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Chapter 3

All about Soil

Soil is the foundation of every great garden. Without healthy soil, plants may grow, but they won’t thrive. Plants take up all of their nutrients from the soil (OK…plus the energy they get from the sun), and they need space to spread their roots, so it’s important to create and maintain a healthy soil environment for your crops. What makes up a healthy soil environment? A lot of things. Let’s take a look at the cast of characters.

Nutrients

Soil contains a vast array of elements and minerals that play an important role in a plant’s life. The “Big Three” are nitrogen (N), phosphorus (P), and potassium (K). Nitrogen is responsible for green, leafy growth. It’s what makes your tomato plants grow big, green, and bushy. Phosphorus helps those tomato plants develop strong roots and, more importantly, make flowers that eventually turn into fruits (yes, a tomato is technically a fruit). Potassium, sometimes referred to as potash, helps support a plant’s overall vigor as well as fruit development and disease resistance. Together, these three ingredients lend themselves to raising happy, productive vegetables.

Crops grow abundantly in healthy soil.

The Big Three do not work alone, however. They have a supporting cast, an ensemble of minor characters that help make their work easier. Trace minerals, including calcium, sulfur, iron, magnesium, manganese, and boron, all have jobs to do. They help facilitate nutrient uptake to plants and perform specialized tasks such as forming proteins, catalyzing chlorophyll, and dividing cells. The Big Three may be the stars, but they can’t perform at their best without the support of trace minerals.

pH

Your soil will likely be acidic or alkaline, and soil pH measures the degree of that acidity or alkalinity. On the acid side of the soil spectrum (about 4.5), plants such as camellias, blueberries, azaleas, and hydrangeas thrive. In fact, the more acidic your soil is, the bluer your hydrangeas. On the alkaline side (about 8.0), artichokes, mint, and asparagus do well. Most vegetables like to grow in an environment that borders a neutral pH, which is 7.0, with many varieties flourishing in a range between 5.5 and 7.5.

Changing the pH of your soil is not like changing the pH of your swimming pool. In a pool or spa, you just add a few chemicals, and—poof!—the pH is different. It doesn’t work that way with soil. It can take years to alter the pH of your garden soil, so the best approach is to find plants that do well in your existing soil conditions. That said, we’ll cover ways to amend your soil to increase acidity or alkalinity later in this chapter.

Soil Texture

It’s time for a very important question: When you stick a shovel in the ground, does it slide right in, or does it barely penetrate the soil? Your soil’s texture is going to determine how hard you will have to work to get your garden ready for planting, or at least which type of planter bed you will use. With texture, there is also a spectrum, just as with the acid/alkaline spectrum, and your soil texture will fall somewhere along the spectrum between clay, silt, and sand. There are pros and cons for each.

Microscopically, clay soil is made up of small particles, with very little airflow between them. Clay soil tends to drain poorly and is difficult to dig. In spring, in places where the ground freezes over, clay soil takes much longer to thaw, drain, and become ready to work than sandy soil. Many gardeners avoid the whole process by building raised beds (turn back to Chapter 2 if you decide you want to do that). The benefit of clay soil is that it holds water and nutrients very well. Gardeners don’t need to add fertilizer as often, nor do they need to water as much, with clay soil, so it isn’t all bad.

Sandy soil, on the other hand, is very loosely put together. Unlike clay soil, which forms into hard clods that are difficult to break up, sandy soil runs through your fingers and doesn’t hold together if you try to form a clump. Under a microscope, you can see that it is made up of large particles. It’s fantastically easy to dig, and it drains very well. The problem is that it drains too well. As a result, sandy soil loses moisture quickly—with all that fantastic drainage, away flows all of your carefully applied nutrients as well. Gardeners with sandy soil have to water more frequently and generally have to stay on top of adding amendments.

Silty soil behaves like a combination of clay and sand. The particles are larger than clay but nowhere near as large as sand. These particles characteristically feel silky, smooth like flour, or some even say greasy. Silty soil has a tendency to become compacted like clay, making drainage and digging difficult. Silt and sand are both made up of weathered rock particles, so they both respond to gravity in the same way—the particles will settle quickly in a water solution.

THE Soil Food Web

In addition to soil nutrients and micronutrients, there is an entire world (or “underworld,” in this case) of insects and microbial life forms in your soil that make the plant world go ’round. It’s called the soil food web, and the fungi, bacteria, protozoa, earthworms, and nematodes all have a purpose—a job to do. They are the stagehands who make the show run flawlessly.

