Tom Newmark - Field Trials in Costa Rica

This is where my journey started, at Rodale’s FST in the Lehigh Valley

40% of the world’s population and 55% of children under the age of 5

live in the tropics. We need to demonstrate that regenerative

agricultural practices work in the tropics.

The Carbon Underground Tropical Farming Systems Trial

Trial Design

Same cassava starter cuttings, same farmers, same sun, same

starter soil, same water

Then a drought happened….

The organic cassava

The “conventional” cassava

Marked Failure to Germinate in Conventional Fields

BD.A BD.B OR.A OR.B CV.A CV.B0

500

1000

1500

2000

2500

Average number plants per treatment groupAverage number per treatment group that did not germinate

BD.A BD.B OR.A OR.B CV.A CV.B0.0000

5.0000

10.0000

15.0000

20.0000

25.0000

30.0000

35.0000

40.0000

Average % of plants that did not germinate per treatment group

Average % did not germinate per treatment replication set

We then replicated germination conditions in a more controlled environment, taking soil from each of the six farming systems and

replicating the drought conditions by planting under greenhouse plastic.

We found that the germination results under greenhouse plastic

were the same as in the field. Here are two photos to show the

differences between regenerative organic and conventional

treatments.

On the left, conventional. On the right, regenerative organic.

Seeking explanations for the organic success vs. the

conventional failure

Bacterial Dynamics

OR A OR B BD A BD B CV A CV B0

2000

4000

6000

8000

10000

12000

14000

Average Bacteria Biomass (ug/g) Feb. 2014Average Bacteria Biomass (ug/g) Apr. 2014

Protozoan Dynamics

OR A OR B BD A BD B CV A CV B0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

Average Protozan Population Feb. 2014Average Protozan Population Apr. 2014

Could there be a deeper cause? Recall that soil organic carbon can

retain up to 40X its weight in water….

So we dug down for information. More precisely, we took 810 soil

samples down to 80 cm, with 135 samples per farming system

And a note on determining carbon sequestration: we use the The

Earth Partners’ soil carbon methodology, approved as a

Verified Carbon Standard

And now we have 9 months of data. Remember: the organic farming systems all used compost tea,

compost mulch (applied at a rate of approximately 7 tonnes per hectare, of which approximately 2 tonnes is organic C), and only had an initial tilling. The conventional systems

used herbicides, pesticides, and had two tillings.

As you’ll see, after the initial tilling, where a decades-old weed

mat was ploughed under, we introduced a significant amount of

“labile” or unstable carbon over baseline.

Let’s look at differing soil depths to see if we can find out what’s

happening with soil organic carbon

0-10 kg of C per m² Pre-till

0-10 kg of C per m² Post-till

0-10 kg of C per m² 12 de agosto

COA COB BDA BDB ORA ORB

TREATMENT

33.63

44.85

56.07

67.29

78.50

kg o

f C p

er

m²

43.77 44.6742.61

46.54

41.23

48.53

43.77 44.6742.61

46.54

41.23

48.53

Change in Kg of Carbon per m² at 0-10 cm




SOURCE: RAW DATA, TFST TEAM SEPT, 2014

P VALUE = NOT STATISCALLY SIGNIFICANT

10-20kg of C per m² Pre-till

10-20 kg of C per Post-till



TREATMENT

26.10

34.00

41.90

49.80

57.70

kg o

f C p

er

m²

32.57 32.72

36.42 36.95

33.5736.28

32.57 32.72

36.42 36.95

33.5736.28


10-20kg of C per m² Pre-till

10-20 kg of C per Post-till








TREATMENT

31.55

40.73

49.91

59.09

68.26

kg o

f ca

rbo

n p

er

m²

47.83 47.42 48.84 47.4244.75

50.1247.83 47.42 48.84 47.42

44.75

50.12











TREATMENT

17.83

27.02

36.21

45.40

54.60

kg o

f ca

rbo

n p

er

m²

28.1630.44

35.13 33.63

38.5241.13

28.1630.44

35.13 33.63

38.5241.13











TREATMENT

6.25

17.30

28.35

39.40

50.45

kg o

f ca

rbo

n p

er

m²

25.9023.16

25.64 27.15 28.08

38.12

25.9023.16

25.64 27.15 28.08

38.12







So let’s focus on the trends at the 60-80 cm

depth

MEDIAN LABILE CARBON ABOVE BASELINE AFTER THE TILLAGE

AT A 60-80 CM DEPTH



Test:LSD Fisher Alfa=0.05 DMS=11.51007Error: 41.8608 gl: 12Treatment Median n E.E. Conv A 13.88 3 3.74 A Conv B 9.85 3 3.74 A B ORG B 8.34 3 3.74 A B ORG A 4.37 3 3.74 A B BD B 1.74 3 3.74 B BD A 0.65 3 3.74 B Medians that share the same letter are not statistically significant (p > 0.05)


Test:LSD Fisher Alfa=0.05 DMS=12.34004Error: 48.1154 gl: 12Treatments Median n E.E. ORG B 7.05 3 4.00 A BD B 2.31 3 4.00 A B BD A 0.61 3 4.00 A B C ORG A -2.36 3 4.00 A B C Conv B -8.82 3 4.00 B C Conv A -12.55 3 4.00 C Medians that share the same letters are not statistically significant (p > 0.05)

MEDIAN CHANGE COMPARED TO POST TILL LEVELS IN CARBON (TONNES PER HECTARE) SIX MONTHS POST TILL AT

60-80 CM DEPTH -


Sharper focus on Conventional A, where 13.88 tonnes (median) per

hectare of carbon were introduced post tillage at a depth

of 60-80 cm

Now focus on Conventional A after 9 months of growing cassava

–Conventional A lost 12.55

(median) of the additional 13.88 tonnes C per hectare. It spent

most of its inheritance.

Let’s focus now on Organic B, where approximately 8 tonnes of C were introduced post initial tilling, and

approximately 7 additional tonnes were added over the next nine

months. It earned a nice return on its inheritance!

And in every case the Biodynamic or Organic treatments maintained

their carbon inheritance better than the conventional practices.

As a result, an “aggregate” look at the test lots, adding up the carbon

at all depths, shows how the organic and biodynamic fields were

far better at retaining their “inheritance,” in contrast to the

conventional lots’ more profligate spending.

treatment

Mg/ha of C added after

tilling Mg/ha of C that was

able to retain Mg/ha of C

lost % Mg/ha of C

lost % Mg/ha of C

retain

Conventional 43,09 5,56 37,53 87,09% 12,91%

Biodynamic 58,21 24,54 33,67 57,84% 42,16%

Organic 37,00 15,54 21,46 57,99% 42,01%

Spending the carbon inheritance

These data do not achieve statistical significance with 95%

confidence. But they paint a picture of what is happening real time in a field that is transitioning

from being overgrazed for 65+ years to productive farming. This transitional moment is of critical

importance.

Join us!www.thecarbonunderground.org

Environment

Tom Newmark - Field Trials in Costa Rica