Johnson-Su Compost / Extract Communities and Performance Data
- zackljones
- 17 hours ago
- 7 min read
The Newcombe family has farmed in Port Williams, Nova Scotia since 1761. Ten generations have managed Cornwallis Farms where they currently produce broiler chickens, eggs, and milk from dairy cows. Brian Newcombe and his wife Edna manage the crops and dairy while Brian's brother and his wife oversee the chickens, feed mill, and record keeping. Together they support 21,000 laying hens which produce about 20,000 eggs a day.
What is especially unique about this 1,700 acre farm is the fact that they are nearly 100% self sufficient in term of feeding their animals from their own land. They consider themselves stewards of the land, going mostly no till or strip till since 1993. I first saw Brian on Twitter posting pictures of his home made Johnson Su Composter (below) and Extract Brewer. Brian's Johnson-Su compost is made out of cow manure and leaves. As you can he used PVC pipes to provide aeration throughout the tote.
I asked Brian if he would be able to send me a sample of his compost and his extract. I was especially interested in it because I hadn't sequenced Johnson Su compost or extract before and these were products that were actually being used at scale in a farming operation. I mailed Brian a collection kit and a couple months later I had the samples in hand (Aggrego Data uses a DNA preservative to ensure sample stability and prevent microbial community shifts).
Johnson-Su Compost Bacterial Community
While Johnson-Su compost is more known for it's fungal community, Â for now we are only going to focus on the bacteria side of things. Aggrego Data is has recently offering fungal sequencing and we'll have some new data coming out shortly for vermicompost and vermi-extract. Hopefully we'll get some more Johnson-Su samples as well so we can get an idea of what's going on with the fungal communities.
Alright let just get into it - below is Brian's Johnson Su-Compost and I've also included a vermicompost sample from a worm breeder in Grand Junction, CO as a comparison. The vermicompost made from thermophilic home composted food scraps, peat moss, and cardboard. These are composted in the black mortar trays that are starting to get pretty popular in worm farming.
Comparison to Vermicompost
There is a lot going on in each sample, but the main point I want to get across is that the Johnson-Su community looks a lot like a vermicompost community. They aren't exactly the same (no two samples are), but if we look at the broader organism types they are comparable. In Johnson Su we have nitrogen fixing Rhizobiales at 7%, Bacilli at 8% a Actinobacteria a 6% of all bacteria. The breeder vermicompost had Rhizobiales 5%, Bacilli, 7%, and Actinobacteria at 13%. Gammaproteobacteria, and Bacteroides are also of similar abundances and both contain some important beneficial organisms. The Actinobacteria are significantly higher in the vermicompost, but otherwise they are very comparable. The vermicompost is slightly more diverse coming in at 6.59 Shannon diversity while the Johnson-Su 6.26. Basically, they are both very diverse samples, but the vermicompost sample slightly beats out Johnson-Su in diversity.
One of the first things I asked Brian after we analyzed the data is if he adds worms to his compost. It turns out he does add worms after the hot stage of his composting. I believe this is a fairly common practice for Johnson Su composting (someone correct me f I'm wrong). Our worm breeder vermicompost also is made from thermophilically pre-composted food scraps and mixes it with peat moss/cardboard bedding. In a sense the processes are quite similar and we end up with similar, highly diverse communities. The worms and their castings are also likely a major driver in microbial community selection and perhaps the increase in actinobacteria found in the vermicompost is due to a greater abundance of worm castings.
I'll end this section with this data is anectodical and only compares 1 sample of each compost type. As we get more samples, especially of Johnson Su compost, we'll have an idea if this similarity hold up.
Johnson-Su Extract Community
Brian converts all of this Johnson Su compost into a compost extract which he has applied about 7 gallons per acre to his wheat, corn and soy bean seeds at planting. He makes his extract by adding his Johnson Su compost to a screened 50 gallon (200L) barrel with holes inside of a 200 gallon (800L) IBC tote. A blower aerates the tote for about 20 minutes
We'll look at the microbial community of the extract first and then get into some of Brian's field trial results.
Previous samples of vermicompost extract have shown that the bacterial community is nearly the same as the seed vermicompost community. This Johnson Su extract is similar to the parent material, but there is a significant increase in both Bacilli and Actintobacteria. Bacilli increases 3x from 8% to 23% of bacteria while Actinos also triple in relative abundance going from 6% to 18%. While I typically lump all of these organisms as beneficial there is a large chunk of Bacilli, specifically Planifilum (5%), which there is no evidence of direct benefit to plants. Interestingly, this genus of organisms are strict aerobes, along with in increase in actinobacteria (mostly aerobes) which makes me think the aeration is responsible for the increase in these organisms.
