Joe’s Journal: Winter Edition – Bed Prep, part 3
Welcome to part 3 of bed prep for spring. In part 2, we discussed what to plant and how to prepare the soil. Read that part before continuing on.
The alkalinity or acidity of soil determines mineral availability. The pH scale, a measure of hydrogen ions in solution ranges from 1 to 14, where a pH of 7.0 is neutral; values <7.0, acidic, and values >7.0, alkaline. Why is pH important? Acidic soils favor the ionization of metals (including iron, manganese, zinc, copper and boron). These are the micro-elements, essential to plant health and growth, but required in small amounts (in parts per million). Slightly acidic to slightly alkaline soils favor solubility of macro-elements (nitrogen, phosphorous, potassium, sulfur, calcium, magnesium) that are required in larger quantities measured in percentages. The “sweet spot” for many plants is a pH range of 6.5 to 7.0, where both the macro- and micro-elements are most available for root absorption. Acidic soils may be treated with limestone to increase pH. Alkaline soils may be treated with sulfur-based products to lower pH (an example is Ecologel’s Nutralyz (12-0-0-26S), an ammonium thiosulfate solution). However, the best buffer in soil to cultivate is organic matter.
Improving the Un-improved Soil: Composting, Cover Crops & Mulches
In simple terms, compost is simply a mix of organic matter. Organic matter is something that once was living. Composts (literally, a mixture) then, by definition, may take different forms. If you are raising farm animals, for example, your compost is likely a mixture of straw bedding and animal manure. Not bad…actually almost perfect! To understand compost, we need to talk a bit about carbon to nitrogen ratios.
A Bit About Carbon to Nitrogen Ratios
Carbon in the realm of composting is “brown” materials. Examples are dried leaves, straw, woodchips, paper, cardboard…you get the idea! Nitrogenous sources are the green materials, such as fresh grass clippings, kitchen scraps, and fresh trimmings.
Micro-organisms prefer a mix of carbon to nitrogen in a ratio of around 20 to 1. That is, 20 parts carbon materials to 1-part nitrogenous materials. Fresh woodchips are anywhere from 100 to 500 parts carbon, depending on who you talk to or your source of woodchips…let’s call it 200. This means that we need 10 parts of nitrogenous (green) materials to break down the woody material. Let’s make it even simpler: for every 20 shovelfuls of woodchips, you need 1 shovelful of nitrogen-based material.
OK, no one that I know is so fastidious, (not me anyway)! However, compost happens even in the face of benign neglect. So not to worry: raw organic materials want to become compost! But there are some attributes of composting that you ought to pay some attention to: for one, it is an aerobic, thermogenic (heat generating) process. This means that the compost pile needs air infiltration to allow the aerobes to decompose the pile. Though not nuclear science, an important aspect of creating a thermogenic pile is size. The pile will heat up when it is at least 4’ high, the critical mass. Why is this important? Organic matter that reaches high temperatures (140 to 160F) are hot enough to kill weed seeds and diseased plants. To be sure you have a well oxygenated pile, you can turn it to aerate it. Or, if you are like me, start with bulky materials (woodchips, small branches, etc.) and drill holes in a PVC pipe that forms a “chimney” for gas exchange to keep those aerobic decomposers healthy (at the same time eliminating turning the pile)! Add organic materials to build the pile up to four feet high and wide. There are many designs for compost construction. I use wire fencing, rebar and zip ties.
So, what if you don’t have the right mix of carbon (brown materials) and nitrogen (green materials)? What then? Well, you could, or just make a pile of leaves. A slower process of decomposition certainly, but will result in good quality organic matter, called leaf mold. It is lower in nitrogen (i.e., slim to none), but incorporated as an organic amendment to soils or alternatively, as a mulch, it’s hard to beat.
To speed things along, run a mower over leaves a bit at a time (4” layer) to increase the surface area where decomposition can take place. Better still, if you have a shredder /chipper run the leaves through. Do this in the fall months, you will have a great product to amend and mulch in the next growing season.
Cover Crops (i.e., Got you Covered!)
Cover crops or green manures: what are they and why do it? Growing live plants combining particular plant species can mimic the composting process in place! Here’s how it works. Grasses have dense, diffuse roots that penetrate deep into the soil and when tilled, are a source of carbon. Examples of grass cover crops are annual ryegrass and oats. Consider legumes as your nitrogen source. Leguminous roots infected with Rhizobia bacteria fix nitrogen from the atmosphere. Examples are clovers (crimson, red, white, sweet), hairy vetch and field peas. Plant a mix of grasses and legumes, and you just made a living compost pile. Plant in fall, till under in early spring, 30 days prior to planting your beds. Compost (and weeds) managed!
Cover crops may be sown spring, summer or fall. Mixes for spring plantings, which are turned into the soil in summer may include a mix of legumes and grasses (for example, field peas, oats, hairy vetch). Summer mix may include field peas, beans, clover, and oats. Fall mix may include winter rye, winter wheat and Austrian winter pea and/or crimson clover. Sources of online seed include:
- Albert Lea Seed
- Cover Crop exchange
- Hudson Valley Seed Co
- Urban Farmer
Your local agricultural supply store also carry cover crop seeds, and will likely mix seed to your specifications.
