Which Garden Mulch Saves The Most Water?
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- เผยแพร่เมื่อ 3 ก.ค. 2024
- Mulch can reduce garden water use by up to 80% but which mulch saves the most water? In this video I test four mulches to see which traps the most moisture in the soil, which still allow water to be wasted to evaporation and which mulch is best for you to use in your vegetable patch!
And, as always, Happy Gardening!
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0:00 - Which Mulch Can Reduce Water Use By 80%?
0:22 - How I'm Going To Test Each Mulch (Experimental Setup)
1:14 - How To Stop Wasting Water In The Garden
2:13 - How Much Water Does Unmulched Soil Retain?
3:06 - Does Compost Work As A Mulch?
3:33 - Can You Use Bark and Wood Chip As A Mulch?
4:05 - Will Hemp Work As A Much?
4:36 - Is Hay or Grass Clippings An Effective Mulch?
5:19 - Why You Should Stop Watering The Surface Of Your Mulch Too
#growyourownfood #vegetablegarden #mulch - แนวปฏิบัติและการใช้ชีวิต
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Now your soils are going to be brimming with water and protected from sun, it might start attracting slugs. You should watch this experiment th-cam.com/video/0xOyu0YrS3c/w-d-xo.html where I tested which slug barriers worked (or didn't).
Happy Gardening!
btw. for slugs I use wood ash after burning wood after trimming fruit trees, dried for a month, and other trees around. It seems to inhibit thrips as well.
Excellent study! I've often said that wood chips are good..... but still allow too much air circulation because of the large chunks not stacking tightly together. As for the grass, use it and rejoice. Not only is it free, but it breaks down faster and is more easily used by worms and such to build up the quality of your soil. I use leaves and grass clippings all the time because that's what's "free" to me, and it makes a world of difference. Even on steep slopes, you can use light mulch and need only add some pegs in the ground to keep the mulch from sliding down. If wind is a worry, place some light sticks on top of the leaves to weight them in place. It doesn't make much, just a few twigs to stop the wind from picking the leaves up.
Thank you so much! Definitely some limitations with my setup (like a lot of the hemp blew away in the wind, and the compost came with it's own moisture) but I think it represents the real-world picture for top/above watering.
I like your thinking with air circulation. You kind of want some small gaps within the material to prevent too much wicking from the soil to the surface and I suspect keeping some air locked in place helps limit evaporation too (and stop the soil temperature fluctuating) but you're probably right about wood chips - the gaps are likely too coarse and air can get to the surface and evaporate away. It also comes with a lot of part-broken down material (basically compost) which fills the gaps and probably behaves like my compost test did, pulling the water to the surface. It's cool they had some effect here though because they make great walkway material and the water underneath the paths can still (slowly) move across to the beds. In a real system you'd probably have a mix of mulches anyway e.g. wood chip down the middle with beds covered in thick compost and then hay or leaves and the plamts would drain water from the soil in the beds, so having an extra source under the wood-chip that isn't being transpired by grass is probably really handy.
Agree it's amazing that the free stuff works so well but because you have to cut some grass anyway and figure out what to do with it, it kind of seems a no-brainer to use it as a mulch. Direct use seems easier than composting. I've not tried leaves but in windy Cambridgeshire I tend to find clumps of grass don't really get blown around if you give them a few days to dry in the rough shape they came out of the lawnmower in. Haven't tried leaves but it doesn't take much to make them accumulate around objects so it's good to know only a few twigs are what's needed.
Quite an interesting topic. I kept the video short for my own sanity during the edit but a lot to be said. Might have to do a few follow-ups.
Yes, i also just use what's free. Sometimes is not the quality but the quantity. I make my own compost. But could have more compost for free, if i was able to get it to my place. And for the slopes. I had a sloping garden in my fronthouse. I removed a lot of soil and made some terrases. Only a small part is sloping in full sun. Thats the place that my lavender and all other woody and dry plants live. The rest is just soaking wet in Holland. My soil is extreemly heavy clay. If you can get the water and nutrients in, it will stay there glued to the clay particles.
Btw, i live in the south. Thus not the normal "sand" and "tulips" part of Holland under the sea level. I live at a river delta for millions of years ago.
What's you soil type and climate ?
@@RogerKeulen Typical sandy loam/clay in the area. Zone 8a/b. Good rain, but also incredible summer heat. About the only upside is that we don't get winter freezes that last long. If you're dealing with heavy clay, plant more natives. They have exceptional root systems that really do a number to open up the clay and get organic material moving through it. Panicum virgatum, for example, is very attractive as a decorative grass, and the fibrous roots burrow down more than 10' into even the worst ground. Every year, about 20% of the root mass dies off, leaving that organic material behind and as it rots.... it opens pathways for air and water to move easily through the ground. A hedgerow of such natives will work wonders for your landscape and be good for the local food web.
Hooray! What’s free on my property is pine straw. The pine trees in the back shed their needles, bounteous and beautiful. When well tired from digging, transplanting, and overall curating my large garden, I sit on the steps near a pile of raked debris, pitch the pine cones and sticks, and accumulate the pine straw. May sound boring but when you’re tired and your legs have had it, sitting with something repetitive is peaceful, like knitting or painting an object when you’re sitting down. Into the lawn cart the pine straw goes. I spread it everywhere, up to the central stalk of the plant and between clumps of flowers. Its reddish brown color contrasts beautifully with the green of plants. Where I live July and August require a good 5-6 inches over the roots of my roses, and when I check I’m always pleased to feel the soil moist but not wet. Over the years harvesting pine straw has saved me hundreds of dollars on mulch, money I’d much rather spend on experimenting with newly purchased plants. Thanks for the sensible video. Blessings.
Amazing. It sounds wonderful. I'm going to have to write this down and think about growing pine whenever I get to own land. And 5-6 inches aligns with what someone else here said about using bark. I can sort of imagine it behaves similarly. If it's free and it works and it displaces the need for buying in nutrients, then it makes total sense.
