Craig Overend

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since Dec 16, 2014
Melbourne, Australia
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Recent posts by Craig Overend

It all depends on the soils, species, and goals as to how many multi-species crops a soil can carry. A rich high carbon and nutrient rich fungally dominated soil that receives a lot of rain or run-off will carry more than another that is low in carbon and bacterially dominated. It doesn't surprise me they saw annual monocultures outperforming multi-species, especially if the soils were also tilled. There is a recent paper[1] on soil networks showing that as restoration progresses those networks become more connected and sequester more carbon despite no appreciable increase in soil biomass. It's the connectivity that makes the entire soil food web more efficient and able to share resources for higher productivity. Building a community of microbes and plants that work together makes a big difference, but that can take time that big ag simply doesn't have, but is something people like Gabe Brown do recognise.

I've seen a large study on native grasslands that showed for up to about 4 grass species the results were a linear increase in biomass at best, with lesser gains all the way up to 32 species. Another flood study showed 16 native species reduced soil bulk density the most and reduced flooding.

I've also seen low count multi-species lab and greenhouse studies showing wildly varying results with researches scratching their heads as to why.

[1] Soil networks become more connected and take up more carbon as nature restoration progresses : Nature Communications http://www.nature.com/articles/ncomms14349
2 years ago
I'm terrible at chemisty, however to produce that calcium oxide John mentions, a study I've browsed showed that to yield well eggshells need to reach over 800C (1472F) which is pretty close to the melting point of calcium at 842C (1547F). Compared to other calcium soil amendments, another study suggested slaked lime was the most effective at reducing soil bulk density. But in a fire would it form calcium carbonate or another compound?

Phosphorus boils at 280.5C (536F), no idea what happens to that. I assume it goes up in smoke unless it bonded into something with a higher boiling point?
2 years ago
The deeper in the soil profile you go, the less oxygen there is, making soil more of a spectrum from aerobic to anaerobic, however a lot of plant available nutrients including nitrogen are formed in the top aerobic layer where there is most microbial activity, which is part of the reason aerobic microbes tend to get the most attention and results. This in the permaculture world is the edge effect in action.



The question however assumes anaerobic microbes are all human or plant pathogens. Studies I've read suggest otherwise, and that both aerobic and anaerobic brewing will result in human or plant pathogens if the material you start the brew with contains those pathogens and creates an environment they thrive and multiply in over other organisms. This is why I believe diversity in the soil food web is important in preventing any one organism taking over and overcoming a host. That means an array of aerobic to anaerobic microbes and that means an array of feed material and environment. The reason many superbugs are super is because they work together as a collective using techniques like quorum sensing to overcome a host that may not have a diverse line of defence.

I'm no Bokashi expert but it's likely there is still some level of oxygen in the upper layer of Bokashi, especially if you keep opening the container to check it or when adding material, however it can be a pathogen to some soil organisms. It's often used to eradicate plant-based pathogens. The phenols it contains, which are weak acids, and other acids such as lactic acid produced in Bokashi have a sterilizing effect on some microbes. Bokashi can be quite acidic with a pH of 3.5-4.5 or lower apparently.
From soil microbial genetic studies I've read, acidic soil reduces microbial diversity. But as the study below mentions, the pH of Bokashi may not be a factor in plant growth when used in appropriate concentration, and used that way it's likely that Bokashi or many other Natural Farming anaerobic or fermented formulations could add to microbial diversity long-term. Especially in soils high in organic matter that tends to buffer changes in pH.

Below is an abstract from a study on Bokashi used to germinate and grow a brassica, with a recommendation of limiting Bokashi to 30% mixtures with soil by volume. Keep in mind the study only trialled one species of plant. It's probably also a good idea to dilute any Bokashi water extract before applying it.

A kind of fermented organic fertilizer known as Bokashi in Japanese has been used by many Japanese farmers for many years. Bokashi is the fermented product of some organic materials such as bran, oilcake etc. mixed with soil under low temperature (below 50 - 60 deg C) during short period (about 10 days). In this study, experiments were carried out to find the influence of application of Bokashi on germination and early growth of komatsuna, [Japanese mustard spinach] (Brassica campestris L.) by using the water extract from Bokashi and different volume percentages of soil and Bokashi mixture. The results obtained were as follows. 1) The germination percentage, stem and root length of komatsuna decreased with increase of concentration of phenolic substances in the water extract from Bokashi, and a close negative correlation was found between the inhibition on komatsuna growth and concentration of phenolic substances. 2) It was found that volume percentages of Bokashi mixed with soil should be limited below 30% because the emergence percentage of komatsuna became lower on increasing volume of Bokashi in the soil, and many plants died, to above 50% of their volume. In addition, the emergence percentage and the concentration of phenolic substances in the soil had negative correlation. From these results, phenolic substances can be used as an indicator to investigate the effects of application of Bokashi on plant growth. 3) Early growth of komatsuna on the soil applied with fermented Bokashi was better than that on the soil applied with unfermented materials of Bokashi. Consequently, it was suggested that fermented Bokashi had an effect of promoting plant growth, but the cause of promotion should be investigated further. 4) pH of the Bokashi fermented under high temperature (above 60 deg C) was higher than those fermented under low temperature (below 50 deg C), but there was no difference on plant growth between them. From this result and 3),it was found that the fermentation was important, but the different temperature ranging from 40 to 60 deg C had few influences on plant growth. 5) The number of lateral root was increased by application of Bokashi and the effects of application of Bokashi on plant growth were more effective at root growth than germination percentage and stem growth. Therefore, it was suggested that detailed investigation of root was very important in order to find the influence by application of Bokashi.  



