What is this blog?

This blog seeks to answer questions about sustainable gardening for those who are not familiar with the practice. The author holds a master’s in environmental science, works as a journalist, and practices a combination of permaculture and native plant gardening in Madison, Wisconsin. Leave your own questions as a comment on any post, and they will be answered soon!

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What is this blog?

What is humanure?

Unlike green manurehumanure is actual excrement. As the clever name might lead you to guess, it is excrement that comes from humans. What does this have to do with natural gardening?

Let’s talk about fertilizer.

Fertilizer is substances – often artificial substances – that help to provide nutrients for plants. A key ingredient in fertilizer is nitrogen, an element that is important to both plants and animals. Nitrogen is found abundantly in our atmosphere – when you breathe, you are inhaling much more nitrogen than oxygen. But most plants cannot absorb nitrogen from the air. They need it in a different form.

This alternative form can be artificial fertilizer, or it can be compost. To make good compost, we must put in materials that contain lots of nitrogen. What contains lots of nitrogen? One answer is (recently) dead plants. Another answer is human waste.

Our own urine and excrement – which to us is useless and toxic – is valuable and nourishing to plants. If we relieve ourselves on plants, they will happily absorb that nitrogen.

While it might be fine to do exactly that on a camping trip in the woods, nobody thinks we should fertilize our suburban yards by defecating in them. Instead, we can use the somewhat more refined process called humanure.

We begin with a composting toilet. This device, instead of using clean, drinkable water to move our bodily waste to a treatment center, simply collects our byproducts in a bucket. A seat can be placed on top of the bucket to make it more comfortable, and a handful of sawdust after every use will hide the mess and absorb all the odors.

When the bucket is full, it can be emptied into a compost pile. At this point, it is very important that the compost be managed well. Human waste is full of pathogens, and the compost pile must get hot enough to kill those organisms. (No need for artificial heat: the beneficial organisms in the pile will generate plenty of warmth as they munch their way through all that delicious organic matter.)

Once the humanure is fully decomposed, it is indistinguishable from any other finished compost, and it is safe to use on our plants – even on our vegetable gardens. However, like greywater systems, humanure is severely frowned upon by many local health departments, due to its perceived hazards.

Humanure is a normal and natural way of recycling waste products back into valuable resources. It connects our own bodily processes to the cycles of the earth. However, because it is dangerous if not managed properly, and because it is not yet legal in many places, please thoroughly educate yourself on this topic before attempting to establish a humanure system. There is no shame in planting some native flowers today, and leaving humanure until you are more experienced and confident as a natural gardener.

What is humanure?

What does plowing do to soil?

In the previous post, we learned about soil compaction. This is one aspect of soil structure. Another aspect is layering.

We all know about topsoil: it’s the valuable layer of soil closest to the surface, that is rich with nutrients and other resources. Below this are other layers, or horizons, which are primarily of interest to soil scientists.

The point we will focus on today is that layers should stay where they are. When each type of soil is at the right depth, the plant community living on top of the soil thrives. When layers are all mixed up, plants suffer.

Mixing within a layer isn’t good for plants either. A third aspect of soil structure is the very specific way that particles are arranged in the soil. When clumps of sand or clay, water droplets, air pockets, and microorganisms get jumbled out of their proper places, soil ceases to function in the way that it’s supposed to.

What can cause this kind of jumbling? Plowing, an agricultural practice familiar even to non-farmers, is the process of deliberately scrambling soil. In other words: plowing is bad for soil.

Why would farmers engage in a practice that damages soil? The answer is that plowing boosts plant growth in the short term. By turning over the first few inches of topsoil, farmers can introduce more air to the soil. While air in soil is good, this is a case where too much of a good thing is not better. Soil microorganisms gorge themselves on the extra oxygen, and start breaking down organic matter in hyperdrive. That makes lots of nutrients available to plants, which consequently grow very vigorously.

The problem comes when those voracious microorganisms run out of organic matter to decompose. Then the amount of nutrients available to plants suddenly drops, leaving them struggling to survive. Farmers start feeding their plants artificial fertilizers in an attempt to maintain their yields from the depleted soil, and the whole system becomes expensive, unproductive, and environmentally damaging.

The practice of rapidly wearing out soil was not much of a problem when there were few people, when the American plains seemed to go on forever, and when farmers could plan to just move to a new quarter-section every few years. Now that pretty much all the land is spoken for, farmers need to farm as if they intend to stay where they are. Plowing is not a form of sustainable agriculture – and, indeed, the practice of no-till farming is becoming increasingly popular.

But many gardeners still use residential-scale equivalents of plowing, like rototilling and double digging. Just like with plowing, these practices increase fertility in the short term, but result in damaged soil that can’t sustain plant life over the long term. Many gardeners now are adopting practices that involve disturbing soil as little as possible.

