worm nests, fermented compost and building highly humic soil

If you saw the last post "microbes in the community" you'll note we had a lot of interest in our pics of worm nests, of which i promised to explain a little more...

"worm nests?" i hear you ask "but worms don't make nests, do they?"

well, maybe they don't, but when a young child sees the likes of this:

 then you have to ask yourself what else you'd call it!

Of course, this is all part of a process and that process we call "fermented compost".  Why fermented compost?  Simply put, we take our (highly nitrogenous) kitchen waste and ferment it with microbes, before adding it to the soil, for the worms to munch away at.

Compost worms (Eisenia fetida) are different than earth worms, firstly. They are commonly known as redworm, brandling worm, tiger worm and red wiggler worm, but are a species of earthworm adapted to decaying organic material. When roughly handled, an eisenia fetida exudes a pungent liquid, thus the specific name foetida meaning foul-smelling. This is presumably an antipredator adaptation.

 Although very simple organisms, worms can be thought of as "cows of the soil" in that they require bacteria in their guts, in order to process the organic matter they consume (along with a grit-like calcium carbonate substance they produce through internal glands).  In studies of soil the world over, scientists have found that where there is a lack of soil bacteria, worms populations are sparse.  Conversely, where healthy worms populations exist, the soil bacteria is plentiful and healthy.  This explains, in part, why fermented compost is so attractive to these little soil-recyclers and why, in a bacteria-rich resource such as fermented compost, they find their way in, eat plentifully, colonise, reproduce and turn the fermented compost into a nursery, replete with cocoons (worm eggs) and white baby worms, as you can see from the pic of the worm nest above.

To give an idea of scale, here are some pictures which zoom in from the spade level, to the close-up, where a 50 pence piece is shown.

As a point of note, that white substance you can see near the 50p is a product of fermentation, specifically a casein (cheese-like) material which is produced by Lactic Acid Bacteria - the very same lactic acid bacteria responsible for preserving Wooly Mammoths in the permafrost regions of Northern Europe.  For an elegant visual explanation of how Wooly Mammoths get preserved, be sure to check out the National Geographic Article here.

As you can see in the above pics, the white baby worms are plentiful.  Human hair gives an idea of the scales involved - you can even make out the tiny worm eggs (cocoons) and how the soil particles are sticking together, thanks to the humic content of their casts.

These photos were taken about 4 weeks after burying the fermented compost in a trench in the soil - half way through the 8 week process (in warmer weather - in colder weather it takes from 10 - 13 weeks for the fermented compost to be fully consumed by the worms).  You can think of these compost worms as a pioneer species, because after the compost worms have done their work, earthworms come in to colonise the now organically rich soil.

Indeed, as these later pics show, the baby worms soon become healthy adult worms, to continue the process:

Benefits of Humus

• Humus can hold the equivalent of 80 to 90 percent of its weight in water, so soil rich in humus is more drought-resistant.

• Humus is light and fluffy, allowing air to circulate easily, and making soil easy to work.

• The sticky gum secreted by microbes while forming humus hold soil particles together in a desirable crumb structure.

• Humus is extremely effective at holding mineral nutrients from being washed away in rain or irrigation water, and in a form readily available to plants. Ample reserves of humus also provide additional plant nutrients in times of need.

• Humus is able, because of its biochemical structure, to moderate excessive acid or alkaline conditions in the soil-a quality known as buffering.

• Many toxic heavy metals can be immobilized by soil humus, and prevented from becoming available to plants or other soil organisms.

• Although the color of humus can vary, it is usually a dark brown or black color, which helps warm up cold soils quickly in the spring.

In the next blog post, i'll show you how to make your own fermented compost system, so you too can start to make your own worm nests!

capturing carbon in the soil - chelation in action?

Discover Magazine ran an interesting article the other day, following studies at Ohio State University to look at how much Carbon Dioxide soil might soak up.  Claims that the agricultural soils of the world have the potential to soak up 13 percent of the carbon dioxide in the atmosphere today—the equivalent of scrubbing every ounce of CO2 released into the atmosphere since 1980- may be bold, but research suggests that biologically rich and diverse soil may be able to help current concerns.

