecurely sequestered as  fossil fuels now being de-sequestered as if there is no tomorrow.

Graph 1 Distribution of carbon in the world including atmosphere.  Hover cursor over a sector to see value in Gt C. Source https://worldoceanreview.com/en/wor-1/ocean-chemistry/co2-reservoir/     

            Carbon  in the atmosphere is not sequestered, nor is that  in ocean surface.  In both of these relatively small compartments there is now too much carbon as CO2.    Some carbon in terrestrial plants (e.g. the wood of   long-lived  trees or in permanent structures)  is sequestered above ground at least for decades ,  while that in leaves, grasses, forbs and other annual plants is not.  Carbon in soil can be sequestered long-term if the soil is not turned over and   there is year-round plant cover on it to prevent erosion by wind and water abetted by heat.

 

                                  Acronyms and abbreviations

BEAM            Biologically Enhanced Agricultural Management

EtOH              Ethanol

MF                  Mycorrhizal fungi

SOC                Soil organic carbon content as % of soil

SOM               Soil organic matter as % of soil

E+ 6                10 to the power of 6 ( = 1 million) = * 10^6

F:B ratio          ratio of fungi to bacteria

M ha                million hectares = 2.47 million acres

Gt                    billion metric tons (tonnes)   = Petagram  (Pg)

M mt               million metric tons ( tonnes) = Teragram (Tg)

mt                    metric ton ( = tonne)  =  Megagram (Mg)        

 

            To brake  global heating, the world must stop de-sequestering fossil fuels and bring to  far above today’s  natural background the sequestration of carbon  from  the atmosphere, most of which is in CO2 .  This essay looks at different methods to increase total C-seq, skipping over the high-tech ones  to focus on low-tech  “natural solutions”  that  sequester carbon in soil,  at the same time improving it.  Amongst  the  low-tech ones  the  highlight will be the potential for  greatly enhancing C-seq in soil by spreading  compost rich in fungi that once interacting with plants in soil stimulate proliferation of mycorrhizal fungi  (MF)    To start, below   is my layout of  most methods for  C-seq  now usable.   It’s not all-inclusive.

High tech Carbon Capture and Storage

            *from fossil fuel combustion

            *from biofuel  combustion

            *directly from air

Low-tech  not using photosynthesis

            Biochar, terra preta

Low-tech  using direct photosynthesis                      

            Trees  (including bushes, shrubs)

            No-till + cover crops  (“conservation agriculture”)

            Short-stay long rest grazing by ruminants   (“holistic or adaptive multi-paddock”)

            Unmanaged vegetation not forests  or  range grasslands (e.g. marshes, peatlands)

            Natural soil amendments 

                        Traditional composts

                        Mycorrhizal fungi

 

            Another schema is nicely shown by Mary Hoff (2017)   in “Eight Ways to Sequester Carbon to Avoid Climate Catastrophe.” 

                        Title                                          Potential for C-seq in  Gt  CO2/yr

            Afforest/reforest                                             1-14

            Carbon farming                                               1-13

            Other vegetation                                             unknown

            *Bioenergy carbon capture and storage          1-20

            Biochar                                                            1-4

            *Fertilize oceans                                             1-4

            *Rock Solution                                               1-18

            *Direct capture  from air                                 3-16

 

            An important 2017 paper by Griscom et al  reviewed “Natural Climate Solutions.”  The many authors assessed twenty natural pathways, none being  any of  the methods  marked  in the lists above  with  an asterisk.  Those must be  considered to be too high-tech or to push  nature too  hard.   The graph below from that paper. shows the twenty pathways  and the climate mitigation potential as of 2030 for each under three scenarios – (a ) maximum under  constraints of land and supply (b) achievable at cost of  $100/t  CO2  (c) achievable at low cost of $ 10/t CO2

             The  seven   categories on my list don’t pour  neatly into  the twenty  in  the  Griscom et al  paper,   but fit the  four in Hoff’s  article that I thought are closest to  natural processes. Those four fairly well comprehend  the twenty in Griscom et al as follows:

  Griscom et al             Max     Cost eff                                   Hoff                Max     mid-range

Forests (6 subcat)        16.2        7.3                            Afforest/reforest         14        7.5

Ag and grasslands      

 (10 subcat)                  4.8       2.5                             Carbon farming           13        7

Wetlands (4 subcat)      2.7       1.5                             Other vegetation         unkn    unkn

Total                            23.7     11.8                                                                 27        14.5

Table 1.   Maximum potential and cost effective potential (<$100/t) in Griscom et al and,  for the corresponding categories in Hoff,  the top of range and the midpoint of range.  All values are in Pg  CO2/yr = Gt CO2/yr.  Global gross emissions in 2012 (Edgar database), for comparison, were 46.4 Gt CO2-e for big three GHG and 34.9 Gt CO2 for molecular CO2.

