I have been rereading the comments that followed my post “No guarantees” – an amazing stream of good thoughts, theories, and hard-won advice. One of the topics that jumped out at me was the bitter claim that no matter what, if we harvest a garden or field, we are depleting fertility by definition.
Wildearthman wrote: “The only historical agriculture found that could be sustained more or less indefinitely occurred on river bottoms where fresh fertility was imported each year from distant mountains. Even with composting, cover crops, and green manures, fertility continues to decline. On my few acres in the Cascades, the topsoil was stripped in clear-cutting. The subsoil is a good quality loam, but I have to import a lot of fertility to make things grow here. How do you keep growing crops in the same old soil, drawing out nutrients with each crop, without at some point adding fertility from somewhere else?”
Jan countered: “The key to continued fertility is to close the nutrient cycle.”
I reasoned that if nature can go from lesser fertility to greater, so could we. Even in pristine forests or grasslands, animals harvest and take away. They leave their poop, true, but they carry away all the energy they need to grow and maintain themselves. That is not returned to the soil until the bird or elk or bison dies.
Osker suggested that a harvest should not be a subtraction from the ecosystem. Clearly, this is possible: a farmer thins the forest he planted 15 years ago, so that all the trees have greater access to the sun; win/win. Relying more on perennial crops – mainly nut trees — is part of Osker’s strategy.
And so all this put a bee in my bonnet. Is it possible to garden in place without depleting fertility? Is it possible to work a field over generations without the soil sinking lower and lower, with the topsoil growing thinner and thinner?
Then I remembered John Jeavons. I took note of him way back when primarily for his effort to shrink the land needed to grow enough food for one person per year. Only now am I discovering his solution to the very question opened up by my friends on this blog.
To refresh folks’ memory, Jeavons runs a farm in coastal California where he decided to find out what is the minimum of land that will adequately feed a human with a vegetarian diet. He proposed 4,000 sq ft (8,000 with pathways etc.) and now has expanded those numbers to 10,000 in fertile situations and 16,000 in challenging situations. Over time, his experimentation developed into a whole system that has a number of components which are elucidated here.
I am not intending to evaluate his system. I will only alert you that his popular book How to Grow More Vegetables has a new edition coming out in July.
I do think that Jeavons has possibly resolved the puzzle of fertility maintenance or even – gasp – its increase. Jeavons – and this is stupendous – keeps only 40 % of his land for growing human food, and allots 60% of it to growing soil food. To feed the soil, he grows nitrogen fixers, carbon-rich crops, root-dense plants, and perennials with deep roots that bring up subsoil nutrients. (He is no slouch with humanure either). He carefully composts the lot, and adds buckets of it to the beds.
So here is my question. Is this the solution we have been looking for? I can see the face of an Amish farmer being told he has to plow up another 60% of his current fields, just to feed the soil. And why 60%? One of my annoyances with Jeavons is that he will make statements neither supported by an explanation nor by a reference to other sources. For example, he claims that vermicomposting is not suitable to his method because the worms make the nutrients too available. Who says?
Minor quibbling on my part. I walked a field this morning, 100 ft by 100 ft, and took in visually the area that would be dedicated to feeding soil. Huge! Feeding soil must precede feeding everybody else. What an idea! (I do believe that Jeavons does not strictly separate the soil feeding beds and the human feeding beds – for example, rye will give its grains to humans, but the bulk of the plant is pure carbon. And the decaying roots feed the soil directly.)
Feeding soil will not do you any good if you let it all run away in erosion. Crop rotation is a topic of its own, and so is minimal tillage. Rock dusts do not steal fertility elsewhere yet may help fertility in your garden (as they help the fertility of tropical islands lucky enough to lie within the plume of the volcanic dust). Wood ash enriches acidic soils, there are compost teas and plant brews, the word is still out on biochar (which can be easily obtained by burning some brush). Try throwing a little in your chicken coop along with some corn to encourage scratching, and soon the coop will have no dust, no smell, and no poop stalagmites. Later apply the bedding to your garden. No chickens? Here is a recipe: a bit of biochar, some worm castings, a bit of corn meal or flour, bit of pee and a bit of rock dust. Mix well, and let ripen a few days. Voilà!
This of course does not apply to those who sell their produce. They have to import fertility. But getting municipal compost or certain horse manures seems not so much like stealing, but recycling. Nah? Another thought… the ancient practice of letting land lie fallow (as long as it’s covered by vegetation, and grazed occasionally) can be thought of as a nascent glimmer of understanding that the soil needs to be fed.
But back to the main topic. Will the magic application of 60% soil food keep your-mine-our garden’s and field’s fertility increasing? Is this the solution we have been looking for 7,000 years?
Ecology Action garden
June 19, 2017 at 4:26 pm
What a great and thoughtful post. I’m familiar with John Jeavons and have How To Grow More Vegetables. It all sounds great but, as you say, he doesn’t back up his claims. Maybe someone should do some research on his ideas and pin down some of it.
Meanwhile, building up soil on 60% of the land couldn’t hurt. You are absolutely correct. We need to feed the soil so that it can feed us. People aren’t talking about peak oil so much anymore. Perhaps it’s time to work on peak soil.
