Soil Basics

Understanding basic properties and principles of good soil is integral to organic lawn and plant management. A degraded soil has poor structure and poor biology and therefore requires large amounts of chemical fertilizers and pesticides to be productive. One of the main goals of Nature Guard Organic Lawn and Plant Care is to improve and maintain soil health.

What is soil? Good soil is a living, breathing, complex mixture of minerals, organic matter (dead organisms), living organisms and air. The most immediately apparent function of soil is a medium to support plant life. It provides support both physically and biologically. Physical support is provided by allowing the plant to grow its roots through the soil to hold itself in place. Biological support is provided by its ability to hold nutrients and water that the plant needs. It also supports other types of life as well. Microorganisms and insects live in the soil and they in turn aid plant life by helping to decay organic material and adding structure to the soil.

Soil Organic Matter-The Residue of Life

Soil organic matter is the residue of plant and animal tissue in varying degrees of decomposition. This dead tissue would accumulate indefinitely if it weren’t for the presence of bacteria, fungi, and other soil organisms actively involved with the decomposition process. The decay of organic matter does much more than simply consume organic debris, it serves to recycle important nutrients and return them to the soil. The stable residues of decayed organic matter are called humus. Humus is valuable for retaining dissolved nutrients and preventing them from leaching.

Soil Biology

Soil organisms interact in many ways with each other and their abiotic environment creating the soil ecosystem. For example, protozoa eat bacteria and some fungi feed on protozoa or nematodes. Other fungi are consumed by protozoa or parasitized by nematodes. Interactions among soil organisms may be very complex, but are crucial to the functioning of a healthy soil. The world beneath our feet is teeming with life.

Biotic Soil Components

  • Plant Roots- Plant roots and shoots are the ultimate source of energy for soil organisms. There may be 1,000 times more soil microorganisms near plant roots than in soil further away from roots. Half of the energy that goes to the roots ends up as exudates to feed the other soil biology.
  • Bacteria and Fungi- These two groups carry the lion’s share of work in decomposing organic matter. This leads to better soil structure and replenishes the nutrient cycle. The improved soil structure allows for roots to grow more easily in the pore spaces between soil particles.
  • Earthworms- Their borrowing activity mixes soils and creates macropores that increase water infiltration and help aerate soils. Aid in nutrient cycling.
  • Nematodes, Protozoa and other Arthropods- All aid in decomposition and nutrient cycling.

This incredibly diverse community/ ecosystem in your soil makes up the soil food web.

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Remember that every chemical based fertilizer, herbicide, fungicide and insecticide kills or harms some of the beneficial life that exists in your soil. The ecosystem beneath your feet helps to fertilize and aerate the soil.

Different Types of Soil Texture

Soil texture is important in determining a soil’s water and nutrient holding capacity Soil texture is defined as the size distribution of different mineral particles. These mineral particles are at their most basic level the following: sand, silt and clay. Sand particles are 2 to 0.05 mm diameter, silt particles are 0.05 to 0.002 mm diameter and clay particles are <0.002 mm diameter. Combinations of these particles exhibit different properties in soil and some combinations favor plant life better than others. The following are the most common classes of soil texture:

Clay soil
Contains a high percentage of clay particles and feels lumpy to the touch. The small size of the clay particles means that they clump together quite readily and there is less room for air spaces. Consequently clay soils have poor drainage and do not hold nutrients very well. This is a heavy soil and is sticky when wet making it hard to work with. As much as possible you should take steps to improve the drainage of this type of soil through core aeration and addition of organic matter like compost.

Silty soil
Contains a high percentage of silt particles and feels smooth to the touch. This soil is a well drained soil due to the size of the particles allowing space for water to permeate. This soil holds nutrients more readily than clay soil due to the spaces. It is easy to cultivate but can be compacted quite easily.

 Sandy soil
Contains a high percentage of sand particles and feels gritty to the touch, allows for quite a lot of space in between particles and as a result is very free draining. This has its disadvantages, however, as it does not hold water and essential nutrients can get washed away.

Loamy soil
This is the best type of soil texture you can have in your landscape. This is soil whose properties are controlled equally by the percentages of clay, silt and sand particles. It is well drained but does not lose water too easily as is the case with sandy and sometimes silty soils. The fact that it retains water means it also retains nutrients for your plants to use. It has a great structure and is easy to cultivate.

Soil Acidity and pH

Soil acidity or pH is one of the most important factors affecting the chemistry and biology of soil. Technically speaking, pH refers to the power or percentage of Hydrogen. It measures the acidity or alkalinity of soil which is important in a biological program in that improper pH will limit microbial activity and nutrient availability. In our Nature Guard Organic Lawn and Plant Program we typically test pH and adjust the acidic lawns found in our area with calcitic limestone.

What About N,P,K and other plant nutrients?

While nitrogen, phosphorous, potassium and other micronutrients are all very important for proper plant growth they are not the focus of the Nature Guard Organic Lawn and Plant Care program. Conventional lawn care programs over the years have used large quantities of these nutrients to maintain color and growth on plant material helping to contribute to nutrient loading of waterways and drinking water. In addition to these environmental concerns the commonly used synthetic nutrients push short bursts of growth to plant material causing a peaks and valleys effect. These peaks and valleys based on nutrient availability can have detrimental effects on plant material, such as, reduced carbohydrate reserves, reduced root development, reduced drought resistance, decreased cold tolerance, and increased susceptibility to insect and disease pressures. Additionally, the bursts are not desirable from the standpoint of mowing, pruning, watering and general maintenance. The goal of Nature Guard Organic Lawn and Plant Care is to improve soil health to a point where the soil’s own ecosystem provides enough nutrient cycling to optimize plant health.