I love mulch, especially when it is free/ low cost and readily available. Pine straw is great, especially on moderate slopes where wood chips washes to the bottom of the slope with rain. I prefer pine straw for shrub beds and around trees since it takes years to decompose. I save paper bags/newspaper, chopped leaves and grass clippings for flower beds since they break down over a season and help build quality soil. Papers are laid first, wet down and grass clippings on top. Chopped leaves that have aged for a year are the favorite top layer of mulch in beds. Cardboard shipping boxes are also saved. We can have free wood chips delivered directly from tree cutting companies. It’s not the prettiest but it is wonderful to use on top of cardboard for paths and utility areas.
That’s fascinating! I wouldn’t have predicted how much more effective grass clippings were than compost or bark. Thanks for sharing ❤
Thanks Tom. Yeah, I was surprised the completely free option did so well. In fairness quite a bit of the lost mass would be have been from the compost/bark but it's a pretty good representation of watering from above and the £5 soil meter (which wouldn't ever lie) seems to back it up. I'm just happy the needle moved in the timelapse
This video earned you at least one new subscriber😊 I sincerely appreciate your scientific approach. ❤
Thank you!!!
this video came up in my "home" feed, I just subscribed as well because of it
Thanks Mike. Glad you enjoyed it!
This is awesome! I always wonder about these kinds of things and simple experiments like this one are just priceless. Thank you for taking the time to make this video!
You're very welcome! I'm just impressed it evaporated quickly enough for the needle to move on the scales for the time lapse. A really fun setup
Excellent video. You deserve more subscribers.
Thank you!!!
Oh I just love these studies! I'm always testing things at home and my bf doesn't even ask anyone when he sees temperature gauges, notebooks, and jars of who even knows what 😂
Love it! Tbh all the best labs are at home & sometimes you really do need bespoke data
Thanks for doing a trial with an actual control.
The number of so-called Garden experts who do this kind of thing on TH-cam regularly fail to do that.
Leaf mould is my preferred rough mulch. I will have to do my own trial to see how it stacks up.
No worries. I actually needed the data for my own simulations and even had a bowl of water on a chair nearby as a control too (unfortunately I dropped the bowl when weighing it).
Some limitations in the setup - I didn't control for initial moisture level of the mulch. But probably representative of water loss from top watering after the initial saturation had cleared.
Imagine leaf mould would do pretty good. I suspect anything that has lots of airy volume to act as an insulative interface would be good. Probably why the grass did well. Imagine a mix is ideal - a nutritional layer for the plants and the worms and then a loose layer for the moisture.
You provided proof of what I found out trying to withstand the Florida heat. My plants needed watering almost daily until I put in a deep cover of leaf mulch. It did the trick and like you said cost me nothing as I have 5 oak trees that gave me plenty of leaves that I stored over the winter. Thanks!!
It's amazing isn't it? I knew mulch was good but I didn't really have any idea it was this good and what that 80% figure really meant until I did this. I also didn't think compost would behave like that which explains a lot about my 2022 season. The results will be different in the ground where the water can drain right down to the water table but in slow soils like clay it should sit around long enough to be useful to plants. I've not tried leaves myself but everyone keeps saying they are great so I'll get on it too this year (no oaks, just that big apple tree)
Excellent experiment and very educational! Thank you!
No worries, thank you so much!!!
I just love your energy. Well done brother.
Thank you so much! It's been great to see all the love for this one
Great stuff, very useful experiment, thanks for taking the time!
No worries, glad you enjoyed it!
I am pleased to hear about grass clippings doing well in your experiment. I use them because they are here, in abundance, I don't run out, and they build soil structure over time. I garden in ground, no dig, and in pots. Peace 🌻
It's amazing isn't it? Really convenient, can guarantee no chemicals and no need for transport emissions or spending money. A wonderful result.
Very good information. Thank you.
This is great!!!😊
Very interesting, thanks for showing your experimenting.
Brilliant! I learned something new. Think I’ll subscribe.
In addition to the very useful information on this video, I just love the enthusiasm of his presentation which made me smile. As a classical musician, I must say “Thanks” for the music which was fun and not overpowering.
Thank you so much for this comment! I spent about a day agonising over the music and almost cut it completely. It's a tough one to get right
thanku for that experiment!!
No worries! It was fun wasn't it? Glad you enjoyed it
Thank you !
This is great! Thank you ❤
You're so welcome!
Useful video.
I cover the soil with plants.
Tbh this definitely helps too! Still some evaporation losses and some move to transpiration but definitely better than bare soil - even if it's just a living mulch. Another video maybe
@@alexgrowsfood I live in Holland. It's summer now and the next two weeks will be rain again. Evaporation is only a problem in full sun or soil that's not covered. Like most modern garden here. They have a large gravel pit (with f**king plastic) or just bair soil with just a couple of plants that you almost can't see. I have a compost bin, but not enough compost. Thus i compost every part of my garden only every 3 years. But when i do composting, it's a very thick layer. I have worms here that have the tickness of my pink finger.
Great experiment! Thanks for doing this.
Thank you! Glad you enjoyed it
Amen bro! You're a natural!
Thank you!
Very informative video. Thanks for sharing.
No worries! Glad you enjoyed it
Nicely done, Alex. Both the study and the video. 😊 This is information I can use!
Thanks Mark! A few shortcomings with the method but these garden experiments are very fun to make. Glad you enjoyed!
Dude you're awesome!
Thanks buddy! Glad you liked it
Great content! I've been using grass clippings since the 80s and they have always been the best option for my garden. Gardening is expensive these days so free grass and less watering is a win/win. It's also good to find a TH-camr that isn't trying to sell us something we don't need. Best wishes for you and your garden.
It's amazing how good the free option is, isn't it? I had expected compost I bought in to do the job for me when I set up the garden but it was a tough year. I'm not the greatest at making my own compost so this is the perfect use
Love this! The only suggestion I'd have is to partially submerge / bury the bowls in soil so that it more accurately represents what happens to an in ground garden. At least put it in an actual plant pot that doesn't have clear sides. Excellent video overall.