            Although Hoff gives more potential for mitigation  to carbon farming than Griscom et al do to their ten subcategories of Ag and grasslands, the two viewpoints agree reasonably on total potential for natural solutions and on potential for forest management.  Is Hoff over-estimating the potential of carbon farming or do  Griscom et al discount it too deeply?  The  answer to that depends on  what  I call “natural soil amendments.”          

            Set aside now   all the  “high tech” methods viz. CCS from combustion , direct capture from air,  ocean fertilization and “rock solution.”  None has the potential to both draw down CO2 and improve soil.  The first three are mightily expensive.  This leaves, from  my list, the following  “natural” solutions:

Low-tech  not using photosynthesis

            Biochar

Low-tech  using direct photosynthesis                      

            Trees  (including bushes, shrubs)

            No-till linked to cover crops

            Short-stay long-rest grazing by ruminants 

            Unmanaged vegetation not forests  or range grasslands

            Natural soil amendments 

                        Traditional composts

                        Mycorrhizal fungi

            Being interested in crop and animal agriculture, I now home in on methods applicable to cropland and grazing land. This means setting aside trees,  though they are in almost everyone’s view the  major  locus  of  biological C-seq anywhere that is at hand  today.  I will also set aside “unmanaged vegetation”  This leaves a smaller suite of methods, the names of which do not correspond neatly  to  the  ten subcategories in Griscom et al  though all fit well  into Hoff’s  “Carbon farming.”

Low-tech  not using photosynthesis

            Biochar

Low-tech direct photosynthesis                                 

            No-till + cover crops

            Short-stay long rest grazing by ruminants                   

            Natural soil amendments 

                        Traditional composts

                        Mycorrhizal fungi

 

 

Solution  and scope

intensity

max

cost effective
     

Tg CO2/yr

   Tg CO2/yr

1

Avoided grassland conversion 1.7 Mha

  

116

35

2

Cropland nutrient mgmt  44 Gt N/yr

  

706

635

3

Biochar  1670 Tg/yr crop residue

0.18 MgC/Mg dm

1102

331

4

Grazing optimal on  712   Mha

0.06Mg/ha/yr

148

89

5

Grazing legumes on 72 Mha

0.56Mg/ha/yr

147

132

6

Grazing improved feed for 1.4 B head

  

680

204

7

Grazing animal mgmt for 1.4 B head

  

200

60

8

Conservation Ag  on 382 Mha

0.32Mg/ha/yr

413

372

9

Trees in croplands 608 Mha

  

1040

439

10

Improved rice  163 Mha

  

265

159
 

Total

  

4817

2456

 

Table 2 .  The  ten natural solutions proffered under “Ag and Grasslands”  in Griscom et al. with the maximum mitigation potential and the cost-effective mitig. pot. given for each.  The scope (extent) is given for each in area or number head or (biochar) raw feedstock tonnage.  The intensity is given for some.  The value 0.18 Mg  C/Mg dm pertains to biochar.  Mg = metric ton  Tg = million metric tons  Gt = billion metric tons [= Pg ]  Mha = million hectares B head = billion head of cattle  C = carbon   N= nitrogen dm = dry matter

 

            Biochar on my highlighted list above corresponds to line 3 in table 2.  “No till plus cover crops” corresponds roughly to table 2  line 8 . “Short stay long rest grazing”  aligns roughly with lines 4 and 5, perhaps also with line 1.  Lines 6 and 7 of table 2 don’t  fit my schema; the descriptions look like recommendations for grain finishing of fewer cattle  in smaller spaces where I would call for  more land under  holistic grazing  management.  “Trees in croplands” [and silvopasture, not so designated in Griscom et al]  are sound solutions which  I  haven’t studied enough to have included at this point . Note that   Drawdown   gives “silvopasture” 9th place overall on its lineup  of solutions, on which  “tree intercropping” ranks 17th  place and “conservation agriculture”  16th .

