In Chapter 2 I suggested using a soil-improvement program based on purchased amendments. Bur isn't this a book about raising food without spending much money: i have three reasons for saying what I did in Chapter 2: (1) because as I write these words in 2005, these materials are still inexpensive and readily available; (2) because when people first start a garden they likely won't have had time to make compost; and (3) because even with an ongoing composting operation in place, using complete organic fertilizer (COF) or something like it is still an excellent practice.
I repeat: leedlot manures and composted chicken manure are widely available and seem inexpensive to most people right now, and industrial agricultural wastes like seedmeals and slaughterhouse wastes are also cheap. But if present trends peak oil, climate change, irresponsible monetary manipulations by central banks, competition over resources — result in the least desirable outcomes, then ordinary people will find it ever more difficult to afford to eat healthfully. It seems almost inevitable ro me that the real (inflation-adjusted) cost of soil amendments is going to increase substantially. Composting is the alternative to purchasing. It allows small-scale food growers to make their own fertilizer, to manufacture "well-rotted manure'without the need to own livestock.
I need to make three brief apologies before gevcing into the substance of this chapter. I write by speaking intimately to imaginary people sitting in invisible chairs next to my computer monitor. I always envision these people as friendly, accepting, understanding. And for this book most of my imagi listeners are new, inexperienced gardeners, feeling a bit bewildered. Up Ct\J chapter I have tried to keep it simple, starting them off on the right f0ot * they'll discover by observation the rest of what they need to know. Bur th,' subject of composting is different. Making low-grade compost suitable f0r mulching ornamentals or fruit trees is not difficult. But producing conip0st that will effectively grow vegetables is a highly skilled activity requiring hard work, close attention, and a desire to "see" what is happening inside the heap This chapter cannot be "made simple," and for that I apologize.
And the second apology. The subject of composting is a huge one. Fifteen years ago 1 wrote a book as big as this one that was only about composting. There is no way I can talk about every aspect of composting in one brief chapter. The techniques I am going to describe in this chapter are the ones most likely to result in success for the new composter. If you want to learn the whole of compost making, there are heaps of books in print on the subject, but be prepared to sort out a lot of contradictory data.
Finally, please accept my apology for not lying to you. Many garden writers present every kind of composting as being inevitably successful and easy, portraying the result, always, as effective fertilizer. This is not actually the case. There are many composting pitfalls. If you can't afford to have your food gardening efforts fall far short of your hopes, if you can't afford to just shrug off this years catastrophe and hope it'll be better next time, you need the truth.
Hot all these reasons 1 suggest that you read this chapter more than once.
1 compost only to recycle garden and kitchen waste. Because 1 nevei tin up with enough of my own compost to satisfy my gardens need for humus, I also use well-decomposed feedlot manure, which is another form of compost« 1 buy feedlot manure because, like my own compost, it gives the soil better tilth and provides food for a healthy, stable ecology of worms, tiny soil animals, and microorganisms, whose activities are essential to keep my plants healthy. Compost also supplies plant nutrients, making the soil more fertile. (This last function could be performed by fertilizer instead.) Since neither my own compost nor the feedlot manure I purchase supply enough plant nutrients to grow a really abundant garden, 1 also feed my veggies COF
This approach seems inexpensive and practical at this time. Each year my garden goes through about three 50-pound (25-kilogram) sacks of scedmeal, one me
2 sack of meatmeal, one of kelpmeal (and the price of that always makes wince), one or two hefty little sacks of high-phosphate Peruvian guano, about 25 pounds (10 kilograms) of ordinary agricultural lime, the same amount of gypsum, and 50 pounds of dolomitic lime. In 2005, the cost of all that came in under $300. This expenditure grew about $4,000 worth of veggies if their value is calculated according to what I would pay for them at the supermarket ar the exact time 1 harvest them, which is an entirely unfair comparison. Still, spending $300 to produce an under priced i}>4,000 seems a sjrear exchange.
So each year I cheerfully pay out that $300 to maximize the nutritional qualities (and output) of my garden. But if my local farm supply store could not obtain the ingredients lor COR or if I could not afford them, I am glad to know I could grow almost as good a garden, producing nearly as nutritious an outcome, by putting out the effort to make high-quality compost and buying only a couple of bags of lime that would, at current prices, cosr me about $20.
Nature recycles. Everything that grows will eventually die, tall to earth, and rot or will be eaten by large animals whose manure falls to earth and rots. Eventually the animals themselves fall to earth, and rh eir bodies rot. The only example of a natural process I can think of that doesn't seem like recycling is when dissolved mineral nutrients end up in the ocean, which seems to be a huge permanent sink for nutrients. But even oceanic minerals recycle over geologic time.