Dr. Elaine Ingham, a soil microbiologist and president of Soil Foodweb, Inc. (soilfoodweb.com), first wrote about and coined the term “soil food web” during her research on soil microbiology in the 1980s and ’90s. Jeff Lowenfels and Wayne Lewis, while tipping their hats to Dr. Ingham, uncover this world in their book, Teaming with Microbes. They deftly explain how plants not only take up nutrients but also “produce chemicals they excrete through their roots.” The excretions or “exudates” are then consumed by fungi and bacteria, which in turn are consumed by protozoa and nematodes, which then excrete waste that is taken back up by the plant as food. How convenient!

Don’t forget the host of arthropods and insects, which burrow and aerate the soil, living and completing their life cycles (naturally or otherwise, i.e., being eaten by birds or other predators). When they die, their bodies go back into the food chain, breaking down into usable organic matter, which is once again consumed by microbes and, eventually, plants. This overlapping series of complicated food chains is the soil food web. It’s fascinating stuff, but why does this matter to you as a gardener?

It matters because when your soil is healthy enough to support this intricate underworld of microbial activity, your garden will be more likely to thrive. Not only that—everything you do in the garden can help or hamper the soil food web. Every box of fertilizer, every shovelful of compost, every bottle of bug spray that is used on your plants affects this underworld. Don’t worry, though, because we’ll give you all the information you need to steward the microbial life in your garden’s soil food web later in this chapter.

Get Tested

The first thing to do, before adding any fertilizers or soil amendments, is to get your soil tested. It takes a little time, and you have to wait for the results, but it’s worth it. There are two kinds of tests available: basic and complete. A basic soil test reveals the nutrient levels of your Big Three. This type of test usually requires that you take a soil sample, mix it with water, and let it settle. Then you draw off some of the liquid and add it to a beaker with specific chemicals that are reactive to nitrogen, phosphorus, or potassium (this is the fun science part). Close the container, shake it, and then leave it undisturbed and wait for the color to change. You’ll compare your results against a color chart to let you know how well supplied your soil is with that particular nutrient. You can buy basic soil tests for N, P, K, and pH at many nurseries or order them online through gardening catalogs.

Home soil-testing kits test levels of nitrogen, phosphorus, and potassium as well as pH.

The second type of soil test yields more elaborate results. A complete test involves sending a soil sample out to a laboratory. Soil technicians provide you not only with N, P, K, and pH ratings but also with ratings for trace elements, salinity, and heavy metals.

Why is this important? Well, let’s say you live in a city, near a busy road. Your test might show high levels of zinc in the soil. Where did that zinc come from? Zinc disperses from braking systems on vehicles, from roads, from airplanes overhead, and from galvanized metal gardening tools (like watering cans or buckets). Excessive zinc prevents the uptake of nutrients in plants. That’s right—it actually blocks the plant’s ability to extract N, P, and K from the soil. A soil test might also show that the pH of your excessively zinc-laden soil is acidic. This would tell you that, if you were to raise your soil’s pH, you would bind up the zinc, making more nutrients available to your plants.

It’s always a good idea to get a complete soil test to rule out the presence of lead (residues from turn-of-the-century oil drilling, leaded gasoline, and house paints), arsenic (used previously for years near railroads as a weed killer), mercury, cadmium, or aluminum. Most university departments of agriculture offer inexpensive soil tests (just search the Internet for “university soil test” to find one near you), or you can send a sample to a soil lab, such as Wallace Laboratories (wlabs.com) in El Segundo, California. To find out the active microbiological composition of your soil (bacteria, fungi, nematodes, and more), look up “biological soil testing” or send a sample to a lab such as Earthfort (earthfort.com).

Make Amends

Once you know the nutrient levels of your soil, you can amend accordingly. Soil amendments—also called inputs—can increase available nutrients, but they also can alter soil texture or improve drainage. Let’s revisit the soil textures: clay, silt, and sand. What can you do to improve these conditions?

Surprisingly, the organic solution to hard-packed clay soil, compacted silt, and loose, anemic sandy soil is one thing: compost. In clay and silty soil, compost serves to create space between particles and allow more airflow, which then helps the soil drain better. In sandy soil, compost works as a sponge to retain moisture and provides structure to hold nutrients. Compost brings these extreme conditions closer to the perfect texture for growing vegetables and fruits; this ideal is called loam. Loamy soil holds nutrients but drains well. It supports the easy proliferation of root systems and is nearly effortless to dig. Loam is the goal that every gardener hopes to attain with soil.

