Combined reports: site assessment, qualitative biological
soil food web assessments of various soils and composts, and quantitative biological soil food assessment of vermicompost
Feb 27 – March 6, 2024
Site Assessment
Four growing areas are present on site: three greenhouses and an outdoor space fed by a greywater source for sunchokes. There is also an outdoor, partially underground vermicompost area.
Flora
Flora is a small greenhouse with a variety of plants, grown both in pots and raised beds. The growers began converting the dirt under the greenhouse into soil by composting in place using humanure, straw, harvested mycellium, and cardboard. A variety of as-needed amendments have been tried in the past, with varying success, for aphids, slugs, and other pests: foliar treatments such as diluted neem oil, horticultural canola-based oils, Safer’s soap, and Botanigard (Beauvaria Bassiana). Sluggo and crushed eggshells were and are occasionally used to deter ground pests as new seeds are being established. JADAM microorganism solution has also been applied to the soils. The grower had no specific goals for improving plant health, but I was curious to look at the effects of JADAM under the microscope, so we’re trying two treatments. The layout of the space follows. Potted plants are indicated by a bold line. Squash leaves show considerable mildew; all other plants show moderate health, with lettuce and parsley possibly the most healthy. Tomatoes and squash soils were assessed for microbiology.
Hoop House
The Hoop House is a large greenhouse with a variety of plants, grown both in pots and raised beds. The growers began creating soil using aged horse manure, woody materials, and grass clippings. The same treatments as mentioned above have been implemented in the past, as needed, for pests. The layout follows. Healthiest plants appear to be the Barese chard, lettuce, kale, and chickweed. All other plants are in moderate health, with some at the far right in pots (not labeled) in poor health. The Barese chard soil (with and without JADAM applied) was assessed for microbiology.
Attached Greenhouse
This is the smallest of greenhouses, attached to the main house, with plants grown both in pots and raised beds, originally with a greywater system feeding the plants down the middle of the raised bed. Past plants included annual greens, peas, and a kale forest that grew tall enough to reach the ceiling and had to be regularly pruned, then cut, and now kale is rotated. For the soil, horse manure, possibly humanure, and worms were used. The same treatments as previously mentioned were tried, except the horticultural oil was petroleum-based, and a baking soda spray and raw milk spray were tried for powdery mildew, but found to be ineffective. The layout follows. The left corner of the raised bed was thought to be water-logged (and was assessed for microbiology).
Qualitative soil food web assessments
Qualitative biological assessments using compound shadowing microscopy and the soil food web analysis approach were performed for soils of actively growing greenhouse plants, as well as for several composts, leachate, and microbial amendments (Botanigard and JADAM). While qualitative methodologies have limited use in determining precise fungal to bacterial (F:B) ratios, these assessments are much easier (less expensive) to conduct than quantitative assessments, and helpful for getting a general idea of the microbial health of soils and potential of microbial amendments, such as composts.
The soils being used for active greenhouse growing show low to moderate beneficial microorganisms, lacking in fungi for some plants and actinobacteria for the brassicas, but with few to no pathogens. Some low-oxygen organisms were present in higher numbers in water-logged areas. Composts (ditch compost and vermicompost) showed beneficial organisms, with moderate fungi and fungal spores and a good bacterial feeding nematode population. There is some visual evidence of mild disease in the greenhouse plants, such as mildew on foliage of squash plants, along with aphids, spidermites, and other pests. No signficant amount of mildew was detected in soil samples. JADAM was applied on February 19 to all greenhouse plants, aside from specified controls. We will monitor progress of the plants and apply a second treatment in March when temperatures are a bit warmer.
Summaries per sample and details follow.
Flora greenhouse tomatoes
Low to moderate healthy microbes detected. Health may be improved with more fungal presence.
Flora greenhouse squash
Low to moderate healthy microbes detected. Algal organisms and bacterial colonies noted (possibly from previous JADAM applications). Health may be improved with more fungal presence.