Nature has designed wild plants to be capable of growing lustily in soil whose rather low fertility is stably maintained
Why do I say my veggies are "underpriced" at $4,000? Because I am not growing stale, flavorless vegetables. And no allowance is made for the superior nutritional qualities of my food Over the last two decades, according to official US government statistics, the average nutritional content of industrial vegetables has declined about 30 percent. And 20 years ago supermarket veggies still weren't the equal of home-garden stuff. I have no doubt that what I grow is at least twice as nutritious as the stuff in the supermarket and is easily worth S8.000.
That figure is still an understatement. Because I have been well-nourished for several decades, I need little medical attention, even though my body has arrived at its mid 60s Entirely disregarding the dollar cost of s.ckness, I do not disregard the cost of the suffering Add that to the value of my garden s output1 ■
I orsp„ic materials rotting on its surface. I discussed ,„ Chapter 2 how Vcg. ¿2 l-'king the vigor of wild plants, have come to reqmre higher ,evcls * nutrient'; in their soil and, often, higher than natural levels of organic m,tter Early farming in all English-speaking countries consisted of clearing the fo^ and then turning under the duff, a thick, half-rotted layer of leaves, bark, anJ other organic matter. The duff is the forests capital accumulation of centuries Dug in, it decomposes far more rapidly, resulting m a huge but temp0rary increase in fertility. Abundant harvests could be enjoyed — for a while. But without the annual nutrient addition from the forests falling leaves, with the export of soil nutrients as crops were sent to market, and without the addition of the manure produced by all the animals (including the humans) eating that food, soil fertility decreased, and all too soon the land was "worn out."
In this industrial era, exhausted land has been temporarily restored to heavy production by the use of chemical fertilizers. Were it not for the use of fertilizers, most of our croplands would be considered "worn out," and almost any soil a vegetable gardener uses these days may be too infertile to grow most kinds of vegetables. So increasing soil fertility is the gardener's main concern.
Since nature maintains fertility through the slow surface decomposition of organic materials and does not dig (except if you count the slow activities of worms), why not copy it: spread organic matter on top of the soil and let it rot. Will doing that grow a veggie garden? The answer is a qualified yes. It will grow veggies in climates where the soil freezes solid in winter and where summers arc hot enough to rot the mulch rapidly. To get the best possible result you have to mulch with something rich in plant nutrients like alfalfa (lucerne) hay or pea straw, or else fortify infertile spoiled hay and autumn leaves with strong manure or heavy sprinklings of the same seedmeals that make up COF. Here are some more negatives.
' prevent'0'1 ^ **Ic the hoe but fails to completely
SHedha;if;urgintlf youVe muichin^ °n the cheap-with seed. You'll end u, Mmulcane°usly sowing huge quantities of grass would do if you'd no SpC|fng m0re dme PatrolIing for weeds than you a hoe. n°C °d and lear"ed instead how to properly sharpen
Mulching keeps the surface moisr but does not, as claim d k enthusiasts, significantly reduce moisture loss. Soil moistur as plants transpire water, not as the sun shines on bare earth" ^^
It works out to be less effort and far more effective to heap-compost enough organic material to maintain soil humus at healthy levels and then use something like COF or poultry manure compost as fertilizer, when needed, on medium- and high-demand vegetables. Mulch gardening does make sense for someone who is weak or whose physical mobility is restricted, someone like 70-year-old Ruth Stout, the author of Gardening Without Work, which started the whole mulching mania, someone too frail to wield a shovel or hoc but who can manage to carry a flake of hay to throw atop a weed coming through an who can afford to get someone to haul in and stack multiple truckloads of spoiled hay bales for her. , , ,
Mulching? I've been there, done that! If you want to reinvent the w e well, a lot of gardeners do. I reinvented quite a few wheels myself.
Carbon to nitrogen ratios , , mT .om.
Y°u can predict how any particular material will behave -hen fc«« Posted, and how well ir can fertilize plants after decomposition, d>
absolute standard of comparison - the C/N of so,l. ' Except in the driest hottest deserts, where the earth contains no organic atter J Soil contains humus, the stable residue of decomposed organic mat. tcr Humus is a complex substance highly resistant to further decomposition, k docs eventually break down completely and vanish from the sod, but that happens very slowly.