Thank you!!! You're right though, that definitely would be more representative. Tbh I was more worried about not measuring any evaporation at all. I did a test with water before filming and got 50ml over an afternoon and was too concerned I wouldn't measure anything in soil, let alone mulched soil. It probably makes sense to interpret this data as exaggerating/enhancing the losses over the three days across the mulches for convenience, but I'd be surprised if the relative losses were different in the ground. That being said there are a few other flaws like not accounting for initial moisture in the mulch and of course the results probably depend on the soil type anyway and I haven't (yet) done a soil test - it's clayey to some degree but that's not precise enough to be helpful. Fun yet flawed but I think still helpful.
great video, thank you!
No worries, glad you liked it!
Bravo Alex, great info well timed as here in Melbourne Australia quite cold atm am keeping soil bare after tidy up weeding etc... for planting new round of veggies and herbs and will use grass clippings as we have it a lot here without any toxic additions. Cheers.
Thank you for your experiment, I've always wondered about this 💚
No worries, hope you enjoyed the video!
@@alexgrowsfood yes It did I've never seen hemp in stores, but I have plenty of grass clippings thanks again...
Great video!! I thought it would be the case...but now we know!! Thank you!
Thanks Richard! I hadn't really considered it before but needed the data for something else. Pretty chuffed that one won though
That was an excellent video
Thank you so much!!! Glad you liked it
thank you very much
Excellent video! I shared it.
Thanks Dolly!
wonderful video! very useful information :) thank you :)
No worries, Maureen! Very glad you enjoyed it!
Wow. This us exactly the sort of experimentation I want to see in videos.
Some very surprising results (now thinking about getting that hemp for the new ducklings, when they hatch, and the chickens afterwards).
Other channels usually only go so far as recommending bark for the most part, then telk their audirnces they get it for free(I can't!)
I've never seen anyone test different mulches before in this way. Would like to see more experiments in the future.
Thank you! I'm not perfect but try very hard not to just repeat things I've heard because it's not as fun for you or me and sometimes the received wisdom isn't correct - the slug barrier test I did in April/May is the best example of that. And I also don't have a supply of wood chips and I try to limit to organic too which only makes it harder to get free stuff. Very glad grass did as well as it did.
Hemp is great bedding. Totally worth trying. I've not had any mite issues (in a Nestera coop) and it's quite nice to clean out. And does a good job of absorbing the moisture that the birds leave behind. I've not tried others but they look messier or have other issues. Not the cheapest way of doing it and a little dustier than I'd like but pretty versatile.
So helpfull! I have a pot garden at S - S.W. on a concrete terrace 1-storey high with extreme winds, so not mulching is certain death. Thank you Alex.
I can believe it, no rain either so you have to be diligent and manually apply the water. I didn't really put two and two together until this experiment so I need to get on it for my strawberries
wow this is incredibly informative! i cant believe you only have 1.8k subs for a video of this quality. I'll definitely sub and keep up with your tips!
Thank you so much! It was even smaller a few days ago, that's for sure. Reaction has been tremendous. Thank you (and everyone!)
Short, concise, with data & graph. I love seeing science & gardening hand to hand. Keep up the good video. Would've love to see more materials tho.
Its counterintuitive that hemp (a very absorbent material) performed amazing as mulch. I thought it would've wicked the moisture
Thank you so much!
Agree, it's kind of weird. Initially I thought it was best at limiting airflow. I've noticed before that hemp doesn't massively spread moisture - when the chicks knock the water over, only the corner of their pen gets wet. I presume it simply locks water in place (I guess it's cellulose or similar and there is some attraction with the water molecule) rather than spreading it about (I guess compost doesn't bind with it in the same way and instead it creates a suspension which allowed for faster water movement upwards). Just guessing really, I've not really looked into the microscale processes
And yeah, these are just the ones I had lying around. Straw and leaves/leaf mulch would have been a nice way of rounding this off.
Silica-based mulchs like straw and rice hulls are great for those who don't want to set up a soaker hose. They're not as readily absorbent as other mulches, plus when they start to break down, your plants may like the extra silica to get stronger!
Very good point. I think, of mine, grass would do best in terms of draining through the mulch but straw makes a ton of sense. It's the one I didn't have lying around otherwise it would have been there instead of hemp
Think this is quite a decent study.
Thanks for sharing.
I'm grabbing what I can to cover the soil.
Harvesting grass and other small plants and use a shredder to rip it into smaller bits is helping me in the spring and summer while in the fall and winter I shred branches to make wood chips.
The goal is to get organic life in the soil first and eventually the plant should thrive on that soil as well.
Don't mind watering the top layer as I'm not a fan of buying something like a irrigation system.
Cheers man, lovely vibe you have filming the video.
Thank you so much! Yeah don't panic too much about watering the top, it'll still be better than no mulch. I mainly care because I think I've got a lot of clay and I'm in the driest spot in the country so it takes a while for the water to get deep in the soil. Compost/manure and maybe bark (depending on the mix) would probably be more wasteful if they absorbed more but shredded plant matter should let the water through and, in the winter, I'd worry a lot less anyway if the sun is out less and low in the sky where you are.
Good job on this. Great idea and thanks for sharing it. In Zambia I also have access to rice hauls, peanut shells, leaves and other things I use for ground cover. I wonder if you can do more comparisons with these things as well as plastic, and other items people use to cover the ground (old roof tiles), etc.
I use grass clippings or coco coir. I also use ouyas or other related items for water delivery.
love the video, mate. I recommend another long form experiment using the same materials but analyzing water content IN THE GROUND with a moisture meter. Cheers! Keep it up
Thanks Vin. Tbh it would depend so much on the soil and distance from the water table and my patch of ground isn't consistent enough. I was really just after evaporation data for some simulations I was running. If I get them working I'll see if I can do something on water content and try and apply it to different soil types
amazing content. i'm pretty packed full of gardening channels, but i thought i'd give it a go !
bravo. i really enjoyed the hemp experiment; as well as the bit about grass clippings being okay, so long as they don't have seed !
well done !
