Do weeds rob soil of nutrients?

Some permies say "there's no such thing as a weed". My gardening books all day that weeds rob the soil of nutrients meaning other plants can't access them.

What's the deal?

I've been putting on a mulch of pie seaweed on my garden bed. I top it with large dried whole maple leaves. Weeds and vegetables are all thriving. I have no problem with the weeds, unless my veggies could do better without the competition.

Now and then I simply pull a weed/grass out while picking my veggies, rip off the root from the leaves and drop it back on the ground as a mulch. Am I doing the right thing?

Good question Tom, I'm sure the experts will be along shortly.  My hunch is that they do consume some nutrients as they grow but if you chop and drop them, the nutrients stay in that area.  They might pull up nutrients from down deeper than your plants can reach, possibly leading to more nutrients for your plants the next year.

I'm guessing a bigger concern could be the water they consume.  Very little is returned to the soil when you chop them (compared to their lifetime consumption).  So I'm thinking that if water is scarce, weeds could be a bigger issue for your veggies in the water department.

I think it depends on the "weed"... dandelions and thistle draw up nutrients from the deep with their magnificent taproot, clover fixes nitrogen... but garlic mustard makes stuff that keeps other plants from growing. I think getting familiar with the plants common in your patch will go a long way in helping you to decide which to keep and which to uproot.

EDIT Also remember that many gardening books are published/sold by companies that make their bread and butter off selling chemicals and the like. They have financial incentive for making you dependent on them for the perceived health of your garden.

I think you are doing the right thing, by your soil.  I'll explain my reasoning, and you can decide for yourself.

The various schools of thought [ search for Elaine Ingham (soil food web) and Susan Simard (wholistic forestry), for instance ] that I follow would indicate that the nutrient base of the soil is directly associated with the biological community (bacteria, fungi, micro arthropods, micro insects, worms) that are interacting with each other and providing, exudates, and their wastes and their dead bodies to the plants directly or indirectly as food and medicine.  The healthier this system is, the more the plants will find what they need when they need it.  Plants (or the fungi that create symbiotic relations with them) will share nutrients/minerals, and water amongst diverse plant species if the individual plants have enough for themselves.  

Ways to make your biological system more robust (so that they have enough):   (not necessarily in the order of importance)

Plant and leave a diversity of plant species in your beds. Put in plants which have a diversity of heights, shapes, sizes, considering not just the above ground plant but the root zones.  This will, as Mike indicated, mine a diversity of nutrients, but I would add that this is partly or even mostly because there are more interactions with differing biological communities with these different shapes; tap rooted species, for instance, on top of potentially mining deeper minerals and leached nutrients, are also building deep compost corridors with their dead bodies, and biological communities.  

Leave your beds intact (no till); this creates a permanent ecological system that is building year by year, instead of starting back from year zero (with the addition of whatever you are tilling in, of course) every time you till.  

Cover your soil up from the impacts of direct pounding rain/irrigation, or scorching sun, or drying wind (mulch). Nature does not generally have a lot of bare soil, if she can help it.  

Incorporate some perennial species, here and there, so that you have perennial soil systems/biological systems that are much stronger than annual plant associated systems.  

Water your soil if necessary, but if you water relatively heavily less often (rather than watering lightly and often), you will do your plants and their communities a greater service.  Generally biological communities thrive in moist environments, not soggy, not dry.  A diversity of plant roots/depths/shapes will help your soil and biological systems retain moisture, with the Caveat : so long as there is adequate moisture getting there in the first place.

Ensure that your desired plants have the adequate sunlight, moisture, and space to make them happy.  You'd be surprised that plants actually can thrive in denser spacing then what plant books recommend, but there is a line that must be drawn.  

Apart from soil biology, water and sunlight are the things your individual desired plants require.  Are they getting their needs met?


Things to watch out for:

Some weeds produce a ton of seed per plant.  Maybe chop them down when or just before flowering.

Some of your preferred plants will go to seed in the first year, and some in the second year.  By allowing your plants to self seed you will make great gains over having desired plants in your garden, and building a seed stock base that is associated directly with your garden's conditions, thus making gains also on their ability to thrive in your soil system.

Do you preferred plants look healthy?  Look in your plant books for specific signs for plants and what they might be needing (this is often trace minerals, or water, but sometimes a bit more or less sun will do the trick),  

Do they seem starved of any nutrient or are they looking like they could use more light or water?  Maybe a bit of weed thinning is in order.  Sometimes just chopping the weed's upper growth is better than pulling it up. (though sometimes the plant will come back up from that root so this depends on how often you are doing it/diligence.  Always remember that it is the communities that are associated with the roots that are doing most of the work to supply nutrients to your plants.  The chopping of the plant might kill the plant, and some of it's biological associates will die or be forced to migrate, but all or most of this will be available to other plants.  

Is your soil hard and compacted?  Plant or allow more tap rooted species to break the soil compaction.

       

If you were to yank the weeds out and toss them in the trash, you would be robbing your soil of nutrients.

It should also be noted that the plants themselves are taking atmospheric gases and sunlight from the surrounding environment and, through using some rather incredible alchemy and biological processes are sending complex sugars down their stems to their roots and giving these nutrients through interactions with the soil food web mentioned in my post above.  The way I see it, the more diverse the plant species, the more diverse the food sources for your soil food web.  Also, the diversity of microbial species which are interacting with each individual type of plant is also multiplied on greater scales by increasing plant diversity.  

Weeds are Nature's way of saying that She wants to cover and heal the soil back to it's full potential.  She uses whatever seed bank is there to do the job.  The weeds tend to be some of the best plants for this soil reconditioning, particularly as they have already adapted a relationship to the local mineral soils, atmospheric conditions, and existing living soil community; something that we need to do with our introduced plants, as mentioned above, by allowing them to self seed, or by collecting the seed and planting it out.  

