Soil Amendments

This is an excerpt from the Book called “Edible Landscaping“ by Rosalind Creasy . Continue reading to learn more about Soil Amendments, thanks to the author.

Soil amendments, fertilizers, and mulches

None of us can afford to think about soil amendments, fertilizers, and mulches in the way we might have a few decades or even a few years ago. It’s not enough to consider whether they do an adequate job or, in the case of mulches, look appealing in the landscape. It’s not even enough to just think organic.

In my opinion, it’s time to go beyond focusing only on what our own plants need or what pleases us or our pocketbooks and start thinking about what’s good for the planet. That means thinking about what’s good for the planet. That means thinking about the origin of a product-whether it is natural (and if it is a limited or unlimited resource) or manufactured-and also how far it has to travel to get to us.

I have long addressed gardening from an environmental perspective, and I’m glad to see others now doing the same. Unfortunately, many books and websites use buzzwords like “all-natural,” “sustainable,” and”green” without thinking them through or more as a marketing ploy than a researched fact. Some authentic information is out there, but you need to sift through everything else to ferret it out. It may help you to know that the information I’m giving you has been well tested-during three decades of growing hundreds of vegetables, fruits, berries, and nuts in my own garden, as well as working with and sharing knowledge with other leaders in the field.

The products I describe here I chose because they do the job while creating the least disruption to the environment. Most will also have less impact on your budget-for example, homemade compost costs you nothing except a little labor.

Your soil: what type? Amendments?

The first test is a quick, down and dirty way to find out what type of soil you have. (Do not perform this test if your soil is very wet or completely dry.) Place a palm-size chunk of soil in your hand, close your fingers, and make a gentle fist. Open your hand and lightly poke at the soil clump to find out what type of soil you have:

Sand. Clump crumbles completely with little pressure.

Clay. Clump holds its shape, retaining the imprint of your palm and fingers.

Loam. Clump may hold together but is not compacted; may break into several discrete clusters.

If you determine that your soil is primarily sand or clay, you’ll need to add substantial amounts of organic matter. Sandy soils require organic matter to hold moisture and nutrients so that both are available to plants. Clay soils need organic matter so that air and water can move through the soil-meaning the soils will drain better and won’t be as prone to compaction. In the lucky event your soil is loam, then generally little remediation is needed.

Soil amendments

Many people freely interchange the words “soil amendment” and “fertilizer.” Technically speaking, fertilizers supply nutrients whereas soil amendments improve soil texture and structure and help build up microbial activity- although, as a bonus, they may also provide some nutrients.

Home-based (DIY) Soil Amendments

This is a category of my own creation, comprising materials available right in your own (or your neighbour’s) backyard:

Compost: In Appendix C, I delve into compost in detail-all its virtues and how to make it. Suffice it to say, compost has rightly earned the moniker “black gold” as the most useful and beneficial soil amendment (and mulch).

Green manure: Grow cover crops such alfalfa, clover, and vetch (legumes) as well as buckwheat and ryegrass; next season, before they set seed, till them under to decay. It’s especially important to sow these crops in newly developed properties before planting lawns or gardens; also sow them in existing vegetable gardens and orchards. Find seeds at Bountiful Gardens, Harmony Farm and Garden Supply, Johnny’s Selected Seeds, Nichols Garden Nursery, and Peaceful Valley Farm & Garden Supply.

Leaf mold: With autumn comes leaf fall. Too many people bag their leaves and set them on the curb to be hauled away. Instead, pile them into a corner to rot over time. To speed up the process, run over the leaves several times with a lawn mower, make a pile, and wet thoroughly. Come spring you’ll discover a much smaller pile of rich-smelling, humus-rich leaf mold.

As a bonus, all of these home-based soil amendments are free—there for the taking—and, if handled properly, a plus for the environment. They have not been shipped over oceans on large freighters or trucked to your local garden center, and they don’t require that you burn any fuel driving to get them. The net energy use for items in this category is nearly zero.

Plant-Based Soil Amendments

These two products are also called soil conditioners; they expand greatly when soaked in water, slowly releasing moisture to plant roots. They are often use for moisture retention in soilless potting mixes. Both have the ability to loosen hard clay soils and bind sandy soils. However, both are shipped long distances, and, as noted in peat bogs take at least a quarter century to regrow.