Thank you so much! There are a lot of us out there, I struggle to keep up too.
Hemp does blow around a lot (you can see the difference in height at the start and the end) and a little pricey so it's very convenient grass performed so similarly
@@alexgrowsfood great reflection; cheers, keep it up !
Beautiful demonstration. I’ve been using grass clippings and it got me through a serious drought, almost ten days no rain, with just spot watering.. i was wondering how much the clippings really prevent evaporating
I can believe it! I pulled the grass back the other day and it was still really wet underneath, like wet clay still. Regret not filming it. Amazing how well the free stuff worked
The compost entirely depends on how broken down it is and whether it was sifted. A good mixture of chunky and small pieces create a better barrier. Also, if there are a bunch of unbroken small pieces, like grass clippings or tiny leaf particles, it helps a bunch, as well.
It's worth noting that compost does more than just act as a mulch. Keeping on the water topic, compost increases the water holding capacity of the soil itself over time. Humic acid will leach out of the compost mulch into the soil, giving the soil more holding capacity.
Definitely agree it'll depend on the compost and tbh it'll also depend a bunch on the soil too. I did try to keep what little structure I could intact but it was basically impossible here. Ideally I would have used a garden bed and tested the mulch in situ but I'm fairly sure one half is completely compacted (and the side that got all the compost a couple of years back is much healthier soil). My biggest concern was the initial water content of the mulch, I should have done a separate test just weighing the loss in each mulch too
It's a super interesting topic, if I had more time I'd definitely try more things out. I really just needed evaporation data for a simulation I was running and thought it would be convenient to make a video about it at the same time.
@@alexgrowsfood Yeah, there are a TON of variables to consider with compost. It's not like bark, grass clippings, or hemp where you have consistency.
I'm using Equinola horse bedding, which is rape seed straw. Tony C Smith here on you tube started to use it so I followed on. So far I agree with Alex here, good water retention and the slugs and snail attacks have lessened.
Oh cool! Thanks for sharing. I've not monitored slug attacks but I could believe some of them are better than others. I do organic so from the looks of things I couldn't promote that specific product but I imagine straw is close to grass or hemp in performance. A few others have been mentioned including sugarbeet straw which also apparently do quite well.
I use cow manure to plant my varigated pittosporum. I’m not sure if it’s a straight manure but my dad bought a huge pile of it.
I've not really worked with manure but I imagine it'd do better than compost in terms of moisture retention if it hasn't broken down yet. And one thing I didn't really talk about was soil structure but if you create an environment that worms like and they work to keep the soil loose and un-compacted (potentially even in containers), then I'd expect you'd see a benefit too.
If anyone else can comment and weigh in here, that'd be great.
Great video and experiment, though it would be interesting to see how the various mulches affect moisture levels in the ground (as opposed to a container). I have to say I really appreciate the conciseness and length of your videos.
Thank you so much! I put a lot of work in to try and never ever waste your time and to avoid rambling or repeating myself so thank you for saying that. 5-8 minutes is easier to film & edit too.
Agree it would have been cool to see the real-world conditions but there are so many variables and I'm not sure what equipment I'd use to measure it (and I really wanted the timelapse of the scales). I spent the last few weeks reading up on vadose zone hydrology and running finite element simulations but I didn't have enough parameters. Soil type and structure have an effect and I don't have a bed that's consistent in that respect over a long enough length. But also it depends on things like initial saturation too (water moves through soil faster in wetter soil) which also depends on your soil type so direct applicability is possibly relatively limited anyway because the parameter space is large. I really just needed the evaporation data for my soil and the mulches so that's the thrust of this video and the conclusion really is limited to 'how well does a mulch change evaporation rates for an almost saturated (predominately-clay) soil surface (and assuming a very very shallow water table).
I think if I had access to more soil types and on land away from buildings and underground pipes, I'd be up for it. My main guess though based on the simulations (with incorrect timescales due to parameter issues) is that the excess water would initially go down deeper into the soil and the surface would dry quicker. It would be slow in clay but I'd expect to see an effect still and then I'd expect to see more similar moisture depletion as the soil at the surface can (slowly) draw on water below and from the sides. The (likely) lower temperature would probably slow evaporation too. Basically I'd expect you'd see less of a dramatic change in that graph but the relative losses due only to evaporation would be similar.
Sorry that was a bit nerdy but it is a super interesting topic. But the tl;dr is I think the soil type and the location will have quite a big effect and I couldn't figure out how to take good readings of the water content in-ground.
It's not a coincidence that the best performance came from the finer ground materials. I use double ground mulch in my beds and it's about 3 inches thick, you do need to look at PH values as tanick acid from bark can be a problem but a bit of lime will help. Enjoyed video.
Thank you so much!
Possibly... The compost was a weird mix of sizes really but parking that for a moment, with the true mulches it seems like you're right. Better packing factor and reduced airflow to the soil.
now i want to try this experiment with pine shavings and other mulch types.
Do it! I reckon pine shavings would do really well - bark in the worst case and hemp in the best case. It's basically hemp but with coarser particles. I just happened to have these ones lying around.
Love your content! I don’t understand why there are so few subscribers and views
Thank you! Ha, I think YT just doesn't love my videos like you guys do. But comments like yours are worth more than view counts
Bloody excellent video. I was surprised by the compost results, although to be fair all compost is made differently and perhaps certain inputs hold water better than others.
I'd love to see sugarcane mulch tested in the future. It's commonly used in Australia. I bet it acts very similar to the hay.
