Category: Soil Science

Soil-The Living Layer of Earth


A noted French theologian once said that “man is the living layer of earth.” He was referring to the spiritual realm, I’m sure. Because there is another “living layer of earth” right below our feet – the soil.

That’s because good soil is alive with millions, billions, trillions – countless mega trillions of living creatures which are born, live, procreate and die every second. A teaspoon of good soil would contain millions of living creatures, while a shovel-full would hold billions. An acre would contain more living organisms than there are starts in our galaxy… perhaps in the entire universe.

These organisms are part of the complex nature of soil – which is different from dirt. I’ll call good soil simply soil in the rest of this article.

I have already written about how soil is formed. Here is a deeper view. Once the tiny bits of grains have deposited and some organic material begins to grow and die, bacteria, single-celled animals and fungi begin to colonize the growing soil and mineral mixture.

Picture yourself in a forest. A tree sheds its leaves. Those leaves, now on the ground, begin to decompose. It’s not a process that just happens. The organic compounds in the leaves are being consumed by living microscopic creatures (and some larger ones). A single bacterium lives about 12 hours, after which it divides. In 7 generations, that single cell with become more than 16 million duplicates of itself. You could see that, in a year, the total bacteria population would completely cover the earth.

However, there is a failsafe, which contributes to the soil being enriched. Bacteria in the soil are being consumed by larger single-celled animals, like amoebas and protozoans. And while these cells are dividing, they are being consumed by even larger creatures.  Now, while all these microbes and macro-organisms are going through their life cycles, microscopically fine threads of symbiotic fungi are making their way from root to root.

It’s not over yet. Larger creatures – earthworms, pill bugs, beetles and other detritus-eating plants, munch away at the larger pieces of debris that the microbes did not finish consuming. The earthworms are especially adept at this, and they do more. By passing the detritus through their gut, they inoculate the particles with beneficial bacteria, which they then excrete back into the soil. Worms also make vertical tubes, allowing air and water to penetrate the soil.

Spiders, bug-eating beetles, ants, and other predators begin feasting on the earthworms and their helpers, adding their carcasses or depositing it as excretion onto the ground.

Now, even larger creatures come into the soil – like moles and birds. These predators love the other creepy crawlers and provide a useful purpose.


Every time I turn my compost in the spring, a robin perches near me waiting for worms. Since my compost is usually full of worms, except during the coldest days of winter, I don’t mind sharing them with this friendly avian. She waits until I have tossed four or five wriggling ones her way, she daintily picks each one up with her beak until she has all of them captured. Still holding them in her beak, she slams the worms against the crushed granite walkway until she has them dazed enough to her satisfaction. A quick flit to her next in a nearby oak, a couple of minutes there, obviously feeding her chicks and she’s back waiting for a more worm largesse. Occasionally, I’ll find her on top of my compost pile, scratching on her own – which is okay with me. I’ve got plenty of earthworms.  


This is the natural flow of things making up the living layer of earth and an essential part of the planet’s recycling process.

Advertisements

Making Your Soil Fertile


It really doesn’t matter what type of soil you have in your yard, garden or landscape. Any soil can be amended to make it fertile and robust.

As you can see from the chart above, each type of soil has its own properties. Clay soil has good nutrient- holding and water-holding capacities, but water and air cannot infiltrate into the clay. Clay is also hard to work. Dig a hole into clay soil and fill it with water. You can see what I mean. It takes forever for it to drain. Since clay is so dense, plant roots find it difficult to penetrate very far, leading to a weakened root structure and unhealthy plants. Soil amendments increase the porosity and allow water and air to flow through the soil.

Silt soils have medium capacities in all the categories, but to get the best results it will need to be changed somewhat.

Sand doesn’t hold nutrients or water very well. Pour water into sand and see how fast it drains through. Adding good amendments to sandy soil increases its water- and nutrient-holding abilities.


Now, loam is a different matter. Loam is an almost ideal plant-growing medium. It’s a mixture of equal parts of clay, silt, and sand. But, to make REALLY good soil, a few more ingredients are needed.

“ A soil amendment is any material added to a soil to improve its physical properties. In other words, you want to increase water retention, permeability, water infiltration, drainage, aeration, and structure. The overriding reason for this is to provide a better environment for roots,” according to a Colorado State University paper by J.G. Davis and D. Whiting.

