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Soil is the most important part of the garden ecosystem. After climate, soil has the greatest effect on the health of your plants. So, if we know how to keep the soil healthy, we will know how to keep the garden healthy. The following is information on what soil is, how it works, and some tips for healthy soil management.
Definition:
By definition, soil is unconsolidated rock and organic material formed through the breakdown of bedrock and decay of organic matter debris on the surface. To a gardener, soil is many things. It is habitat. It is plant food. It is an anchor medium for plants. It is a place of storage for water, carbon and nutrients. It is a structural foundation for hardscape features. And soil is an ecosystem.
Soil Texture and Structure
The part of the soil that is composed of weathered bedrock is found in three physical forms; sand, silt and clay. The ratios of these soil components determine the texture of the soil. A loamy soil texture is one that is intermediate between the extremes of the three components. Sand, silt and clay can be bound into tiny clumps by decayed organic matter so that the soil feels crumbly. This crumbliness of the soil is described as soil structure, and is determined by the amount of organic matter on the soil surface and the degree of decayed organic matter in the body of the soil. A soil that has a high degree of this crumbliness is said to have good soil structure. Soils with good soil structure hold water for plant roots and also have air pockets so that plant roots can respire freely. Plant roots (and thus the rest of the plant) grow maximally in soils with good structure.
Organic Matter
Organic matter is the most important part of a soil. Once the organic matter has decayed and been incorporated into the soil, it has the ability to moderate the physical properties of the soil determined by the soil texture. For instance, if the soil has a high clay component, it will hold water very strongly and take a long time to drain. Organic matter will increase the drainage of this soil. On the other hand, if the soil has a high sand component, it will drain very fast and have a low nutrient holding capacity. Organic matter will increase both the water retention and nutrient holding capacity of this soil.
Micro-organisms
Organic matter is incorporated into the soil and its inherent nutrients released to plant roots through the biological processes of micro-organisms and small animals such as insects and worms. It is the micro-organisms that breakdown the organic matter into nutrients that the plant roots can readily absorb. As the demand for these nutrients by plants increases with increasing temperature, so do the biological processes of the micro-organisms increase with temperature. As the nutrients are released from the organic matter, they are taken up by plant roots. In this way, micro-organisms supply plants with nutrients in appropriate forms, in appropriate quantities and at appropriate times.
This supply of nutrients to plants via the biological processes of micro-organisms on organic matter can only be awkwardly approximated by the application of chemical fertilizers. In fact, if the fertilizers are chemical based, they have a high potential to actually inhibit these biological processes by the creation of chemical environments unsuitable for micro-organisms. Furthermore, chemical fertilizers are most often in a water-soluble format that is readily leached out of the soil with rain or irrigation.
Mulch
In a garden ecosystem, the plants themselves supply the organic matter to the soil. As the leaves of deciduous plants fall to the soil surface and the perennials die back, organic matter is returned to the soil. In this way are nutrients recycled in the garden ecosystem. The organic matter, in effect, is mulch for the soil surface. This organic matter mulch has many beneficial physical properties as well as the important biological benefits mentioned above. Mulch physically protects the soil surface from raindrops that can plug soil pores and reduce water infiltration into the soil. Mulch also helps soil retain water by inhibiting water evaporation from the soil surface.
Furthermore, mulch buffers the soil and plant roots against temperature extremes. As alluded to above, mulch provides the organic matter that is the food and habitat of the myriad of micro-organisms that live in the soil and feed your plants. The greater the diversity of these soil micro-organisms, the healthier and more vibrant your garden will be. If leaving the dead parts of the plants as mulch does not appeal to your aesthetic, it is important that you cover your soil with an imported/home-made mulch. Keep your soil mulched.
Soil Compaction
In order for most plants to grow maximally, there has to be a highly developed soil structure. As mentioned above, a soil with a good structure is described as being crumbly. It holds water for plant roots but also has air pockets so plant roots can respire. Some soils, such as clay soils, have a high potential to become compacted, thus destroying the soil structure. Compacted soils have reduction of water movement into the soil and through the soil column, as well as have a reduction of air pockets. Thus, compacted soils are a poor environment for plant root growth. Furthermore, because there are reduced air pockets and water drainage in the soil, an environment is created that is very unfavourable for micro-organisms. Therefore, soil compaction will lead to a decline in plant health.
Some Tips for Healthy Soil Management
Let the leaves of your deciduous plants lay where they fall. If the depth of leaves is thick enough, you may not need to annually import mulch to your garden. However, if it is just a thin layer of leaves on the soil surface, mulch should be imported and applied in a 2-3 inch layer.
If you prefer a tidy garden, you may remove the leaves and dead parts of perennials from your garden beds. (If using a rake to remove the leaves, do so with a light touch to mitigate damage to plants with surface roots such as Rhododendrons and Camelias.) However, if this organic matter is removed, it is very important to apply a 2-3 inch layer of mulch to provide food and habitat for your soil microorganisms.