People today have different knowledge and different values than people in the past. Plowing was once an iconic practice in the agricultural landscape. Now we know better ways of sustainably managing our land.

What does plowing do to soil?

What is soil compaction?

In previous posts, That Blog has covered properties of soil, such as soil types and soil pH. One property not yet written about is soil looseness.

Good soil, gardeners say, should resemble chocolate cake – in both its color and its crumbliness. Good soil has lots of air in it. Why?

First, because these channels and pockets of air also serve as pathways and holding places for water. As discussed in the previous post, we want water to move down into soil. Loose soil structure helps that to happen. Soil that is dense and hard will resist water, leaving it pooled on the surface, where it will either cause flooding, or run off to cause flooding somewhere else.

Second, because the air spaces in soil provide room for roots. Plant roots grow easily through loose soil. Under these conditions, plants are able to find nutrients, absorb water, and anchor themselves securely. In contrast, roots struggle to penetrate soil without air, leaving the plants sickly and weak.

Soil without air is compacted soilSoil compaction is events and processes that lead to compacted soil.

What kinds of things cause soil compaction? One major perpetrator is development: covering soil with pavement is, of course, not good for the soil. Another cause is heavy vehicles. A bulldozer or brush hog may be the fastest way to clear a site of unwanted vegetation and prepare it for new plantings, but these huge machines also cause serious damage to the soil on the site, making it more difficult for the new plantings to get a start in life.

Even lighter vehicles are tough on soil. ATVs can cause compaction and damage, which is one reason some people oppose the use of ATVs in natural areas. And finally, a person on foot is heavy enough to squash down soil and destroy those crucial air pockets.

For this reason, treehuggers may want to curb their desire to hug trees. When we walk up to a tree’s trunk, we are stepping on its critical root zone – the area directly under the tree’s canopy, where its roots are most actively performing their vital functions. Compacting the soil in this area can be very detrimental to a tree’s health. While some tree species – such as those that have evolved to live in perennially soggy areas – are adapted to compacted soil and able to withstand those conditions, many other species suffer from the suffocation of their roots.

Humans like hugs. Trees are indifferent to them. In a few weeks, That Blog will look at simple things tree lovers can do that trees will really appreciate.

What is soil compaction?

What should we do with water?

The availability of clean water is becoming an increasingly pressing problem in many parts of the world, including some areas of the United States. We need water; we also need to be mindful about how we use it.

Many practices in conventional American yards are not water-wise. We plant grasses that are not suited to our local climate and, in some parts of the US, shower them with twice as much water as is used for the people in our household. We do this sprinkling un-carefully, letting the water splash onto sidewalks or evaporate directly into the air. We point our downspouts onto paved surfaces, diverting precious rainwater to areas where it will do nothing but contribute to street flooding.

Permaculture practitioners have five better ideas for how we should manage water on our land.

Slow it. As water comes onto our property, we want to slow it down. If we let it move quickly, this valuable resource will continue straight on to someone else’s property, likely taking good soil with it. Our loss, our neighbor’s gain. It is to our benefit to hold on to as much free water as we can.

Spread it. Water is a powerful force, and too much of it in one place can lead to unhelpful outcomes. We want to spread out the water instead of letting it pool in one area. We can do this by observing how water moves on our property, and then making small adjustments to change its flow.

Sink it. The best place to put water is in the soil. Soil can hold a tremendous amount of water, and when water is in soil, it is a beneficial, rather than a destructive, force. Once we have slowed the water down and spread it out, it will naturally seek to move downwards. This is good.

Store it. Of course, it is also handy to store water in a form that we can access whenever we need it. Rain barrels or cisterns can hold many gallons of water, fill quickly in even a modest rainstorm, and provide us with a source of water in times when rain doesn’t come.

Share it. In line with the three pillars of permaculture – Earth Care, People Care, Fair Share – we are not slowing, spreading, sinking, and storing water in order to hoard it for ourselves. If the water is in a tank, we can and should share it with those who don’t have enough. If the water is in our soil, we can share the produce that grows from it. There is enough water to go around, if we use it mindfully to take care of ourselves and others.


As you follow these principles, be aware of your water rights. In some parts of the United States, it is not legal to divert water from following its natural course downhill onto your neighbor’s property. If you live in the western part of the country, you may be limited to only small changes in your water management, or you may need to work with neighbors to agree on how water will be shared.

What should we do with water?

What is green manure?

Is it a euphemism for plants someone views as being comparable to excrement? Not at all. Green manure is a valuable resource closely related to green mulch.

While there are plenty of contexts in which manure is not desirable, it is good in the garden: it is an excellent fertilizer, providing the nutrients plants need, while not involving any of the environmentally-harmful industrial production processes associated with artificial fertilizer. It is this positive aspect of manure that the phrase green manure refers to.

