Soil Biology

本站添加: 2026-05-10

[00:00:00]hello everyone it's me again so this is our fourth lesson and today we're gonna look at the biology of soil and then in the lab normally we would get out microscopes and look at slides this is sort of where one of those labs where it kind of sucks to have to be at home so on the lab folder I'm going to dig up as many videos for you as I can and there's a couple of webpages that do a really good job of showing you live videos of what we can expect in soil to be more specific we're actually looking at compost tea but I'm going to get into that towards the end of the lecture so let's let's start by summarizing the biology that we have in soil I think and this is just one lesson some people can spend years studying this so let's keep our expectations reasonable but anyways so soil is alive there's a lot of living organisms in there that are both breathing and eating and that's important to keep in mind we're looking at in a typical forest context there's both plants there's arthropods there's worms there's mammals there's microorganisms and specifically we're really mostly looking at what are called decomposers so these are organisms that are responsible for breaking down complex structures that plants have built back into useable nutrients so we can kind of say organic garbage and converting it back to nutrients I've mentioned this in another lesson and I will continue through the term because it is a really important concept on the Left we have a slow nutrient cycling this is a typical deciduous forest you would find in Ontario in the winter all the leaves have fallen down there's lots of detritus down here that can decompose and feed organisms even in the dead of winter organisms are busy breaking down those leaves to feed nutrients back into the biosphere and on the right we have a picture of a tropical jungle I don't know if that's really obvious to you but that's what it is it's a rainforest and that's an example of where we have rapid cycling so here because it's hotter there's lots of moisture a good amount of oxygen the microorganisms can go really quickly and take all the detritus that's on the ground convert it back into nutrients when go right back into plant material and that makes the jungle look so incredibly productive but the caveat here is that the nutrients are cycling constantly and if you take nutrients out I II harvest something and remove it there's less to go around which means nutrition starts to collapse and this is where clear-cutting jungles is so destructive so let's look at the organisms that are responsible for this nutrient cycling we are not going to go into all these things we're gonna sort of summarize a few really important ones but this is a pretty good snapshot of what you would see if you kicked a log over on your next hike so deep decomposers we're looking at fungi bacteria protozoa nematodes acting on my seats and animals nematodes are gonna break that into Metazoa are gonna call those Metazoa but that's okay what do decomposers need so I mentioned this already they need air water and food they're essentially just like us right good thing we're not decomposers though that'd be kinda gross but whatever important here at the top two feet of soil this is where most of them reside and I did not try to draw a worm there but I can't resist there we go it's a worm an underlying worm anyways top two feet of the soil is where most these guys live and what do they feed on they feed on plant residue and root garbage that's an important one let's take a closer look when we talk about Route garbage what we're actually talking about is a fancy term called the rhizosphere the rhizosphere is basically in an area it's about it's very small two millimeters distance from the root and this is where we get old root caps root hairs and I don't know if you remember from plant science one but plants also exude butyl egde to help them to move through the soil without causing a lot of damage to the root so this sort of like a worm lubricates the roots so they can pass through the soil particles with minimal damage those exudates and dying cells that have slough off the front provide a lot of food for biological activity now remember root caps are cells that are produced on mass constantly and they're just left off so that the root is protected behind it so it can pass into the soil similar to the Musil edge with minimal damage so that's what a root cap is whoops I'm trying to lean that's what a root cap is for and all these cells that are slough off and all the Meuse lives that's left behind in this area around the roots is food for microorganisms so that's what we call the rhizosphere I always ask that question on quizzes in midterms so you should remember that okay so the vast majority of decomposers are microorganisms we're talking very small organisms top two feet of the soil is where all that activity is and immediately around the roots in the rhizosphere is where the most intense activity is okay so let's look at the individual decomposers starting with fungi which i think are probably the coolest but anyways fungi cannot use the Sun to make energy which means they have to feed off other organisms in order to get fuel to survive and grow and they spread out thin structures like roots that we call high fee and in this picture over here the high form and network all throughout the soil accessing nutrients masses or lots of high fee are collectively called my Celia so the my Celia so when you do your Plant Pathology you might look at or talk about my Celia or mycelium for a fungal species not all fungi are bad right we're talking about beneficial ones in this particular class - can cover a very large area it's been a while since I've read