We can manage weeds by chopping and dropping in place – i.e. just cutting them at the surface while leaving the root system intact. This accomplishes many things. It removes competition for sunlight. And because the weeds are chopped down they have less surface area performing photosynthesis, so they are not drawing water out of the soil as quickly, and by mulching the surface they slow evaporation. And at some point there will be dieback of the roots, leaving soft structured organic material and places for our crops’ roots to grow large and healthy. And as the weeds become less vigorous, they also will not be tying up the nutrients found in the soil. By keeping them from flowering they can’t reseed, and will become less prevalent in the garden.

There are nuances to this, however, especially at the beginning.

But before we get to that, I want to mention that competition is a mode of interaction between plants that occurs when there is not enough of a resource to go around. In soil with wonderful fertility and texture, ample water, in a very bright place, you can get away with a lot more than in an environment that is more constrained. There are many ways that plants, even weeds and crops, can operate in cooperation. Just something to keep in mind. However, “weeds”, aka pioneer species or early successional species, are typically more competitive than other plants and can cause issues for us when first establishing a garden. Especially if the soil has been tilled or otherwise disturbed!

[This post was inspired by an excellent discussion thread in the Permaculture group on Facebook here. I’ve been learning a lot about chop and drop from Matt Powers of thepermaculturestudent.com, and wanted to consolidate it in a single page that I’ll keep updated as I continue learning.]

NUTRIENTS

First, the nutrients that the weeds already tied up in their foliage are *not* available until they are broken down, which takes some time. Some of what they are made of (like nitrogen and carbon) will in part escape back to the atmosphere. Weeds, being pioneer plants, are *exceptionally* good at extracting all the resources available to them – including nutrients in the soil.

Soil that has a robust soil food web is capable of making nutrients available to plants – the microbes can convert rock, sand, and silt into water soluble nutrients for plants, and in partnership with some plants can fix nitrogen. Essentially, these microbes can manufacture new fertility in the soil. A pound of soil has an incredible amount of minerals that can be made available to plants via those microbes.

But that doesn’t mean competition doesn’t exist! Those microbes get their energy ultimately from the sun, via sugars the plants pump out of their roots or via organic matter in the soil. The amount of energy they have available, and oxygen and water, limits the speed at which they can produce plant available fertility. So if you have weed roots running around with your crops, they will suck up the bulk of the nutrients that are ready, and then gobble up all the new fertility as fast as it can be produced.

And then that fertility is locked up in their roots and foliage until weeks or months later when they break down. This is wonderful, because no fertility is being wasted. Those weeds are gathering nutrients and sunshine to feed the soil… but in the short term, that can definitely interfere with getting a desired crop.

My plan to deal with this is to over time transition from weedy pioneer species growing among my crops to perennial, not-weedy plants growing among my crops. In the short term, I’ll take some of the chop-and-dropped weed material and create liquid fertilizer with it, so that I can be cycling the fertility from weeds quickly back into the soil.

WATER

In the Pacific Northwest where I garden and farm, our soils charge with water during the rainy fall, winter, and spring, and that water is drawn out of the soil by plants during the summertime. The classic way to dry farm here is to eradicate all plants except the desired crop, and plant the crop with a wide spacing. As the plants grow through the summer, their roots expand into moist soil, pump the water out of it into their leaves and then into the atmosphere, and continue expanding as they turn the soil dry.

That methodology normally goes along with tilling. And that causes reduced soil organic matter, reduced fungal populations, and damaged soil structure, all of which reduce the water holding capacity of the soil. If we can come from a different direction, we gain by simply increasing the amount of water stored in the soil at the start of the year, so we can support more growth. Still, it is a limited quantity.

Every plant coming up out of the ground can be viewed as a hose venting water vapor from the soil to the atmosphere. As plants perform photosynthesis, they are releasing water into the atmosphere. If you have a big plant with a lot of leaves, it is generally going to be releasing comparatively a lot of water. If you have a small, low-growing plant, or a succulent, it will b releasing much less water.

So if you allow weeds to grow thickly, and only chop and drop them after they get a foot tall – well, they will have sucked a lot of water out of your soil by that point. And once that water is gone, where I am, it won’t come back until the fall time, or unless we turn on a sprinkler.

If water is an issue, then chop and drop can be of tremendous assistance, but *only* if you keep on top of it and don’t let the weeds get too tall.

…but there is even more nuance here! Some deep-rooted plants, especially ones with a taproot like dandelions, burdock, or thistles, can help. They send their roots deep, and can access water that is further into the soil, bringing it to the surface and releasing it – increasing the humidity at the surface, and slowing water loss from the soil and from your crop plants. If you are planting something with a shallow root system that can’t access deep water anyway, the taprooted plants may *help* your crop by pumping water out of the soil. Counterintuitive, eh?

Root Space

I don’t have too much to say here, aside of pay attention to the kinds of roots that your weeds have, and how they might be physically interfering with your crops. If you have a grassy turf, there will be incredibly thick roots for a few inches or so, and that can be enough to strangle any attempt at direct seeding. Even if you keep that grass mowed very short, your seedlings may not have the capacity to punch through that tangle. Dandelions send down a deep taproot, and will not be competing too strongly for physical root space with your crops. But if you are growing carrots, having dandelion roots growing among them could change the nutrient profile through the soil, which can lead to crooked carrots. Would that happen? I don’t know. You’d have to try and see.

Anyway, as you repeatedly chop and drop weeds, eventually their root systems will eventually start dying, leaving behind organic matter and channels through the soil. Wonderful!

Sunlight

This is one of my favorite resources to manage with chop-and-drop. Early on, having some weeds growing around fragile young transplants or direct seeded crops can help them to not die if there are a few hot days in a row. The moist, dappled shade can be incredibly helpful. And as the crops get more established and begin to grow taller, the sun becomes more intense coming into summer, and you cut the weeds shorter… it all works together beautifully.

You also get a feeling of instant gratification – you can literally see the difference the instant you cut the weeds.

How to Chop and Drop

Chop and drop has a lot of factors at play, but doing it is really simple, so don’t let yourself get worried about the details!

In your first year of chop and drop, here is what you need to do:

1. Keep the weeds chopped short. Weeds regrow quickly, so this can take a lot of diligence. Like with anything in permaculture, if you are willing to be patient and have lesser yields the first year or two, you can let the weeds go longer between chopping sessions.

2. Don’t let the weeds go to seed. Over time, the pressure from these pioneer plants will decrease, because there will be less of their seed in the soil.

3. If you can, turn some of the weed material you’ve chopped into liquid fertilizer, and return those nutrients to the soil for your crops that seem to need them. Do some searching online for “Jadam Liquid Fertilizer” to find some recipes and discussions about that.

4. Keep doing this every year. Your soil will become more fertile, have fewer pioneer species, and give you better crops with less maintenance. Keep at it!

Chop and drop really is transformative, but it isn’t an instant quick fix. It takes less work than meticulously weeding a garden, but it does still take work. And if you want high-yielding crops the first year, it’ll take a lot more work keeping weeds short and applying nutrients. It takes time to bring the soil to full health, to where it has rich amounts of available nutrients for the plants and high organic matter content. And it does take time to reduce the strength of the weeds (and if you have perennial weeds, they may need to be smothered with mulch or dug out).