The material imported for your mulch should be nutritionally diverse and have been composted for a period of time. There are a variety of fish composts that make very good mulches. These are generally composed of dead salmon composted with woody plant debris. Fish compost brands found in the Comox Valley and Campbell River areas are 'Sea Soil' and 'Earthbank Organic.' Both 'Sea Soil' and 'Earthbank' are Certified Organic by the Organic Materials Review Institute. 'Earthbanks' has an additional 'Rodale's' organic certification. In addition to providing your garden with nutrients and organic matter, compost also provides a source of micro-organisms.
Very often a bark mulch is used in the garden, especially in commercial landscapes. It is usually used because it it cheap and does not break down through the action of micro-organisms so lasts a long time. Also, very little grows in it so there is less weed germination. However, there are a couple compelling reasons not to use bark mulch. A tree puts into its bark chemicals such as turpene compounds that are toxic or unpalatable to potential herbivores. As such, they are also toxic or unpalatable to the micro-organisms in your soil. If the micro-organisms in your soil cannot act on the organic matter you apply as a mulch, this organic matter will not be incorporated into the soil and thus, will provide little or no biological benefits to your soil. Furthermore, trees also place lipids (fats) into the bark to repel water. Because both soil micro-organisms and plants require water for their health and survival, it is problematic that a water-repelling substance be used as a mulch.
Soil compaction can lead to a decline, or at the very least a stagnation, in plant health, so it is important not to compact the soil. When the soil is saturated with water, it has an extremely high potential to be compacted if walked on. So wait a while after a good rain, or irrigation, before walking on the soil. Remember that your lawn is growing on soil. Also, be aware that lawn mowers have the potential to compact the soil beneath the grass, especially if the lawn is mowed in the same pattern every time. Alternate the mowing pattern to avoid compacting your lawn soil.
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 Birds have a variety of readily observable characteristics. They forage, build their nests and perform territorial and courtship displays. They also sing vociferously and oft-times have colourful plumages. Furthermore, they do all of these things during the day. And it is for this reason that birds are the most visible wildlife in your garden.
At this time of year the birds we observe are usually residents, as our migrant bird populations have left for their wintering grounds. These resident birds are able to sustain themselves during our winters because of their ability to find food. As insect populations have declined or are hidden in the leaf-litter or rotting trees at this time of year, means that birds are usually eating seeds or berries, or at least that these foods compose a large part of their diet.
Small flocks of the ubiquitous darkeyed junco can readily be observed as they fly about looking for seeds near the ground or in the lower tree canopy. We often see multi-species flocks foraging together in large groups. Chestnut-backed chickadees and golden-crowned kinglets can be found together in search of seeds as well as insects and spiders. These tiny acrobats will often hang upside-down or even hover beside a branch while they glean insects from it. These two species are in many instances joined by ruby-crowned kinglets, red-breasted nuthatches, brown creepers and bushtits. We also may see groups of finches, whose diet is composed mainly of seeds year-round, such as house finches, purple finches and pine siskins as they forage in the trees. While these birds are regularly observed flitting about in the taller shrubs and the canopies of trees, other birds, notably the sparrows and thrushes, are generally found foraging lower to the ground. Spotted towhees and fox sparrows are commonly found hopping about in the leaf litter at the edges of shrubs. These two birds will stir up the leaves in search of insects and other food items by jumping forward and then quickly back. Song sparrows and golden-crowned sparrows will also be seen foraging on the ground, as will American robins and varied thrushes. If you have a stand of trees, especially trees with some rot, you may be lucky enough to see a woodpecker such as a red-breasted sapsucker, Northern flicker, or a hairy woodpecker.
Birds have a variety of requirements for their life needs to be met. These include food, water, shelter, nesting sites and nest building materials. Furthermore, the importance of each of these requirements changes with the demands of each season. During autumn and winter, food and shelter become essential to help them cope with the rigours of scarce food and cold temperatures. In the spring, birds need nesting sites and nest building materials to help meet their life goals of raising enough young to replace themselves. In the summer, water is important to help regulate their body temperature.
You can attract birds to your garden by installing plants that provide food and shelter, as well as supplying nesting materials in the spring and providing a source of water in the summer. Native plants are the best possible providers of food and shelter for birds as they are adapted to the local climate and, if planted in the correct place, can require less care than imported ornamental species. In addition, the native bird life will be adapted to the types of food and shelter the native plants provide! Berry, nut and seed producing plants such as red-elderberry, wild rose, Oregon grape, red-osier Y dogwood and Indian plum provide food for thrushes, sparrows and finches. Other plants, such as red-flowering current, salmonberry and orange honeysuckle provide nectar for hummingbirds. Furthermore, all plants should be a haven for a myriad of insects, which are food for insect eating birds and the young of seed eating birds. Let this be a reason not to apply pesticides, especially insecticides! Plants with a dense branch structure such as salal, oceanspray, snowberry, red elderberry and red-osier dogwood, provide important shelter as well as nesting sites. Grasses and plants with small twigs are good sources of nest building materials. In the summer, supply an elevated birdbath with gently sloped edges with a consistently fresh supply of water.
By providing food, water, shelter and nesting opportunities in your garden, you will create a haven for birds and a hotspot for bird watching!
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