the paper but the largest living known organism in Canada is a fungal body that occupies a good chunk of Northern Ontario and right into Quebec and they were sampling this the hyphy from this fungus and it was identical genetically through the entire region so it's all one connected Highfill structure which is pretty amazing when you think about it that entire mycelium is massive so when a fungus gets to a certain size or season the hyphy will organize themselves and produce a fruiting body which we know is a mushroom but that's actually just a tiny little structure relative to what's underneath it but we call that a fruiting body that's where it's going to produce spores or it's going to receive spores for cross-pollination and producing new fungi so yeah the fruiting bodies are what releases spores so when you're looking at a log you're looking at the fruiting bodies this log is probably completely infiltrated with - the entire thing and you're only seeing a fraction of what makes up that fungus in that particular log so this is rolling over a log and looking at the Highfill structure underneath in the soil you can see it's like a network of fine roots and these are where the fungus is reaching into the pores and slowly degrading the wood for nutrients under the microscope this is a 200 times you might see like broken root like structures those are often Highfill structures you can tell because they have sort of individual cell-like structures this is one cell making up a piece of that - then here's another etc etc right so here's another one here and they connect to form like a root and so they would be shattered obviously in and you're trying to sample them it's very difficult these are delicate and in the context of making compost tea the bubbles and everything will break them up into shards so it's difficult to grow a lot of beneficial fungi and compost tea but so what makes fungi so special well they do the hard work breaking down wood if you remember from my lesson talking about humans not humus the idea is that fungi produced this fancy enzyme called phenol oxidase which is the only thing that can break down lignin which gives us the wonderful humans that gives that organic component of soil all the properties that are desirable so fungi are incredibly important in terms of rejuvenating the houmous in soil okay moving on to bacteria all right so we're talking single cell or cellular organisms they are probably the most abundant organism in soil this is a low magnification under maybe a two hundred times microscope actually a bit yeah forty times this is 60 times this is obviously a scanning electron micrograph image that I scammed off the internet Shh so anyways bacteria come as both broads and cocci which are circular right so rod-shaped and cockeye and this this picture here actually does a good job of highlighting so these would be cockeyed bacteria and these are beer odd bacteria it's pretty self-explanatory and it doesn't really matter that much to us to be honest as horticulturalists we just need to know there's bacteria in there and we want to grow the right bacteria so what do they do they eat organic matter it's I try to use an analogy that helps us understand how important these guys are the bacteria break down and mineralize nutrients back into the basic elements that we need to reconstruct things that for our own good or for plants to construct and so it's sort of like having sheep out pasturing in a field and then along comes Derrick and he has himself a sheep for the long weekend as a barbecue so the Sheep did all the the work of chewing up the grass and converting the nutrients making it part of its body and then I ate that sheep honestly I did not eat a sheep I big into that kind of thing seems like I don't know let's not talk about because it gets everyone in our family upset yeah anyways so the point is in back in soil the bacteria are sort of like the grazing organisms that are breaking down the basic nutrients and then large organisms eat the bacteria releasing the nutrients for them to consume and you so it's like a food chain right then we're right near the bottom of the food chain is the bacteria but they are incredibly important even though they're hugely abundant they are very important so we look at other organisms later like protozoa and stuff like that they're actually eating bacteria they don't often eat plant material it's the bacteria that and the fungi that are eating the plant material and the organisms are just the beginning of the food chain sort of like a protozoa eats the bacteria and then a rotifer eats the bros OA and then a worm eats the rotifer and then the worm gets eaten by a bird and the bird gets eaten by fox and the fox gets eaten by a wolf and then Derek shoots the wolf and he has steaks for dinner which is really again such a horrible thing I would not shoot a wolf and eat it that's just wrong cuz they're top predators that's important but yeah whatever um okay sorry distracted today it's raining for like I don't know I think I'm gonna build an ark actually know we've had some Sun it's good it's all good but we have a lot of rain so again bacteria and soil important decomposers right these are principle organisms that are responsible for what we call nitrification so when i was talking about bringing nutrients out so they can recover nitrogen that's in weight decomposing material and some can even fix nitrogen from the atmosphere you would have learned that in plant science one right like Rhizobium in root nodules these are these nodules we see here they're fixing nitrogen from air that's infiltrated into the soil and they're fixing it into nitrate which of course plants can use as a fertilizer by the way if you have a chance some time