Organic matter is basically material that was living or was produced by a living thing, including grass clippings, leaves, hay, straw, pine needles, wood chips, sawdust, manure, and anything else that used to be alive. It’s a miracle worker that improves soil by

• Feeding microorganisms and other soil life
• Improving the soil structure
• Increasing soil’s reserve of nutrients

Add organic matter to your plantings any time you can — whether it’s straw mulch between vegetable garden beds, compost around perennial flowers, or bark mulch around trees or shrubs. Try adding a 3- to 4-inch layer of dead leaves to your garden, either in the fall or up to one month before you start your vegetable or annual flower garden, and work it into the soil.

Soil microbes, such as fungi and bacteria, don’t work efficiently when soil is cold and wet, such as in early spring. They also use nutrients in the soil to fuel their eating, so if you give them too much material to work with at once, they tie up the nutrients, creating a deficiency for the plants. If you live in a cold-winter climate, add straw, leaves, and other raw organic matter in the summer or autumn when the soil is still warm to allow them plenty of time to decompose before plants need the nutrients.

Compost: The Prince of Organic Matter

The best and most refined of organic matters is compost, which is organic matter and/or manures that have decomposed until they resemble loamy soil. Thoroughly decomposed compost contains a lot of humus — the beneficial, soil-improving material your plants need. Whether the original source was grass clippings, sawdust, animal manure, or vegetable scraps from your kitchen, all organic matter eventually becomes compost.
Whether you make your own compost (see the “Composting: Turning Waste into Garden Gold” section, later in this chapter), or buy it ready-made, you can add finished compost anytime to the garden or around plants. Pile on a 2- to 3-inch layer annually around plants and on garden beds.

Why not just add raw organic matter to your garden instead of composting it? By composting the materials first, the final product is uniform in color, nutrients, and texture; is odor free; and contains fewer viable weed seeds and potential disease organisms (depending on how it was composted). Your plants will be happy with you for treating them so well.

You can buy compost from a number of sources either in bulk or bagged, depending on where you live. Bagged compost is the easiest way to go, especially if you have a small yard or container garden. The down side is that you don’t really know the quality of the compost until you get it home.

For larger quantities of compost, buy in bulk. The price is lower, and you can check the quality of the compost. Many private companies, municipalities, and community groups make and sell compost. Often, they even deliver the compost to your yard for a fee.

Use these tips to evaluate bulk compost:

• Consider the source. Before buying the compost, ask about the primary organic matter sources that were used to make the compost. Compost made from yard waste (leaves and grass clippings) is usually considered the safest and best. Other compost may contain ingredients that had contaminants, such as herbicides from agricultural crop residues and heavy metals from municipal wastes, which may affect the growth of your plants or accumulate toxins in your soil.
• Look at the color and texture. Finished compost should look dark and have a crumbly texture without any large pieces of under composed organic matter, such as branches or pieces of wood.
• Squeeze it. If water oozes out when you squeeze a handful of the material, it’s too wet; if it blows away easily, it’s too dry.
• Give it a whiff. The smell should be earthy without a strong ammonia or sour smell.  ....read more