So how much compost should you apply to your soil? The general rule of thumb is to add compost in inches. Add a 1/2- to 1-inch (1.25- to 2.5-cm) layer at the beginning of each season before planting and, if needed, again during mid-season to boost production. You can either top-dress, meaning spread it out on the surface and leave it, or you can work it into the top few inches (7 or 8 cm) of soil. Soil food web aficionados prefer to apply compost on the surface, without disturbing the delicate strands of fungal hyphae and microbial life hard at work in the soil. The microbes will utilize the compost as it filters through the soil during regular watering and as larger insects and earthworms till it into the soil for you. All of this activity makes nutrients available to plants with less work from you.

Gardeners with very sandy soil may choose to ignore the 1/2- to 1-inch (1.25- to 2.5-cm) rule of thumb and add compost with reckless abandon. It’s OK. Add compost, then add more compost, and when you think you’ve added enough, add more. Your soil will be just about right at that point.

In addition to benefiting soil texture and structure, compost adds nitrogen and inoculates your soil with those stagehands we talked about earlier. Compost does much more than feed the soil; it brings it to life with fungi, bacteria, microscopic insects, and earthworms. It supercharges your soil with the microbiology needed to help plants thrive. You can buy bagged compost from nurseries, but why not make it yourself? It’s a great way to recycle nutrients in your garden and cut down on waste that goes to the landfill. Food waste happens to be one of the top contributors to climate change, by the way. So if you aren’t composting, now is a great time to start! Best of all, making your own compost means you know exactly what’s in it, and you don’t have to drive anywhere to get it.

Start a Compost Bin

A compost bin can be any structure that holds garden biomass (use this term instead of waste, because you’re not wasting anything). A compost bin can be a cylinder of hardware cloth, an old trash can with the bottom removed and holes punched in the sides, or an official store-bought compost bin. You don’t even need a bin, per se, to store your compost. You can make a pile in your backyard and let it cook. The important thing is to start using your own garden biomass to give back to your garden. Here are a few guidelines for creating a viable composting system.

Compost is a valuable soil amendment in many situations.

 Size: The ideal minimum size for a compost bin is 3 x 3 x 3 feet (0.9 x 0.9 x 0.9 m). That is the magic size at which organic mass begins to generate and hold heat.

 Space: Allow enough space for your compost bin or pile, plus enough space right next to it for another pile. Why? At some point you will want to “turn” the pile (to aerate it and expose new surface area to all of those microbes that will continue to break down the organic matter, which makes the pile heat up again), so ideally you can use that space next to your compost pile to flip a pile from one side to the other without exerting much effort.

 Browns and greens: Composting is a chemical reaction between carbon (usually brown-colored biomass) and nitrogen (often, but not always, green-colored biomass). Carbon-rich materials like dried leaves, wood chips, dead corn stalks, wheat chaff, and cardboard are combined with nitrogen-rich materials like kitchen scraps, coffee grounds, grass clippings, cover crops (such as fava beans, alfalfa, and bell beans), and garden trimmings to start the process. See Appendix A for an expanded list of browns and greens.

 Other ingredients: Compost requires moisture in order to break down brown and green biomass. Water is a key ingredient. In climates with regular rainfall, you may never need to water your compost pile once it’s built. In fact, some gardeners have to cover their compost piles with tarps to keep them from getting too wet (excess moisture promotes anaerobic bacteria—the kind that stink). In dry climates, though, you will need to water your pile regularly. Start by thoroughly watering each layer of the pile as you build it. If you use alfalfa or straw, it will take a lot of water to wet the material completely. Be patient and don’t be afraid to use plenty of water. According to Alane O’Rielly Weber, a certified Soil Foodweb advisor at Botanical Arts in San Mateo, California, you should be able to squeeze a drop of water out of a handful of biomass. If not, it’s not wet enough. A helpful tip to use as a guideline for moisture is that your pile should be wet like a wrung-out sponge. Water begins the process of biodegradation and invites beneficial microbes to feast upon the decaying matter, so it’s a really important ingredient in your pile.

 Soil: Soil is another key ingredient, and it is often omitted from many composting guides. You don’t need to buy those silly boxes of “compost starter”—use soil instead! Healthy soil inoculates your compost pile with fungi, bacteria, and microorganisms, which go to work to break down organic matter, to aerate the pile as they crawl through, and to digest material. The result is high-powered, high-vitality compost that improves your soil with every application.

