You want your vegetables and fruit trees to grow well and provide you with good food, so you seek advice about how to create the best soil conditions for your plants.
You encounter this recommendation in Sunset’s The Edible Garden book about how to grow broccoli: “Feed with a high-nitrogen complete fertilizer before heads start to form.”
And then you try to figure out how to apply such a recommendation: Feed how much — a tablespoon, a cup, a bucketful? And what kind of fertilizer is considered “high-nitrogen?” What makes a fertilizer “complete?” And then you think a little further and wonder, what if the head of broccoli starts to form before I notice — should I still feed, should I feed more or less?
Maybe you also come across instructions about preparing your soil before planting, such as the tens of pages dedicated to the topic in the book How to Grow More Vegetables by John Jeavons. There are multiple diagrams, side notes, illustrations, suggested tools, and within the text you find the ironic phrase, “Do not strain yourself . . .”
Alas, after crunching your brain figuring out how to apply the recommended fertilizer and getting a workout from all that “double digging,” you’re convinced that fertile soil requires a degree in chemistry and an Olympian’s energy. You can go that route and you’re likely to get good results. But there is another way. In fact, achieving and maintaining fertile soil can be child’s play.
I learned to grow vegetables and fruit trees while living on the outskirts of a rural village in Africa, where no chemical fertilizers were available and where everyone’s days were filled with chores like fetching water from the spring and hand-washing clothes. Food was grown in the simplest and most expedient way. When I returned to the U.S. and took training classes to become a Master Gardener I learned a lot, but I also very often remember listening to a PhD’s lecture and thinking, “It doesn’t have to be that complicated.”
Well, who am I and how do I know? I’m just a guy who’s been doing it a simpler way for more than a decade now, and I eat the proof that my soil is fertile every day.
For my vegetable beds, I add about two inches of compost each year. I usually add about an inch in late winter before planting tomatoes and corn and peppers, and then I add about an inch again in late summer before I plant my cauliflower and cabbage and onions. There’s nothing special about those times; it’s just when I usually do it.
I merely spread the compost on top of the soil. I don’t dig it in. There’s no need. It gets incorporated into the soil naturally, eventually.
Compost laid; to be spread once lettuce is harvested.
Sometimes I use compost that I’ve made in my yard, which includes some of our chickens’ poop, and sometimes I use compost from the Miramar Greenery in San Diego, which is what my sons are helping me load in the photo at the top. I’ve noticed over the years that plants grow better with my compost compared to Miramar’s, but unfortunately I’ve not yet been able to produce enough of my own.
For my fruit trees, I sometimes add a little compost too, but only if I have more than my vegetable beds need. Mostly for the fruit trees I just keep a thick layer of wood chips as a mulch under them. Over time, the wood chips break down and are incorporated into the soil just as the compost is in the vegetable beds, but I tend to only replenish the wood-chip mulch once a year. I like to do it now, in late winter, so the rains soak the mulch for free, but I do it at other times if good wood chips become available then. I aim for a new, replenished depth of about five inches each time. There’s nothing magical about this depth, but a thinner layer will vanish into the soil more quickly and a thicker layer gets awkwardly close to low-hanging branches.
Fresh wood-chip mulch under a young Pinkerton avocado tree.
Sometimes I also get wood-chip mulch from Miramar Greenery, but often I get wood chips from a tree trimming service who is working in the neighborhood. It means they don’t have to pay to dump their load elsewhere, so it benefits both of us. I was lucky enough to get a load dumped last week, so I’ve been replenishing the mulch under my trees over the past few days.
One steaming pile of wood chips.
Is compost really enough for fertile soil in vegetable beds? As I said above, I eat the proof every day, but so do others. My friend Erik, for example, has added only compost on his vegetable garden for a number of years and his plants do as well or better than mine.
And are wood chips really enough for fertile soil under fruit trees? Again, the proof is in the pudding. I couldn’t imagine getting any more fruit out of my Valencia orange tree:
But it’s not just me. The other day I visited a friend who has an extensive orchard in her backyard. This woman is a certified arborist and a certified Master Gardener, she grows an astonishing variety of fruit trees — from Jan Boyce avocados to Honeyheart cherimoyas to SpiceZee nectaplums — and she puts nothing more than a thick layer of wood chips under them.