Some people will try to notice what a weed is doing, and it's size and shape, and then try to plant more desirable species that behave similarly to do the job.      

Industrial agriculture has long held the view of "competition is bad" in fields and pastures when it comes to growing things. Unscientifically, I would say this bias is the result to being poorly informed about soil function. If the content of a gardening book was written more than 10 years ago (not the copyright date, but when the content was written), it's a good chance it was written without the more recently knowledge of soil function focused in it's biological community. As scientific understanding goes, it's pretty recent. I bring up industrial agriculture because as has already been pointed out, much literature that is published is based on the understandings of agriculture at scale. Since they are in the business of selling seed and agrochemicals, they will be hard pressed to publish content that could prove contrary to the practices of the advocates of large-scale industrial agriculture.

Roberto's reference to Dr. Engham is a good one and I recommend everyone become familiar with her writings and presentations. What I think I understand is that the idea of competition in a growing environment is grossly over estimated and the positive impact of a diverse biological community in the growing ecosystem far outweighs any negative impact of competition -- a net positive effect. Remember, a diversity of plants attract a diversity of microbial life in the soil which can make available a larger palette of nutrients. A diversity of plants also attract a diversity of beneficial insects, some of which will be predatory to pests.

Are there examples of large sections of monocultures in nature? Technically we can point to a minority of examples, but it's not the natural norm and what we are seeking in permaculture is to work with the natural norm, not the exception. Remember, the principle of the edge in permaculture. We usually find more life and productivity on the edge between two systems. Why? In my opinion the edge of two systems are where we find the greatest biological diversity.

Now, is our western thinking of clean rows and right angles and spotless spaces impacting our view when it comes to gardens? I believe those things dramatically impact our garden management decisions. However, I believe we need to redefine many of our notions of what constitutes a good garden plot or bed. To some it may look like a mess or even chaotic. But, beauty can also be found in a bed of healthy plants doing well and being productive though there may be scattered among them plants that were not originally desired.

All plants take nutrients out of the soil, and they also absorb nitrogen from the air. When the plants die and rot they then release the nutrients back into the soil. The real question is, do your vegetables have what they need right now? Are they showing signs of a deficiency? Just because a decomposing weed will return the nutrients next month does not mean your vegetable might or might not benefit from nutrients now.

So, look at your vegetable plants: do they look healthy now? If your vegetable plants are looking good then they probably have what they need.

Industrial agriculture has long held the view of "competition is bad" in fields and pastures when it comes to growing things. Unscientifically, I would say this bias is the result to being poorly informed about soil function.  

 I think that industrial ag rapidly, perhaps exponentially, increased the misconception, but i also think that this mindset is somewhat ancient.  

Not all pre-industrial farmers had good soil tending practices and the concept and wide spread use of tillage, via oxen, mule, or draft horse etc (which created the straight rows) and mono-crops (which allowed maximum desired plants per area)  were well established in many cultures centuries if not millennia before chemicals, machinery and advertising amped it way up.  

These practices had (and still have) a function in the mind of many farmers who are not influenced by industry, including, on the tillage front, our very own Master Seedsman, Joseph Lofthouse (but I think he really likes his weeds too, if I remember correctly).

As a personal example of the possible conception and evolution of the idea :  Without newspaper, or cardboard, or laying extremely deep dense mulch the preceding year, I might find it extremely challenging to convert my meadow of dense grasses into a garden without flipping the sod and chopping it up with shovel and hoe, and weeding it to keep them out.  If i do this to initiate a crop area, and have success, then I might be more inclined to do it again in the spring and thereafter.  In my mind, I think it's easy to see how the cult of the seed and plow evolved the way it did and why weeding was part of that.  

I'm a no-till advocate and I enjoy the idea of keeping some weeds, but i still tend to reduce the weed pressure and give my plants a bit of space to maximize their individual root zone, and there are some plants that I simply do not welcome, like quack grass, Canada thistle, hawkweed, hedge nettle, and daisy, and these are weeded without considering their potential usefulness.  When others show up, like lambs quarters, plantain, yarrow... which I recognize as food or medicines,  I tend to consider leaving it be.  

I'm inspired to not uproot a single weed for a year and see what happens. I'll rip off the leaves off some to let them die, others I'll just leave unless they get really big..

If you have good growth in your crop plants, and you are mulching as you say, I think you should be able to do this just fine.  Please inform us of your results!  

In my thinking, it's a matter of observation, and diligence.  This would include making sure that plants that you think might become a problem (overseeding, too prickly, spreading perennially by rhizomes, etc) don't get past their flowering stages at all.  In this way, by cutting out extra leaves and also topping before they can seed, you will gain the vast majority of their fertility (in the ground/root zone), without increasing your surface seed reserve of potential undesirables.  

If you have a bucket of your mulch materials with you as you go through the garden, you can place a bit more mulch on top of cut leaves/tops, thus ensuring that even more of the aerial fertility of these weeds is incorporated into your top soil system when it is at it's most nutritious (damp/green), rather than drying out on the surface of the mulch (which isn't a bad thing at all).  

The only warning, for immediately mulching on these cut parts, is that some plants might regrow from these layered cuttings if the growing conditions are right.    

Weeds are the number one mode of crop failure on my farm. Greater than all other failure modes combined. I'd go so far as to say that weeds are responsible for an order of magnitude more crop failures for me than everything else combined....

On the other hand, the field that I keep perfectly weeded, is my least fertile field, because there are no weeds contributing fertility to the soil. I grow cover crops in that field, but they don't generate fertility as effectively as the weeds.

If I'm importing organic matter into my garden, then I feel like I'm desertifying the source of the bio matter. Therefore, I don't rob other areas to enrich my garden.