 Layers: Composting guides vary and will tell you that the ratio of brown material to green material ranges anywhere between one part brown and two parts green to five parts brown and one part green. It can get confusing. Keep it simple. Use depth instead of parts or volume measurements. Put down a 2- to 3-inch (5- to 7.5-cm) layer of browns, then a 2- to 3-inch (5- to 7.5-cm) layer of greens, and then a shovelful of soil, and water it in. Repeat this process until you have used up your ingredients.

Three compost bins at Gardenerd HQ

Geek Alert: Active Batch Thermal Composting

If you want to get more technical and build an amazing compost pile, try this method for active batch thermal composting. Wait a minute. What the heck does that mean?

 Active—you are turning the pile and monitoring temperatures.

 Batch—you are building the whole pile all at once rather than adding materials over time.

 Thermal—it gets hot, up to 160° Fahrenheit (71° Celsius), with the right materials.

 Composting—you are breaking down garden biomass into black gold.

Here’s the method: Figure out how much material your compost bin will hold in gallons (liters). Next, gather your browns and greens in 5-gallon (19-L) buckets using the following ratio that Dr. Ingham recommends for beneficial bacterial-dominated compost, which is great for vegetable gardens:

 35 percent high-carbon/brown materials like wood chips, saw dust, dried leaves

 45 percent nitrogen/green materials like chipped tree and garden trimmings, coffee grounds, grass clippings

 20 percent high-nitrogen biomass like alfalfa, legume cover crops (such as fava beans), or manures. These high-nitrogen materials kick up the heat quickly and provide food for the bacteria to feast upon.

 Note: If you have powdery mildew or other fungal imbalances in your garden, swap the percentages in this list for carbon and nitrogen ingredients for a more fungal-dominant compost. It will help increase fungal diversity to restore balance to garden soils.

Multiply the number of gallons or liters that your compost bin holds by each percentage. That will tell you how many gallons or liters of each type of biomass you will need. Then divide each number by 5, if you are using 5-gallon buckets (or 19, if you are using 19-L buckets), and that will tell you how many buckets of each material you will need. For example: if you have a 50-gallon (189-L) compost bin, you will need 17.5 gallons (66 L), or 3.5 buckets of browns; 22.5 gallons (85 L), or 4.5 buckets of greens; and 10 gallons (38 L), or 2 buckets, of high-nitrogen/legume/manure materials.

Active batch thermal compost pile

With active batch thermal composting, you don’t have to use layers, because you are building the pile all at once. You do need to mix the materials together as you put them in the bin, though, and water the pile the entire time. Check the temperatures between eighteen and twenty-four hours after building the pile, and it should be hot. When it gets to 160° Fahrenheit (71° Celsius), it’s time to turn the pile. Each time the pile is turned, it will heat up again (remember, new surface area will be exposed, giving microbes more food to consume). Turn the pile after temperatures peak, again watering thoroughly throughout the process. Repeat turning and watering at least one more time. Eventually the pile will cool down, and, within three to four months, you will have microbe-rich compost for your garden.

Geeky Gardening TiP:

Keeping Critters Away from Compost

Always end your composting layers with brown material on top. It keeps fruit flies, odors, and the vermin who love odors away. To add more kitchen waste, pull back the top layer of browns, add your scraps, and then redistribute the brown material on top.

If you don’t have enough material to build a pile all at once, that’s OK. Building a pile over time is still considered composting—cold composting. Your pile will just take longer to process and won’t get as hot as active-batch piles do.

Fertilizers: Chemical, Organic, or None?

When it comes to fertilizers, there are three roads to take: use chemical fertilizers, use organic fertilizers, or don’t use any fertilizers at all. It’s an argument that’s been going on since the mid-1950s between farmers who use conventional growing methods and those who farm organically. Permaculturists and some biointensive farmers would argue that nature provides its own fertilizer, so we don’t need to add any inputs.

It’s easy to be enticed by all of the options on the nursery shelves. Those boxes of fertilizer offer the promise of quick-fix solutions and gigantic, succulent vegetables. Some of them prove helpful, while others can cause long-term damage. Before you pour anything onto your soil, it’s important to know what fertilizers do and why you might need them.

