Mulch

Mulch? What is it? Why use it? How to use it?

By Christopher Harrod

With the rise of the suburban landscapes, there has been an increased focus on manicured landscaping. When leaves fall on the ground or lawn, they are raked, bagged, and sent to some another place. These leaves would naturally provide the soil with what would be considered “organic mulch,” (I’ll explain later).  Mulches like leaves help reduce evaporation, increase organic matter in the soil, and improve drainage. In our Mediterranean climate where we have no rain in the summer, mulch should be in wide use, helping conserve our water.

Why use mulch? First of all, it’s putting money back into your pocket by saving you on your water bill. It also provides organic matter that eventually breaks down to humus, which provides nutrients and stimulates biological activity. Also, the organic matter improves soil drainage in clay soils and increases water-holding capacity in sandy soils. Mulches also help reduce weeds by smothering and blocking sunlight to seeds. They also make it a whole lot easier to pull weeds when you do have them because the soil is nice and loose.

What are the different types of mulches? They are mainly divided into three categories: organic, inorganic, and living. Organic mulches would include wood chips, straw, newspaper, etc. Inorganic mulches would include rocks like river stones, sand or lava rocks. Living mulches would be plants, mostly plants that spread and form a dense cover above the soil. A few plants that I recommend include comfrey, thyme, and low growing California natives such as Manzanita (Arctostaphylos sp.) or California Lilac (Ceanothus sp.). California Lilac and Manzanita are the most drought and deer resistant. While, comfrey (high in potassium) can be cut multiple times a season for nutrient rich mulch.

Wood chips as an organic mulch
Wood chips as an organic mulch

There are lots of choices when it comes to applying mulch in your yard. How do you choose one for your landscape? The organic and living mulches provide the most benefits. The inorganic mulches do not provide organic matter but are great when used with succulents, cacti and other seaside and desert plants. Straw is great for vegetable gardens, because it breaks down relatively fast. For orchards, you may want to go with wood chips cut into different sizes that will provide weed control for a longer period. Pine needles and oak leaves work great for acid loving plants. There are many resources online that are easy to access that can provide more information on choosing your mulch.

There are certain guidelines you want to follow when applying mulch to your landscape. First of all, it’s important not to cover the crown of the plant because this can cause moisture to build up around the trunk, which will result in crown rot. Horticulturalists have different opinions on how much mulch should be applied. Through my experience and research, I believe a couple inches or less is all you need in most situations. If mulching summer vegetables, wait until mid-spring because you want the soil to be warm. Also, be sure to water the mulch after you apply because sometimes it can be very dry, acting as a barrier to water.

Finding materials for mulch in Sonoma County is easy, local soil yards like Sonoma Compost will usually have a few options to choose from. Also, at local nurseries, you can find bagged mulch. Wood chips are sometimes offered for free on sites such as Craigslist and Freecycle. The easiest option would be to let the leaves and branches from your own plants decompose on site. That method doesn’t require you to get in your car or pull out your rake on your day off.

Useful Links:

Benefits of Mulch Pamphlet (PDF)

University of Illinois Extension (Great description list of mulches)

Guide on ground cover Ceanothus

The fungus among us

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There is something mysterious that grows beneath our feet and plays a very significant role in the health of most plants and yet, often goes unnoticed until the fruiting body, called a “mushroom,” appears on the surface.

Even then, most people don’t bother to take a closer glance. Fungi often get overlooked when people talk about the landscape. In America, it’s common to have a “fungi-phobia,” because in this country, we don’t have a rich history of collecting mushrooms in the wild, as compared to many places in Europe, for instance.

Fungi and the ecosystem
Fungi play an important part in almost every ecosystem. Biologists in the past haven’t generally studied and focused attention on fungi as much as they have on plants and animals.

Although there is a lack of extensive research on fungi, there is a basic understanding of fungi and their unique relationship to plants. A few fungi types are parasitic, meaning that while they derive benefit from a plant, the plant itself is harmed. However, most fungi have a mutually beneficial relationship with plants.

Certain types of fungus decompose wood, which then provides nutrients for plants. If you have ever turned over a pile of leaves or woodchips and have found thick white netting, somewhat like a spider web, then you have a found the “roots” of a fungus, called mycelium.

The mycelium feeds on the decomposing litter. They also have the one-of-a-kind ability to break down lignin in oak leaves and pine needles. Lignin is a substance that helps reduce rot in conifer trees. The mushroom is the fruiting body of fungus and its way of spreading its spores. The spores can be considered the fungi’s “seeds.” It is important to understand not all fungi produce mushrooms.

Plant roots, fungi relationship
There is an often-unknown relationship between fungi and plant roots. Certain fungi have a symbiotic or mutually dependent relationship with plants; these types of fungi are called “mycorrhizal” fungi.

These types of fungi have the ability to exchange nutrients with plant roots. They act as an extension of the root, absorbing nutrients from the soil that the plant can’t necessarily access. In exchange, the fungi obtain carbohydrates such as glucose and sucrose from the plant, which help the fungi grow.

There are two types of mycorrhizal relationships between plants and fungi. One is called an AM (short for arbuscular mycorrhizal) relationship. The fungi penetrate the roots to exchange nutrients. AM are found in about 90 percent of plant families. AM fungi do not produce the fruiting bodies we call mushrooms.

The other type is call EM or ectomycorrhizal. In this case, the fungus doesn’t penetrate the root but fuses to the outside of the plant root. EM is found in approximately 10 percent of plant families, and these do usually create a fruiting body, or mushroom.
This means most plants, including most of our native plants and the plants we grow for crops, have some sort of relationship with these symbiotic fungi. This is an important reason to maintain a healthy and fungicide-free soil.

I hope you have a better understanding of fungi and the roles they perform in ecosystems. They provide essential nutrients to over 90 percent of plant families through two kinds of mycorrhizal relationships. Fungi also have the ability to break down organic matter and lignins. Mulching with leaves, woodchips, and most organic matter, can provide the food needed for the fungi to thrive while also providing benefits to surrounding plants. Also, not using fungicides can greatly improve your soil life.

This article was orginally published in the Community Voice on April 7th, 2011.

A link to the original article: http://www.thecommunityvoice.com/article.php?id=2739

Photo credits: Christopher Harrod

Related Links:

Mycorrhizae Research Paper from World Journal of Agricultural Sciences

Mycorrhizae Handout from Washington State University