Coir: A by-product of the coconut industry, coir is the sterilized coarse fibre from the outer shell of a coconut. Often sold in “bricks,” coir resists compacting and does not crust when dry.

Peat moss: Also called sphagnum peat moss, this material is harvested from peat bogs in Canada, Dried, and shipped to garden centers. Its low ph. makes it an appealing soil amendment for growing acid-loving plants like cranberries and blueberries. Once dry, peat moss is challenging to re-wet.

Fertilizers

Personally, I liken fertilizing the garden to feeding my family. I would never give them a steady diet of canned protein drinks, multivitamin pills, and powdered fiber instead of real nutrients: fresh fruits, vegetables, whole grains, eggs, and fish. I know that real food contains a trove of health-giving pectin’s, fiber, antioxidants, and enzymes our bodies need that are not in those products. Commercial chemical fertilizers contain only the nutritional salts that plant’s needs, though they are not used efficiently by either the plants or the life in the soil. These salts can even burn tender root hairs. To make matters worse, much leaches away, contaminating waterways.

In contrast, a varied diet of organic fertilizers from compost (for humus, enzymes, bioactivity, plant hormones, and so much more), kelp powder (for trace elements and plant growth hormones), hydrolysed fish and fish emulsion (for nitrogen as well as various amino acids), and minerals duplicates nature’s way. They release their nutrients slowly and evenly and are less likely to leach away.

It’s not necessary to apply nutrients on a set schedule. Using materials as needed to correct deficiencies and not as a precautionary measure “just in case” saves money and resources.

For organization’s sake, I have put each of the many organic fertilizers into one of the following three categories: plant based, animal based, and mineral based. If you have questions about whether a product is organic, visit www.omri.org.

Plant-Based Fertilizers

Generally, these fertilizers provide nitrogen and sometimes potassium. Farmers grow some of these plants solely for organic fertilizers, while others—like corn gluten—are simply waste products of another industry.

Alfalfa meal: The meal consists of ground and dried alfalfa; a pellet form is also available. In addition to supplying primary nutrients, alfalfa meal contains some trace minerals. This fertilizer is beneficial to soil organisms and contains a plant growth regulator that results in larger flowers as well as increased cold tolerance.

Corn gluten meal: A by-product of corn refining sold as an organic pre-emergent herbicide or wed blocker, corn gluten meal also makes a good fertilizer, as it breaks down quickly, releasing its 10 present nitrogen. Caution: Do not sow seeds for 6 weeks after applying corn gluten meal.

Cottonseed meal: This slow-release fertilizer—the waste product after ginning cotton and pressing the seeds for oil—can acidify soil in addition to supplying nutrients. Look for organic cottonseed meal, as cotton is one of the most heavily pesticide-sprayed crops and some is genetically modified.

Kelp and seaweed: Excellent sources of trace minerals and amino acids that enhance soil microbial activity, these algae are sold in meal or liquid form. Work the meal into the soil; use the liquid as a foliar feed. They are renewable resources harvested off both coasts, so check the origin of products for the one closest to you. “Cold-pressed” on the label indicates a higher biologic activity.

Soybean meal: This is a ground-up leftover of soybeans after the oil has been extracted (mechanically or with a solvent). Look for organic versions.

Animal-Based Fertilizers

Some folks, especially strict vegetarians and vegans, choose to avoid any animal by-products in their gardens. So if you fall into that category, you’ll want to stay away from these fertilizers, by-products of the meat-and fish-processing and dairy industries.

Blood meal: This high-nitrogen powder from slaughterhouses can burn plants if applied too heavily. In addition to using petroleum energy in the drying process, blood meal attracts dogs and other animals to dig in the soil.

Bonemeal: Steamed, ground-up bones from slaughterhouses, bonemeal is high (22 present) in calcium. It releases its nutrients slowly and reduces soil acidity. This fertilizer is irresistible to some dogs.