Influence of the application of "bokashi" a kind of fermented organic fertilizer on germination and early growth of komatsuna (Brassica campestris L.)  [2001]

If you want to read more about how different natural farming formulations can impact microbial diversity, the following genetic study compares a number of fermented products and sequences their genomes to see what microbes are in the formulations.

Cultivable bacterial diversity and early plant growth promotion by the traditional organic formulations prepared using organic waste materials


The heat map shows the number of bacterial species isolated from different organic formulations and their ingredients. T1 100 % panchagavya; T2 33 % panchagavya; T3 plant extract with native microorganisms; T4 commercial organic fertilizer extract with 2 % leaf soil extract; T5 commercial organic fertilizer extract with 2 % yogurt; T6 cow urine; T7 cow dung; T8 cow milk


Effect of different organic formulations on dry weight of radish (a) and Chinese cabbage (b) under pot culture condition. T1 100 % panchagavya; T2 33 % panchagavya; T3 plant extract with native microorganisms; T4 commercial organic fertilizer extract with 2 % leaf soil extract; T5 commercial organic fertilizer extract with 2 % yogurt. Control, 0, 50 and 100 times of dilution organic formulations are represented in different shades. Values are mean ± SE of three replications, and same letters in each treatment are not significantly different from each other at P < 0.05 according to DMRT

2 years ago
I haven't seen any microbial fuel cells with high power outputs yet. The following better explains plant-e for nerds. It requires aquatic plants, hence a lot of water and in their case plastic to hold it. It would be interesting to try if you had a pond and a bunch of carbon plate electrodes for a larger surface area.
One of the following videos in Italian shows a pot plant outputting 180mV and 10uA, which isn't much power.

The other MFC example below may be better and uses Soil + Microbes + Blood meal + Electrodes.

I also remember reading about a filamentous organism in river sediment that exchanged electrons between upper and lower layers. I can't remember if it or other aerobic organisms were photosynthesising in the upper layer providing the electrons for exchange, I can't find that article now...

Now it's been discovered that if you combine organisms you can also create anaerobic microbial photosynthesis, and if I understand that correctly, you may not need the plant and electricity could be harvested in tubes or bags like those used in algae production, while being fed waste water https://news.wsu.edu/2017/01/09/wsu-researchers-discover-unique-microbial-photosynthesis/






2 years ago
If they are LEDs and not hot to touch, the closer you can get the lights to the plants, the better. NASA studies I've seen have even embedded their LEDs inside the plant canopy to maximise use of the power available. You could also try adding a reflective material around them. Basil ideally needs about 6 to 8 hours of bright sunlight per day. Consider veges that grow well in partial light and shade and like lower temperatures if that's a problem. Large leaf plants high in chlorophyll that make them dark green are probably your best bet. Temperature plays a large role in how long seeds take to germinate and how fast plants grow, as shown in the Basil photo below. Sometimes thick or insulated containers can help keep the soil warmer, so can a dome over the plants which also keeps in moisture. I've just started adding a stick-on temperature gauge like those on fish tanks to my domes to monitor them, when it gets too warm they have to be opened up or come off or the plants will bake. A quality propagation soil mix that holds moisture but is free draining to let air in is important too. The more soil the better too, it acts as a thermal mass buffering temperature and moisture changes, and it can be surprising how long and fast roots will grow from seed when given the space. Watering once a day should be enough unless the plants wilt, water more if the soil looks or feels dry, so long as that soil drains freely. I've taken to using wicking to keep the moisture up. It saves me having to guess, and I'm not washing nutrients out of the soil.
2 years ago
That's a great technique Joseph. I read a few days ago that being overweight can change the dopamine receptors in the brain in a way that means those people don't experience the same reward for physical activity that others do. This could be a great way to help those people starting out. I've also read that the opposite may be true for those with anorexia nervosa that exercise excessively.