Mulches and Mulching
The word mulch dates back to the 1650’s middle English meaning “soft moist”, a “strawy dung, earth, leaves to protect shoots or newly planted shrubs” (www.etymonline.com). Interesting. The implication here is that mulch ought to be composted (soft, moist). But does it, really? I can think of exceptions. I was taught never to use raw woodchips as a mulch, because it could tie up nitrogen from the soil, leaving plants in deficit. I don’t think this is in fact, true. I have seen sawdust (which has a greater surface-to-volume area) used as mulch tie up nitrogen, but not woodchips. If applied as a surface dressing, only a limited surface area makes contact with the soil. It will take some nitrogen from the soil, but won’t deplete your soil significantly. Alternatively, you may make the decision to add a fertilizer with a nitrogen value. If one has the luxury of composting woodchips ahead of time, then by all means do so. However, should one wish to take gardening diversity to its ultimate conclusion (and assuming there exists an interest in edible fungi), then consider by all means, the application of raw unadulterated woodchips (hardwood chips, of course are best). A note of caution: avoid woodchips from black walnut. Black walnut contains juglone, an allelochemical that is antagonistic to some plants including tomatoes and apple trees.
Swales (a Swell Idea?) and Raised Beds (Taking it to a Higher Level)
So, what is a swale and why make swales? Swales are contoured earth used in agriculture for watering crops efficiently. It is an extended, shallow ditch. Crops are planted in the soil mound, created when digging the swale. Irrigation water is applied to the rill (swale, extended ditch) effectively supplying water to the crop. From the plant perspective, it lives in a raised bed, without the definition of solid framing.
Raised beds however, may use structural framing. Choices of framing include wood, brick, block and stone. Why raised beds? Make raised beds when you:
- Have poor soils, especially those that drain poorly
- Have a bad back (garden at waist height)
- Need a structure that can be covered (to exclude pests and the elements)
Raised beds allow for the creation or amendment of soils that plants will do better in. By simply raising a structure above grade, you have effectively improved drainage. Built high enough, you can eliminate bending, important to the elder community (myself included)! Tie in cattle fencing bent to the width of the bed, and covered with Remay fabric, glass or poly, and you made a low-cost greenhouse for controlled growing.
How much water do you apply to your garden bed? A rule of thumb is one inch of water a week for your plantings during the growing season. However, there are a number of factors that will determine just how much water you need to apply to your planting beds. These are:
- Amount of natural rainfall
- Soil type
- Presence of mulch
- Plant species
- New versus established plantings
Let’s start with naturally occurring rainfall. This can be gauged fairly accurately using, well a rain gauge! These are simple, and inexpensive, but essential tools. Place the gauge in a convenient location (that you pass frequently). Barring a rain gauge, you can simply use the “cupcake technique”. When my wife bakes cupcakes, she probes them for moisture. When she determines the cupcake is sufficiently dry (baked), she removes it from the oven. The adapted technique is to sample the top 6” of soil using a soil probe (you can purchase one for <$20). A simple trowel will work as well. Note whether the soil is wet, moist or dry. If dry, then water your planting thoroughly. If using a sprinkler, place a bucket mid-way in the plot to gauge just how much water was actually applied.
Soil texture and structure will determine just how well water percolates in and how much will be held to provide roots with moisture. Soil texture refers to particle size. The larger the particle, the less its water-holding capacity. Sand is coarse (large) in texture, silt, intermediate, and clay is finely textured. Clays have the greater moisture holding capacity. Soil structure refers to how well the soil is aggregated or put together. Particulates of varying sizes, free of compaction will allow water in, and will hold water fairly well. Check on the condition of your soil 3-days after a good soaking rain: the amount of moisture held, after it has drained naturally, is called field capacity.
Mulches do very good things for soils and the biome it contains. Mulches:
- Add organic matter
- Discourage weeds
- Regulate soil temperature
- Reduce evaporation
If you have an adequate (4”) layer of an organic mulch in your garden, then you will certainly take advantage of the various benefits it provides. By reducing the suns evaporative effects, mulches make the demands of irrigation less so demanding. Mulches and cover crops (living mulches) are the very basis of “dry farming”.
The species of plants planted and their age determine water demand. In short, the more foliage, the greater the surface area for evapo-transpiration (water loss). Of course, plants have certain adaptations to reduce water loss from foliage. These include:
- A thickened cuticle (waxy layer)
- Have stomates (pores) only on the leaf underside
- Have hairy leaves (trichomes)
- Have pudgy leaves (succulents)
Stage of development factors into water balance within the plant. New transplants have a limited root mass. Roots function to anchor plants and to absorb water and dissolved minerals. Root loss occurs when plants are transplanted. The loss of roots causes an imbalance in the plant: the same leaf surface area puts a greater demand on the now smaller root system. New transplants, especially herbaceous (non-woody) plants often respond by wilting. Wilt can be mitigated by:
Established plants (that is, those with a restored root system) require relatively less water, although the demand grows over time with plant growth.
Pulling it Together
When you approach gardening, think first about how plants naturally grow. This may be new to you, but that is what makes it interesting. Consider that plants are forgiving. They will bend (within reason) to where you put them. If they do not, then they have taught you something about their growing conditions.
Here are the best conditions, and some tips:
- Plant plants that are best adapted to your region
- Plant a diversity: mix in flowering plants and aromatic herbs
- Plant facing the southern sky: low growing in the foreground and tall plants and vines to the rear
- Consider a simple 4-year rotation of legume, leaf crop, root crop & fruiting crop
- Plant annuals among perennials, and perennials among annuals
- Make compost and use it
- Mulch your garden
- Observe and take notes through the growing season. At the end of which, enjoy the fruits of your efforts!
Next time: spring trees!
~ Signing off for now, Joe