Attached greenhouse: kale and red-veined sorrell
Low oxygen conditions (most likely due to water-logging) confirmed. Health may be improved with more actinobacteria present.
Hoop House barese chard
The correct balance of bacteria to fungi is likely present in these plants, supporting their optimal health.
Pit compost
Good development of the soil food web microorganisms, though slightly lacking in fungi and fungal spores.
Vermicompost
Excellent development of the soil food web microorganisms, possibly slightly lacking in fungi and fungal spores at this stage, and some oddly behaving nematodes. This material may benefit from additional assessments.
Vermicompost leachate
No beneficial life present. Ciliates indicate low oxygen conditions.
Botanigard
Inconclusive assessment.
JADAM
Wide diversity of beneficial and facultative bacteria, with large, multi-species bacterial colonies and motile algal species present.
Aged humanure
Little life present, including bacteria. Suitable for its current purpose rather than as a soil amendment.
Details of findings
Documentation of details per sample follows.
Flora greenhouse tomatoes (Feb. 19)
- Successional stage: nightshades, mid-successional. Target F:B ratio is 0.8:1.
- With very few fungi seen under the microscope, these tomato plants are not as microbally supported as they could be. Health and flavor may suffer as a result.
- Indication of low oxygen conditions was present, due to a few ciliates observed. Healthy protozoa and protozoan cysts were present.
- Tomato soil sample with ciliate shown below:
Flora greenhouse squash (Feb. 19)
- Successional stage: curcubits, mid-successional. F:B ratio is not conclusively determined for curcubits, but esimated to be 0.6-0.75:1
- Therefore, these soils may lack fungi. Health and flavor may suffer as a results for some plants.
- Algal organisms noted (see still image, left), along with a bacteria colony, healthy protozoa and protozoan cysts (see video, left).
- Mildew noted on some leaves.
Attached greenhouse: kale and red-veined sorrell (Feb. 19)
- Successional stage: brassicas are early successional plants (target F:B ratio is 0.3:1), with goosefoot at early to mid-successional (target F:B ratio is 05.:1).
- These plants require little fungi, so their absence here was not problematic. However, early successional plants suffer from excess moisture, and the appearance of ciliates (see video to the right) confirms the grower’s suspicion that the soil for these plants is water-logged. Actinobacteria also appear to be lacking.
- Algal microorganism noted here (see second video to the right.
Hoop House barese chard (Feb. 19)
- Successional stage: goosefoot, early-mid. Target F:B ratio is 0.5:1.
- Qualitative assessment of the biology indicates the bacteria and fungi are in correct balance to support these plants.
- Healthy protozoa also present (see video to the left for 2 amoeba types in one field of view). Overall health of plant appears good.
Pit compost (Feb. 2)
- Bacterial-feeding nematodes noted (see video, right), indicating higher trophic levels of the microscopic soil food web are present.
- Some fungi noted (see still image, right), but relatively low in number for compost. Few fungal spores noted.
- Healthy protozoa noted.
Vermicompost (Feb. 24)
- A relatively high number of bacterial-feeding nematodes noted (see top video, left), indicating solid presense of higher trophic levels of the microscopic soil food web.
- Some bacterial feeders were barely moving (see second video, left), which is somewhat unusual and suspect of a possible disease/illness in the nematodes (such as fungal trapping). Visual indicators of this possibility are present near the mouths of the nematode and around the bodies from mid-section to tail. However, research on this possibility has proved inconclusive; further, as nematodes do nap, we can assume a sleeping state in these mostly immotile appearances of nematodes.
- A microarthropod (Collembula) was also observed (see third video, left), indicating the highest trophic level of the microscopic beneficial soil food web was present.
- Healthy protozoa and protozoan cysts noted.
- A fair amount of fungi and fungal cysts were noted (see still image, left), but could possibly be improved.