I do something somewhat similar on my exercise bike, but instead of joy, my gauge is how much I sweat! That way I can get off before I'm dripping with sweat, cool down and go again. It made starting back on the bike after a break much more pleasant.
2 years ago
My understanding is that algal blooms form from excess nitrogen and phosphorous where there is a carbon and oxygen source that is then consumed. I'd be hesitant to use a lot of manure or other high phosphorus materials unless a bioinfiltration system was in place. While manure is much slower at leaching phosphorus and other nutrients, it can still leach a lot with a lot of rain. If it's all you have, you can always buy some cheap nutrient test strips, simulate or wait for a downpour, and take a water sample and measure it. Inorganic fertilizer can be much much worse however.
One Aussie superphosphate farm study found that “Over 92% of P, 76% of total dissolved C, and 93% of S was lost in overland flow.”
Other farm nutrient runoff studies I've seen have shown that surrounding them with a trench of woodchips, biochar, or creating a biodiverse green boarder some meters wide that is then left to act as a bioinfiltration/bioretention system, do work.
Studies that inoculated bags of woodchips with fungi and distributed them along waterway edges also worked.
A swale on contour that was planted out with a diverse range of plants, or a hugelkultur with high carbon content and plants should also work, but I haven't seen any documented studies.
When I was learning about Terra Preta and the African Dark Earths with high charcoal/biochar content, I noticed they had high levels of phosphorus which tells me the soil carbon was likely filtering and retaining it for plants and soil organisms to consume.

My advice would be to at least have a green strip on contour, swaled or not, with high plant diversity such that water is infiltrated into the landscape and doesn't simply runoff into the lake when it rains, especially under heavy downpours. And also to reduce the soil bulk density as much as you can so water infiltrates the rest of the fields.
A plant diversity study showed that using at least 16 species produced the best water infiltration and soil bulk density results, but that may depend on the climate.
Another 5 year tree study showed that for compacted soil compost tea improved soil bulk density as much as 2" of compost did (many composts have high levels of phosphorus), but that 6" woodchips (low phosphorus) performed twice as good, and grew twice as much, mostly because it was able to maintain soil moisture and keep the microbes active and improving soil bulk density and water infiltration. Ramial woodchips are a good option. Mulch, living or dead, matters!

Keeping the carbon loving microbes that build the soil organic carbon that then helps sequester phosphorus and nitrogen, is very important.
A study of Brazilian forests showed that soil organic carbon was correlated with 86% of soil nitrogen, so the more soil organic carbon may mean the less nitrogen runoff. Higher carbon content also increases the moisture holding capacity of soils.

Soils are complex though, and what works for one soil may not another, or may cause detrimental effects, case in point was a study on a forest that researchers added calcium to replenish acidic clay soils affected by acid rain. Adding the calcium resulted in increases in dissolved organic carbon runoff into streams, not what the researchers expected!
The best way to really know how what you're doing affects nutrient leaching and runoff, is to observe and test.
2 years ago
Good to hear they're improving. Maybe they were just cold and had wet feet? I found the following graph of peas in a propagator with and without a lid from vegplotting. You can see how not having a lid and those peas possibly being colder, slowed them down, but almost caught up again at 5 weeks. Perhaps the soil was colder this year or that the brown you're noticing is from another type of pathogen slowing progress, it's hard to say. Sometimes seeds do carry the pathogens with them.
I learned recently from a NASA plants in space talk that plant growth tends to follow an s-curve where the seedlings start in what's called a lag phase where they're trying to establish roots and once they have they then enter an exponential phase, so sometimes we just have to be patient or work out ways to help like warm the soil. Apparently the lag phase for lettuce is about 15 days in perfect conditions, I'm not sure what it is for peas. Otherwise it might be soil density impeding root growth, soil acidity, moisture or nutrients.
Last week I read a study indicating that legumes are some of the first to die off after floods, and also that in the dig versus no dig garden of Charles Dowding in the UK, the broad beans were the only plant to produce more yield in his dug beds. So legumes may love aerated roots for the rhizobia in the nitrogen-fixing nodules to do their thing!






2 years ago
From memory they were sown at the start of May and have been picked since the start of September. So four months. I grew Snow Peas, Sugar Snap, and Shelling Peas. Those that found a trellis to climb are doing well. Broad beans I also planted at the same time in a sunnier spot have loads of flowers but no seed pods as yet. The garden is really loving all the rain we've had and I haven't watered at all.
2 years ago
As David suggests it could be fungal, carefully pull one, wash and have a look at the roots and rest of the plant for any signs of disease. Snow peas I planted over winter that didn't get much sun grew slowly but are now producing well for me here in Melbourne.
2 years ago