Rattan Lal first came to the idea of soil as a powerful carbon sink (pdf) not through an interest in climate change, but rather out of concern for the land itself and the people who depend on its productivity. While carbon-depleted soils tend to be dry and prone to erosion, carbon-rich soil is dark, crumbly, fertile, and moist. In the 1970s and 1980s, Lal was studying soils in Africa so devoid of organic matter that the ground had become like hardened cement. There he met Roger Ravelle, a pioneer in the study of global warming. When Lal made a despairing remark about the impoverished soil, Ravelle suggested that the carbon had moved into the atmosphere. “I told Roger I didn’t know where it had gone; I just wanted to put it back,” Lal recalls.

Ravelle was right. For millions of years, a natural partnership between plants and soil microbes has helped regulate carbon dioxide levels in the atmosphere. During photosynthesis, plants absorb carbon dioxide from the air and transform it into sugars and other carbon-based molecules. Some of those carbon products transfer from the roots to symbiotic fungi and soil microbes, which store the carbon in the soil as humus.

The invention of agriculture some 10,000 years ago disrupted these ancient soil-building processes. When humans started draining and plowing up the natural topsoil for planting, they exposed the buried carbon to oxygen, creating carbon dioxide and releasing it into the air. Animal husbandry made things worse, as domesticated animals began grazing grasslands down to the earth. In places where the ground is bare—from overgrazing or from the common practice of leaving fields unplanted for part of the year—photosynthesis stops, and so does the storage of carbon in the soil. Lal calculates that land-use changes such as these have stripped 70 billion to 100 billion tons of carbon from the world’s soils and pumped it into the earth’s atmosphere, oceans, and lakes since the dawn of agriculture. Today agriculture and other land-use changes account for about a third of global greenhouse gas emissions.

To quantify soil’s carbon sequestration potential on agricultural lands, soil scientist Whendee Silver of the University of California, Berkeley, is conducting a first-of-its-kind study on a 539-acre cattle ranch near Nicasio, California. In a collaboration with ranchers and local and state land management organizations called the Marin Carbon Project, she and her students are testing the effects of compost created from city yard waste (such as leaves, branches, and lawn trimmings) and agricultural waste (including manure and cornstalks) on carbon storage.

Although previous experiments have shown that compost increases soil carbon, Silver is among the first to examine whether real-world ranchers can use it effectively to enrich the soil on their rangeland. She has already found a large increase in soil carbon two years after a single application of compost, probably due to enhanced vegetation growth. On the basis of her results, Silver projects that 28 million acres of grazing land in California could absorb 42 million tons of carbon dioxide—nearly 40 percent of what the state’s electrical power plants produce in a year. To accomplish that, each acre of land must absorb just 1.5 additional tons of carbon dioxide. “Given what we’ve seen in our experiments,” Silver says, “one and a half tons is doable.”

In Australia, Christine Jones, soil ecologist emerita of the New South Wales Department of Land and Water Conservation, is testing another promising soil-
enrichment strategy, one that relies on perennial grasses. Since carbon sequestration stops in the absence of living plants, Jones and 12 ranchers in Western Australia are working to build up soil carbon by cultivating grasses that stay green year-round. 

Like composting, the approach has already been proved experimentally; Jones now hopes to show that it can be applied on working ranches and that the resulting carbon capture can be accurately measured. Over the course of four years, she has charted the carbon content of the grasslands, and when the first phase of the project concludes this August, philanthropist Rhonda 
Willson will pay the ranchers for every additional ton of carbon tucked away in their soils. 
“The changes we’ve registered over the past few years will surprise the world,” Jones says.

Silver and Jones hope that projects such as theirs will demonstrate the role that farmers, 
ranchers, and other land managers can play in mitigating the effects of heat-trapping greenhouse gases. Lal says that the greatest opportunities lie in the world’s most depleted and eroded soils, in sub-Saharan Africa, south and central Asia, and Central America. Success there will rely on providing farmers the tools and knowledge to improve their land, as well as financial compensation for their carbon enrichment of the soil.

The same is true in wealthier societies like the United States, where most farming operations chase productivity through large applications of fertilizer. Changing long-standing habits will require a system that rewards land 
managers not just for the corn or beef they produce, but also for the carbon they can build into their property. “Farmers should get compensated for protecting the ecosystem,” Lal says. “This is something worth paying for.”