But what exactly is green manure? Quite simply, it is plants that have been uprooted and lain on or plowed into the soil. Essentially, it is the practice of composting in place. Instead of pulling plants, bringing them to a compost pile, waiting for them to break down, and then carrying the resulting compost back into the garden, the organic material is simply placed where the compost is wanted, to gradually break down and return its nutrients to the soil.

That is, of course, how the process works. Plants are made out of exactly the stuff that other plants need (even more so than animal droppings), and when a plant is no longer alive to hoard and use those resources, it passes them on to other plants. Thus, green manure is the perfect fertilizer in terms of its effectiveness in providing nutrients to plants – as well as being cheap, abundant, and readily available without the need for manufacturing or transportation.

Pretty much any plant can be used for green manure. We can cut down the stems of plants that have died back (after insects are done overwintering in them) and use those as green manure. We can pull weeds and use them as green manure (though we should take care to educate ourselves about which species will simply take this as an opportunity to spread themselves around more). Or we can cultivate plants that are especially good at being green manure.

Two characteristics make a plant suited to this role in the garden. First, the plant must either spread rapidly – so the gardener can harvest some individuals for green manure and still have plenty of living plants to continue reproducing themselves – or the plant must regrow rapidly, so that it can survive having its leaves harvested on a regular basis. (When a gardener cuts down a plant, uses the leaves and stems for green manure, lets the plant regrow, and then harvests it again, that’s called chop and drop.) Second, a great green manure plant is a dynamic accumulator.

What is a dynamic accumulator? All plants pull nutrients from the soil and incorporate them into their bodies. But some plants are especially good at finding and absorbing nutrients. When these plants are used as green manure, they are similarly talented at making nutrients available to the next generation of plants.

As one example, many permaculture practitioners cultivate a plant called comfrey for its value as green manure, as well as its many other uses. Comfrey is not native to North America, though, so those who strive to be native plant purists may prefer to find another species to provide this valuable function.

What is green manure?

What is green concrete?

People who are knowledgeable about the environmental importance of gardening choices sometimes refer to lawns and geometrical hedges as green concrete.

These types of plantings share certain visual similarities with regular concrete: they are flat, square-cornered, uniform in color, and unchanging. They also have some ecological similarities: like concrete, lawns are not very effective at absorbing water, cleaning the air, providing habitat for wildlife, moderating the local temperature, or performing other ecosystem services.

In fact, by some measures, lawns are worse for the environment than concrete. How is this possible? The answer is maintenance.

Concrete is environmentally damaging to produce and install. Once in place, however, it more or less just sits there until the end of its lifespan. A lawn, on the other hand, has little impact while it’s being planted, but then consumes a steady supply of water, fossil fuels, and toxic chemicals in an unproductive cycle of maintenance that can continue for many, many years.

It is worth considering: if you own a home for thirty years and mow the lawn every week, what will you have to show for it at the end? Will you look back with pride that for three decades, you prevented grass from growing? If the answers to these questions are unsatisfying, it may be time to consider alternative gardening practices.

What is green concrete?

What is green mulch?

We all know what mulch is – it’s that stuff we pile around our plants to prevent any other plants from growing. That’s good, as far as it goes. But mulch is pretty limited in its ability to provide any other benefits to our gardens. And the need to constantly bring in more mulch from off site creates a variety of costs. Is there a better, more multi-functional way we can stop unwanted plants from sprouting?

Enter green mulch.

“What stops plants from sprouting?” some inventive gardeners asked themselves. One answer is herbicides. Another answer is the absence of sunlight, water, and soil. But a third answer is other plants. In general, a plant simply can’t grow in a space already occupied by another plant. And so these creative gardeners came up with a simple strategy: to keep out plants you don’t want, fill all the available growing space with plants you do want.

Well, how do you that? The trick is layers. In order to create a planting so dense that nothing new can squeeze its way in, the members of that planting community must grow in a variety of shapes and sizes, so that they fit around each other, leaving no room for anything else. A monoculture – of pine trees, corn, bluegrass, or anything else – will always be made up of repeating plant shapes with predictable gaps that can easily be colonized by opportunistic newcomers.

And in a dense, layered planting, gardeners have discovered that the real gatekeepers are the lowest-growing species. Trees, shrubs, and other tall plants will always have open space underneath that unwelcome guests can sneak into. In contrast, plants with a creeping habit – that is, plants that spread along the ground, putting a few leaves into any available spot and then stretching onward to the next opening – efficiently cover soil, making it very difficult for any arriving seeds to germinate and get a foothold on a new life.

This is green mulch – living plants that take up space and crowd out unwanted interlopers. It serves this purpose just as well as traditional mulch, while involving less long-term cost and maintenance, and providing a host of additional benefits associated with healthy plants.

Wherever you live, there is sure to be a native plant that will happily serve as your green mulch. These little plants may not be eye-catching showstoppers, but they pull their weight in the garden, helping the community as a whole to thrive.

What is green mulch?