Yeah I imagine different composts behave differently. This one was quite chunky, quite woody, but quite broken down. It was peat free and I imagine peat-based will have very different behaviour. One that was composted with a lot of leftover food would behave differently to one from composted with a ton of wood chips and it would depend on the compost duration. I think the main issue is that there isn't a barrier / the interface is too similar while the grass has a lot of air in between and the path for soaking and wicking upwards is more complex and narrower so it's slower. That's my guess anyway. A lot of viewers have suggested the colour difference and the increased sun absorption might be the cause.
And yes, I think you're probably right about the sugarcane mulch. Somewhere between grass and straw from the looks of things and I bet straw behaves similarly too.
salt marsh hay is useful here in New England!
Thank you for highlighting this. I'd not heard of that but sounds like a cool option. I really need to travel more, the wildlife you have is so interesting. From the name alone, I was a bit concerned it might soak up salt like samphire being a tidal marsh plant and deposit it in the soil but that doesn't look to be the case at all.
I love the scientific approach:). I wonder how leaf mulch would rate?
Thanks Martha! Hard to say but I would guess leaves themselves would be somewhere in between grass and bark and, over time as it breaks down and looks more like leaf mould, it'll probably start behaving more like compost. Would probably depend on the type of leaf (I suspect different composts would behave differently too).
Thank you for the video and your testing technique! Any chance you or someone else could repeat watering after the mulch has been applied? Also it would be interesting to include a layer of live grass on top for an additional test.
No worries, glad you enjoyed it! I'm not sure how soon but it would be interesting. I suspect a similar set of results though as grass won't be able to absorb as much as the bark and that won't be able to absorb as much as the compost. I sort of expect the compost to be wetter and evaporate earlier and the grass to dry quickly and the excess to get trapped below. Grass or any living mulch would be interesting but you would get transpiration losses too. I really can't remember what I read about it though - if I recall it's beneficial though. Something like clover that fixes nitrogen and doesn't grow too tall is probably manageable, I guess that's why they under-sow.
The biggest factors I see here are colour, thickness of application, and density of the applied mulch. Would love to see a test using deeper wood chips and the same price amount of hemp.
Thickness is a big one for sure. Seems like a lot of people use six inches of wood chips. I tried to press them in like i might firm compost into a bed but yeah, whether that's best or not and for the others too.
Also soil type and structure. I tried to keep the lumps together but I don't know how uniform they were. They were pretty coarse with some backfill too but given the clay content it might make a difference. Main issue with that is the applicability to other gardens. I think the relative measurement per inch of mulch is sound but the absolute values will differ.
Also the hemp lost a lot of its weight because a lot blew away in the wind. Could imagine slightly different behaviour on a cloudy week with high wind or a sunny week and still days. We had sunny & windy for this run.
A great demonstration. It would also be interesting to take temperature readings of the soil. Thanks for pointing out that compost is not a mulch, as I tire of correcting the many experienced YT gardeners that recommend it as such. Anything that wicks water, by definition, cannot function as an effective mulch.
Thank you. Honestly, I had more or less absorbed the information that compost was a mulch and took it as a given which is why I included it in the test series. I did a quick Google to check because it seemed very different but it 'confirmed' it was a mulch. I try very hard not to repeat information without testing it and it worked out here.
It had some effect here on final moisture in the core but, given the mass changes were similar, that might be because I didn't fill the no-mulch bowl all the way up or pack the surface as densely as I did with the compost. Agree it would have been nice to see the temperature at the surface and in the core given how sunny it was but it was pretty windy so I presume things were closer to air temperature (c. 20-25C highs, 10-15C lows) than they would have been on still days.
Testing leaves for their mulching effectiveness would have been of interest to me but leaves would come with certain factors to account for such as the size of the leaves.
Totally. Leaf size but also shape and all sorts will affect how much water it traps but also how fast it breaks down or any initial moisture content is released. Compost is probably the same, I just happened to have these materials lying around. Imagine they'd do well though, bark or higher would be my guess but as they break down it'd probably be more like compost/soil.
What's your opinion on mulching during the rainy season and how to effectively do it? I read it's preferable to having bare dirt since the soil won't erode as quickly and dirt isn't splashing on the plants and spreading diseases.
I like the idea of never having bare soil so that everything underneath is definitely protected (and insects have a place to nest) but it's hard to do well. This year I let a load of weeds grow and left the dead annuals in place which did some good but has been a nightmare to sort out this year. I think the sensible choice really is to look at collecting leaves (maybe even storing some dry) and scattering them on top. The other option is to under-sow with something like clover that can be removed relatively easily and never really grows high anyway. Or to pay to bring something in - I guess manure in the autumn makes sense if the bed is unused. The main thing is make sure that the soil can still get oxygen and some more solid barriers aren't as good for this.
Slugs will love it but my understanding is limiting the amount of bare soil is long term a good strategy for water retention and by covering it with something that breaks down slowly you're more naturally feeding the veg patch. Totally think you're reading the right stuff
Thanks for creating & sharing this @alexgrowsfood 🌱 I have a stubborn family member, set in their ways, who is anti-mulch!? Their garden soil is as dry as talcum powder 😵 Perhaps your video can help . . .
No worries. There are a few limitations with this experiment which may affect applicability to your garden - being in a bowl, using my clayey soil, breaking the soil structure to test, initial moisture content of mulch and soil etc. but the relative evaporation rates (the gradients on the graph) should hold true, especially towards the end of the experiment.
The best thing to do is a side-by-side test. Find a 1m patch and cover it with grass, wait for a sunny forecast and then water it and check the moisture each day. There will be some water transfer horizontally under the ground but the difference should still be pretty compelling a few days in. You can use a moisture sensor or you can dig it up, weigh it, bake it till dry and weigh it again, or I suspect even just touching the surface and a few cm down will be enough.
