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Four Scientists on Natural Farming: Proof, Biochar, Minerals

Ted Radovich, James Rushing, Josiah Hunt, Jana Bogs, UH CTAHR, UH Hilo, Pacific Biochar, Beyond Organic Research · USA (Hawaiʻi)

Part of the full session video: this talk runs from 1:22:20 to 2:29:30. Times below are the video's.

Four short research talks that followed Drake Weinert's keynote. Ted Radovich (UH Mānoa CTAHR) showed his lab's work on Hawaiʻi soils, cover crops, compost and compost tea; James Rushing (UH Hilo) listed what science does and does not yet know about natural farming, and said no top-tier peer-reviewed paper showed it working; Josiah Hunt (Pacific Biochar) explained biochar and read results from published studies; Jana Bogs, a nutritionist and soil consultant, argued for testing soil minerals and microbes, and warned about the sodium in seawater. Each talk got a few questions from the floor.

What they found

The question

What does research say about building soil with local materials, compost tea and biochar, and what is still unproven about natural farming?

How they tested it

Four talks of about 10–20 minutes each, with slides. Radovich: a summary of his CTAHR lab's work (soil comparisons, cover crop and rhizobia trials, compost bioassays with eggplant, and a published compost tea study, Pant et al. 2012); plot sizes, crops and durations were mostly not stated. Rushing: a talk of opinions and a reading list, no data shown; his 3.5-year IMO-4 thesis (three farms in Hakalau, per his answer to a question) was not presented here. Hunt: findings read from published papers on screen, plus his own photos and work. Bogs: her testing method and charts from other sources; no trial data of her own shown.

What was compared
  • Compost tea (Radovich, Pant et al. 2012) — ACT, ACTME and NCT (labels on the chart; commonly aerated compost tea, aerated tea with microbial enhancer, non-aerated tea; the slide did not spell them out) vs a complete soluble NPK solution vs water at the same volume, in soils first fertilized with either compost or synthetic fertilizer
  • Rhizobia on perennial peanut (Radovich) — Adding rhizobia to perennial peanut seedlings in poor, weathered soil vs more fertile soil; rates not stated
  • Compost quality bioassay (Radovich) — Eggplant seedlings planted the same day in 100% compost with too high a C:N ratio vs well-matured vermicompost
  • Living mulch vs weed mat (Radovich) — Soil CO2 emission under perennial peanut vs black weed mat vs bare soil
Results
  1. Weathered soil vs fertile soil: P 0.9 vs 480 ppm, Ca 38 vs 4,524, Al 142 vs 15

    Slide comparing a red, weathered soil (said as Ultisol) with a Mollisol, plant-available ppm: pH 4.7 vs 6.5, C:N 29:1 vs 18:1, P 0.9 vs 480, K 17 vs 876, Ca 38 vs 4,524, Mg 26 vs 1,744, Al 142 vs 15. Low pH makes aluminum more soluble and toxic.

    ▶ 1:25:01 Said and shown on the slides

  2. Rhizobia helped perennial peanut nodulate and grow in poor soil, not in fertile soil

    Slide: adding rhizobia to perennial peanut seedlings improved nodulation and plant growth in poor soils but not more fertile soil. Most tropical legumes (sunn hemp, perennial peanut, cowpea) nodulate with native bacteria; he recommends adding biology only when starting on a poor, weathered soil, and says building with organic matter makes it less of an issue. No numbers shown.

    ▶ 1:27:16 Said and shown on the slides

  3. Eggplants grew far better in matured vermicompost than in woody, high C:N compost

    Bioassay photo, planted the same day; shown as a picture, no measurements.

    ▶ 1:30:05 Said and shown on the slides

  4. Compost tea raised soil respiration; synthetic NPK solution lowered it below plain water

    Soil respiration, CO2 flux in µmol m⁻² s⁻¹, read from the bar chart (approximate). Compost-fertilized soil: NCT ≈6.6, ACTME ≈5.5, ACT ≈5.0, water control ≈3.7, NPK solution ≈2.3. Synthetic-fertilized soil: NCT ≈2.6, ACTME ≈2.3, ACT ≈1.9, control ≈1.5, NPK ≈1.0. Letters show NPK significantly lower than control in both. Compost-fertilized soils were higher in activity whatever went on after.

    ▶ 1:34:45 Said and shown on the slides

  5. Three ways compost tea assisted growth: nutrients, the root hormone GA4, more soil biology

    Micronutrients alone did not explain the growth; gibberellic acid GA4 correlated with the most stimulating teas.

    ▶ 1:33:12 Said and shown on the slides

  6. Soil under perennial peanut was as active as a forest floor; under black weed mat it was way down

    Spoken only; no numbers shown.