June 19, 2017 at 4:40 pm
A number of authors have addressed this question–I did a review of several books about sustainable gardening and farming or resilience.org some time ago http://www.resilience.org/?s=multibook+sustainable .My favorite–largely because the author lives in Virginia and I live in West Virginia, in a similar climate, so her solutions work well for me–is Cindy Conner’s Grow a Sustainable Diet. She was trained by the Ecology Action folks. And here’s the thing–you don’t have to devote more land to compost crops than food crops–you have to devote more square footage-months to that. In other words, you can grow cover crops over the winter in many places for your soil-building operation, and that counts. Probably some places are so cold in the winter that nothing grows at all, and other places don’t have much of a winter off-season, but here in zone 6 you can pretty well count the whole winter, between harvest and sowing of cover crop in September, October or in some cases as late as November, and somewhere between April and June when you turn the crop under, or leave parts of it on the ground as mulch. That’s not going to get me to 60%, but it will get me fairly close. I should say, I am still trying to figure this out, how to make it work without any heavy equipment, in heavy clay soil (nutrient rich but low in organic matter). I still haul in manure and sand. My permanent bed , well fenced garden is in pretty good shape now and I turn it only with a shovel, but my two flat crop fields are a continuing headache…
June 19, 2017 at 5:50 pm
In Farmers of Forty Centuries F.H. King describes the farming practices of Japan, China and Korea around the beginning of the 20th century. Population per unit arable land was very high. Virtually every place that could be farmed was farmed. But their farming nutrient cycle was as closed as it could be, with most of the food waste from consumption in the cities returned to the soil as a liquid mix of feces and urine (all food and water was consumed after being cooked or boiled). Needless to say, all harvest residue stayed in the fields or was composted and returned to the fields. No organic matter was wasted.
Even so, biomass and other soil amendments were harvested from non-arable land, composted and applied to the soil. I doubt that the ratio of land harvested for soil amendments to land used for food crops was 60:40, but fertility was not maintained only by rotating food crops (such as beans to add nitrogen).
Those areas that can afford pasture have an easier time of it. With proper stocking rates, pasture can maintain a continuous harvest of high quality food in the form of meat with minimal labor. With proper paddock management, pasture grasses can recover completely after a paddock is grazed. Adding nitrogen fixers to the pasture makes it even more productive. But paddock rotation is just another form of fallowing. The land area always occupied by animals can never be as high as 40%. Three percent is more common (daily intensive grazing with 30 paddocks in rotation).
I think your basic point is correct. No parcel of land can be kept in continuous food production forever only by using food crop rotation to increase fertility (unless perhaps the food production was so sparse as to use the space between food plants as cover and fallow areas). A farm or garden can maintain fertility forever only by using significant area/months to produce nutrients. The more food taken off the farm, the bigger that fallow area or the longer the fallow time must be.
June 20, 2017 at 12:41 am
Vegetation for food can grow with certain wild vegetation that is naturally compatible with it, and the vegetation for food will be scattered among such, and there won’t be that soil depletion, nor will there be such problem with pests that concerns agriculture.
June 20, 2017 at 10:26 am
Nice avatar, Raven! 🙂 Peak soil is where it’s at. I really love the idea of starting a new bed, and giving 2/3 of it to crops that feed the soil. It’s one of my “eureka” moments! (Cheers me up no end.)
Frank, I think Musuoka interspersed clover with edibles… worked for him, but I hear people are having a hard time emulating his methods.
Thanks, Joe. Good to hear your thinking goes thataway too. I wonder if Chris could convince his customers to bring back their humanure in buckets. Probably not… but if we are talking the Republic of Wessex… surely, this topic would figure largely!
So Mary, how does Jeavons count the 60%? Say you plant 10 sq ft of rye, How do you figure the food for the human part, and the food for the soil part? Do you count the 10 sq ft twice, once for humans, once for soil? I am a bit befuddled.
June 20, 2017 at 1:41 pm
What Cindy Conner does (she loves charts and paperwork) is calculate how many beds (she has 36 I think, all the same size) are in crops versus cover crops for each month. If she grows rye for the grain, I would guess she would count it as partial, since the maximum value from it comes if you cut it at pollen-shed, which is in May in her area. Then you can dig out a couple furrows and plant some things right away, others need a couple weeks wait because rye has allelopathic qualities. The cut tops, which are about four feet long, can be laid down as mulch, or composted. But if you let it go all the way to ripe seed and harvest that in late June, you don’t get as much good out of the crop for soil feeding purposes, so maybe she’d count it as partial. It’s also true that it and other crops aren’t as beneficial if you cut them too soon, before flowering. Her book got me to try Austrian winter peas–the tops make good salad cuttings, are much like lettuce, and can be used much of the fall and winter and spring; they’re hardy in her zone 7 and maybe here in zone 6, fix nitrogen out the wazoo, and are easy to rip out in spring–unlike the rye. A professor who is a fruit expert came by here today, invited by my neighbor. She told me that if I plant brassicas like mustard, and till them under after 45 days, which I can do in spring and fall, it will fumigate the soil, reduce diseases and bugs as well as weeds.
SOME people think farmers are dumb hicks who couldn’t hack a real job! They have no idea how much there is to learn!
June 23, 2017 at 1:52 pm
If I understood the research correctly, the indigenes of the Amazon basin used a mound and ditch system. Leafy crops such as the Three Sisters were planted on the mounds and the ditches were filled with water into which fish were drawn out of the river, kept as livestock, and caught by weir traps for big feasts or for drying and smoking racks late in the season. When summer came, the ditches dried out, leaving edible water cresses and stuff usable as green manure that got heaped onto the mounds for next year. Also, they burnt stands of brush and added the charcoal to the soil. Terra preta, I think it was called. https://en.wikipedia.org/wiki/Terra_preta