Interesting. Would be nice to see this experiment again where you add the water on top of the mulch (this experiment was more of a "evaporation prevention" experiment, would be nice to see if the results would differ from a precipitation-soakthrough-evaporationprevetion experiment)
Yeah I very much wanted to measure evaporation rates to support some hydrology simulations I was running. It's also an easier setup because watering the bowl and waiting for it to seep into the soil is dependent on the mulch but also the soil type and structure and it could be quite slow and differ a lot between areas. We then probably want to look at moisture build up and then it matters how often and when in the day I water the bowls. Agree it would be cool to know the net effect of adding mulch from a top water scenario but I very much chose the simple option (just measuring evaporation for an irregular bottom watering scenario). Might follow up though on water content if I can get my simulation working and apply it to different soil types.
I used chopped straw last year and it was great. I used a new bale this year and it's driving me nuts with wheat seeds germinating in it. Not sure what I'm going to do next year.
Sounds like the farmer messed up when harvesting. It's tough to source things well. Probably worth considering elsewhere next year. I try to use on site where possible but appreciate it's not always an option and the timings aren't perfect
Now try mixing everything together as a mulch and try it. I suspect it will do really well or at least hit a middle ground with the rest but with the advantages of also being a slow release fertilizer as it breaks down since there is variety.
I think it would be interesting. I reckon layering would have the best effect so you have multiple interfaces and evaporation would be rate limited by the slowest interface. My guess would be a blend would be an average or skew to the worst performer (I'm just guessing, agree it would be interesting to try).
In reality you'd probably have something like a no-dig bed with compost, covered in grass clippings/straw with a thicker layer of woodchip or bark around the edges/through the paths. Much more exciting but harder to test
My friend puts hay over her garden. Soil stays moist but also houses a HUNDREDS of slugs which come out of the hay at night and eat all her plants.
I use grass clippings, which shade the soil but light enough to not encourage slugs.
If you use a heavy layer of hay, I suggest, that you invest in slug pellets or you won’t be harvesting much after the slugs dine on your food.
Thanks Marianne. You're right about that but I tend to find slugs will make a home in anything wet that isn't exposed soil/compost. Although it has been a terrible year for slugs - I went outside with a torch on Friday night at 11pm after a week of scorching heat to find my phone and there were hundreds in the grass. One of the downsides of preventing the surface from drying is that you create that nice moist habitat. Imagine bottom watering via a soaker or drip hose is better but won't eliminate the problem either.
While they probably do work very well, I can't advocate pellets and normally just accept a certain number of losses but thinner mulch layers are one approach for sure. Otherwise you might want to delay planting until your plants are substantial and are less appealing or more resilient to damage. I also tested several slug barriers like copper and wool here th-cam.com/video/0xOyu0YrS3c/w-d-xo.html although the results were mixed.
I think the light color of the two winners has a lot to do with their success.
I grow cover crop over the fall winter and spring and then chop it down and leave it in place and it turns a light tan color and have noticed an improvement in water retention even over the shredded leaves that I used to have in place (I still put the shredded leaves on but they get covered by the cover crop)
The light color reflects the sun. Based on my casual observations I think you would see an even greater difference if you were measuring how fast plants used up their water with different mulches. I saw a dryland farmer YT video and I no doubt have these numbers wrong but it was something like once the SOIL gets over 80 degrees 70% of the water the plant uses is just to cool itself - similar to us sweating.
I suppose this might be a downside for certain crops that like really hot conditions or in some areas where it is cold but most crops like their soil cooler than it is in most places in July and Aug.
I do notice that I have to pull the 2 or 3" of shredded leaves off to top of the soil in the spring to get early spinach going but I can usually pull it back around as soon as they are 6 inches tall.
I could believe it. I specifically decided not to put plants in it to simplify things but my understanding is most water loss is via transpiration. I would like to see how a living mulch compares but maybe that's one for later.
Agree colour probably has some impact here although the grey soil and black compost did quite similarly in terms of gradient (evaporation rate) later on so I think much of it is down to the materials ability to transport water. I did try to do a test with water but I made a mess of it but it looked like the heating effect on the soil and compost was present, I just can't confirm for sure. A test in the shade would probably be the easiest way of finding out
@Yogi Hollow Farm interesting.
Thanks for this information! Do you think you could do another study showing how much water is absorbed with the mulch already placed on top? I water with a hose so I am just wondering what would allow for the most water to pass through and actually get to the ground 😊
Thank you! This is a really interesting idea, it's just figuring out the practicalities of it. I actually did this one because I wanted to simulate the water content in soil and needed some evaporation data but there are loads of variables at play. One thing that really might make a difference is the soil type (water moves through clay sometimes thousands of times slower than sandy/loamy soils) and the initial water content (water moves slower when the soil is drier). I think it forces the experiment you suggest to be an even spray application of water and then try to capture the initial evaporation step. That probably means more or less taking simultaneous and continuous/minutely readings over an afternoon. Then after a while you'd start to pick up measurements of the evaporation from the soil (which should be slower) - basically you'd see an initial drop at the start of the graph which would be the losses from the mulch and then a slower decline for the soil. It's probably do-able for all of them except the compost and that would get a measurement of the water that didn't make it to the soil.
Not sure when but I'll write it down and that's how I would probably do it, if that's helpful for now.
My suspicion is that grass would win here because it can't store that much water and it would pass through. Compost could be a dark horse if it's very loose/sandy/loamy in structure, anything peaty or heavy would probably dry out before it got too deep. One other variable is how deep we want the water to go. In my preliminary simulations the water moved so slowly downwards that evaporation dominated everything but my parameters (e.g. hydraulic conductivity) didn't account for saturation making water move faster. A bit nerdy but the tl;dr is mulches where moisture is absorbed really well on soil where water moves really slowly is probably less good than materials that don't absorb much and on light easy to work soils.
It's a super interesting topic though and thanks for the idea. It's definitely made the list
That meets with expectation. with the lighter colored mulches you will have more reflection of the sunlight so the mulches themselves will be much cooler. the opposite is also true of the compost where the soil surface heated up more allowing more evaporation to occur. likely in your test conditions sun intensity is the primary drying force once you cover the surface with something. you could repeat the experiment with a white construction paper and a black construction paper to test to make sure. great showcase.
