nitrogen – Lee Reich

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FERTILIZING 101

October 6, 2021/20 Comments/in Soil/by Lee Reich

Feed Sooner, Not later

Although shoot growth of woody plants ground to a halt weeks ago, root growth will continue until soil temperatures drop below about 40 degrees Fahrenheit. Root and shoot growth of woody plants and lawn grass are asynchronous, with root growth at a maximum in early spring and fall, and shoot growth at a maximum in summer. So roots aren’t just barely growing this time of year; they’re growing more vigorously than in midsummer.

Compost mulch on pears Remember the song lyrics: “House built on a weak foundation will not stand, no, no”? Well, the same goes for plants. (Plant with a weak root system will not be healthy, no, no.) Fertilization in the fall, rather than in winter, spring, or summer, promotes strong root systems in plants.

By the time a fertilizer applied in late winter or early spring gets into a plant, shoots are building up steam and need to be fed. Fertilization in summer forces succulent shoot growth late in the season, and this type of growth is susceptible to damage from ensuing cold.

They Hunger For . . .

The nutrient plants are most hungry for is nitrogen. But nitrogen is also the most evanescent of nutrients in the soil, subject to leaching down through the soil by rainwater or floating off into the air as a gas. The goal is to apply nitrogen so that it can be taken up by plants in the fall, with some left over to remain in the soil through winter and be in place for plant use next spring.

Two conditions foster nitrogen loss as gas. The first is a waterlogged soil. If you’re growing most cultivated plants — yellow flag iris, marsh marigold, rice, and cranberry are some exceptions — your soil should not be waterlogged, aside from considerations about nitrogen. (Roots need to breathe in order to function.) Nitrogen also evaporates from manure that is left exposed to sun and wind on top of the soil. Manure either should be dug into the soil right after spreading, or composted, after which it can be spread on top of the soil, or dug in.

Leaching of nitrogen fertilizer is a more common and serious problem, especially on sandy soils. The way to prevent leaching is to apply a form of nitrogen that either is not readily soluble, or that clings to the soil particles. Most chemical fertilizers — whether from a bag of 10-10-10, 5-10-10, or any other formulation — are soluble, although a few are specially formulated to release nitrogen slowly.

Fertilizer label The two major forms of soluble nitrogen that plants can “eat” are nitrate nitrogen and ammonium nitrogen. Nitrate nitrogen will wash right through the soil; ammonium nitrogen, because it has a positive charge, can be grabbed and held onto negatively charged soil particles. Therefore, if you’re going to purchase a chemical fertilizer to apply in the fall, always buy a type that is high in ammonium nitrogen. The forms of nitrogen in a fertilizer bag are spelled out right on its label.

Go Organic

Rather than wade through the chemical jargon, nitrogen loss through the winter can be averted by using an organic nitrogen fertilizer. Nitrogen in such fertilizers, with the exception of blood meal, is locked up and held in an insoluble form. As soil microbes solubilize the nitrogen locked up in organic fertilizers, it is released first as ammonium nitrogen. So by using an organic nitrogen source, the nitrogen is not soluble to begin with, and when it becomes soluble through the action of microbes, it’s in a form that clings to the soil particles and not wash out of the soil.

(Except in very acidic soils, other soil microbes then go on to convert ammonium nitrogen to nitrate nitrogen. This reaction screeches almost to a standstill at temperatures below 50 degrees Fahrenheit, so the ammonium nitrogen can just sit there, clinging to soil particles, until roots reawaken in late winter or early spring.)

Common sources of organic nitrogen include soybean meal, cottonseed meal, fish meal, and manure. Hoof and horn meal, leather dust, feather dust, and hair are esoteric sources, though plants will make use of them as if they were just ordinary, organic fertilizers. Even organic mulches, such as wood chips, straw, and leaves, will nourish the ground as they decompose over time. Fertilizer application Woor chip mulching

The Cadillac of fertilizers is compost. Compost offers a slew of nutrients, in addition to nitrogen, released slowly into the soil as microbes work away on it. Compost — most organic fertilizers, in fact — are not the ticket for a starving plant that needs a quick fix of food. Compost bins

Every year I spread compost an inch deep beneath especially hungry plants like vegetables and young trees and shrubs to keep them well fed. Less hungry plants get one of the above-mentioned organic mulches. The benefits of these applications continue, trailing off, for a few years, so annual applications build up continual reserves of soil nutrients, doled out by soil microbes, that translate to healthy plants and soil. Composted garden beds
(More details about fertilization can be found in my book Weedless Gardening.)

COMPOSTING, A DIDACTIC & A PERSONAL VIEW

October 14, 2020/10 Comments/in Soil/by Lee Reich

Start With The Carbs

A bit of chemistry might be good for your compost. Just a bit. Actually, we mostly need to deal with only two familiar elements of the 100 plus known ones. These two elements are carbon and nitrogen, and they are the ones for which the “bugs” that do the work of making compost are most hungry.