(Paul Gautschi follows a similar routine up in Washington, and Ruth Stout was doing something similar a hundred years ago.)
How is it that compost and wood chips do all of this work — creating and maintaining soil fertility without any additions of specially formulated fertilizers or constant tillage to loosen the soil? That is a question whose answer is book length. But here is a list of some specific effects that compost has on the soil, along with an attached bibliography for deeper reading.
And here is an excellent publication by Linda Chalker-Scott of Washington State University on the documented effects of using wood-chip mulch, which you’ll find are nearly the same as compost.
However it works, and however much we do or don’t understand it, the evidence is there. You can give your mind and your back some rest, and perhaps give your kids some fun with a shovel every now and then. For a simpler path toward soil fertility exists.
You might also like to read:
(listen to the Karl Hammer episode about compost)
I balked at the idea of urinating into a toilet bowl of fresh, drinkable water when I first returned from Lesotho. Not that I’d forgotten that was the norm in America. I’d done it my whole life until moving to Lesotho. But as the G.K. Chesterton quote goes, “The whole object of travel is not to set foot on foreign land; it is at last to set foot on one’s own country as a foreign land.” For the first time I saw it not just as going to the bathroom, but as urinating into a toilet bowl of fresh, drinkable water. To this day, it seems ridiculous. I generally avoid it. I’m wondering though — How much water do I save by feeding the plants instead?
On average, a person urinates five times a day, and the toilets in my house use the standard 1.5 gallons per flush. This adds up to eight gallons a day, or about 250 gallons a month, or 2,920 gallons over the course of a year. That sounds like a lot.
But I haven’t saved that much. I can make a wild guess and say I haven’t used a toilet half of the time (I’m often at work or at someone else’s house), and I’ve been back from Lesotho for seven years now. Over those seven years that would add up to about 10,000 gallons.
Just for fun I can calculate the cost of that. At my current rate of $0.007673797 per gallon, that comes to $76 worth of water.
But I really don’t care about the cost. The cost is secondary to the insanity of using a bowl of water that has been transported thousands of miles from the Rockies or the Sierras and filtered and treated and pumped through millions of dollars worth of infrastructure to get to my house only to be pissed in and flushed into the septic tank. The stupidity of that kills me.
It especially kills me because there is this simple alternative of walking outside and feeding the plants. Or there’s the option of letting the yellow mellow, which is at least a little less stupid.
There’s talk all over the place of changing our habits because of the drought. There are signs on the roads: Severe drought. Save water. And our water district mandates that we only water three times per week between the hours of 6 p.m. and 10 a.m. The University of California, San Diego is converting some median strips of turfgrass over to lower water plants, and they are advertising it everywhere, congratulating themselves for their immense awareness. The governor made his big show of demanding 25% cuts in use. (I’d like to see how he uses water on a daily basis.) He calls this a “State of Emergency.” Water is scarce; we must conserve what little of it we do have. Meanwhile, we piss in it five times a day?
We know that urine has nutrients which plants use, but how to give it to them? The simplest guideline is to pee in a spot once and only once. Here are some details and research that support this guideline.
One approach is to use the following statement by Håkan Jönsson, a researcher at the Swedish University of Agricultural Sciences, in this article from Scienceline: The urine that one person produces can fertilize about ten square feet of soil a day, he says. Jönsson has been studying urine as fertilizer for many years and he has also been applying it himself in his own vegetable garden.
(I don’t know exactly what he means by “fertilize” since all plants have slightly different requirements and tolerances of various nutrients. I also don’t know for sure how long he means the urine will fertilize that ten square feet, but I have to assume he means for a short summer growing season since in Sweden that’s all there is — there’s no growing broccoli through the winter as we do here, for example.)