So for me, it's a balancing act. Grow enough weeds to provide soil fertility. Eat or compost enough weeds so that my crops compete adequately. Tilling is super-effective at killing most grasses and annual weeds. Tilling multiplies perennial weeds by chopping them up into many plants. Perennial weeds are better dealt with by shading, for example by growing crops that quickly produce a closed canopy that is taller than the weed can reach. Smothering with compost, or wood chips can be effective on perennial weeds, but it is unaffordable to do on anything other than a small garden.



 

I've mulched with a layer of large, whole maple-looking leaves. Months later they haven't degraded the slightest- still whole and crispy.

I 'decorated' them around the plants I want, putting them on top of the weeds. Now beneath those leaves are all the weeds but they're kept in full darkness so they don't grow. The soil's permanently moist and green beneath, and we've had a dry winter this year in South Australia.

Summer was awful last year on my exposed clay soil as it became one hard brick. I'm hoping this summer will prove different.

GREAT content in this thread.  There are some wonderfully bright and helpful people in this community, and this thread is evidence to the generosity of their wise and experience-enlightened advise.  Bravo.

Let me add a couple of additional thoughts.  Do weeds "rob" the soil?  Well, they certainly "borrow" but then later play it back as they decompose.  So, yes, perhaps they "take" nutrients for a short time, but most of that is given back because "weeds" (READ: plants that are growing in the wrong place at the wrong time, not evil biological enemies) are annuals.  In the grand scheme of geologic time, they are a mere blip on the time-line.  They quickly grow and die seasonally—they ain't no redwoods.

I would argue that ANYTHING that captures energy and channels that energy into the soil-building process is, in the long term, contributing to soil health.  Nutrients (commonly positively charged) are captured by negatively charged clay molecules.  However, clay particles form long, tightly-packed chains that do not allow for water or anything else to flow through.  Picture a stack of paper plates, one nesting tightly inside the next.  Clay forms such tight bonds that even if their were wonderful nutrients deposited on the surface of the soil (animal poop, volcanic dust, nitrogen rich rotting bio-mass), those nutrients will not pass through and be captured by the negatively charged clay molecules.  Unless something breaks up the tight clay soil, nutrients sit on the surface and wash off with every heavy rain.  

Considering that 60% of a plants energy is used below the soil surface, whatever the weed may be "robbing" and transferring to above ground biomass is less than what it is pushing down into the soil.  Between the sugary exudates that the roots are pumping into the soil to feed the biological community, and the actual root itself (which remains and slowly decomposes after the weed dies), that horrible weed is doing a tremendous amount of good below the soil surface.

So not only are weeds an additional layer of solar panels throughout the bio-system, capturing energy (BECAUSE, as we all know, the entire system is solar powered, so the more solar panels you have, the more energy you are going to capture), but just as important, their roots are punching through the soil profile, pumping exudates down into the soil and opening channels for surface nutrients to infiltrate.  

On a micro scale with a one-season time frame, yes, weeds are robbers.  But on a macro-scale with a long-term perspective, no, weeds are a tremendous asset to soil health and nutrient accumulation.

One more thought I neglected to write in my post above:

Assuming that weeds "rob" the soil, they don't have a get-away car waiting for them outside the bank.  They "rob" but are stuck there in the bank lobby with all the loot in their hands.  If they have successfully robbed the bank (the soil), how do they take their loot to another location?

But if I, the gardener, comes along and pulls up those weeds and carry them away, I've become the get-away car.  The heist is complete!  You'll never catch me as I carry away those precious nutrients.  The poor bank (the soil) has been robbed, and is poorer as a result.  This is why chop-and-drop weeding keeps the nutrients right where they belong.  You leave the root in place rather than yank it out and complete the heist.  It would be like taking money out of the ATM outside the bank, and then walking into that very same bank and asking them to deposit that cash into the safety deposit box down in the vault.  Someone from the outside has to come and replenish the ATM, but I keep making deposits down into the vault.  Eventually, that vault would be filled with cash, all borrowed from the outside and deposited inside.

Using this metaphor, the sun is the entity that keeps filling the ATM.  The plant root is the entity that keeps transferring that "cash" (nutrition) into the vault (soil).

Ok, here's a question...  If you rob the bank and the getaway car stops at the compost pile, and the finished compost goes back on the garden, is that good, better or worse than dropping it?

I feel like when I pull a weed and leave it lay on the mulched soil, it desiccates quickly and then eventually disappears into the ground.  If I pull 100 weeds and put them on the compost pile as a wad, they seem to not dry out right away.  I lazy compost so I'm not digging them in or turning it more than once a summer.  If I buried those weeds into the compost pile would that be even better or no different?

It seems like the only "greens" I get for my compost is weeds.  Other than small amounts of food scraps.

A lot of great replies in here. One thing I would definitely underscore is something Mike Jay first brought up — water usage. Out here with our sandy soils and dry summers, weeds can quickly decimate other crops around them. They will germinate in a thick mat in the spring, go to seed in a few weeks as the rains stop, suck up all the water in the area, and die off — months before your veggies will have had a chance to mature. If I forget to irrigate for a week, weedy places will be completely dead, while weeded places will be doing just fine.

If you rob the bank and the getaway car stops at the compost pile, and the finished compost goes back on the garden, is that good, better or worse than dropping it?

I think this is one of those places where you'd have to really work on defining what you mean by good. I make compost to breed beneficial organisms, and a compost pile will do that orders of magnitude better than mulch will. At the same time, my compost pile is burning up the fuel that these beneficial organisms need to survive — the same organisms that live in your garden soil that might be able to use that fuel if it were chopped and dropped. At another look, a compost pile can heat up enough to kill unwanted seeds, while chopping and dropping will just leave the seeds in place… I guess I look at it all as a complex equation without an easy answer.

Thanks Kyle, I figured it could certainly be a very complicated equation.  And very dependent upon the location in question (soils, rainfall, etc).  We don't need to delve into it here or we'll pull the topic too far off subject.

I second Marco's comment about the awesome info contained in this thread.  Permies are wonderful!