          I  must   move past   biochar .  It  has ardent proponents as a technique for C-seq, especially if the gas generated in the low-oxygen heating can be combined-cycled to drive a machine.  Leaving biochar undisturbed guarantees sequestration  for decades, perhaps centuries.  It is not, however, well suited  for  boosting  carbon in  large areas of  soil.  To make a ton of biochar, more than five tons of feedstock (wood, crop residue) are  required
(inferred by me from  Supplementary Information for Griscom et al  p 9) ,  That ton of particulates has to then  be distributed throughout a large volume  of soil to be of  benefit.  Too much biochar can hurt soil.  Application rates are high; Lehmann et al  write  of 40 tonnes/ha.  In 2010 a review by the International Biochar Initiative gave a range of rates from 5 to  50  tonnes/ha, calling attention to problems in spreading crushed material on soil such as wash-away and blow-off.    I gather that a high proportion of carbon in biochar is recalcitrant, stable for decades or centuries against  oxidation  but  less interactive with soil than particulate carbon and humus carbon. Biochar stands  #72 in Drawdown.

            Eagle et al  (2012) tabulated four studies of  biochar, on three of which Prof. Lehmann was an author.  I could not tell how much of the sequestration potential in any of  these would translate into increased soil carbon elsewhere than at   the burial site.  In  Nature 2007, Lehmann writes that the biochar resulting from pyrolysis of 600 M mt of fast-growing vegetation could when put into soil sequester 1.6 Gt C (= 5.86 Gt CO2) per year.  I could not, however,  find  the land area that would be treated.  Eagle et al record in discussing that paper  an associated potential  seq rate of  19.57 t  CO2/ha/yr [though I don’t know how they came to that figure].   Even at that  high rate, 290 Mha  (716 E +6  acres) would have to  be treated  with  uniform dispersal throughout the topsoil of  those hectares to maximize benefit to soil as well as pure sequestration. 

            Other reports in the same table in Eagle et al have  much lower rates for C-seq..  I’m fuddled, but gather  that  (1)  biochar itself when sealed away can sequester perhaps a fifth of the carbon that was in the feedstock, which means much less C emission than burning that feedstock or letting it decay on soil surface  (2)  biochar in soil adds carbon but  may not add it by stimulating microbial activity, for  which it may be more  housing  than  a nursery (3)  no matter how  biochar is made, it would be difficult and expensive to spread  it into millions of hectares of soil.

            I am sure that modern biochar mixed with something like manure  is an excellent soil amendment for lawns, gardens and trees.  That said,   Griscom et al – and this is significant – do not regard it as a soil amendment for a global scale.  I guess this is because it would  be so  hard to  use on  millions of hectares.

             Griscom et al do not have  a category for what my list calls “natural soil amendments.”  This to me is an understandable but regrettable omission.  “Composting”  stands only  60th position in  Drawdown, below the median.  In my list, “traditional compost” includes manures and vegetal farm waste that have been stockpiled or more properly composted, but not raw manure from storage pits.    Eagle and colleagues did distinguish, among twenty-one  areas of possible intervention “Apply organic material e.g. manure.”   Their report tabulated eight studies of  “land application of organic material, USA.”  The potential for soil C-seq ranged from 0.70 to 3.5 t CO2/ha/yr with a median of 1.85.  The mass of organic material that must be applied to get rates like this, however,  is too much  make the practice  widely useful.  The Marin Carbon Project, for example, applied 70 tonnes/ha  finished compost to get C into soil at rates (per Toensmeir p.390) of 2.1-4.7  t C/ha  into soil.        

            Besides traditional  compost,   however, a little-known  innovation  for creating humus has shown results that could revolutionize soil management and potentially out-downdraw  all the ag and grasslands solutions presented by Griscom  et al.   The  innovation  is composting  that  bio-magnifies populations of desirable pathogen-fighting microbes.  It  reverses the usual ratio (<1) of desirable fungi to  bacteria.  This reversal  be done with or without turning. If  turning is not used, aeration requires a special design of the pile.  A high F:B humus must interact with living plants to sequester  carbon in soil.  I will showcase these highly bioactive preparations after a look at the C-seq potential of  “regenerative” solutions that do not use  them.

 

            There remain three “natural solutions” on Table 2 that have a counterpart on my list. 