maybe let's say later in the summer July August if you can find a soybean field I mean I don't think you should destroy those field but the farmer will forgive you if you gently dig up one near the edge of his field and you'll see lots of nodules on the soybeans and modern agriculture is pretty darn efficient they pre inoculate all their soybean seeds and and some other varieties that are cultivars that are grown with Rhizobium bacteria and they form huge amounts of nodules so they're very nitrogen efficient crops in fact the image you're looking at here is a typical soybean plant in your average farm field so pretty pretty cool that they're that high-tech this is a picture you'll see throughout your courses I don't want to go into great detail in this context but it really does help summarize the nitrogen cycle that as far as plants are concerned right so it's important to understand that you know we have nitrogen gas in the here right and that percolates into the soil and is fixed by bacteria like Rhizobium bacteria often going through the first step is forming ammonium and that ammonium is then converted by a different bacteria into nitrate and the nitrate which is then turned into nitrite so then turn into nitrates this is really complicated isn't it everyone's got their own job and those nitrates are then absorbed by the plant and it happily grows now if the cycle is not carefully maintained ie we don't have the right temperatures or the ground is too wet usually when the ground is too wet we actually get nitrogen loss so instead of having the nitrogen used by the plant it's actually stolen by me denitrifying bacteria and what do they do they convert it right back into nitrogen gas which is bad news which is why when your ground is wet your plants are yellow because the nitrogen is being lost to the atmosphere really important lesson here if you're the kind of person to over waters your plants all the time guess who you're feeding your feeding denitrifying bacteria and all your fertilizer you're putting money into is is gone you're not actually benefiting it's just being evaporated into the atmosphere by denitrifying bacteria so it really is important that you don't overwater crops this is probably one of the most common errors with amateur growers is that they keep their plants too wet and they end up feeding denitrifying bacteria how can you tell take the pot off your plant and sniff the bottom of your root ball and if it's got a sulfur you smell to it guess what you're just putting your nitrogen into the atmosphere the plants hardly getting anything okay let's move on again so bacteria are important for fresh green early organic material so brude's own raizou rhizosphere type stuff green leaves that have fallen into the soil fresh stuff that's newly perished where fungi are for old stuff like trees dead trees old leaves so the more woody type structures so bacterias for fresh fungi is for old important to remember that yeah we'll talk a little bit more about that next class when we talk about composting so let's just remember that moving on to protozoa so protozoa is coming let Andra day of different shapes and sizes and we are not that kind of a biology class so we're not going to get into the nitty gritties of you having to identify everything under the Sun but I do want to talk about flageolets amoebas and ciliates because it's important to look at these guys and if you are in a real serious job horticultural job I don't know if too many like this but they do require you to be able identify ciliates and flageolets and amoeba because it can give an indication of the health of your soil but I alluded to this before right these these are protozoa these are the organisms that eat bacteria they eat the bacteria so an amoeba surrounds the bacteria and then cracks it open releasing the nutrients right and just like a flageolet here or a Paramecium ciliate or a rotifer with its little antennas that are filtering water into the stomach they're trying to catch bacteria and crack them open for the nutrients that are inside them like little chocolates I wish they would not taste like that so protozoa is our single cell right we have things like amoebas I'm sure you've all heard of an amoeba before slow-moving organisms Paramecium these have thousands of hairs that swim them paddle them through the water at very fast paces they have a mouth that kind of curl as they go and they eat bacteria Euglena is a really interesting one that actually has chloroplasts in it so it's sort of an algae like organism it has it's not like a hybrid you know it's like your Toyota Prius effect of organisms it not only eats bacteria but it can also take sunlight and make sugar so mother nature has lots of surprises worse this is a rotifer this is one we typically see in our labs from our compost they have a tail that anchors on to a structure and they just float there and you can kind of see the little hairs here and they just swirl water into their stomach it's a pretty sad existence but that's what they do and every once awhile they'll let go of their tail flit around and react or somewhere else I suppose if they get really bored this is actually a terrible picture but it's vorticella I think something went wrong with this photo but it's a lot like a rotifer except their tails are a little more springy and they kind of lurch out when they see some sort of shadow these don't have eyes they have eye spots so they can sense light or dark shades and then when they see something dark they think ooh I'm gonna zip out see what I get it's crazy days there man you got to be on the ball if you're living in that world diatoms diatoms are pretty darn cool I love them because there just aren't beautiful and you love them because