Fish products: By-products of the fish industry come in numerous forms, all of them good N-P-K sources. For years fish emulsion (steamed and fermented fish waste) was the benchmark, but hydrolysed fish (the technical name is fish hydrosolates) is slowly replacing it. Hydrolyzed fish doesn’t smell as bad, and some products readily flow through drip irrigation without clogging. Cold processing leaves natural organic compounds intact (look for names like Eco-nutrients, Neptune, and MultiBloom). Fishmeal is ground fish waste with oils removed and dried at high temperatures; it is a good soil amendment but not easily soluble. Fish powder is heal-dried, water-soluble fish matter.

Manures: Farm animal excrement is a good soil amendment, though often high in salts. The N-P-K content varies widely. Look for manure locally—free for the taking or at low cost. Do not use any manure fresh, but rather let it age and rot. Horse manure often comes with weed seeds and may be high in salts. Commercially available cow manure is high in salts, usually contains antibiotics, and typically sits exposed to the elements in feedlots, where it loses a lot of nutrients. If you have chickens, you can’t do better than your own chicken manure, as long as you let it age before adding it to the soil.

Mineral-Based Fertilizers

I cannot underscore enough how important a detailed soil analysis is. There is no need to add any fertilizers unless the soil is deficient. As noted earlier in this chapter, if the soil PH. Is off, certain minerals will be unavailable. When adding rock minerals, first mix plenty of organic matter into the soil and then work the minerals into the root zone.

Chilean nitrate (16-0-0; sodium nitrate, nitrate of soda): The only rock mineral nitrogen fertilizer, Chilean nitrate is mined in the Atacama Desert in Chile. Apply it just before planting; nitrogen will be available almost immediately. Do not use it in low-rainfall areas of the Southwest where soils are alkaline, as it raises soil ph. and sodium levels.

Epsom salts (magnesium sulphate):

The effects of this highly soluble, fast-acting source of magnesium last for up to two growing seasons. Use it in magnesium-efficient soils; it’s also good for container-grown plants and magnesium-hungry plants like roses, tomatoes, peppers, and potatoes.

Granite dust: A by-product of quarry activity, granite dust releases potassium slowly, lasting 5 or more years in the soil. It works best when used in conjunction with compost.

Greensand (0-0-3; glauconite, iron potassium silicate): Mined in New Jersey from ancient sea deposits, greensand takes years to release potassium. It is effective only in acidic soils.

Lime: Add lime to acidic soil to raise the ph. Level. Choose a form of lime suited to the amount of magnesium in your soil. Dolomitic limestone (50 percent calcium carbonate, 40 percent magnesium carbonate) is mind worldwide. Use it in soils with low to medium magnesium levels; it lasts 3 to 4 years. Pelletized calcitic limestone, also mined around the world, is good in soils with adequate magnesium because it contains high amounts of calcium and very little, if any, magnesium. It lasts 3 to 4 years. Oyster shell limestone (75 percent calcium, 10 percent magnesium) is best in soils with high magnesium levels.

Rock phosphate: This finely ground rock is high in phosphorus, calcium, and micronutrients, supplying long-lasting benefits. Nearly insoluble in water, rock phosphate needs microbial action and slightly acid conditions (ideally ph. 6.2) for slow release of the phosphorus. To provide the right conditions, mix manure into the soil several months before applying rock phosphate. Because phosphorus does not move in the soil, it’s crucial to incorporate rock phosphate at root depth. Colloidal, or soft rock, phosphate, which is mined in Florida, contains colloidal clay; use it only in sandy soils.

Sulfur: This fertilizer lowers soil ph. And also supplies the nutrient sulphur. Apply it in spring or summer when soil-dwelling bacteria are active. Mix sulphur well into the soil to avoid hardpan.

Sul-Po-Mag: (langbeinite, a mineral containing sulphur, potassium, and magnesium): Mined in New Mexico, this short-term fertilizer consisting of 22 percent potassium (readily available) lasts for up to 6 months. Apply it in spring or during the growing season to supply all three nutrients; use it in low-magnesium soils.