- Overall, this material should yield good quality compost, but additional samples should be assessed for fungi and to ensure pathogenic nematode-trapping fungi or root-feeding nematodes are not present.
Vermicompost leachate (Feb. 24)
- Very little life present, aside from ciliates (see video, right), indicating low oxygen.
- From a microbiology perspective, vermicompost leachate is not helpful to plants.
Botanigard (@ Feb. 10)
- This was a novice and inconclusive assessment of an ammendment containing Beauveria bassiana, a fungus marketed to control pests, particularly in greenhouses. This container had been left out by mistake overnight, and the grower was concerned about the viability of the organisms.
- This microorganism was recommended for use by the Soil Food Web school in the past, but is no longer; hence, reference materials to support correct identification were lacking. The school’s position now is that this fungus may be detrimental to certain beneficial organisms, including bees; additionally, the school now recommends applying only endemically derived microbial ammendments.
JADAM (Feb. 9-19)
- Samples of two different JADAM solutions were assessed in mid-February, and then again on March 7. The first three videos to the right show the mid-February solution, which may not have developed properly the first time, as bubbling did not appear at the surface of the solution; however, we let that solution sit longer, and more species of bacteria appeared than in the March solution.
- A great diversity of bacteria did develop in both solutions, aerobic and facultative anaerobics, but no pathogens. The longer we let the first solution sit, the great the diversity and number of facultative anaerobes.
- Bacterial colonies formed and appear to be made up of a variety of bacteria species.
- Protozoan flagellates appeared (see fourth video, motile organisms grazing the colonies, right), indicating one higher trophic level of the soil food web was supported.
- There was more plant material and great numbers of bacteria attached to in in the second solution, shown in the fourth video, to the right. (There may also be a fungal strand in this aggregate, but it’s difficult to tell.)
- No fungi or other soil food web microorganisms were found.
- Ciliates appeared in great numbers in the second solution; ciliates are associated with low oxygen conditions and therefore, normally a warning flag in soil tests. (See fifth video, to the right, for a good view of the ciliates grazing at the edge of the aggregate.)
- Currently hypothesizing that the notable bacterial colonies may have a beneficial impact on plants, possibly in support of nitrogen fixation, as certain species of bacteria that are free-living nitogen fixers do form colonies. A test solution applied during the seeding/seedling planting phase, specifically, may be worth pursuing.
- Motile algal microorganisms, propelled by flagella (sixth video), are just fun to view! We discovered that they are in the greenhouse rain water, however, and not unique to JADAM.
Aged humanure (Feb. 2)
- Little life detected, even bacterial; an occasional fungus or protozoan was observed after much searching (see left image for beneficial fungus covered with oxylate crystals).
- This material is therefore considered not very helpful biologically to plants (its current use as compost toilet recycling material is ideal).
Quantitative assessment: vermicompost
The grower expressed interest in creating new soil using the vermicompost, so I assessed the material using the quantitative soil food web methodology, in order to be more precise about what this material could provide in a new soil. The findings were consistent with the qualitative conclusions above, with these additional details:
- There is a robust predator population, even at higher trophic levels of the soil food web, as indicated by bacterial-feeding nematodes, an omnivore nematode population (correction to previous ID, which indicated a predatory nematode) and a microarthropod population, indicating strong nutrient cycling. Protozoa (particularly amoebe) were also present in very large numbers, with additional protozoan cysts (dormant form) observed.
- Compost appears a bit darker than ideal in color.
- The fungal biomass is low and bacterial biomass is high. The F:B ratio indicates this material will not be helpful in balancing soils for fungal and bacterial populations, but combining it with some woody materials (such as mulch) could help the limited number of fungal spores observed germinate. Recommendation to add more woody material (wood chips, leaves, small cardboard pieces) to the worm pile in the future.
Below are excerpts with exact calculations from the generated reports.
Susan Stuart
Certified Soil Food Web Lab Technician, Life Underground Labs
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