When buying soil, compost and mulch, get the dirt on what is “good”
Every gardener wants the best soil for their garden. How do you know if your soil is “good”? What do you add to make it good? When you visit a plant nursery or the gardening section of a large box store, you will see bags of things advertised as garden soil or mulch or mushroom compost.
Which ones do you use for your garden? And what about the gardening mix from landscapers or free stuff from the landfill? Can you plant this
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It is confusing. Compost can, for example, be used as garden soil or as mulch or as a supplement to the local soil in your garden. And what’s the difference between mushroom compost and the compost you make in your own garden? Let’s start with earth – what is it and what makes it “good”?
Soil: What’s in the soil
The soil is a major component of the earth’s surface and provides plants with a place to root as well as a source of necessary materials for plant growth. The soil consists of minerals, organic matter, microorganisms, air and water. It usually consists of about 45 percent mineral material, five percent organic matter (or less in Florida soil), and 50 percent pore space, which is occupied by air or water.
The organic portion of the soil provides most of the nutrients that plants and the microorganisms that support them feed. The mineral part of the soil consists of particles sorted by size, with sand being the largest, silt being smaller and clay being the smallest.
The particles in the soil collect in clumps called aggregates that form the soil structure. Organic matter helps by coating the soil’s mineral particles and helping them clump together. Florida soils are generally low in organic matter and adding organic matter helps bind soil particles into aggregates and improves soil structure. Improving the structure of the soil offers the gardener many advantages. The structure of the soil affects its ability to transfer and store water and nutrients, and allows the roots to penetrate deeper for access to more resources.
A soil test can determine the pH of the soil and the concentration of phosphorus (P) and potassium (K) in your soil – two of the three essential elements for plant growth. Nitrogen (N) is the other essential element but is not determined from soil samples. The soil test doesn’t tell you how much organic matter there is in the soil or what the soil structure is like.
Organic material and microorganisms
Organic matter consists of decomposing organic materials, which when completely decomposed are called humus. Organic materials in your garden are anything that was alive and now exists on or in the soil. Common organic materials include plant debris, leaves, clippings and other garden waste, food waste, and animal manure. Organic matter in soils offers a variety of benefits such as:
Maintaining a stable soil pH: Soil organic matter mitigates major changes in soil pH. This will help keep the soil pH in the low neutral range (5.5 to 7), which is optimal for most garden plants.
Energy supply of soil microorganisms: Organic matter is the main food source for microorganisms. When fresh organic material (e.g. plant residues, compost, organic waste) is added to the soil, microorganisms start the decomposition process. In the process, nutrients are released, soil aggregates are formed and humus is formed.
Preservation of soil fertility: Organic matter needs regular replenishment as decomposition is complete and nutrients are consumed by microorganisms and plants. Plants get P, K and trace elements from the decomposition of organic substances. It also feeds specialized soil bacteria that convert N from the atmosphere into a form available for plants.
Preservation of the soil structure: The presence of sufficient amounts of organic matter in soils helps to coat soil particles (sand, silt, clay), supports aggregation and improves soil structure.
Removal of harmful pollutants: Soil organic matter binds some harmful pollutants such as pesticide residues and trace elements so that they do not escape from the soil and pollute our waters.
Adding compost and growing catch crops improves soil structure, increases the population of microorganisms, and improves the overall health of the soil ecosystem.
Compost improves the soil
Compost is a dark, crumbly material that is created when microorganisms break down organic materials such as leaves, grass clippings, animal dung and kitchen waste. Compost does not decompose completely (like humus); It contains small pieces of debris such as twigs and leaves. The decomposition process has advanced enough in the compost to make nutrients more readily available to plants.
Converting garden waste and kitchen waste into compost is an environmentally friendly way to reduce the amount of waste incineration and provides useful and useful products for gardens. Compost is an excellent soil conditioner that improves the health and structure of sandy and clay soils. It can be worked into the garden soil or applied as a mulch over it. It can be mixed with other materials for use as potting soil or brewed into compost “tea” for plants.
This is the residual waste that is sold by mushroom farms when it no longer produces commercially usable mushroom crops. It is generally a mixture of cereal straw, blood meal, animal manure, and lime that are composted together.
Mulch fights weeds and more
Mulching is one of the best ways to upgrade your garden cheaply or for free. Mulch helps to control weeds, saves moisture, lowers the soil temperature, improves soil fertility and, last but not least, contributes to the order and beauty of the garden.
Your garden soil should always be covered with closely spaced edible plants, companion plants, catch crops or mulch. When the ground is bare, pioneer plants – known as weeds – sprout; Nutrients are washed out; Soil eroded; Predatory insects, spiders and other gardening helpers move on; and entire populations of beneficial microorganisms die. Your garden ecosystem needs to be restored when you plant your next crop so that it starts slowly each season.
Mulch is any material that is placed on the bare soil surface or around plants to soften the soil environment. Mulches can be inorganic or organic, but in a vegetable garden, organic mulches are preferred as these are simply additional organic materials added to the top of the soil. Microorganisms soon begin the decomposition process, and the mulch eventually becomes part of the soil’s organic matter.
As organic mulch breaks down, they improve the structure of the soil and release nutrients. Some examples of organic mulching are wood chips, pine straw or bark, hay, oak or other tree leaves, compost, and cover crops that are growing or that have been cut and dropped. Materials like newsprint and cardboard can also be used as mulch and will break down along with other organic materials.
Break open leaves and fir straw
The best mulches are those that are readily available (and free), such as leaves and pine straw. Some tree care services will put you on a list to get free wood shavings when they cut or prune trees in your area. You may have to accept a full charge if you choose this option. Neighbors who rake their garden in the fall are also good sources of additional mulch.
At Leon County’s waste disposal facility, free mulch is often available in two sizes – wood chips and “fines,” which are ground much smaller. Occasionally, partially composted material will also be available. Visit the Leon County website at leoncountyfl.gov.
The question is often asked whether these mulch materials can be incorporated into your garden soil as organic material or whether the fine grain can be used as garden soil. All of these materials are suitable for composting, and since mulching will provide organic matter to your garden as they decompose on the ground.
Microbes consume large amounts of nitrogen in the decomposition process, and when carbon-rich, non-composted materials are incorporated into the soil, the possibility of nitrogen depletion is a factor. This is usually not a problem if the materials are left on the soil surface to decompose. For the same reason, planting in non-composted fines could be a problem.
Bagged Supplements and Garden Mixes
All of these materials are more or less beneficial for your garden. No general statement can be made about which are the best, but some best practices include reading the labels to see what materials are in the bags and noting the concentration of NPK in each type that is on the Pouch is given as a percentage, such as 10-10-10 or 5-2-3.
In general, you want to avoid materials that are just high in nitrogen (first number) or low in nitrogen (potassium). The middle number (phosphorus) can be as low as zero because Florida soils usually contain enough phosphorus.
Bulk garden mixes usually work well for raised beds or to improve your home soil, and are generally made up of a mixture of composted animal manure and other materials. As a rule of thumb, the darker the mixture, the more organic material is incorporated and the better it is for your garden.
Janis Piotrowski is a Master Gardener Volunteer at UF / IFAS Extension Leon County, an equal opportunity institution. She hosts a blog about gardening and sustainable living in North Florida at https://northfloridavegheadz.blogspot.com. If you have any questions about gardening, contact the extension office AskAMasterGardener@ifas.ufl.edu by email.
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