Feel like a dump physicist not testing the heating effect due to colour. Probably had an effect although hard to say what the temperature was under the mulch. They don't feel dissimilar to me but I suspect we're getting faster evaporation at the surface due to material structure and material temperature and wind and light. Initially I had considered air temperature and humidity but you're right, locally it would have been hotter in the top layer of the mulch under direct sun.
Think if I were to do it again I'd find a shaded spot that still had exposure to high wind. I had assumed that would be the main driver but it would be interesting to see how much each component contributed
@@alexgrowsfood your methodology is sound. you can repeat the experiment and test any number of variables so long as you keep something at baseline for reference between tests. If you have access to a IR thermometer it might be an interesting showcase during peak hours for sunlight.
its entirely possible that the material composition is playing a role which is why I suggested the colored paper test. You could also do different particle sizes with something like Gravel or Wood (plane fines, shavings, sawdust) so long as you can source similar materials.
For science!
It probably makes a difference how thick the layer on top of the soil is.
It definitely should. It would act to amplify the differences I suspect (assuming evaporation is mostly/entirely at the surface). I tried to keep them similar here but for bark some people suggest about 6 inches is good. My guess is compost would still struggle unless it was very stodgy. But all of them will depend on the exact composition and material anyway (and probably the same for the soil underneath too)
Interesting would BE
Straw
Agreed. Unfortunately I didn't have any lying around or have a good source for them and I just happened to have these ones left over. If I had to guess I would expect it to behave like grass though, maybe slightly worse if it's coarser but better than bark. Just a guess though
@Alexgrowsfood how is sand in comparison, could u please test it ❣
Could the reason that the wood chips performed worse than the hemp and grass clippings is because of the larger size of the wood chips?
Only thing with grass is if you don't use pesticides, there will be weeds that are shorter and can flower at shorter heights. Do you think cedar mulch and woodchips would perform similar to the bark mulch?
I suspect so although it would depend on the wood and the coarseness and if there is any properly broken down material in there (mine has a lot of compost-like dust). From what people have been saying, they use six inch layers which I expect would bridge the gap between my experiment and their gardens. So use more if you need a better mulch effect.
Only thing I'd say about grass is if you mow once a week or every two weeks on a high setting you should be able to get most flowers before they set seed and you can always hand weed lawns rather than spraying. I go around with a hoe and use the corner to lever out dandelions. With the exception of buttercups, the other flowers tend to be easy to pull out anyway, or they fail to spread if cut early so I don't target daisies or anything like that.
And general comment for anyone reading this, spraying areas near a veg patch is a big no-no so if you've got grass paths like I do, then hand weeding and regular mowing is usually best.
@@alexgrowsfood The cedar mulch I have has quite a lot of fine material, maybe only 1/4 wood chip sized and 70% smaller, softer bits and fibers and a tiny bit that's fine enough to blow away. I'm trying to work on my dandelions but there's almost as much dandellions as grass and a fair bit of lawn, maybe 4000sf of lawn. There's other weedy flowers too.
Assuming all the bowls have the same relative evaporation loss, do you think the actual glass bowl somehow alters the way water evaporates? not to mention light has an effect on exposed soil, glass and exposure, perhaps it could cause an unnatural reaction to evaporation. this is just an idea, it's a great experiment i'll do in my garden, thank you
Great question! Yes, I definitely think there is a difference in absolute evaporation here but mainly in that the water can't fall deep into the soil so my soil would remain wetter than if it were in the ground, especially if it was relatively dry down to the water table. The hydraulic conductivity is also dependent on water content so if the water can drain into the soil, I'd expect less evaporation there than in the high moisture content soil in the bowls. Conductivity also depends a lot on soil composition and structure which is very location dependent - and I know my bed gets more compacted as you go along it so it was important to take samples from one area. It's also likely the temperature of the soil would have been lower in the ground than in the bowls and probable that there would have been a slight reduction in wind speed.
My goal here was really just to see the relative effect of the mulches on evaporation rate for a given water content in a way that's easy to measure - I needed parameters for a simulation. I think the soil and other local effects probably make getting an absolute number that's applicable elsewhere quite difficult unless I also did a series on soil types anyway. And my understanding of accurately measuring soil moisture in the field is that you need to extract a sample and then bake it and weigh the difference which also limits the number of samples and the method for taking the sample needs to produce consistent shapes and depths. The bowls seemed a more reliable and easy way of getting evaporation rates for the sample sample at near saturation and near-dry.
That was a bit nerdy but it's a very interesting topic and there's a lot going on under the ground, it's just hard to quantity and get more general results.
In your next test, would you put down two or three layers of cardboard under your bark covering. That's what I do for my trees. More videos like this please. Thanks!!!
Thanks Terry! It's a good point and cardboard will probably help a bunch. I think in real systems it wouldn't be as simple as this anyway - the compost would probably be over cardboard too for no-dig and you might even decide to put grass on top of that. Also layer thickness will have a big effect on bark/grass/hemp/leaves and some effect on compost. I think what you are doing for your trees is probably perfect. There's someone here who uses 6 inches of wood chip, if you're doing that you're probably doing plenty. The exact behaviour will probably depend a lot on your soil type.
lighter colors resist heating up. That can make a big difference. Legitimate compost works best when naturally incorporated into the soil, not as a single layer on top. Wood mulch tends to work alright, but it does best with a lot more volume because its large pieces don't catch evaporating water very well. I mulched my garden with hay this year. I acquired 100 bales of moldy alfalfa/grass hay and it's done pretty well. I've never seen so many worms and nightcrawlers out there.
Agree, didn't really think about it at the time, although I think the high wind and ambient temperatures played a good part. I think the main thing is how much easier it is to get a hold of grass and it worked so well.