“Work” is too strong a word, though, because these composting bugs do nothing more than eat. Nonetheless, a balanced diet — one balanced mostly with respect to carbon and nitrogen — does these bugs, the composting microorganisms, good.

This time of year, the microorganisms’ smorgasbord is set with an especially wide array and abundance of carbon-rich foods. You can identify these foods because they are old plants or plant parts. As such, they are mostly brown and mostly dry. Autumn leaves, for example. Other carbon-rich foods include wood chips, straw, sawdust, hay, and even paper, made — after all — from wood pulp or other old, dry plant material.
Haystacks and compost piles

By far the bulk of high carbon — carbohydrate — foods for my compost organisms this time of year is hay that I scythe from odd corners here and there in my meadow. (Most of the meadow gets mowed by tractor once a year.) The hay is a mix of a wide variety of plants, mostly various species of grasses and goldenrods, but also, depending on where I cut, loosestrife, asters, New York ironweed, Joe Pye weed, and others. That varied mix is good for a compost pile; those microorganisms, like us, thrive on a varied diet which provides a slew of macro- and micronutrients which then end up in the finished compost and then my vegetables.

Next, Some Proteins

Just as we humans cannot live on bread and pasta alone (carbon-rich foods), so it is with composting microorganisms. So let’s now peruse the smorgasbord for some nitrogen-rich fare. This would include green stuff: young, succulent plants and plant parts. There’s not a whole lot of this stuff around this time of year, but there is some, including grass clippings, kitchen scraps, and microbial fare such as old, spent tomato, broccoli, pepper and other garden plants.

My scythed hay also provides some nitrogen-rich food — early in the season when its lush and green and only a foot or two high. But it has to be used in moderation because there’s not a whole lot of carbon-rich foods early in the season. Except that is, for the previous autumn’s fallen leaves and arborist wood chips that I stockpile. I also make some haystacks to save late-season hay for use in winter and early in the growing season.

Early season scythings

When there’s insufficient nitrogen foods to balance out all the carbon foods you could now find for your compost, it’s time for dietary supplements. Nitrogen-rich supplements for the compost pile include manures and nitrogen fertilizers. Manures usually also add some carbon food, in the form of the straw, wood shavings, or whatever else the animal was bedded in.

No need to get out the chemistry set to analyze how rich a food is in carbon or nitrogen so that you can get them in exact balance (which, if you must know, is a ratio of 20:1). Just keep in mind that the younger the plant part, the richer it is in nitrogen. Also that rabbit manure is richer in nitrogen than is chicken manure, which is richer than, going down the line, sheep, horse, duck, cow, and, finally, pig manure. Nitrogen fertilizers are very concentrated sources of nitrogen.

If I need to supplement the compost diet with extra nitrogen, from fertilizer, I use something that acts organically in the soil, such as soybean meal, which is readily available from feed stores. Its nitrogen is released as various microorganisms feed on it.

Pile It In, and Monitor

So pile anything and everything that was once or is living into your compost bin, balancing carbon-rich foods with nitrogen-rich ones. After garden and backyard cleanup is finished for the season, the scale tips the other way as vegetable scraps become the most significant additions to your compost pile. Balance the food value of this nitrogen-rich material with an occasional cover of wood chips or hay from a pile you keep handy next to your compost bin.

The most important thing in making compost is a good bin. A “good” bin will keep scavengers at bay, be a barrier to weed seeds that might waft into the finished compost, is convenient to fill and empty, and maintains moisture and warmth within. It also keeps everything neat, looking like a compost pile rather than a garbage pile.

If you want to see how you’re doing as a compost “bug” dietician, monitor the goings on within your pile with a long-probed thermometer and your nose. If the materials are moist and outdoor temperatures not frigid, the well-fed pile will be decidedly warm — 120 degrees F., or more. Lack of heat reflects an excess of carbon-rich foods or insufficient water; odors are the result of excess nitrogen or too much water.
Compost thermometer

I take care of my pile’s water needs in two ways. First, when I build the pile I add materials of various texture so that the mix drains well — but not too well so that it can’t cling to sufficient moisture. A lot of water is needed to really wet the innards of pile. Add a lot of material to a compost pile at one sitting and you’d have to stand there, hose in hand, for a long time to really wet it. I’m not that patient, so the second way I take care of the pile’s watering needs is to hook up a small, static sprinkler to a hose along with a valve for adjusting the width of the spray to only cover the top of the pile. About 20 minutes of watering does the trick. (I periodically check moisture deep within the pile with a long-probed moisture meter.)

Keeping records of what you add to your compost pile and how it responds helps you remember what you did right and wrong. But “wrong” is too strong a word, because the material you put in your compost bin

Compost happens bumper sticker

will always turn to compost. As my bumper sticker reads, “COMPOST HAPPENS,” even if the process takes longer or becomes “aromatic” along the way.

For me, making and spreading compost is as rewarding and enjoyable as is gardening per se.