Ah yes . . . the compost branch bank, where the proceeds of the heist are laundered and put back into circulation in the local economy.

If you wanted the best of both worlds, you cut off the weed at the ground so that much of the biomass stays in situ, while the greens above ground are deposited in the compost bank.

All biomass eventually gasses off, particularly lush nitrogen-gilled greens (grass clippings, fresh green leaves, veggie scraps).  A thoughtfully constructed compost pile captures a lot of the nitrogen that would otherwise gas-off and blow away with the wind.  The carbon-heavy "browns" in a compost pile (shredded paper, dried leaves, wood chips) capture a lot of that nitrogen as the greens heat up and the nutrients gas off.  In this way, a compost pile pays you "interest" if you deposit the weeds there, where as chop and drop banking doesn't give you nearly as much of a return on your investment.

Money laundering is always the big hassle (so I'm told) of organized crime.  They say that the kingpins of the drug trade have entire sea cargo containers of cash that they have to find a way to deposit and launder.  How do you turn giant bundles of $20s's and $50's into an electronic deposit in a "recognized" bank account?  In the same way, how do you turn big piles of messy corn stover and tangled tomato vines into easily managed soil amendments?  The compost pile takes weeds and turns them into tomorrow's soil deposit.  Thus, even if there is a robbery, those "funds" are reinvested back into the economy via the mechanism of the compost pile.

Constantly taking a heavy crop of a field like in a mono-crop of corn or soybeans, is another robbery where the loot is not reinvested back into the field.  If you grow a grain crop, harvest the grain and then bundle up the straw and sell that as well, its robbing the community (the soil).  As much as it kills me to say it, the humanure people are onto something in terms of closing the loop and keeping all the nutrients in the system.

A truly senseless crime is when the weeds are pulled, piled up, and burned.  At the end of that crime, the soil is poorer and everyone suffers.  

I don't think that any of the above last conversation is necessarily off topic at all.  

I'm only in partial agreement on the idea that weeds rob the soil of nutrients.  I think they pretty much don't, and here's why:  Most of the aerial (above ground) portions of a plant are carbon, nitrogen, hydrogen, and oxygen, and other atmospheric gases.  While only a very small fraction of the mass is made up of minerals.  They do take complex vitamins and nutrients, but these are trace amounts compared to the atmospheric and solar contribution that is adding to the mass of biological growth below ground that is not including the plant itself.  This is the reason why plants basically vaporize on the surface of mulch, leaving pretty much only their carbon skeleton after the vast majority off-gases.  When we consider something like a dandelion or carrot, and we think about the amount of root that is produced, and the fine feeder root hairs that can be miles long when added up from all those fine hairs branching off of a single plant's roots, and the associated fungi that can also be miles long, and then add up all of the non fungal microbes which flourished because the plant was there, then I would say that the balance is greatly on the side of the plant's not robbing nutrients.  This seems to be what I recall Elaine Ingham saying as well.

Just on a break right now.  I'll come back and comment more on some other stuff after I do some more work.    

What's working for me ATM is:

- plant lots of seeds in a small planting box in a perfect spot;
- when they've grown to overcrowding, transplant them right next to a weed in the garden;
- rip off the top of the weed and place a big leaf on it;
- now the seedling and the leaf/mulch are robbing the weed of sunlight so it doesn't grow. The leaf/mulch is also keeping the seedling's roots moist so it gets lots of water.

I don't have a single weed as large as my veggie plants. I planted lots of dwarf endive which when closely planted gets so thick when growing together that it's hard for anything else to spring up above it.

You leave the root in place rather than yank it out and complete the heist.

 In my garden, leaving the root works, but only for sure with annuals... but not all annuals, most.. but not all.  It definitely works better if I mulch over the cut plant.

One annual that comes back in my garden when totally chopped is Galiopsis (hemp nettle), unless I get it very young.  If allowed to mature into a multi stalked two foot plant, and go to flower, and beyond, it produces spiky seed pods which are unpleasant to touch, and they throw thousands of seeds.  These come up right through my deep straw mulch.  

I also have perennial weeds seeding in my garden, and these just keep coming up after they have had their aerial bodies severed off:  Quack grass, Timothy grass, ox eye daisy, are some of the ones I deal with in quantity, and they want to rebuild the meadow back to it's old sod glory.  I do allow some perennial plants, and I want to tilt my garden towards having more, but I am very selective with weeding out certain species, which simply want to take over.  These grasses and daisies, like hemp nettle, are not welcome, but they have an enormous seed bank in my top soil, and keep coming every time I disturb the soil. I try to root these guys out when I see them.  

Others like dandelion, I just chop down if they are in the way of my smaller growing plants.  All of these plants, as seedlings, do tend to be quite small and less invasive if they are shaded out.        

Ok, here's a question...  If you rob the bank and the getaway car stops at the compost pile, and the finished compost goes back on the garden, is that good, better or worse than dropping it?  

 That would depend on too many factors, depending on the species and the garden locale.  

In my case, digging out a daisy that got away from me, and composting it is a much better option then chopping it, and leaving it, as it will regrow.  Unless I lay cardboard on it, it will come back to haunt me.  In the compost pile, the daisies breaks down to nitrogen gold quickly.  Timothy is not as quick, but it breaks down.  Fescue grasses are worse than Timothy, but not as bad as quack grass.  I only put these grasses in the compost if I'm working the compost, turning it, and heating it up.  

Quack grass, on the other hand is not worth composting with anything else, in my opinion.  It will only break down in a compost that is basically just it's own and is very specific.  I do this as a heap of quack sod and rhizomes beside the creek (which is very shaded by big cottonwoods, poplars, and birches),  This basically just feeds my horse tail patch and is left there).  The only other way to kill this crazy quack grass is to properly sheet mulch with thick newspaper or cardboard and grow potatoes in holes that are tenaciously weeded of grasses for the season.  Deprived of light and forced to deal with the rot of being in a very wet but aerobic (through heavy worm activity) composting environment, the quack breaks down.