First, let’s step back in history. Around the turn of the nineteenth century, farmers used one of two methods to fertilize their croplands:

 Method 1: They tilled in manure from farm animals or acquired copious amounts of horse manure from what was then known as the “transportation department” (think mounted police here). Farms were different then: they grew more than just one crop, and there were always plenty of animals around to contribute to soil fertility.

 Method 2: Farmers infused their land with nitrogen by growing a cover crop of legumes such as fava beans or peas. The fields were seeded with bean seeds, and after the crops had grown tall, farmers cut them down and dug the biomass into the soil. The biomass decomposed and improved the soil structure, but the magic was happening underground in the roots.

The air we breathe is 76 percent nitrogen. Legume crops have the ability to pull atmospheric nitrogen out of the air and lock it into the plants’ roots. Here’s how it works: Friendly bacteria called rhizobia (part of the soil food web) establish a home in the roots of leguminous plants. The bacteria are able to “fix” nitrogen in the roots, in the form of little pink nodules. When bean plants just begin to flower, the roots are full of these pink nodules. The crops are strategically cut down, and the roots are left in the soil to biodegrade, a process that eventually releases the fixed nitrogen into the soil. A farmer would then plant crops and enjoy the benefits of amply supplied nitrogen.

A third, unpredictable way to fix nitrogen into the soil as fertilizer was to hope for lightning. Lightning deposits hundreds of thousands of pounds of nitrogen into soil every year. It happens when the energy of lightning breaks the bonds of nitrogen molecules in the air. The particles mix with vapor and rain, fall to the earth, and are absorbed into plants and soil. This method is helpful but not enough to supply the full amount of fertilizer needed for most farmers.

Along came German chemists Fritz Haber and Carl Bosch, who figured out how to manufacture synthetic nitrogen. They did this in the early twentieth century by combining atmospheric nitrogen and hydrogen to create ammonia (widely used as ammonium nitrate in fertilizers today). The technique, the Haber-Bosch Process, was lauded as one of the most important inventions of the day, and it gave the farming community tools to solve world hunger. The German duo won Nobel Prizes for chemistry in 1918 and 1931.

Despite the promise of increased yields, history has uncovered several issues with synthetic nitrogen. First of all, synthetic nitrogen is made from natural gas. Natural gas is a common source of hydrogen, and while that’s perfect for the Haber-Bosch Process, it’s a natural resource with a finite supply. Strike one against synthetic nitrogen: it is not sustainable.

Before applying fertilizer, learn about its advantages and disadvantages.

How Much Nitrogen?

The next thing to consider is how much nitrogen, synthetic or otherwise, is actually taken up by plants. Much like humans, who absorb nutrients in minute quantities over time, plants take up only a small amount of nitrogen, in much lower doses than synthetic brands of fertilizer provide. A box on the nursery shelf might list the Big Three (N, P, K) ratios as 20–20–20 or 30–30–30. Those are very high numbers when it comes to fertilizer.

Think about this: What happens when you take a multivitamin? Your body absorbs some of it, but what happens to the rest? It flushes away. The same is true for plants. What isn’t absorbed by the plant is released down into the water table. Once there, it travels out to sea through waterways. Rivers and bays with excess nitrates develop algae blooms, because—remember—nitrogen is responsible for green, leafy growth. Algae are hungry for oxygen and rob the water and fish of that life-giving resource. The result is a dead zone. Strike two against synthetic nitrogen.

The third strike is that nitrates are very high in salts. High salinity diminishes a plant’s ability to take up water, which causes stress and stunted growth and can eventually kill a plant. Arguments have been made, even by reputable soil scientists, that plants can’t tell the difference between organic and synthetic nitrogen. While it may be true that the plants may not be able to tell the difference, your soil can. Study after study has shown that high-salinity, high-nitrate fertilizers reduce populations of soil microbes. It diminishes your soil food web. OK—some types of soil biology may survive the onslaught, but the overall system will take a hit. If you worked hard to create your ecosystem both above and below ground, to create an environment where nature does much of the work for you, take a moment to consider what synthetic fertilizers do to the soil before you apply them.

The Benefits of Organic Fertilizers

Now, let’s talk about organic fertilizers. These amendments range from plant-based materials such as alfalfa, to minerals such as rock phosphate, to animal by-products such as bone meal. Each has its own properties, and typically several nutrients are combined to create “balanced” fertilizers for different plant groups. On nursery shelves, you will find a box of fertilizer for vegetables, one for roses, another for acid-loving plants, and yet another for fruit trees. Each brand has a proprietary blend that it feels is best for its customers. The blend of nutrients appears on the box as the ratio of our Big Three, and those numbers will range between 3 and 7—much lower than synthetics. For example, a box of organic citrus fertilizer may list a ratio of 7–4–2, meaning that the total content of each nutrient is 7 percent nitrogen, 4 percent phosphorus, and 2 percent potassium.