they keep your teeth clean yeah so these guys grow a silica shell on the outside which is basically like glass and when they die you're left with diatomaceous earth which is you've probably heard before is used in pool filters it's used as a safe insecticide because the shards get into insect joints and it braises them so that they get crack and dehydrate and die but it's not toxic it's just very fine glass powder and it's not like the kind of glass powder that's gonna get you sick it's just a very fine powder under microscope all right specifically a scanning electron microscope they are absolutely gorgeous their shapes are beautiful you can see by the shapes why they would be so good at filtering water in a pool because when water passes through that structure everything's getting filtered out right horrible air Carol anyways beautiful things to look at it just shows how creative Mother Nature is yeah Desmond's another type of protozoa these guys they're pretty cool they're the bananas they don't change change their shape much or like they kind of only turn left kind of thing so yeah well it depends which way they're flipped obviously but the point is they they can't change their shape too much and they just circle around and suck stuff up so anyways there you go the three that we often see in our labs are Radha firs Paramecium and amoeba those are the ones we normally would see and I'm sorry that you can't but why are they important because they give us an indication of oxygen alright how much oxygen is in your soil or your liquid this is actually a lot of the science was developed for water wastewater treatment plants the scientists in wastewater treatment plants are constantly taking samples and seeing what pair protozoa are living in their water if there's lots of ciliates zipping around we know that we are somewhat low on the oxygen level and that means they have to slow the introduction of new food or whatever our poo into the water so they have to start a new tank and let the other one catch up or they can if there's lots of options and they can bring in more materials so that they they can keep feeding so scientists are always checking for amoeba and Paramecium because they give us a good indication and as far as looking at compost tea if under a microscope you see that you have a lot more ciliates than you do amoeba it tells you you're not getting enough oxygen in the process of making your compost tea but not everyone that's making compost he has a microscope eye there and I'm not sure why I'm circling all these but anyways so if we see lots of ciliates it means we're on the anaerobic or low oxygen side if we see lots of amoeba we have really good oxygenation ok let's move to the next decomposers Metazoa so these are multicellular organisms larger than protozoa nematodes and tardigrades are kind of the most common ones that we would come across the tardigrade which was on the last slide as well sometimes called a water bear this is a herbivore actually in the sense that it's chewing away at plant material chunks that it finds probably some bacteria get in there but it's principally eating organic matter directly nematodes which are like these semi rigid worms are there's actually lots of them but essentially for as far as we're concerned there's two big ones and small ones the big ones are generally are good for us because they eat small nematodes the small nematodes tend to be parasitic and they damage plants get into the roots by piercing them with their short they're sharp style and damaging and feeding off the plants what you're seeing here is a really cool fungus they have these they look like life rings on a boat then they suspend the on stocks and the nematodes actually get caught in them and when a nematode touches them the life ring expands and traps it and then they plant of the fungus produces an enzyme which basically breaks down the wall of the nematode and then it grows hyphy into the nematode and feeds on it so you can actually buy these fungi to inoculate the soil to prevent nematodes from infecting their crops so farmers will buy you know big bags of Spore powder and a mix and they'll spray their fields with it to prevent nematode infestations turf growers I believe use a lot of that and before I start this light I just want to mention like I kind of like to bring these stories up because I think a lot of times farmers get a lot of bad press like all they do is kill the world and use toxic chemicals it should you should try I want you to try to at least give people some of the benefit of the doubt that farmers are trying to be stewards of their land you know they're most of the time these are farms that have been in the family for a long time and they've recognized the value of their soil and their that it's generating their livelihood and so they look for the best technology that they can afford that's an important one that will do the job that needs to be done so they don't always turn to chemicals they look at any possible means to maintain the livelihoods that they have in their soil so keep that in mind next time you watch someone on YouTube who wants to tear down farmers okay so nematodes they eat bacteria again these are eating the bacteria to crack open the mineralized nutrients that are inside those there are some that feed on fungi and roots these are not so good and then of course there's beneficial nematodes that feed on other ones you can see that in this picture here where the large nematode is feeding on the smaller one sometimes you'll see what looks like root nodules and those are actually small nematodes that have infested roots causing damage so it's actually not Rhizobium nodules those would be nematode nodules so you would know that if you