But to answer your question, compost is good, great, and better, at boosting bacterial and fungal life than chop and drop.  It is without equal at doing this, although certain manure and fungi preparations have proven very effective.  Dropping it, or better yet, burying it under your mulch layer, is, however, very effective in a very different way:  The way I see it is that if you have a plant and it is taking elements from the soil and air in that very specific location/conditions, and it is chopped down and left to compost  in that location, then it is mostly able to accomplish the job that nature would intend it to do, in that very spot. (which is healing the soil system back to a perennial state).  I think there is something to this very specific thing that in the future may be studied to reveal that it is very beneficial to have the plant do this, as opposed to having it composted and brought back to 'the garden' but not necessarily to that exact spot.  

That all said, I do both.    

In one of my fields, purslane is a tremendous problem. In every other field, if I see a purslane plant, I pull it up, and hike to the nearest paved roadway, and deposit the plant onto the hot asphalt: To be scorched, and squished. I don't care about the lost nutrients. Seems like a good trade-off.

I pull it up, and hike to the nearest paved roadway, and deposit the plant onto the hot asphalt: To be scorched, and squished.

 Wow.  You must really LOVE purslane in your gardens!  Sounds like it's the equivalent of quack grass to me, but I found a place/use for it in my creekside horsetail patch.  Horsetail, by the way, is also not at all welcome in my garden.  It's nearly impossible to get rid of if it get's established.  It's spreading rhizomes are unstoppable, much like Canada Thistle... but at least it is not a prickly bastard.  Thistle is the ultimate bane, with quack grass and horsetail neck and neck for a close second.  Fortunately horsetail is not nearly as common in my garden, and so I think I will have it done with if I keep on it in the next few years.  Quack grass is the one that I deal with most, because of the seed bank.  Thistle comes up as a clone from deep spreading rhizomes and as such it takes a while to get it under control but my in garden patch is relatively small compared to the main meadow, where there are acres of the stuff.  

Hi Tim Kivi

What's working for me ATM is:

- plant lots of seeds in a small planting box in a perfect spot;
- when they've grown to overcrowding, transplant them right next to a weed in the garden;
- rip off the top of the weed and place a big leaf on it;
- now the seedling and the leaf/mulch are robbing the weed of sunlight so it doesn't grow. The leaf/mulch is also keeping the seedling's roots moist so it gets lots of water.

I don't have a single weed as large as my veggie plants. I planted lots of dwarf endive which when closely planted gets so thick when growing together that it's hard for anything else to spring up above it.

Considering your system, Tim, this sounds like a really good plan/method.  If your weeds are less vigorous than your desired plants (already!-which is pretty unique and amazing for many people's gardens!), and you use that method with your endive, or something similar (some people have a nurse crop of spinach for this purpose... sometimes I use field peas... any fast growing early season crop will work), you should have little problem with this method, in my thinking.  The seedling - as it develops it's own established root system within soil of the new bed, and beside the covered up weed root - will get itself involved in the parts of the covered weed's microbial nutrient system due to cutting it's top.  

Hi Kyle Neath

One thing I would definitely underscore is something Mike Jay first brought up — water usage. Out here with our sandy soils and dry summers, weeds can quickly decimate other crops around them. They will germinate in a thick mat in the spring, go to seed in a few weeks as the rains stop, suck up all the water in the area, and die off — months before your veggies will have had a chance to mature. If I forget to irrigate for a week, weedy places will be completely dead, while weeded places will be doing just fine.

 I just wanted to acknowledge this.  This is an important observation by Kyle.  Not all garden's and locations are created equal.  Do you mulch at all, Kyle?  Tim's endive method (or some similar fast growing weedy plant of favor) might be something to try.

And:

I make compost to breed beneficial organisms, and a compost pile will do that orders of magnitude better than mulch will. At the same time, my compost pile is burning up the fuel that these beneficial organisms need to survive — the same organisms that live in your garden soil that might be able to use that fuel if it were chopped and dropped. At another look, a compost pile can heat up enough to kill unwanted seeds, while chopping and dropping will just leave the seeds in place… I guess I look at it all as a complex equation without an easy answer.

 Also very good observations and comments.  It's unlikely that the chopped and dropped plant will be accessed by your garden soil's microbes much unless you live in the tropics, or place it under mulch on the soil surface, or otherwise keep it moist, or you have tons of fast working compost worms in your garden.  Compost is pretty much all about making beneficial organisms, and killing weed seeds is a bonus if it's done right.  I would strongly suggest chopping weeds before they flower, or just as they begin to, so that they do not go to seed.  It should be noted also, that only a properly made hot compost heap will have a substantial effect on strong seeding weed's seeds.    

Constantly taking a heavy crop of a field like in a mono-crop of corn or soybeans, is another robbery where the loot is not reinvested back into the field.

 If the land grows good maize without aid, transitioning such land is pretty easy.  Instead of the constant heavy removal of it's biomass, a person could harvest the corn off the stalks, leaving them standing, and in the spring plant a cover crop of spinach and greens, and later when it  warms up a crop of scarlet runner beans can be planted at the base of the corn stalks, given a little space and light to start with.  Corn has a remarkable carbon sequestration in it's roots, and the above ground portions will be slowly incorporated as the beans bring them down.  Once the runner beans are done, there will be a good green manure from the greens, as well as mulch of partially degraded corn stalks and runner bean stalks, the mixture of the green manure and the dry stalks makes an excellent sheet compost to plant into next year or as a short late fall crop.      