Nevertheless, most adults urinate about five times per day. So using Jönsson’s calculation, a person can fertilize a spot about the size of two square feet with a single urination. Or, if you’re not urinating directly on the ground, then once a day spread the collected urine over ten square feet of ground. Therefore the guideline: Pee in a spot (a spot of about two square feet), and only pee there once (once per growing season for vegetables, which would be twice a year here in Southern California — once in the summer and once in the winter).
Another way to come up with the guideline of applying urine as fertilizer by peeing in a spot once is to look at how much nitrogen you are adding to the soil with each single urination, and compare that to the need of the plant. Let’s look at a tree for this example. The suggested application amount of nitrogen for a mature citrus tree is about one pound per year, according to the University of California Master Gardener Handbook.
And how much nitrogen is in urine, such that we can apply one pound of it over the course of a year? We can find that by first determining how much urea is in urine because it is within that molecule that nitrogen is held. (Urea’s chemical makeup: CO(NH2)2.) An estimate on this Wikipedia page is that there are 1.318 ounces of urea in a gallon of urine. Because urea is about 45% nitrogen, that’s 0.593 ounces of nitrogen per gallon of urine.
A person produces between a quarter and a half gallon of urine per day, which means a person produces between 0.148 and 0.297 ounces of nitrogen per day. And as a person urinates about five times per day, then each single urination contains anywhere from 0.0296 to 0.0594 ounces of nitrogen.
From this we can estimate that in order to satisfy a mature citrus tree’s nitrogen requirement of one pound per year a person would have to pee beneath it between 269 and 541 times. This is something like once per day. It could be an evening routine.
To relate this approach with Jönsson’s, take a look at my own mature citrus tree, a Valencia orange that is over twenty feet tall. It has a canopy of about 450 square feet. But the roots of this tree extend beyond the canopy edge, as I know from digging near the tree, and many people say that a mature citrus tree can have roots extending up to twice as far as the canopy edge. The roots then might cover between 450 and 900 square feet. Urinating beneath it once per two square feet would mean urinating between 225 and 450 times. That’s pretty close to the 269 to 541 times above, which was estimated to add the one pound of nitrogen.
Again, the simple rule of thumb: Pee in a spot once.
If you were to urinate on the ground beneath plants, it turns out that you would add many of the same nutrients to the soil that bags of fertilizer add, and in similar quantities.
Bags of fertilizer are always labelled with their proportions of the three “macronutrients” that plants need most: nitrogen, phosphorous, and potassium. And these are listed as three numbers somewhere on the bag. Take E.B. Stone’s Citrus and Fruit Tree Food, which is labelled 7-3-3, meaning it contains 7% nitrogen, 3% phosphorous, and 3% potassium. E.B. Stone’s Tomato and Vegetable Food is 4-5-3. Then there’s Dr. Earth’s Premium Gold All Purpose Fertilizer at 4-4-4. Miracle-Gro’s Tomato, Fruit and Vegetable Plant Food is 9-4-12.
Though urine is greater than 95% water, the remaining constituents include nitrogen, phosphorous, and potassium. How much of each element one’s urine contains depends on diet, of course. (What is put in affects what comes out.) Studies I’ve read vary on their estimates. One report estimates urine to be 11-1-2, and another report estimates 15-1-2, and yet another estimates 7-1-2. In short, while your urine does not contain exactly the same things as your neighbor’s, it is agreed among the above reports that the nitrogen content is high relative to the phosphorous and potassium, and it is higher than in the commercial fertilizers mentioned above.
When considering urine’s usefulness as fertilizer it should be remembered that these large companies — E.B. Stone, Dr. Earth, Miracle-Gro — create fertilizer formulations that they intend to sell nationally, if not globally. These are not fertilizers geared toward growing in California, let alone Southern California specifically. And our soils here are very different from those in many other parts of the country. California soils generally naturally have sufficient phosphorous and potassium for optimal plant growth but are naturally low in nitrogen, and “nitrogen may be the only supplement necessary,” according to the California Master Gardener Handbook, published by the University of California.
That makes urine look like an even more appropriate fertilizer for us than many of the commercial products.