There are easy ways to develop good soils.

I have found that organic materials are best, although some swear by inorganic methods. Organic amendments have come from something that was once alive…composted leaves and grass clippings (although it’s much better to mulch the clippings as you are mowing), peat moss, manure of many kinds, organic humates,  straw (not hay because hay has tons of seeds),  rotted wood (not fence slats or loading pallets) but wood from trees), fresh vegetable scraps, worm castings, and more. Although wood ash is organic, it is also high in sales and has a high pH.

You should also know this about organic materials. It helps the soil retain water, while also providing infiltration of both air and water. Soil with five percent of organic matter can hold up to three quarts of water per cubic foot. A 4,000 square foot lawn with that amount of organic matter (thus 4,000 cubic feet) can hold up to 3,000 gallons of water, and an acre can hold about 33,000 gallons. If water is a problem (many residents along the coast have their own water wells), it pays to remember that a good soaking rain can save a ton of water-and money – just by adding organic material. Some people make their own compost -others buy organic material (or steal it from their neighbor’s green recycling bin.)

Inorganic materials include vermiculite, perlite, pea gravel, sand, several other mined materials, and man-made crosslinked polymers. These materials are readily available.

I definitely prefer organic methods. I make my own compost- although I can never make enough to meet my needs. I do buy a lot, but I purchase it from local organic compost manufacturers. You can find a local organic composter near your area here.

One other good thing about organic material is that it inoculates the soil with beneficial organisms, which in turn help make nutrients more available to plants, as well as increasing the health of the soil.

What is Soil? It’s not just dirt!


Plants obtain water and nutrients from the soil surrounding their root systems. Plants also use the soil to anchor them physically, allowing them to stand upright.

Soil is made up of weathered rock fragments which contain minerals, the decaying remnants of plants and animals, including micro-organisms, and the secretions from the plants and animals living in it. It contains varying amounts of air, water and micro-organisms.

Good soil is made up of about half solids and half pores or open spaces between the solids. The solids consist of minerals and organic matter. The minerals consist of a myriad of particle sizes, from those that can be seen with the naked eye to those so small that an electron microscope is needed to view them.

These minerals make up about 45 to 48 percent of all the solid matter in soil. An additional 5 percent is made up of organic matter – decaying plants and animals.

An ideal soil would consist of the above concentrations of minerals and organic matter and the other 50 percent would include 25 percent air and 25 percent water in the porous areas.

The air and water provide sustenance for plant roots. The organic material allows microbes to grow. The microbes in turn, help the plant retrieve minerals and nutrients from the soil.

For more information on soil, please click here.

Lawns need little care now


With Christmas right around the corner and the National Weather Service predicting a cooler- and wetter-than-average winter for the Gulf Coast region, the next few months might be the perfect time to sit before the fire with a good book and a warm drink.

During the cooler weather, you might have to take some of your more subtropical and tropical potted plants indoors, but you shouldn’t have to worry about your lawn.

Lawn Dormancy

Warm season grass goes dormant during the cooler months.That doesn’t mean it is dead. It does mean that the grass blades turn yellowish or even brown during the winter months. That’s because the grass plants are shifting their growth from above to below the ground. This is when St. Augustine and other warm season turf grasses build their root systems. Good root systems built during the cooler months mean stronger and more disease and pest-resistant plants in the spring.

Good soil practices

Taking care of your lawn is a process. We’ve all heard the phrase “don’t put a $10 plant into a $1 hole.” What that means is that for any plant – turf grass included – the soil must be fertile, full of beneficial microbes, and must provide a nutritious environment for plants to generate new roots and expand existing root systems. To create good soil conditions, homeowners must make sure that the soil beneath their lawn is healthy.

Since increased precipitation is expected, there should be little or no reason to water lawns during the winter and early spring (late February and early March along the Gulf Coast). In fact, last year, our systems indicated that lawns needed no irrigation during the entire winter period.

Soil Science and Compost


Soil scientists agree that natural compost is the best way to create and maintain healthy soil. This video is an interview with John Ferguson, soil scientist and owner of Nature’s Way Resources.