Regenerative 
 Agriculture 
 An approach that aims to protect natural resources such as soil through techniques including crop diversity and rotation.

Carbon Sink 
A reservoir that can hold carbon and prevent it from escaping into the atmosphere. Proper management could turn agricultural soils into a powerful sink.

Marin Carbon Project A joint effort by scientists and ranchers in California to study rangeland’s potential to soak up carbon.


Compost 
Fertilizer made of decaying organic matter. By boosting plant growth, compost helps to increase soil carbon storage.

Perennial Grass 
 According to an ongoing study in Australia, planting ranch lands with grasses that remain alive year-round also increases the amount of carbon trapped in the land.

Microbial Inoculants: an Approach to Sustainable Agriculture

originally an article published here by Sunita Gaind, i thought i'd repost it, given there's a wealth of good information on the subject, which gives a broad overview:

The green revolution though made India self sufficient in food production, but at the cost of soil health. Persistent use of chemical fertilizers and low input of organic material in soil reduced its organic matter content, resulting in stagnation of food grain production by 1.5 %.

To restore the productivity of soil, efforts need to be focused on use of natural resources that can be an alternate to costly chemical fertilizers and restrict soil impoverishment. Current developments in sustainability involve the rationale exploitation of soil microbial activities and use of less available sources of plant nutrients. Nitrogen and phosphorus are the macronutrients that limit the plant growth. To meet the crop need, these are generally supplemented through chemical fertilizers. Soil inhabits microorganisms that possess the particular trait for nitrogen and phosphorus transformation. Their application to soil under crop cultivation can improve the nutrient availability; reduce the input of chemical fertilizer and a way to sustainable agriculture.

What are microbial inoculants?
Microbial inoculants are the formulations of beneficial living microorganisms that when added to soil, directly or indirectly, improve the nutrient availability to the host plant and promote plant growth. Microbial inoculants for biological nitrogen fixation are both strain and crop specific. However, phosphorus solubilization and mineralization can be mediated by potential isolates of bacteria and fungi. The latter being the key components of soil plant system can be developed as phosphate solubilizing microbial inoculants.

Fungi vs Bacteria as Phosphate solubilizeres
 Fungi maintain their P dissolving efficiency even on repeated sub culturing
 The extracellular production of phosphatase and organic acid is higher with fungi compared to bacteria. Therefore, fungi are more effective phosphate mineralizer/ solubilizers compared to bacteria.
 Their hyphae can travel long distance in soil more easily than bacteria and can prove more beneficial for solubilization of phosphorus in soil.
 They can tolerate low moisture, high temperature, heavy metals and agrochemicals.
 Their spore forming nature is an additional advantage for their survival under environmental stress.

How do microbes improve the availability of nutrients?
Soil microorganisms are involved in large number of processes that affect the P transformation and influence its availability to plant roots.
 By the excretion of hydrogen ions.
 By release of organic acids.
 By production of phosphatase enzymes that can mineralize soil organic P.
 Chelating metal ions that may be associated with complexed forms of P or may facilitate the release of adsorbed P through ligand exchange reactions.
 By displacement of sorption equilibria that results in increased net transfer of phosphate ions into soil solution or an increase in the mobility of organic forms of phosphorus.
 Growth stimulation through production of phytohormones.
 By production of siderophores.
 Phosphate dissolving fungi may also provide micronutrients for formation of polyphenol and other aspects of phenolic metabolism.
 Phosphate dissolving Trichoderma harzianum has shown the ability to accelerate the oxidative dissolution of metallic Zn.
 They also provide disease resistance to plants due to production of antibiotics and protection against soil borne pathogens.

Phosphate dissolving microorganisms used as microbial inoculants
Fungi: Aspergillus awamori, Aspergillus niger, Penicillium digitatum, Pencillium radicum, Penicillium bilaiae, Trichoderma koningii

Bacteria: Pseudomonas striata, Bacillus polymyxa, Bacillus megaterium, B.subtilis, B. circulans

Carriers: Charcoal- soil mixture, vermiculite, press mud, peat, cow dung cake powder, farm yard manure, wheat bran etc. Amendment of charcoal soil - mixture carrier with calcium alginate resulted in better retention of moisture.