planted the crop because if you had bought seed that was inoculated then you would expect that if you didn't and you saw lots of this you would say either I have a nematode a problem or I have a lot of root nodules from Rhizobium lastly tardigrades these are really cool actually have a t-shirt with a tardy grade on the front probably one of the more popular Internet photographs is the tardigrade in a astronaut suit anyone know why maybe you remember that NASA actually stuck tardigrades on the outside of a satellite no on a device that they took up with a space shuttle and they left them out in space for the entire duration of that mission and then they brought them back to earth and they actually rehydrated and were alive again so they are a fascinating organism they mean the look of the thing it looks tough it's got thick skin they can dehydrate and rehydrate almost like look you'd think they'd be dead so they managed to survive space for quite some time and not die so that's why geeks have pictures of them in spacesuits on the Internet some theories are of course that you know organisms that somehow survive space travel and made it to earth or what inoculated life on Earth who knows everyone's got a favorite theory I have no idea I just figured somehow we're gonna maintain whatever is alive on earth anyways water bears are pretty cool don't often get to see those in the labs it would be cool but we don't get to see them all the time but they're pretty pretty hard to find but I'll get you some videos on YouTube acting on my seats next on the list of decomposers these are anything these are these are non mobile bacteria so they look oftentimes they're confused as fungi but they are fungal alike because if you look here these look like - right but they're actually rod bacteria that have assembled here you can see a little more clearly they assemble into these filaments and actin my seeds are really important in soil I can't stress this enough they are they are essentially the last stages of decomposition so when we talk about composting next class we'll get into this a little bit but essentially what they do is they produce antibiotics and it might make sense when you look at the name my seat's things like streptomycin right erythromycin you've probably heard of these antibiotics if you've ever been sick and had to have antibiotics you can thank acting to my seats for that when the decomposition process is finishing acting my seeds tend to take over and they finish off and give that earth the real nice earthy smell that's you know that acting oh my seats are present when the soil smells really nice and those antibiotics actually protect plants from bacteria and fungi that are not good for the plants so the these are really important in terms of root health you can again farmers by this act innovate is a bulk powder this is just a sample pack we can get this in like 100 kilogram bags or whatever and and farmers will then inoculate their fields with acting on my seats to prevent roots fungal infections and and whatnot they would know what's prevalent in their particular fields I've used this in greenhouse crops a lot of greenhouse growers use this so they don't have to use fungicides it'll protect the crop against a lot of Pythium infuse area and then rise like Taniya I mean it can't solve everything but it will it will really make a big difference from a cost perspective it's it's definitely worth it lastly we have animals right so I got a picture of worms here and moles animals obviously these are larger organisms that are feeding on the Metazoa the protozoa and even the bacteria they're sort of like the top of the food chain in the soil so let's break free from the decomposers discussion and I got another sort of little lesson vignette here comparing bacterial soil and fungal soil so when we talk about what's in the soil we do have to keep our mind aware of what's the context is that are we looking at a forest floor or we're looking at a grassy meadow there they're actually very different typically grasses are what we call bacteria dominated so there's a lot more bacteria in grasses than fungi primarily because grass is where you have small leaves coming off detritus that bacteria can quickly important quickly break down so there's more rapid nutrient cycling around grasses where in forests which are fungally dominated we have a lot of wood and leaf material which has much more lignin and cellulose in it and so that's a lot harder to break down and so it's mostly fungi that are dominant in the soils of force why do I bring that up because this is actually by the college greenhouse when you have a tree it's often boarded by a grass right and so it's important to understand that around a tree we a tree and its little ecosystem is expecting a fungally dominated soil to cycle the nutrients that are around the base of the tree right so things like even woodchips you put on or dead leaves so we mulch around trees to encourage that fungal population to develop and we keep the grass away from the base of the tree if you've ever tried growing grass around a tree you'll know that they are not very compatible for reasons of shade water consumption nutrient use but instead of trying to force the grass right up to your tree why not embrace it and mulch around the base so that the tree is happy and it's it's well fed from that fungal population that develops so when we look at grassy meadows they are bacterially dominated soil and in forest fungally dominated because of all the leaves and twigs and branches all that lignin type stuff that's sitting there ok so factor is affecting the quantity of soil organisms so we've talked about we went down the list of all the decomposers and then we've talked about the