Why Mulch? Because it's Great.
Written by Adam Mohammed
To start off, I need to say that mulching is pretty much my favorite thing to do. You know that feeling you get when putting a blanket over a sleeping child? Warm, cuddly, and fuzzy all over? Same deal. Aside from keeping roots warm and cozy in the winter, mulching your garden has a huge number of benefits.
First of all, what is mulch? Define! Mulch is organic matter that you put on top of the ground, whether that be around a tree, a fresh garden bed, or in preparation for future plantings. It can be anything from straw, hay, leaves, twigs, decomposing logs, wood chips, to manure, compost, cardboard, newspaper, coffee beans... These different mulches have different properties, and different uses in the permaculture landscape. They are used in different situations, and in different combinations.
One of the basic and most common reasons for mulching is weed suppression. As we talked about in the 'Weeds' article, bare soil is a rarity in our a temperate climate ecosystem. It typically occurs either post forest fire, under very heavy tree canopies, or after an area has sustained serious damage. The response to these situations are what we call the 'pioneer' species, (dandelions, clover, lambs quarter, thistle, etc), known in our society as weeds. These species often spread by airborne seed. Cover up the bare soil in your garden, and all of a sudden airborne seeds have nothing to root into. A heavy mulch, such as wood chips, cardboard or newspaper, can prevent leftover roots of weeds from shooting up into our carefully prepared beds. After the initial work of mulching, the amount of labour spent tending to weeding gardens can be vastly decreased. Having to weed, beyond your initial planting and in some rare circumstances, is simply bad design.
Secondly, moisture retention. When you have bare soil with full sun, water is basically baked out of it. We're all familiar with that dry, cracked look soil can get during a long spell between rains. Take a patch of well mulched soil in the same conditions, and you'll still find healthy looking soil beneath. Layers of organic matter stop the suns rays from scorching the water out, and stop water from evaporating from the bottom up.
Thirdly, building soil. We're familiar with being told we need to add fertilizers to keep our plants healthy and growing strong. But in a 'natural' (no space to get into this issue!) ecosystem, there's no one around to add fertilizer. The nutrient cycle is, in part, maintained by organic matter dropping to the ground (whether it be a tree's leaf, or a bird's dropping) and decomposing. The nutrients of this organic matter then become available to the roots in the area. We can attempt to mimic this cycle by creative mulch use. If one our goals is long term fertility (which it should be, to be blunt), we can 'stack' different mulches together to create the best soil profiles and health. This is usually accomplished by combining carbon rich with nitrogen rich materials. Carbon rich materials are things like hay, wood, newspaper, and leaves. Manure and compost, and blood meal are the common nitrogen rich components. Sprinkling at least something rich in nitrogen when heavily mulching is always important, especially with wood mulches. A layer of nothing but wood mulch will actually leach nitrogen out of the soil as it decomposes, potentially reducing growth.
A technique known as 'sheet mulching' is something used to prepare a new garden area. It consists usually of a base layer of cardboard or newspaper (for weed suppression), followed by alternating layers of carbon and nitrogen rich organic matter (cardboard, manure, hay, compost, straw). The idea here is that as we kill the layer of 'undesirables' where we want our new garden bed, we simultaneously create what is basically a large compost, which, given a year or two, will turn into beautiful new soil to plan into. It can be a lot of work; covering a large area with this type of construction. But much less work than digging it up by hand! (As a side note, digging by hand, or any other sort of digging, massively disrupts soils structure, reducing productivity and long term health.)
A final reason (that I'll go into, there are many more!) is basic soil health. The last two reasons, moisture retention, and theconstant addition of yummy organic matter creates wonderful condition for bacterial and micro bacterial growth. Bacteria is the basis of soil health, it fixes nitrogen (converting atmospheric nitrogen into a form usable by plants), and it breaks down organic matter and makes it available to plants.
And a number of other things I can't quite remember right now. But they're great, I assure you. At the core, mulching isn't for the plants. It's for all the critters and organisms that live in the soil. By mulching, you're giving them the best living conditions they could ask for. Nice and moist, shady, undisturbed, and with lots of food. You make these little guys happy, and you have happy, strong, resilient plants. And rich new soil. And you don't have to weed. Or buy fertilizers. Further, nutrient soil means nutrient food. 'Standard' agriculture (monoculture with pesticides and chemical fertilizers) have such depleted, dead soil that the nutrient content in the food it produces is radically reduced.
One thing people don't always realize is how mulch is often free! Need leaves? They're usually on your neighbors lawn, often conveniently put into bags! Rural dumps often have large piles of wood mulch that are free for the taking (if you ask nicely). Drop by an appliance store, and try asking for their cardboard. Farmers often have tons of extra well rotted hay, and piles of manure just lying around, often available if you ask. Cities often will sell compost for very low prices as well. I find if you mention that you're part of an “ecological garden/agriculture project”, people are very excited to help. I've even had stores help me load their cardboard into the trailer! The added advantage of these methods is that, first, you get what you need for free, and second, you're diverting otherwise unused organic matter and working it into your own edible ecosystem.
The reasons for mulching go on, and I encourage you to learn as much as you can. It's literally one of the most important aspects of a healthy garden, and I'd be hard pressed to find examples of 'to much'. One of the most advanced farms I've seen has literally a foot and a half high piles of mulch spread two meters around their trees, and some of the happiest plants I've ever seen. Listen to your land, listen to your plants, and you won't go wrong. Happy mulching!