One other thing to note is the nature of the vegetables in your garden.  At our place, we've found that onions and beets simply cannot compete with much of anything, and have to be weeded thoroughly if we are to have a good crop.  However, potatoes, beans, and squash seem to be okay with indifferent weeding, and will grow and put out a decent crop without too much attention.  I don't know if the competition is for water or sunlight; I don't think it's a nutrient issue at all, though, at least in our garden.  There are a number of 'weeds' that we tend to just let grow around the potatoes, beans, and squash - yarrow, dill, clover, alfalfa, and chickweed, we just leave in those rows.  Around the beets and onions, though, it all goes.  Try weeding half of each row, and leaving the other half, and see what works best for you.  You might be surprised.  

If during the time your desired plant is establishing itself, growing, or producing your desired output whether it be flowers or crops you have a weed competing with it for nutrients, water, or light it will hinder your desired plant. What happens over the long haul is irrelevant. Don't forget that even if your weeds return nutrients it used while growing, it has still diverted the nutrients while you needed them in your rose or tomato plant.

Hi Jess.  Yeah, I can relate to that.  Good call on mentioning that some plants do alright, and some plants struggle with it.  I suspect it might be early season water for the onions and light for the beets, but it might be water for the beets too.  Onions really seem to like water in the early season.  I think that you hit the nail on the head though, that it is water OR light; meaning that I don't think it's necessarily a nutrient issue.  It might be, particularly if a person's soil is poor, or if a weed is in too tight of spacing with your choice edibles, but, as you say, you don't think that is the case in your garden, and I think that given really good nutrient rich soil, that the gardening book's 'rule', as mentioned in the opening post of the thread,  can be thrown out, or at least completely reconsidered.

Hi John Duda:

If during the time your desired plant is establishing itself, growing, or producing your desired output whether it be flowers or crops you have a weed competing with it for nutrients, water, or light it will hinder your desired plant. What happens over the long haul is irrelevant. Don't forget that even if your weeds return nutrients it used while growing, it has still diverted the nutrients while you needed them in your rose or tomato plant.

 I think your opening line states the crux of the issue.  Plants need to get established.  Often this is a water or light issue.  Sometimes heat.  I tend to think that if I can knock the vigor of the weeds back a bit through chop and drop (or altogether remove the real troublesome ones that I mentioned), then my plant's thrive, but if I let the weeds have full ground, full tilt, no holds barred, then I end up with some resulting issues with some of my chosen crop plants.  Generally though, I have to disagree with your statement.  It's a matter of ensuring that your plant's get what they need, sure, but this does not, in my thinking, necessitate a weed free garden.  

I think the actual science on the issue is proving that that there is a lot more going on then mere competition, and that there is great value to having weeds in the garden for soil microbial diversity and soil building.  Nature is trying to build soil, all the time, and these are the volunteer soldiers on the front line who do the grunt work.   Compared to plants which come in the form of imported seeds from elsewhere, these are adapted to your garden to build soils and cover bare land.   I'm not saying to let weeds over-run your garden, but that some weeds are not that bad, and many are beneficial, and that plants in general can deal with a much larger diversity of close neighbors than was conventionally or traditionally thought in many cases.  And, it is up to the horticulturalist to observe and figure out a strategy in which both his plants and soil community thrive, to the maximum of their capacity to do so.  

If for you, John Duda, that means that in your garden and in your location that every weed must go, then so be it...  But I think the science is tending now to show that soil systems and plant communities have much more dynamic inter-relationships than simple competition, and that intensive weeding can have a host of issues, and these can include nutrient depletion/loss from the soil.  We all have choices that we make about how we garden.  As the local gardening expert said in his column in the newspaper:  "There are a hundred different ways to grow a garden; all of them are right."  And I would add that in some cases, in some places, all of them are also wrong.  Some people mulch, some people till, some people leave bare earth, some people weed, some people have permanent beds, some garden their veggies with shrubs and trees, others keep these systems very separate, some folks have beds that are raised, some of them garden only on the flat, some people garden in trenches or pits, some on tall hugulkulturs or berms...   All of them might be right or wrong for me to try at my place, or you at yours.  I suggest trying some of the stuff that is mentioned by various people in this thread in small amounts to see if it is effective.  

Clearly, Tim Kivi thinks that his crop plants are not being harmed by allowing weeds to be 'present' in his garden.  This is not to say that Tim is allowing the weeds to take over the garden.  Not at all.  He's still in control, and he is designing a system a system that is working to grow both healthy robust crop plants and living increasingly dynamic soil systems, and he's hoping for advice to improve on it.  And I salute him for all of it.  And I think that many people would benefit greatly from reading this thread and learning of the potential benefits of leaving at least some surprise volunteer plants in the veggie patch.  

Roberto:

The title of this thread is:

Do weeds rob soil of nutrients?

If we're discussing this issue and some say that when you chop and drop a lot of weeds, then what you're saying is that next spring you'll have the same nutrition in the soil that you had last season as the nutrition is returned to the soil by mulching out the weed plants. I'm just pointing out that while the weed is growing this year it's reducing the nutrition available to this years crops. I don't know where you got the idea I have a weed free garden. I suffer from fatigue issues and my medication side effect is fatigue. And I have trouble kneeling. I'm sure my neighbor is horrified  looking at my garden. I never could hoe, so I resort to using my spade to chop vertically and then take a five minute break after each tomato plant.

We should also while discussing the idea of what effect weeds have in the garden discuss what they do to air circulation and how that effects the late blight my tomatoes suffer from.

I dropped lots of seeds (spinach which has deep roots, dwarf endive which has shallow roots) in a spot and they all germinated together. They don't grow more than about 2 inches. When I separate and transplant them where they have room they thrive. If even good plants of the same species do this to each other, weed roots must do the same I suppose. But it's no longer a matter of nutrients, it must be the competition for space factor.