difference between bacterial soil and fungal soil now we want to look at what are the conditions in order to make sure we have all these beneficial organisms and this is really just common sense you shouldn't have to stress over this think about what we need right we need air we need water we need to be warm enough and we need food and then of course pH should be reasonable if it's really acidic or really alkaline none of us like that competition that depends right sometimes we can't control that if there's a lot of other organisms you know what let the strong survive I guess I don't know but and then of course soil texture so if we got a really coarse undeveloped soil very young soil I'm really bad at drawing arrows by the way right a coarse soil that's not gonna have a lot of organic matter you're not gonna have much in the way of soil organisms developing which is important when we're talking about soil health right and why is that small percentage of organic matter important well because that small amount of organic matter helps organisms develop because it feeds the bacteria which feeds the other organisms which ultimately feeds fungi that are beneficial so that little bit of organic does make a difference this is a some propaganda picture I took off the internet which of course it's true you know I have a horrible lawn but I live in the country so there's no pressure I don't care what grows in it if it's full of barnyard grass or who knows what clover I I don't care and more often than not it's greener than anything else in the summer because it's got a diverse population of plants in it whereas the perfect turf like on the Left here you know no weeds nothing but look at the poorly developed brood system right very poorly developed this is obviously a caricature of what I'm trying to say but the idea is that if you feed your soil if you take your soil seriously and you have lots of organisms in it it will feed back into your plants and your plants will be happier and healthier and you'll require less fertilizer so the person who's dumping fertilizer on their lawn is disrupting the microbiome that's in the soil and they're not going to get that healthy structure below the surface which will impact their root structure and also alter their drought tolerance when times get tough and then they rely on much more irrigation to keep their lawns green when the soil starts to dry up all right last bit of this lesson I know it's another long class I'm sorry we have so much information to cover but I want to talk about compost tea okay so this is kind of a bit of the horse before the cart or the cart before the horse because we're talking with compost next class but compost tea is really not so much about the compost but about the microorganism so that's why I stick it into this lesson so what is compost tea compost tea is a microorganism soup all right lots of different organisms in there there's different kinds of compost teas the Internet is rife with lots of claims some of them are true some are not but essentially the bare basics what we do is we take a small amount of compost so it actually does start with compost and then we suspend it in a bag or a sock and some water and we bubble the water with lots of air so that we have it aerobic and of course then all the little organisms we just talked about all the decomposers that are in that compost because compost is about decomposition right so there's lots of bacteria lots of protozoa maybe some Metazoa I doubt there's worms and things like that so much it's mostly going to be those organisms they will begin to accelerate their growth and increase in numbers because of the oxygen and water availability once it's bubbled usually for about 24 hours you can take that liquid out of the compost tea generator and then water that into your soil what does that do so this is where the misinformation starts to abound if you remember what compost tea is it is elevated organisms so we're growing microorganisms by making compost tea you're not creating a lot of nutrients you're creating a lot of organisms so typically what that means is you can add compost tea to your soil and it can help only and this is true only if there's enough or suitable organic matter in your soil to begin with so if you've worked organic matter into your soil you can accelerate the decomposition by adding compost tea so the other important thing to remember here is that we're talking about living organisms in compost tea I laughed myself silly when I go to a hydroponics store because I see all the goofy stuff they sell the people just imagine if you take aerobic microorganisms and you put them into a bottle and you cap it put it in a box ship it across the country put it on the shelf for a few weeks and you sell it to people who girly by this compost tea for their plants how alive do you think the organisms are every time I brought a bottle of compost tea in from a store and we put it on a microscope slide we find absolutely nothing zip zilch waste of money don't do it you want compost tea gotta brew your own so essentially we're releasing elevated numbers of microorganisms into our soil to accelerate the conversion of soil particles into nutrients that's all compost he is okay you can if you have the right acting on my seats but keep in mind acting on my seats are a fibrous bacteria they have a delicate structure when you're vigorously bubbling compost tea it's very difficult for those organisms to form structures so they do not grow very well so when people make a lot of compost he claims about them being ante full of antibacterial compounds I'm gonna tell you that for the most part they're stretching the truth and this is one of my frustrations in life is that people who are