Soil humus has a carbon-nitrogen ratio of around 12:1 m every climate, in every soil. Amend soil with something decomposable and the amendment will be converted into a far smaller quantity of humus. If the original C/N of that material is higher than 12:1, the soil microbial population will"burn"its
Carbon nitrogen ratios
Horse manure *
Cow manure *
Seaweed legume hulls
Grass hay (green)
* Containing no bedding t The glues used contain a lot of nitrogen, lowering the C/N compared to paper Figure 7.1
carbon for fuel while preserving rhe nirrogen until the C/N lowers rhar Q( the surrounding soil. At the end of this burning off there wiltp'ba bly be a higher level of humus in the soil then there had been before the soil was amended. In simple terms, the soil becomes healthier and will havebml tilth. Also, once the average C/N (soil plus amendment) comes close to 111 rhe plant nutrients that had been contained in the undecomposed organk matter become available to plants growing in the earth; again in simple terms", the soil becomes more fertile. Why did the soil not become more fertile immediately? Because until all the amendment is eaten, the soil microbes assimilate rhe nutrients and withhold them from the plants.
If soil is amended with organic material having a C/N lower than 12:1, the opposite happens. To increase the C/N to match that of the surrounding soil, different sorts of bacteria will convert the surplus nitrogen to ammonia gas. 1 his reduction of nitrogen content continues until the stable desired ratio of humus, 12:1, is reached. The ammonia is almost instantly converted by other soil-dwelling bacteria into water-soluble nitrates, first-class fertilizer that makes plants grow fast. The resulting higher soil nitrate level also encourages soil microbes to multiply. More of them means they more aggressively attack humus. The end result is a soil with a slightly lower quantity of organic matter than there was before this low C/N material was mixed in. This loss of humus is also what happens when chemical fertilizers are added to soil, which is why organicists are so strongly opposed to the use of chemicals.
This deserves to be said again. If we put something into the soil with a C/N below 12:1, whether it is chemical or "organic," the consequence is the immediate formation of nitrates. The plants rapidly start growing faster, but when it is all over we have slightly reduced the soils humus content, meaning a less-healthy microbial population and poorer tilth. If we decompose high C/N organic matter in soil, the result is that soil microbes co-opt nitrates and other plant nutrients present in the soil in order to eat that organic matter. For a time the plants grow less well. Bur when things settle back down, we have increased the soils humus level and its fertility. And after the main decomposition, the plants grow better than before.
Finally, the higher the C/N of the amendment, the longer it takes to decompose; die longer the soil chemistry is disordered, the longer we have to wait before our vegetables grow well. That wait can be ruinous. Many gardens have been wrecked for an entire growing season or even longer because thCy were heavily amended with high C/N materials.
Here's another good idea: Fertilize by spreading a layer of nutrient-rich, decom. posable, organic matter atop the soil and then shallowly digging it in. Things rot much faster when they're mixed into well-oxygenated soil than when they're merely spread on the surface. This method, called "sheet composting," will grow a good vegetable garden — if you do it far enough in advance that there is time for it to decompose before planting time. And if you are sheet-composting fresh animal manure, it only works well as fertilizer if you spread fresh manure and, in hot sunny weather, incorporate it immediately after spreading it. In a personal e-mail, a Texas farming consultant I am acquainted with said of this:
Throw manure on the top of the ground on a cool day without wind and the values might hold tor several days. Put the same manure on the ground in 98 degree sunshine on a windy day and you will lose 25
percent ot the nutritional values by sundown. The best with manure is to put it under the soil as quickly as possible — the shortest dwell time between the cow and the soil means the highest efficiency of conversion.
Farmers raising livestock frequently sheet-compost. They haul a few days accumulation from the barn or loafing area to a field, spread it over a small parr of that land, and immediately disc or rototill it in. Over the course of a month or so, they fertilize an entire field.
In the North American garden, vou ran k • > , iust after the <W fV» - j \ " bnng ln * load of fresh manure just after the hrst frost, spread it, and shallowlv disr ir a l-
there wouldn't be a huge loss of nitrogen if it jA* At C0°' ^^ ir under. You can sheet-compost with 7^ " ^ ^
mighty difficult to spade in grass hay; alfalfa^ but * *
expensive. Short grass clippings and leaves can be cW R '
ing of digging in high C/N vegetation, keep in mind ,y°U're think" needed to decompose it depends on the following thin " ^^ °f
Immediately after the blanket of decomposable material is dug in, the soil ecology begins to consume it. Microorganisms multiply incredibly rapidly on this new food supply. If the soil is warm, in a few days they'll be going at the material in much the same way yeast fills a brewing vat. These microbes obtain the raw materials co construct their bodies by gobbling up almost all the available mineral nutrients in the soil around them, nutrients chat plants would otherwise use to grow with. The microbes especially need nitrogen compounds to form proteins, but they also need all the other usual plant nutrients: phosphorus, potassium, calcium, magnesium, etc. In other words, when undecomposed organic matter is mixed into soil, even though chac organic matter contains a loc of plane nucriencs that will become available after decomposition, these nutrients are not soluble, are pocencial, are not available yet. Bur the organic matter creates a microbial bloom whose need for nutrients is so great that plants growing there are deprived of- nutrients.