    ▶ 1:35:26 As spoken

  7. Avoid simple sugars like molasses in compost tea; well-made compost matters most

    Simple sugars push up some bacteria at the expense of others and reduce diversity. If you add foods, you must aerate; without them you can skip aeration. Details are in the CTAHR handbook Tea Time in the Tropics (Radovich & Arancon, eds.).

    ▶ 1:31:23 As spoken

  8. No top-tier peer-reviewed article showed natural farming working, as of 2015

    Rushing's 'myths' list: we don't yet know that it works across locations, or why; it doesn't work every time (one plot fails, another two miles away does well). He hoped his thesis would become such a paper.

    ▶ 1:46:42 Said and shown on the slides

  9. Possible harms to study: pathogens surviving fermentation, pests carried in materials, soil mining

    He knew of farms where disease showed up just after natural farming amendments went on, and fire ants moving with IMO and plant material. When asked, he said he had found no pathogens in his own ferments.

    ▶ 1:42:11 Said and shown on the slides

  10. Breadfruit flour worked better than some prescribed carbohydrate sources

    His preliminary experiments; no numbers given.

    ▶ 1:47:28 As spoken

  11. Iowa's fertile soils: 30–50% of organic matter is charcoal from fire

    Slide and spoken; he credits work by Bruno Glaser.

    ▶ 1:53:51 Said and shown on the slides

  12. Vineyard trial: biochar plots yielded up to 66% more over four harvests, grape quality unchanged

    Genesio et al., Tuscany, four-year field experiment. The gap was biggest in dry years (inversely correlated with rainfall).

    ▶ 2:04:16 Said and shown on the slides

  13. Biochar cut N2O emissions 14–73% (Alfisol) and 23–52% (Vertisol); ammonium leaching down 55–93%

    Singh et al., read from the slide; he said '14 to 37 to 73' aloud. N2O is a strong greenhouse gas.

    ▶ 2:06:04 Said and shown on the slides

  14. Biochar in poultry-litter compost cut ammonia up to 64% and total N loss up to 52%

    Steiner et al. Also on slide (Glaser et al.): 1 t/ha biochar with mineral fertilizer raised maize yield 20%; biochar with biogas digestate 30%; 10 t/ha biochar in compost 26% over pure compost.

    ▶ 2:07:20 Said and shown on the slides

  15. Biochar lowers plant uptake of contaminants rather than removing them

    Slide, Cao et al. 2011: 5% dairy-manure biochar, after 210 days, cut extractable lead and atrazine by more than 57% and 66%, and earthworm uptake by up to 79% and 73%. His own California cadmium test plots: soil cadmium unchanged, plant uptake reduced (work in progress, no numbers).

    ▶ 2:08:57 Said and shown on the slides

  16. Seawater: 10,500 ppm sodium and about 19,000 chlorine vs 400 calcium

    Slide: oxygen 857,000; hydrogen 108,000; chlorine ≈19,000 (faint on screen); sodium 10,500; magnesium 1,350; sulfur 985; calcium 400; potassium 380; bromine 85; carbon 28; strontium 8 ppm. She recommends ocean water on some soil tests, diluted a lot, only where the soil needs it.

    ▶ 2:21:23 Said and shown on the slides

  17. Fungi-to-bacteria ratio: vegetables 0.75:1, row crops 1:1, fruit trees 5:1 to 100:1, weeds 0.1:1

    Chart credited to Rodale Institute and Dr. Elaine Ingham. She says most soils she tests have bacteria but hardly any fungi.

    ▶ 2:24:25 Said and shown on the slides

  18. Hawaiʻi Island soils she tests often run high in magnesium for their calcium

    Her field observation; she recommends gypsum or calcitic lime over dolomite (about 20% Ca, 10% Mg) when magnesium is already high, and says Epsom salt adds magnesium most local soils don't need.

    ▶ 2:20:41 As spoken

  19. Food nutrient content has fallen as much as 70% for some nutrients over about 70 years

    She cites studies comparing USDA data from the 1930s–40s with today; chart credited to Dr. August Dunning. Not a study of hers.