My last residence was on lots of acreage. There was a heavy wood lot. A 24+ inch diameter oak with two 8 foot long veneer logs back to back seemed to the most valued tree there. In all the years I lived there I noticed there was always a lot of 4 foot high woody plants. I never tried to identified them. I'd assume oak and maple and wild black cherry. My point is that the seeds germinated, got so high and then died off. Lived there 20 years, always looked the same. I assume if a tree fell over and made a big hole in the canopy that one or some of them would have reached heavenward and fought it out for the light. Before I lived there the kids built a log cabin with a log chimney, which of course burned down. Scorched the bark only on the small trees, lots of them, lots of firewood. But since they were the small ones they never made much of a difference in the canopy. I guess you could call them reserve stock.

When I get purslane, I eat it.

When I get horsetail, I chop it to add nutrients to the soil.   With one type of horsetail, I make medicine out of it.

I import weeds into my yard that taste good and are edible.  During some parts of the year, I eat more weeds than anything else.

Then the weeds I get are the ones I want.

I had thistles. If nature wants me to have thistles, I planted artichoke and medicinal milk thistle.

Now I get the thistles I like.

There are also some vegetables that reseed them selves. I have been eating them for 20 years.

During this time, my soil has gone from extreme compacted clay with no drainage to good garden soil.

If I'm tryiing to get something new going, I eat all of the weeds around it so it will grow.  

Plants in all areas of your garden will use the sun, like the other poster said, to make nutrition, and they will stop the soil from drying out.

THink about your climate and what would naturally grow there, and grow something simlilar to that.

John S
PDX OR

Hi John Duda:

If we're discussing this issue and some say that when you chop and drop a lot of weeds, then what you're saying is that next spring you'll have the same nutrition in the soil that you had last season as the nutrition is returned to the soil by mulching out the weed plants.

 That's not really what I said.  What I said in part is that the chopped plants are not nearly as beneficial if they are left on the surface of the mulch.  If the mulch was lifted and the chopped plants were added beneath the mulch where they would stay moist and be readily available to the soil surface, then those nutrients would be nearly all returned (particularly if your soil's worm population included a good proportion of composting worms).  But i will elaborate on the sameness or equality or balance of soil nutrition as a result of leaving weeds a bit and chopping them down later on in this post.  If you read all my posts (and i know that I wrote a lot of posts and a lot of long posts at that, so if you don't remember it all, that's entirely understandable), then you would be understanding me a bit different, I think, on other aspects of this.

The greater gist (and I will elaborate  quite a bit on some to make it clearer and I apologize if I am repeating things unnecessarily) is that the vast majority of the upper part of the plant's mass is made of atmospheric gases, with only a tiny fraction being minerals and soil nutrients.  If a weed is chopped down, and then laid actually on the surface of the mulch, most of what is left will dessicate to a carbon shell, the remainder will end up off gassing back into the air (water vapor, nitrogen, oxygen, carbon dioxide, hydrogen, et cetera).  The vast majority of the underground plant that is left, however, will decompose and become compost corridors and become microbial food in the soil, some immediately, and some over time.  Included in this is the huge amount of the root's bodies that is made up of atmospheric gases (The vast majority by %).  These become nutrients as they compost and thereafter.  Also, while it was growing, the plant was releasing root exudates, and these were being utilized by all the microbial (bacterial and fungal) life plus worms and whatnot that were directly or indirectly in food chains extending outward from the main and feeder roots, furthering the release of atmospheric gases based nutrients and solar energy throughout the nearby soil system.  This is done via the living micro beings which have short life spans.  They give their bodies back to the soil in the form of complex carbon molecules.  Similar molecules are formed by their bodily wastes which accumulate rapidly as these beings have very fast metabolisms.  Most of these wastes and bodies all are stable forms of what are the actual soil nutrients (complex bio-chelated molecules combining minerals with atmospheric gas based elements).  These soil nutrients that were formed by the life processes of the microbial world last a long time if the soil is not disturbed by tillage or intensive digging.  

What I am saying is that the addition of all of these things below the ground, is far greater than the sum of what was removed via the chopping of it's above ground parts, even if that above ground part is left to dry out on the surface (be it on the mulch or on the soil).  I'm not saying that it will be the same nutrition at all; I'm saying that it will actually be more nutrient dense !!! It will be more,, but only if the gardener is observing things well, and is adjusting the chop and drop according to the needs of the existing soil/microclimate/garden and specific crop or weed plants.  This assumes that you are ensuring that plants are indeed thriving---that they indeed have adequate sun and water to go to their full potential in health.  It's not a set strategy that is one size fits all; it must be adjusted to fit your plant's specific needs and the specific weed's growing strategy.  It has been advocated by Bill Mollison and other people in the permaculture movement for decades for these very reasons that they suspected, but now there is increasing evidence that they were right in their suspicions.  By researching the work of Elaine Ingham, you may be able to verify this.  By researching other scientists who work with plants and soil then you will have further verification of other things that I have written in this post. It's sometimes hard to find the scientific work of Masanobu Fukuoka, for instance, but the gist of his research can be found in his books, and some of the work of Susan Simard is available on Youtube and Ted Talks.  

Not only is all of that the case, the way I see it, but the above ground part, when it was still alive, will attract it's own list of predators and pests and pollinators.  And birds and butterflies will rest on it, and spiders will span it with it's webs, et cetera, which contribute then to a much stronger web of life interacting by crawling or flying about the garden doing their other business and contributing in myriad ways.    

I'm just pointing out that while the weed is growing this year it's reducing the nutrition available to this years crops.  

 And what I am saying, is that the more plants that you have growing (while not decreasing your chosen crop plant's ability to thrive, via shade, lack of moisture, excessively close proximity) the more life that you have in your soil and thus the more nutrition is available, both in the short and long term.  Tim's garden is an example of this, as is mine.  Others have also corroborated.  When you chop and drop the plant at a young age (I recommended several times to not let the plants mature unless you really like that particular species around in your garden), there is an enormous amount of benefit/nutrition that is left in the soil.  So I have to disagree with what you are pointing out.  These statements that I am making are particularly true, in my way of thinking, if the nutrient base (living soil matrix) is already at a high % level and the living soil and mulch is left as intact as possible (% of non disturbance).  The higher these %'s are, the more likely that the soil will retain and drain water at the proper rates according to the needs of the plants, for instance, and also the more they are able to handle tighter spacing because the nutrient load is readily available via the microbial networks.  In my way of thinking, the more a gardener does the things that myself and most others have been discussing here, the more life, and thus nutrition, is added to the soil right away.  The situation also compounds on itself in a positive way as time goes on.  