Strange, isn't it! You sheet-compost to fertilize, but for a time the soil becomes less fertile. As the microorganism population busily"burns"the carbon, they also incorporate plant nutrients contained in the organic matter into their bodies. Microorganisms are more aggressive than plants in this respect. They get what they need first. Only when this new food supply has been almost entirely consumed does the population of decomposers begin to die for lack of fuel. At this point the plant nutrients held in bacterial bodies are released back into the soil for the plants to use. Some of these nutrients will be simple water-soluble chemicals, much like those that are applied as fertilizer. But some of them will be in the form of complex organic chelates that nourish the plants much as vitamins nourish humans. To be folly healthy, to achieve the highest nutritional quality for the humans using them as food, vegecables need co assimilate a goodly portion of their nutrients from decomposing microorganisms.
Like every other organic chemical or enzymatic reaction, che speed ot sheet composting depends on soil temperature. In moderate or short-season climates it goes slowly in autumn, does not happen at all dUl, resumes in spring, and by the time the land has warmed up enough ro ' heat-loving crops, the decomposition process will almost certainly have ^ completed - unless the material being sheer-composted started extremely high C/N. In early spring, because massive decomposition js ^ going on, chill-tolerant spring crops may nor grow well, so in regions with freezing winters, avoid autumnal sheet composting on beds where spr,n, crops will be going in unless you're using low C/N material - and not to! much of it. Where the soil does not freeze or chill too severely during winter, sheet composting goes on much more rapidly, unless there is sawdust (incredibly high C/N) mixed into the manure.
You can sheet-compost in spring or summer it you can afford ro have some land out of production during the prime growing season. In warm soil it usually takes around six weeks for decomposition ro proceed ro the point where vegetables get the benefits of all the nutrients added. I liar's six weeks if the average starting C/N of what was turned in was no higher than 30:1 and the layer being amended isn't over an inch (2.5 centimeters) thick. A few more cautions:
material. If you're sheet-composting ro start TT *
low-potency horse/cow/sl Jp .Jure ™ ^^f ^ cers) thick. Avoid having much bedding maten ^ ^ T'"
7.1 explains why). Don't sheet-compost a thick layer ofa T ( ^
1 UI autumn leaves and woody grasses of late summer on a brand-new Dlcr(. n( ■ c Thcsc materials also have a high C/N (consult the ta^rfT^ Calcium and magnesium are just as vital to the format,on of protein as they are to making plant protein. I wouldn't like to h readers discover in spring that their sheet composting had not fimshTd and that nothing would grow well until midsummer. This is a common catastrophe.
* S nor w,se to shcet-compost with poultry or rabbit manure; these strong, low C/N materials arc best used as fertilizers. Plants will grow better immediately after low C/N materials arc mixed into soil — if you don't mix in too much and end up poisoning the plants. However, if you are sheet-corn-posting leaves and dried vegetation or old dried manure, and the average C/N of this stuff is high, the average can be lowered a lot .and the whole composting speeded up considerably by including a thin layer of poultry or rabbit manure. It is the average C/N that determines the outcome.
Sheet composting is risky. Before you incorporate organic matter into soil it is safer, and the outcome more certain, if you decompose it first so its C/N is lowered until it approaches 12:1. This is done with heap composting, which will be explained later in this chapter.
Temperat ure and decomposition
I have already mentioned that the speed at which organic chemical and enzymatic reactions go on is determined by temperature. To repeat: The rule is that for every 10*F (5°C) increase in temperature, the speed of the reaction doubles. This increase is geometric (with each 10c F increase, the speed goes from 2 to 4. 8. 11>. 32. 64, 128, 256). not linear (the speed goes from 2 to 4. & 8, 10. 12). It is not quite that simple, however, because organic chemicals and enzymes are not able to withstand high temperatures. Enzymes arc usually destroyed at around 120°F (50°C); a few, such as the enzyme that converts brewer's malt into a sugary wort or the enzymes that can work in a steaming hot compost heap, can handle temperatures as high as 155*F (68cC). If its hotter than that, the enzymatic reaction instantly and permanently ceases.
The temperature at the soil's aUr&ce under a thick mulch during summer is cooler than the air temperature. In summer in the northern United States.