part of a noble cause feel sometimes like facts can be bent because hey what they're saying is noble anyways well I I really don't like that the scientist in me gets very upset so I am often harshly critical of people who make unnecessary claims even though compost tea is a good thing but you know exaggerating the benefits that's not helping anyone when they have high expectations there is definitely some mineral leached from the compost by bubbling it but not a lot don't don't bet much on that most compost tea has nutrients in the range of around 0.5% so we're talking very very low percentage of actual fertilizer content but that's not why we're adding compost tea remember all we're doing is growing larger numbers of microorganisms to accelerate the population in our soil to accelerate the conversion of those soil particles into nutrients so that our plants can benefit these are some pictures this is the compost tea unit we have at the college we have a couple of these that's an air compressor in the back and it just bubbles this tank bubbles non-stop and you suspend compost in a sock in the center but you can make your own it's really not that hard for this class because I'm not at the college I have a bucket just like this with a bubbler attached I just flipped the slide back cement so how do you make compost tea you start with some compost right so some healthy soil in my case I went to a ditch where there's a lot of leaves that are decomposing and I dug down to below the dry layer of leaves into the wet layer and I took a whole bunch of samples and some soil along with it and then I bubbled that in my bucket with air suspended in a screen if you can like a tea bag i I didn't but I don't think I matter too much and then basically aerate as much as possible and then after 24 hours you remove the water and you irrigate it into your crop or your plants or whatever you have and away you go those microorganisms will infiltrate your soil and get busy both eating bad bacteria converting dead organic matter into plant food important considerations yes we've talked about this enough by now but obviously it had we do not want anaerobic right because then we grow the wrong bacteria the wrong organisms and we actually lose the nutrients but to complicate things there was a paper published which showed that an aerobic compost he had more antimicrobial benefits I don't know you know what they say when you only have a couple of papers it's it's hard to say if it's true or not but I thought I would include that because it's out there if one of you does a literature search you like but I thought you said it has to always be aerobic well let's just be safe and say generally speaking aerobic is better okay but there are some interesting Japanese compost tea methods that are anaerobic almost like like a fermentation process and those have also been proven to be beneficial I don't get into that with this course because you know compost tea can be a whole science to itself but I thought it'd be interesting if you want to look into it more Google's your best friend and again reminder that when you see lots of ciliates we're dealing with anaerobic when you have lots of amoeba we're dealing with aerobic so in the case of compost tea this is a really good example of how you would assess the quality of compost tea all right as far as your what do you put in the source material so if it's green or recently dyed plant material you have lots more bacteria older dying leaves more fungal so my source material for my compost he might not generate as many bacteria as I'd like because I was mostly dealing with rotting leaves which would be fungally dominated but we'll see chuck it under a microscope but I can find one and see what we get lastly I wanted to mention one other thing that confuses this issue and sometimes when people are talking about compost tea this is what they're talking about it's actually more like compost leach and if you want if you're looking for fertilizer this might be the better way to go so over here we have a composter or oftentimes it's vermicompost thing which again we'll talk about later in the course where you've got worm feeding on material in layers you take the after this has been going for a few days you pour water in the top and the water leeches nutrients out of the composting process and comes out the spigot into your bucket this type of leech is very high in nutrients now to some extent you could say you're actually just robbing the nutrients from your compost but let's talk about composting another day and then we can have a better discussion around nutrients but I just wanted to let you know some composting devices have a spigot and this is what we're talking about this could also be called compost tea but it's not the tea we talked about in this class you could call it compost brew or leach I don't know what you want to call it it's not necessarily a bad thing like I said a really good way to get a concentrated nutrient solution for your plants this is a slide that I usually leave up in the classroom while we start looking at samples just to help you identify what it you might see under the microscope silly it's so like your Paramecium flageolets which have a single tail that swim around your egg Leena's and then there's algae which you might see these are food sources Volvox and other kind of algae food sources for these guys not just dead plant material but also algae can be a food source I can't remember there's another slide or not I think there isn't so I'm gonna wrap it up here and encourage you to take a look at the videos that I'll post so you can better understand what these bacteria and microorganisms look like and I guess I'll talk to you next class take care stay healthy