   

We should also while discussing the idea of what effect weeds have in the garden discuss what they do to air circulation and how that effects the late blight my tomatoes suffer from.

Certainly air circulation is a part of any permaculture strategy, regardless of whether we are talking about yard, a garden, a house, or an individual plant.  Plant spacing is sometimes the factor that contributes to diseases.  It has also been proven that plants grown in nutrient rich soils (particularly those rich in micro fungi) are able to provide antibiotics and other medicines to the plants in their exchanges for plant sugars.  Bacterial based compost tea sprays, applied to both the aerial (above ground) parts of the plant and the soil or mulch surface, have been also shown to have great benefits to aid disease resistance or to cure the symptoms.  Weeds in general, can not be, in my thinking, pointed out as the source of the problems associated with late blight or other diseases.  If you find that your spacing is contributing to late blight, then by all means keep your tomatoes clear of most weeds, keep your tomato plants separated by air space, and encourage air flow at every turn where they are growing.

I suffer from fatigue issues and my medication side effect is fatigue. And I have trouble kneeling. I'm sure my neighbor is horrified  looking at my garden. I never could hoe, so I resort to using my spade to chop vertically and then take a five minute break after each tomato plant.

 I'm sorry to hear that, John.  It sounds like you are doing your best to get those tomatoes happening, and bravo for getting out there and doing it; a lot of people don't when they are suffering with fatigue.  I would suggest cardboard and/or mulch to keep weeds down so that you do not have to work so hard at it.  There is work in doing that, but in the end you do a lot less, the microbes seem to thrive under this cover, and the tomato roots and their associated microbial life will not be disturbed, thus making your soil system that much stronger/more resilient.

I don't know where you got the idea I have a weed free garden.  

 Ok.  So, even if you are not having a weed free garden, you seem to be saying that you do not approve of leaving weeds in the garden.   I, for my part, am not saying that all weeds should be left, or that all weeds need to be chopped, or any other ultimatum about weeds at all, except that they can do good.  What I am really saying for the most part is that weeds have the potential to provide great benefit to the garden's soil, if they are utilized to work for you, rather than against you.  You still need to ensure that your desired crop plants are getting what they need in terms of space and light and water, but those needs might actually be different if the soil system is being boosted by the weeds being left for a time or for their duration. My thinking on this, and the greater thinking that is being discussed, is that the information about such things that is in most old garden books will be turned on it's head in coming years as a result of what is being discovered about plant-soil and plant-plant, and plant-soil-plant interactions.  That is my understanding, and I'm sorry if it troubled you that I implied that your garden is weed free.  

If during the time your desired plant is establishing itself, growing, or producing your desired output whether it be flowers or crops you have a weed competing with it for nutrients, water, or light it will hinder your desired plant.

I'm saying that this quote potentially assumes that you do not want or have weeds in your garden.  Sorry if that assumption was false.  What I am saying is that I agree with your thoughts:  A desired plant should be given all that it needs for nutrients, water, and light, and weeds should be chopped and dropped or brought to the compost heap if they are hindering these essential processes.    

Outstanding posts, Roberto! Another way of looking at it that I've seen from studies is that if you leave a "weed", there are many microbes living in it.  If you chop the top, there will still be quite a few living in the roots.  If you completely remove it, you are removing much more of the microbiology and interrupting the soil food web.  The soil food web needs those bacteria to be eaten by other microbes, such as nematodes, fungi, ciliates, flagellates, and those microbes eating each other, exuding, and eating each others wastes creates nutrition to be bioavailable. Without the microbiology, the minerals are there, but our intentional plants can't get them, so we can't get them into our bodies, nor can other creatures.  
John S
PDX OR

The way I look at chop and drop, is that it does mimic a natural process much more than traditional weeding.  For instance, when a weed is taken down by a cutworm it falls over.   The root is intact and the top falls on the surface.  Pretty much exactly the same thing happens with the soil disease damp off; the top falls over.  If the wind blows the branch off a tree, same sort of thing.  If a bear steps on part of a plant and breaks it, same thing.  It is far less common for a plant to get completely ripped out of the ground; although a bear or badger or two has been known to do such things from time to time...  

I completely agree with your statements, John Saltviet.  The food chains are very much disturbed and the entire system is challenged when plants are removed fully from the garden.  It doesn't mean that I don't remove plants from the garden, but that I look at this as the potential loss to my soil system that it is, and try to consider not doing it as much as possible.  

Fortunately we can create nutrient dense compost out of many of these weeds and bring this back to the garden, and weeding can also do the small service of aerating the space from which it was removed.  If a person has a pail of compost along, one can add some in the space where the weed was removed.  

There are many ways to make the most out of your weeding and soil building experience, and I hope that this thread has shed some light on the possibilities.

Outstanding posts, Roberto!  

Thanks Tim Kivi for initiating this thread with his question, and for the rest of you for adding to the discussion.  This community really is bursting with knowledge; and sometimes it's through a deeper discussion of something like this, that I actually formulate much more solid strategies, and get on them more, myself.  Thanks all.      

The only weed I pull out now is grass. I then immediately replace that vacant hole with a seedling. Not only is it compensating for the loss, the hole in the soil makes it easier to slip in the new plant's roots without disturbing the soil around it.

I personally leave all “weeds” that aren’t growing becoming excessive. I chop and drop everything. Sometimes I pull them. There is a loss of microbes, but it also does small scale aeration of the soil, give some take some..