(For more about making compost, using it most effectively, and buying compost, see my book Weedless Gardening.)
Composted garden beds, S garden

SUSTAINABLE DIRT

November 19, 2015/13 Comments/in Gardening, Planning, Soil, Tools, Vegetables/by Lee Reich

Dirt is Free, Almost

   Sustainability is such a buzzword these days. Okay, I’ll join the crowd and say, “I’m growing fruits and vegetables sustainably.” But is this true. Can they really be grown sustainably, that is, in such a way to be able to continue forever?
   As any plant grows, it sucks nutrients from the soil. Harvest the plant and you take those nutrients off-site. Eventually, those nutrients need replenishment. That’s what fertilizer does, but spreading fertilizer — whether organic or chemical — is hardly sustainable. Organic fertilizers, such as soybean meal, need to be grown, harvested (taking nutrients off site), processed, bagged, and transported. Chemical fertilizers need to be mined and processed, or manufactured, and then also bagged and transported.
   About half the volume of most soils is mineral, the rest being air, water, and organic matter. The mineral portion derives from rocks that, with time, temperature changes, and the jostling and chemical action of plant roots, fungi, earthworms, and other soil microorganisms, are ground finer and finer. Plant nutrients once locked up in those rocks become soluble and available to plants. Over time, a soil naturally offers a pretty much unlimited supply of plant nutrients. That sounds sustainable . . . but wait; three important caveats.
   First, it takes time to release those nutrients. Remove too much too fast and it’s like taking money out of the bank faster than you put it in.
   Second, one very important nutrient, nitrogen, does not come from rocks. It comes from the air, “fixed” by soil microorganisms, then incorporated into plants. As plants die, the nitrogen is incorporated into the organic fraction of the soil, from which it is slowly released into the ground for other plants to use — unless it washes away or becomes a gas again. Nitrogen is the most evanescent of plant nutrients.
   And third, a soil could be naturally lacking in one or more essential plant nutrients. If so, the deficiency needs to be corrected by bringing in and spreading what’s needed.

Hay, Time, & a Little Manure

Okay, here’s my stab at sustainability: My vegetables get “fed” only compost, a one-inch depth laid on top of each bed each year. This much compost releases enough nitrogen, as well as other nutrients, to keep plants happy and healthy for a year.

The season’s last hay gathering

   But the sustainability meter must examine what goes into the compost. The bulk of my compost is made from hay harvested from my one acre hayfield. Here’s the rub: If I harvest the hay too frequently, I’m mining the soil, pulling out nutrients faster than they are naturally replenished. So I focus on different parts of the field in different years, giving previously harvested portions time to rejuvenate.
   Early morning forays into the field with my scythe provide enough hay for compost making during the growing season. Last week, I did what I do each fall, attaching the brush hog to my tractor and mowing the whole field. (Mostly, this prevents the field from morphing over time, first to a field of brambles, multiflora roses, and autumn olives, and then on to forest.) After brush hogging, I rake up a few clumps of hay here and there for the final “feeding” of the season’s compost piles.
   This end-of-season stuff is not very nutrient-rich, so what little I harvest takes little from the field in terms of nutrients. This cutting mostly supplies carbon compounds, which it got from via photosynthesis from carbon dioxide, to feed the compost microorganisms.
   Keeping an eye on the character of the hayfield should give me some idea of how it’s doing nutritionally. More grasses, more nutrients. Areas of goldenrod, yarrow, and other forbs get mowed, but not raked.
   My compost pile also gets fed horse manure that I haul in from a local stable. My use of manure is sustainable only in the sense that it’s someone else’s waste product. Other additions to my compost pile are kitchen scraps and spent garden plants (which recycles rather than adds nutrients), and old blue jeans and other biodegradable clothing. Using humanure (see The Humanure Handbook by Joseph Jenkins), if I had a composting toilet, would further close the nutrient cycle.
   Two final additions, sustainable except that they need to be transported here, are ground limestone and kelp. The limestone holds soil acidity near neutral, which, among other benefits, puts nutrients in forms most accessible to plants. The kelp, replete with a spectrum of micronutrients, is for insurance, just in case my soil naturally lacks any essential plant (or human) nutrient.

And Now for the Cart’s Sustainability

Garden cart, all dressed up in aluminum

    Hay is bulky stuff; same goes for manure. I move all that bulky stuff to my compost piles, then move the finished compost away from the piles. All this moving is done with the help of my “Vermont garden cart,” which has two heavy duty, bicycle-sized tires sitting just about midway across a sturdy plywood bed surrounded by three sturdy plywood walls. Although the cart can haul up to 400 pounds, shoveling out manure or compost scrapes away at the plywood base. That, along with jabs from the pitchfork as I pile in hay severely compromised the wood . . . until this summer.
   A sheet of aluminum, a friend’s brake for making sharp bends in the sheet, and some screws, and I had the bottom of the cart, and a few inches up each side, protected from my shovel, pitchfork, and moisture. These carts should be sold already aluminized.
   The only problem is that aluminum is very unsustainable. Although abundant, enormous amounts of electricity are required to free it from the raw material, bauxite. On the plus side, aluminum is very long-lasting; I’ll never have to replace it in my carts.