    ▶ 2:13:19 Said and shown on the slides

Hold it loosely
  • These are short talks, not papers. Most results were shown as one slide or one photo, with no plot sizes, replicates or durations.
  • The soil respiration values are read by eye from a low-resolution chart; the x-axis labels were cut off, so which group is compost-fertilized comes from what Radovich said. Abbreviations ACT/ACTME/NCT were not spelled out on screen.
  • Radovich said plainly he had not done much natural farming. None of his data tests the natural farming solutions.
  • Rushing's IMO-4 thesis results were not presented here. His reports of disease after amendments are anecdotes from farms he consulted for.
  • Hunt sells biochar and a biochar fertilizer; the studies he cited were chosen by him ('some of my favorites'). His cadmium work was unfinished.
  • Bogs's nutrient-decline and disease charts come from secondary sources; she showed no trial data of her own. The 70% figure is from her talk, not checked.
  • The '0.001' figure for soil microbes known 30 years ago, and the '3,500 papers' on biochar, are from memory.
For your farm
  • On poor, weathered Hawaiʻi soils, adding biology (rhizobia, compost) helped more than on rich soils, per Radovich's slides.
  • Make sure compost is mature before planting into it; woody, high C:N compost held eggplants back next to matured vermicompost.
  • A living ground cover like perennial peanut keeps soil life far more active than black weed mat.
  • Test before adding minerals: dolomite and Epsom salt add magnesium that many Hawaiʻi Island soils already have too much of.
  • Treat your own good results as a start, not proof; many factors affect a crop. Rushing asked farmers to offer land to researchers for proper trials.
  • Charcoal in soil gives microbes a place to live and helps hold nutrients; blending it into compost or fertilizer is a cheaper way to use it than spreading it over a whole field.

Next to Master Cho's teaching

  • Agrees

    Charcoal as housing for microbes Cho later taught the same idea: unfolded, rice-husk charcoal has huge surface area and 'serves as a home for microorganisms.' Hunt's figures on N2O, contaminants and yields go beyond anything Cho taught.

    2017/Advanced Cho/advanced fruit/IMG_3461 @ 0:48:40 (translated)

  • Differs

    Seawater: lots of sodium, dilute it Both say never use it raw. Cho dilutes seawater 1:30 and counts it as an essential nutrient alongside NPK and calcium; Bogs would use it only where a soil test shows the soil needs it.

    Cho, Janong Natural Farming (2003), p. 142–143

  • Agrees

    Use what's local, not what comes off a boat Cho told Hawaiʻi farmers with no rice bran to use local materials such as taro or banana. Rushing's breadfruit flour fits that. Calling boat-shipped materials 'organic farming' is his own line, not Cho's.

    2017/Advanced Cho/advanced fruit/IMG_3300 @ 0:20:33 (translated)

  • Goes further

    Cover crops and rhizobia Cover-crop research isn't core Cho teaching. The closest thing is 'grass cultivation' listed with charcoal and Microbes (IMO-4) in Cho's soil groundwork stage. Radovich's legume work adds to that rather than testing it.

    Cho nutrient cycle prescription table (Oct 2017, transcribed) — Agriculture Materials by Growth Stage

  • Unclear

    Sugar and microbes Radovich advises against molasses as a food in compost tea because it narrows diversity. In KNF, brown sugar has a different job: at 1:1 in Microbes stage 2 (IMO-2) it pulls water out and puts the microbes to sleep for storage. These are different uses, so the two don't directly clash.

    IMO / mugwort presentation (LSS 2017), p. 35–40

“I'm actually not a soil biologist. I do a lot of work with vegetable quality, crop quality.”

▶ 1:22:29

“To me, plant is ultimately the biggest integrated measure of soil quality.”

▶ 1:34:53

“There are top tier peer reviewed scientific articles that show significant data. Not one. Not one.”

▶ 1:46:42

“Don't fall for the proof is in the pudding.”

▶ 1:49:26

“Biochar is a term. It's a term, not a material.”

▶ 1:53:06

“You can't manage what you don't measure.”

▶ 2:18:54

In this talk

  1. 1:22:28Ted Radovich: Hawaiʻi soils, cover crops, compost
  2. 1:31:18Question: molasses in compost tea
  3. 1:33:06Radovich: compost tea and soil respiration data
  4. 1:37:15James Rushing: the good, the bad, the facts
  5. 1:41:45Rushing: possible harms (pathogens, pests, soil mining)
  6. 1:45:30Rushing: ten myths about natural farming
  7. 1:50:19Questions for Rushing: soils, pathogens in ferments
  8. 1:51:45Josiah Hunt: what biochar is, terra preta
  9. 2:03:15Hunt: published biochar studies (water, nitrogen, contaminants)
  10. 2:11:28Questions for Hunt: cadmium, Hāmākua
  11. 2:13:17Jana Bogs: nutrient density and managing microbes
  12. 2:21:15Bogs: what's in seawater
  13. 2:24:15Bogs: fungi-to-bacteria and C:N ratios
  14. 2:26:33Questions for Bogs: dolomite, Epsom salt, seawater

Transcript

Transcribed and checked by hand against the recording. Click any time to play from there.