How thick do you mean when you use bark? I was pretty happy with the inch in the bowl, but imagine loss is proportional to thickness. Definitely see why people use it in their walkways
@alexgrowsfood When I use wood mulch (usually fresh arborist chips) I use 6 inches at a minimum. At that depth, it's really quite hard to beat the benefits to soil function and healthy soil biology. I personally don't use grass clippings because I only cut my grass about 4 or 5 times a year (2 to 4 feet tall) and use it for animal feed and nesting material. With grass clippings, a thicker layer tends to mat together and choke out the soil causing too little airflow for healthy garden soil. Grass clippings are best used not much thicker than an inch or two around your plants.
@alexgrowsfood When I use wood mulch (usually fresh arborist chips) I use 6 inches at a minimum. At that depth, it's really quite hard to beat the benefits to soil function and healthy soil biology. I personally don't use grass clippings because I only cut my grass about 4 or 5 times a year (2 to 4 feet tall) and use it for animal feed and nesting material. With grass clippings, a thicker layer tends to mat together and choke out the soil, causing too little airflow for healthy garden soil. Grass clippings are best when used not much thicker than an inch or two around your plants.
Your bowls should be opaque for the test. It likely doesn't make a difference in relative results, but under normal conditions, mulch protects soil fully from sun. In your experiment, sun was shining to unprotected areas of the bowl.
It's true although there are so many other issues affecting the absolute results (destruction of soil structure, my soil type, how the soil was packed, drainage, heat transfer via wind on sides of the bowl) that I don't think it's likely that I'd be able to recover the absolute results anyway. Was more worried I wouldn't measure anything at all really
The only problem with grass clippings is they will have any fertilizers used on it and introduce it to your garden.
Yes they would. But my advice would be not to use them, imo grass doesn't need it and you often get drift or transport of the chemicals underground anyway, it's just not worth it. I cut the video quite heavily but for a time I was going to point out that if you use your own clippings you can guarantee no fertiliser/pesticide and there's no emissions from transporting it either and it's free. It's perfect. And an additional issue with buying stuff in is that, unless you personally know the supplier, you still might have some contaminants.
Strawberries don't like to be watered from the top. It is best practice to water the soil around the plants. And the leaves seem to show the beginning signs of a nutrient deficiency, which can be caused by a PH that is too high, or because there are not enough magnesium or iron minerals in the soil. Or they have been watered too much. Or the soil is not permeable enough. If the soil PH is too high, or the roots are somehow suffering from too much water or a pest then the plants can't take up the nutrients that they need, so it is best practice to check that first. And if that is all good you could try to add minerals to the soil.
Oh those strawberries are very unhappy. Good spot though. They are in half-filled pots which was half compost half coir and wasn't refreshed this year. They were in a greenhouse and not watered for ages and now they get a spray from above. I just haven't had the time to sort them out really.
@@alexgrowsfood Aaaah that explains it. Then I am sure that they will recover if they have some fresh soil that is not depleted from its nutrients.
how about 1 inch deep of pee pebble stone (gravel), 1 inch deep of sand, and a plastic liner?
What about cardboard? I wonder what it would do.
It's tough to say, it'd probably depend on the cardboard. Corrugated stuff would probably do better than the flat sheet in breakfast boxes or the cardboard envelopes as less water would soak and then transfer to the top to evaporate. But I tend to find that the top part of corrugated comes off quickly anyway, at which point you've got a radiator-shaped structure soaking water and evaporating it. So maybe some early benefit which gets less strong but possibly better than bare soil? Hard to guess but imagine it helps the no-dig approach. Other issue potentially is if it prevents oxygen transfer, being a sheet material, but I really don't know enough to comment.
What about straw? I bet it would do better than hemp.
I wish I had some. I only tested these because I had them lying around anyway. My guess is it would be like grass which is pretty close to hemp tbf. But straw, hemp, pine shavings, anything absorbent and used as animal bedding are probably good bets
I have straw so I use it. I don’t know how to use grass without it becoming a Matt. Maybe I should let it dry out better. Ty this was a great video sir
Thank you! And Maybe. I've not tested how to make mulch and I'm not certain which method is best tbh and I have a cat and birds that like to disturb my garden beds anyway so it's possible that helps keep things loose. My process is to shake it out of the lawnmower box so it spreads quite a bit and leave it spread out for a few days to a week depending on the weather so it gets a nice brown-ish colour. Then I sort of fluff it out like you can cotton wool buds as I throw it down and then press it down very gently. It might become one mass at one point but not for a while I don't expect. For this experiment I took grass directly from the beds (after my process) and then pressed it in again into the bowl. Imagine shorter grass blades (more regular cuttings) clump and interweave less.
I just chop and drop
The best mulch to reduce water is the one you have.
Biochar
Not sure tbh. It'll probably depend on the exact material. I've read it improved retention when dug into the soil so I presume it soaks up water and holds onto it. My guess would be that it would be somewhere between compost and bark if placed on the surface but I'm not sure and it probably depends on the material and the layer thickness. Possible the pitch black colour might enhance evaporation if it's very sunny, especially on thin layers. If I had some lying around I'd try it
Grass will clump and stop water infiltration…
Possibly, especially if packed densely. Although significant water application should still seep through and the other materials have their own issues with top watering too. I recommend watering underneath anyway
So none did the 79% from the thumb nail?
The grass lost 79% less water than the no mulch. I appreciate that I didn't make that very clear, sorry about that. The final slide with the % was the total water loss relative to the 500ml, not the comparison to the unmulched soil --- that would have been better but I didn't notice until after I published. You can 'see' the 79% as the gap between the two in the graph but it's not the raw number and it's bad comms on my part, apologies.
100% - 20% = 80% and as he said ABOUT 20% so would be close enough to make the 79%
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Crucial error in this test is using water loss by weight as the main tracker without first correcting for the moisture levels of the mulches. Compost is already damp so it will lose a lot of its own weight, skewing the data. This can be evidenced by the moisture meter clearly showing the soil is more moist than the bare soil.