. „Iched soil might be no more than 75T (24°C) averaged t^Ts Decomposition is slow at that temperature, so rhe release of ^ 24 L Ikh is slow. A six-inch-thick (15-cennmeter) layer of spoiled h,y £nCS straw might take a year to decompose at the average year-round Cem. pcnture of temperate climates, both because of low average temperatures and also bccausc only the material in direct contact wuh the sod „ decomposing ■ ficant speed. There will not be many plant nutrients being released. ^ ^ButTuppose you took the same amount of hay before it spoiled, passed it through a cows gut. and then spread the cows manure (and unne) and sheet-composted it. All that material is now in close contact with the sod. It was also thoroughly mixed with the cows digestive enzymes and inoculated with all sorts of intestinal microoganisms. In this case, the process of decomposition is pretty much completed in only a few months, even m the ch.lly soil of spring. The nutrients are released much faster and the sod becomes much i* * •
What is this thing called compost ?
Composting decomposes organic materials before they are put into the soil so they have become instant plant food. Compost contains large quantities ot recently deceased soil microbes, whose nutrient-rich bodies are virtually water soluble. It resembles loose, dark brown soil. With luck, it is mostly humus.
This sort ol compost only forms during an intentional, controlled, microbial ferment, much the same process used to make beer, wine, yogurt, sauerkraut, vinegar, aged cheeses, or tempeh. Food fermentations are delicious, but only when made with precision. Ferments can also be done casually, with highly erratic results. It is the same with compost.
For the ultimate in erratic," take my grandmother Annas Rosh Hashanna wine. Grandma Anna always made a batch of kosher grape wine for the High Holy Days A month before the big event she would buy a few pounds of
Pl|,rF>1C1 ^ gT and CrUSH tHem ber hands into a big m.xing bowl. Then everything skins, seeds, twigs, juice, bowl - was co*
ered w, h a piece of cheesecloth to keep rhe fruit flies out. The bowl sat on the kitchen counter. It was too ear y in the vear m e
. . ' meycar to start fir ng the coal furnace, so unless the oven was go.ng, the temperature in the kir I I
the same as whatever the temperature outs.de w/, ^ pretty much r uts.de was that ycar. Wild yeast arrived on the skins of che grapes themselves, so, of course, the yeast was dif ferenc every year. 1 he sugar content of the grapes fluctuated wildly fr0m vea'r c0 year because sometimes they were purchased before they were fully „ (the dare of Rosh Hashanna was calculated on the Jewish lunar calendar sTk could be any time f rom mid-September to mid-October). If the juice seemed a bit tart, Anna might add a cup of white sugar. And of course nothing was sterilized before she started, so all sorts of other microorganisms contributed ro the fermentation, including the ones that make vinegar. The mash would bubble away for a few weeks, and then Anna would pour it through a strainer. With most of the sediment removed, she would pour the raw wine through a few layers of cheesecloth to remove the fine particles, then pour it into an old whiskey bottle. If this wine sat around for only a week or two before the big Holy Day meal, it wouldn't be roo vinegary when we sipped it in tiny glasses. You may be sure that no one drank more than the required minimum to sanctify the event.
Serious winemakers would never do as my grandmother did. They precisely regulate every aspect of the process — the temperature of the fermentation, the exact sugar content, the sterility of every utensil. They would carefully select .1 pure strain of yeast to suit the type of wine being made. And despite all those controls, the result still varies, which is why we have gourmet magazines and wine experts.
People who make homebrewed beer know exactly what I mean. Some homebrew is really foul. Oh, if you raise the octane high enough with table sugar it'll get you drunk, but it'll have a sour aftertaste, like hard cider does when it is made with baking yeast, and if you drink more than one bottle you'll have a splitting head the next morning. But homebrew made skilfully with the best ingredients, then aged for a few months on the shelf before you pop the cap, can be so superior to most industrial beer that you can hardly stand to buy the ordinary stuff.
Let me underscore the two essential differences between a talented vintner's wine or a proper homebrew and what my grandma Anna did. (1) Complete control of the conditions. (2) Standardization of materials — regulation of &!gar content, the correct pure strain of yeast ro inoculate the ferment. The same is true of making compost. If you avoid a few big mistakes while tossing almost any material that is handy into a heap, get it damp, and let ir work, you II
192 gardening when it counts
192 gardening when it counts f a sort But if you want high-quality compost tl, CnCl ^ Withifi«ntPthmls.you have to be actively and intelligently in ^
every part otche process.^ ^^ frQm home gardeners to a degree.
|his reality i ^ ^ gardening m0vement was fomenting a SOcial because the organ y ^ ^^ ^ ^ ^^ Fqi. propaganda purposes it Wj5
rarrmthatau'eompost was good compost, and that any compost would
Was this article helpful?