N-P-K

By law, labels on all commercial fertilizers must indicate the percentage by weight of each of the three primary nutrients they contain: nitrogen (N), Phosphorus (P), and potassium (k), a synthetic formulation labelled 20-20-20 means that the product contains 20 percent nitrogen, 20 percent phosphorus, and 20 percent potassium. Labelling also includes information about nutrients’ sources and the presence of micronutrients. The nitrogen may be in the form of ammonium sulfate or urea, for instance, and the product may also contain other nutrients such as iron or zinc. Although organic fertilizers generally have lower numbers than chemical fertilizers, those numbers don’t fully reflect potency, as the organic fertilizers fortify plants with many other life-giving substances. They also feed soil microbes, which in turn feed plants when they decay.

Mulches

A mulch is a top-dressing applied to the soil surface to conserve moisture, control weeds, prevent compaction or erosion, and moderate soil temperature. It can be an organic material, such as compost, pine needles, or grass clippings, which gradually decomposes and feeds the soil; a natural material that does not break down, such as gravel, shells, or sand; or a manufactured substance, such as plastic.

When vegetable gardens were far from the house and screened from view, the odor and appearance of mulch were inconsequential. But for an edible landscape, foul-smelling, spoiled hay near a front walk or ugly black plastic bordering the patio just won’t do. Mulches can be utilitarian and also enhance the appearance of the landscape. Shredded oak leaf mulch and well-rotted and screened compost are attractive.

Availability of the following recommended mulches varies from region to region. Most are products you have to purchase. See “Mulching” in Appendix C for how to use these materials.

Bark: Packaged tree bark is available regionally, usually shredded or as small, medium, or large chips. Avoid dyed bark. Look for the Mulch & Soil “Council seal.

Cocoa hulls: This handsome mulch breaks down fairly quickly and smells like chocolate. Caution: Cocoa hulls can be toxic to dogs.

Compost: Well-aged compost, screened and spread around landscape areas, is pleasing to the eye. Since most of us don’t produce enough compost to fill our mulching needs, give priority to new fruit trees and annual flowers and vegetables.

Grass clippings: Apply no more than an inch of fresh clippings at a time; otherwise they form an impermeable mat. Use only herbicide-and pesticide-free clippings.

Gravel or rock chips: Many different types, sizes, and colors of rock mulch are available. They do not break down or improve soil structure. Pea gravel works well as a cooling mulch under herbs in a hot, humid climate. Although most types are good-looking, the large ones are a challenge to rake—a particular problem under fruit trees when decaying fruits and dropped or diseased leaves need to be removed.

Newspaper: Recycle and save money by laying down four to six sheets of wet newspaper. Make sure the sheets overlap or weeds will squeeze their way through. Some folks shred their junk mail (black and white only) and wet it in the same way. Top with a thin layer of any attractive mulch.

Nut hulls: Depending on where you live, nut hulls (hazelnuts, peanuts, pecans, and others) may be available free or at low cost from processing plants. Because of their coarse consistency, they are better around trees and shrubs than around annual vegetables or on pathways. Do not use walnut hulls—the juglone in them inhibits most plant growth.

Pine needles: This mulch gives an informal look; it is ideal for woodland or acid-loving plants and perfect under strawberries to keep them from rotting on the ground. Pine needles acidify the soil when they break down.

Regional mulches: These mulches are available only in certain parts of the country and generally are not packaged or shipped to other areas. In the Midwest, soak ground corncobs in water before applying. In the South, mix peanut hulls with a weightier mulch or risk them blowing away. Bagasse, available in the warmer regions of the South, is fibrous sugar cane residue that decomposes quickly and lowers soil ph.

Rubber (recycled tires): Although this is a recycled material, I don’t think it should be used near edible plants because of possible toxins. Besides, the rubber does not break down over time, and it gets hot in the daytime.

Sand: use builders sand, not beach sand (unless rinsed well to remove salt). In moist climates, mulch with an inch of sand around Mediterranean herbs to prevent rotting.

Sawdust: Apply well-aged sawdust 2 or 3 inches deep around edibles. When using fresh sawdust, mix it well with an organic, nitrogen-rich fertilizer like blood meal before spreading near edibles; otherwise microbes will use available soil nitrogen as they break down the sawdust, starving the plants. Use this plant-starving effect to your advantage to prevent weed growth on garden paths; apply 3 to 4 inches of raw sawdust on the paths to discourage weeds for several years, Years later, when the sawdust, is well composted, it can be added to the garden bed.