While I haven't tested very many extract samples, but I have yet to see this type of community behavior before where bacilli and actinobacteria grow significantly in relative abundance compared to the parent material. In fact, if we go back and look at Troy Hinke's vermicompost and extract samples we actually see these two groups of organisms shrink in abundance. It's definitely something we'll have to keep our eye on in future extract samples.
Extract Performance in the Field
As I mentioned, Brian applies this extract at seeding (~7gallons/acre) to his corn, wheat, and soy bean crops grown primarily for feed. Overall he's had mixed results with limited effectiveness on soy and wheat and the most success with corn.
Soy Beans
Brian plants typically plant his soy beans without any starting fertilizer. The image below is a comparison of soy planted with the JS extract (left) and an unfertilized control (right) in 2024.
As you can see there is a significant difference in root mass in the JS extract treated soy and possibly a little more above ground biomass. Interestingly, there was no significant yield difference at harvest. The extract treated crop produced 60 bu./acre while the untreated control produced 60.7 bu./acre.
Corn
In 2024, Brian ran a similar trial with corn. The main difference was that the "control" corn received 5 gallons per acre of 6-24-6 synthetic fertilizer and the other "experitmental" condition was treated with JS extract at planting.
Again, the increase in root mass is very clear on the left corn plants that were treated with extract. The plant above ground biomass looks pretty similar between the two. As with the soy beans, there was no significant increase in yield at harvest. The extract treated corn produced 164 bu/acre and the synthetically fertilized corn produced 160 bu/acre. However, the main upside in this case was Brian saved 40 dollars per acre by not fertilizing his corn.
This study would be more comprehensive is there was a control condition without any fertilization. A drop in a yield of an unfertilized control would indicate that the extract is making up for the lack of fertilization. It's possible that the soil still had residual nutrients in the soil from previous years of fertilizing. I understand it's a lot of ask of farmers to try to purposely reduce their yield and the fact that Brian is experimenting at scale should be applauded. After Brian reviewed this post, he told me he is running an unfertilized control this year for corn. I'm also curious how well an unfertilized field only treated with extract would hold up overtime. I would imagine at least some type of organic or synthetic fertilizer would have to be used at some point to make up for the lack of nutrients .
Biological amendments and increase root biomass
This phenomenon of increased root length and biomass without increased yield is fairly commonly observed with biological amendment like compost extracts. It isn't fully understood what is going on here but there are likely a couple different mechanisms at play.
Microbiology and plant hormones
Firstly, yes the additional biology added to the seeds and soil at planting is likely having a big effect. The phytohormones such as auxin, gibberellin, and cytokinins produced Bacilli and Actinobacteria species that are in Brian extract are likely stimulating root growth. Humic acids in the extract have also been shown to stimulate root growth as well in a similar fashion to auxin (more on this to come).
Soil Nutrient Density
Compost teas and even more so extracts, are not high in macro nutrients like nitrogen and phosphorous. It's possible that root systems in conventionally fertilized crops are smaller simply because they do not need to grow bigger to seek out additional nutrients. If all their needs are provided in close proximity the plant has no "motivation" to grow an extensive root system.
Yield, Cost, and Resilience
Despite the evidence of lack of increased yield from teas and extracts there are still other upsides to consider. Most people would agree that a larger root system is a sign of a healthier more resilient plant. Perhaps this has more of a benefit in healthy soils which don't use concentrated fertilizers. Maybe teas and extracts might have more of an effect in dryland agriculture where deeper root systems allow access to water longer in drought periods. In some cases like Brian's maybe there is some cost savings to be had and farmers can at least reduce fertilization or use organic fertilizers to greater effect. There is still a ton of research on application of microbially diverse liquid biologicals and these are just some of the topics I think need more attention outside of yields.
Well that wraps up this post and hopefully explains why people seem to be having success with both vermicompost and Johnson-Su compost and highlights some of the benefits and challenges in suing these liquid amendments in soil. Any questions please comment below. Finally, a huge thank you for Brian for setting example for large scale farms not only with biologicals, but also cover crops, no till, and generally being a steward of the land.