With numbers that low, the total nutrient content is more likely to be taken up by plants, leaving little behind to infiltrate the water table. Still, any fertilizer should be used with caution; more is not necessarily better.

Available Nutrient Options in Fertilizer

Nitrogen: Green Leafy Growth

Animal-based sources of nitrogen include blood meal, feather meal, hoof and horn meal, and fish meal, which generally have a rate of 9 to 15 percent in pure form. Both hoof and horn meal and fish meal also contain some percentage of phosphorus, fish meal being higher. Blood meal and feather meal may have little to no phosphorus, depending on its source.

Nonanimal-based sources of nitrogen are alfalfa meal, cottonseed meal, soybean meal, and kelp meal. These fertilizers offer a lower rate than their animal-based counterparts, between 1 and 7 percent. Another great source of nitrogen can be found in your coffee maker. Spent coffee grounds supply nitrogen at a rate of about 2 percent, with trace levels of phosphorus and potassium. Compost is a source as well, but it may surprise you that compost is relatively low in nitrogen. However, as we discussed earlier, plants take up nutrients in small amounts, so the available nitrogen is sufficient in many cases. Plus, with the bonus of the vibrant, nutrient-building microbial life forms that compost provides, it makes a fantastic fertilizer.

Animal manures, which straddle the aforementioned categories—being from animals but not by-products of slaughter—are higher in nitrogen when dried, according to North Carolina State University research. Dried cow, chicken, and hog manures and fresh rabbit manure all provide nitrogen at a rate between 1 and 2.2 percent.

Potatoes growing in a container

Phosphorus: Roots, Fruits, and Flowers

Bone meal is the predominant animal-based source of phosphorus but, as mentioned, many of the animal-based nitrogen fertilizers also supply some phosphorus. Bone meal supplies phosphorus at a rate ranging from 11 to 22 percent.

Rock phosphate and soft rock phosphate are nonanimal sources of phosphorus. They are both mined from sedimentary rock: rock phosphate as tricalcium phosphate, and soft rock phosphate as a by-product of the mining industry. They supply 2 to 3 percent phosphorus.

In the manure category, seabird or bat guano (a nice way of saying poop) is excellent. These resources range from 10 to 15 percent phosphorus and also have between 1 and 3 percent nitrogen.

Potassium: Overall Vigor and Fruit and Flower Development

Animal-based fertilizers supply virtually zero potassium, so we’ll skip right to nonanimal-based options. Sulfate of potash, also known by the commercial name Sul-Po-Mag (meaning sulfate of potassium-magnesia) is the most common source of potassium. Potassium remains in the soil for years, so make sure that you test your soil first before applying, because it may not need potassium. Other options include greensand, which supplies between 3 and 7 percent potash. It is marine sediment mined from ocean-adjacent rock formations. If you have very sandy soil, avoid greensand, because it will make soil texture even sandier. Kelp meal and liquid kelp emulsions generally supply low levels of potassium but offer the benefit of trace minerals as well. Wood ashes, depending on what is burned to create them, can provide small amounts of potassium and phosphorus. Don’t use wood ashes if you have highly alkaline soil, because it tends to raise pH.

Animal manures, both in dried and manure tea forms, supply potassium as well as the other aforementioned nutrients. Like liquid kelp emulsions, animal manures and manure teas also supply a broad spectrum of trace minerals.

Is It Organic?

Remember, as mentioned earlier, that even if that box of fertilizer says “organic,” it doesn’t mean that the source of that bone meal or manure was raised organically. It just means that the fertilizer was derived from organic matter and that it is safe for use in organic agriculture.

pH Adjusters and Trace Minerals

Trace minerals play a role in nutrient uptake, and, depending on geographic location and farm practices, these minerals can become depleted. As mentioned, some organic fertilizers supply a small amount of trace minerals, so a fertilizer may be all you ever need to use. But you might be wondering what all of those other boxes on the nursery shelves are for. It’s important to know what they are and what they do before applying them to your garden. Often, products that provide trace minerals also serve as soil pH adjusters. They will raise or lower your pH, and sometimes this is a good thing. Sometimes, not so much.