 

Solution  and scope

intensity

max

cost-effective

 

 

Mg C/ha/yr

Tg  CO2/yr

  Tg  CO2/yr

1

Grazing optimal on   712   Mha

0.06

148

89

2

Grazing legumes on   72  Mha

0.56

147

132

3

Conservation Ag  on  382 Mha

0.32

413

372

 

Total

 

708

593

 

Table 3.  The three natural solutions in Griscom et al that best fit the term

“Regenerative Agriculture” insofar as it is “carbon farming.” Excerpted from Table 2

 

Their total maximum potential (see table 3)  is 708 Tg CO2/yr = 0.708 Pg = 0.708 GtCO2/yr, about 15% of the Ag and grasslands total  in table 2.   This is disappointing for advocates  of  “Regenerative Agriculture,”  because these  three are  the  mainstays  of Regen Ag: no till, cover crops and holistic grazing.   Don’t despair.   The potential for optimal grazing may be  seriously underestimated.   Stanley et al reported, for instance, a  C-seq rate of 3.59 Mg C/ha/yr due to adaptive multi-paddock management, while Wang et al estimated  that converting from heavy continuous to multi-paddock grazing led to C-seq of  2 Mg C/ha/yr.  Machmuller et al (2015) reported 3.2 Mg C/acre.   Moreover, at  0.32 t/ha/yr, the estimated potential for “conservation agriculture” is also on the low side.  Toensmeier (p. 390) tabulates twelve figures ranging from 0.1 to  6.3 t C/ha/yr,  median 2

            At last we get to the central point  of this essay:  bioactive fertilizers with a high F:B ratio that enable a  thriving  population of mycorrhizal fungi are reported to promote extraordinary C-seq rates after  comparatively light application.  (see my companion piece “Biologically-Enhanced Agricultural Management”).  This potential has not been acknowledged in any wide-ranging authoritative review such as Griscom et al or Eagle et al  or Garnett et al.  Treating all 150 Mha of  U.S. arable land with 449 kg/ha of one such product –BEAM inoculant –could,  if small field trials are validated,  sequester 1.6 Gt C ( = 5.86 Gt CO2)  nationally/yr.  This represents more than total yearly US emissions of  CO2 and 16% of global emissions.  1.6 Gt  C  is the same figure that Lehmann projects  biochar could sequester.  It would come through BEAM, however, at much lower cost for processing, for transportation and application than  biochar would incur.

            On a global scale, high F:B bioactive fertilizer such as BEAM could bring back world cropland soils from the brink of collapse while sequestering carbon.  I don’t know its impact on grasslands but expect that it would work  well in conjunction with holistically  managed grazing to sequester C and make the soil more resilient and productive.

 

Graph 2. Global potential for C-seq in soil =  CO2 draw-down in 2030 for four categories of “natural solutions” in Griscom et al and for BEAM treatment of 1000 Mha (~2/3 of world’s) arable land.

                                                                                       References

http://edgar.jrc.ec.europa.eu/overview.php?v=CO2andGHG1970-2016&sort=des8

 

Eagle, A., L. Olander, L.R. Henry, K. Haugen-Kozyra, N. Millar, and G.P. Robertson. 2012. Greenhouse Gas Mitigation Potential of Agricultural Land Management in the United States: A Synthesis of the Literature. Report NI R 10-04, Third Edition. Durham, NC: Nicholas Institute for Environmental Policy Solutions, Duke University

Garnett Tara et al “Grazed and Confused?” Food Climate Research Network 2017

Griscom BW, Adams J, Ellis PW et al Natural Climate Solutions pnas 114(44) 11645-11650 2017

Lehmann J . A Handful of Carbon Nature vol 447 10 May 2007 : 143-144

Lehmann, J., Gaunt, J. & Rondon, M. BIO-CHAR SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS – A REVIEW  Mitig Adapt Strat Glob Change (2006) 11: 403

Drawdown The Most Comprehensive Plan Ever Proposed to Reverse Global Warming Edited by Paul Hawken.  New York, Penguin 2017

 Machmuller MB, Kramer MG, Cyles TK et al  Emerging land use practices rapidly increase soil organic matter. Nature Communications 30 April 2015  | DOI: 10.1038/ncomms 7995

 Roberts KG, Gloy BA, Joseph S et al [Lehmann senior author] Life Cycle Assessment of Biochar … Environ Sci Technol 44 (2) p. 827-833 2010

 Stanley P,  Rowntree JE et al  Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems.  Agricultural Systems 162: 249-258 2018

 Want T, Teague RW et al GHG Mitigation Potential of Different Grazing Strategies in the United States Southern Great Plains. Sustainability 7, 13500-13521 2015,

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