loam Tagged ‘loam’

Some Notes about Soil fr/Dr. Elaine Ingram

Thursday, February 28th, 2013

 

Posted by: Susan Handjian, 8:11 PM GMT on February 25, 2013 +1

“The soil is the great connector of lives, the source and destination of all. It is the healer and restorer and resurrector, by which disease passes into health, age into youth, death into life. Without proper care for it we can have no community, because without proper care for it we can have no life.”
-Wendell Berry

Soil is a largely overlooked and misunderstood part of the garden ecosystem, and as a result is often mistreated, or ignored, even abused. As with all dynamic ecosystems, there is interaction and interdependence in the garden. Much more is happening out of sight than we can ever know. This is particularly true of soil, which is about as out of sight as it’s possible to be. The importance of soil goes well beyond the fact that it supplies anchorage for plants and holds a reservoir of water on which roots can draw. It is a complex amalgam of mineral particles and organic matter developed over millennia and is inhabited by a universe of soil dwelling animals and billions of good and bad fungal and bacterial microorganisms that are essentially in an ongoing battle for balance. As hard as it may be to believe, a pinch of soil may contain as many as 100 billion bacteria, comparable to the number of stars in the galaxy.

Soil begins with the physical deterioration of bare rock, worn or broken off by the force of temperature, rain or wave action, and wind to form a loose aggregation. Chemical decomposition of the aggregates then occurs, beginning the process called weathering. When weathering reaches a point where a seed might germinate and take root, webs of relationships begin to develop between plant and the microscopic life underground. Several factors are at play in this process. The parent material, climate, topography, and types of organisms present evolve over time to create the multitude of soil types the world over, whether it’s the dense, humus rich soils of the great forests to the lean, dry and sandy soils of desert lands.

Soils can be residual, forming in place, or depositional, transported from elsewhere by gravity, or rivers or wind. They are named for their texture, which remains unchanged. Texture is the result of the combination of mineral particles, sand, silt, and clay that they contain. The ideal soil is loam, an optimum mixture of the three. It contains a healthy population of soil-dwelling organisms, has minerals, air pores for root growth, and excellent water retention. Since natural loam is elusive for most of us, we have to improve the soil structure, fortunately a quite achievable goal. Our soils are identified by the proportion of their mineral components, sand, silt, and clay. How these different types behave is fairly predictable. Clay soils, with greater surface area of their tiny particles, can easily become gooey and waterlogged, while the larger sand particles give water less to cling to and as a result dry out very quickly. Texture also determines how well soil holds onto nutrients and how quickly or slowly it will warm up in the spring.

Gardeners are often puzzled about what to do with their soil. As tempting as it is to believe the ubiquitous television advertisements that show a dejected man digging one bag of soil conditioner into poor, depleted soil only to joyously see a complete transformation take place immediately, we know this is not how things work.

When we discuss soil development, we’re talking about geologic time. Many of the old notions of soil improvement achieved by adding great quantities of organic material by deep digging, tilling, and otherwise disturbing the soil are falling out of favor. Let me say now that for edibles, these techniques are necessary and effective. Vegetable and fruit crops are heavy feeders and require additional organic material incorporated in the soil to take care of their intense nutritional needs during the growing season.

In gardens that support mostly ornamentals, the double-digging and tilling simply aren’t necessary, and the application of organic materials from the top down are becoming widely accepted as a benign and effective method of soil improvement. If you favor native plants, they are adapted to both climate and soil. Often, over-amended soil is detrimental to them. Believe it or not, you already have most of what is needed to improve your soil in your garden itself. You can gently loosen the soil by inserting and rocking a garden fork back and forth to allow better air circulation, but other than digging planting holes, there’s already an underground army at your disposal to make things better. All you have to do is supply the raw material.

Remember, an ecosystem works in cycles. Nothing is static. The leaves falling from your trees, the spent flowers from annuals or perennial plants, twigs, branches, these all are fodder for the compost that will nourish the life in the soil. To be sure, there are imbalances that may need to be addressed with specific fertilizers or amendments. Some plants require additional nutrients that compost alone may not provide. Knowing this comes with experience. But providing plants with healthy soil brimming with microorganisms is always at the heart of a thriving garden.

Remember, an ecosystem works in cycles. Nothing is static. The leaves falling from your trees, the spent flowers from annuals or perennial plants, twigs, branches, these all are fodder for the compost that will nourish the life in the soil. To be sure, there are imbalances that may need to be addressed with specific fertilizers or amendments. Some plants require additional nutrients that compost alone may not provide. Knowing this comes with experience. But providing plants with healthy soil brimming with microorganisms is always at the heart of a thriving garden.

Now, the natural processes that create this ideal situation are not nearly as attractive and effortless as that man working with his bag of magic soil improver. Just as above ground, there’s a food chain in the life of the soil. What we’re talking about is decomposition. In a continuous cycle of life and death, plants, flowers, and animals live and die. What remains is either eaten by a huge array of microorganisms living underground or carried there by animals like pill bugs, worms, or beetles, where it continues to break down further and further. Decomposers attract predators. Bacteria are eaten by protozoa, fungi trap and eat nematodes but are then eaten themselves. Larger animal like earthworms, large in the sense that you may be able to see them with the naked eye, not only transport decaying organic material but eat it themselves. You can begin to see that a balance is being achieved by soil biota with little assistance from us. Further, nutrients that are created from the decomposition processes are dissolved when water is added to the soil, providing roots with a constant supply of nourishment over time.

It’s when we deprive the ecosystem of the raw materials for decomposition that we run into problems. The desire for “clean” garden beds, raked clear of any and all organic materials, has an unintended negative consequence. Soil biota cannot survive without dead and decaying plants, which are the raw materials necessary for their work and will simply move away or die. Nutrient recycling will stop, and the garden will then have to be supported artificially by applications of fertilizers. Fertilizers derived from petrochemicals very effectively keep soil microorganisms from ever returning to your garden. The answer? Feed the soil, not the plants. This general rule will bring results that may surprise and achieve a peace you’ve never had with your soil.

Fortunately, there are many resources for learning how to make soil better. I’ll be the first to admit that there are some soils so difficult the only solution is to avoid planting in them. In these cases, using raised beds or building mounds may be the only alternative. Before giving up completely, though, give some remedial methods a try. To learn more about helping your ordinary garden soil be its best, here are some suggestions:

The Soil Food Web

The concept of the Soil Food Web was developed by Dr. Elaine Ingham. Her research and methodology has opened up a whole new way of looking at the soil, and I can’t recommend her methods strongly enough. She is a proponent of the benefits of compost and compost tea to improve normal soil and remediate problem soils. You can find out more about her at:

Soil Food Web about the work of Dr. Elaine Ingham

from:    http://www.wunderground.com/blog/gardencoach/show.html?entrynum=14