HEALTHY SOIL: Is probably the single most important factor contributing to the health of all vegetation. If you do nothing else for your garden than to improve its soil it will be time and money well invested. Lets take a look at some of the components that affect soil health.
Soil is comprised of different sizes of mineral particles. The relative amounts of each of these different sized particles constitute a soils texture. There are 3 main soil textures; sandy, silty or clayey and there are pluses and minuses to each soil one.
- Sandy Soils: Have a gritty texture. Their larger particle size serves to create larger spaces between particles and this translates to faster drainage and easy root penetration. Sandy soils are easy to work, do not clump, are quick to warm up in the spring and can be cultivated when wet. Their excellent drainage also helps to keep plants relatively free from soil borne diseases. On the down side they do not hold water and nutrients well and require more frequent fertilizing and watering.
- Silty soils: Have a silky feel to them and like sand do not clump, but this consistency puts silty soils at high risk of erosion. They are slower to warm up in the spring and are harder to cultivate when wet. On the positive side they are fairly easy to work and hold nutrients and water better than sand.
- Clay soils: Are almost cement like when dry. They are very slow to drain and should never be cultivated when wet. These soils compact very easy and are difficult to work. On the up side they are excellent at holding in water and nutrients and require less frequent watering and fertilizing.
- Loam: Is the technical term used to describe the ideal soil texture. It consists of a mixture of 30-40% sand……30-40% silt……..and 8-28% clay. This mix provides good aeration, excellent drainage, is easy to work and will hold nutrients well. Unfortunately loam rarely occurs on its own.
The most effective way to improve your soils texture is to add plenty of organic matter. Organic matter helps sandy soils to retain moisture and nutrients; for silty soils it helps the soil to stick together better reducing erosion; for clay soils it helps to improve aeration and drainage.
For information on how to test your soil texture
SOIL STRUCTURE: Deals with how a soil hangs together. Ideally you want loose crumbs and clods. If you were to squeeze a handful of soil in your hand it should form a loose ball, but with a light tap it should easily break apart. This type of structure provides adequate porosity, no matter what your soil texture is. Soils with good structure are able to absorb more rain water, drain freely and roots and soil organisms are able to move through the soil with greater ease.
A synergistic partnership between organic matter and soil organisms is the main agent behind good soil structure. As organic matter is broken down by earth worms and soil microorganisms, small air pockets are created in the soil. Additionally the decomposing matter is turned into gelatinous substances that serve to gently hold soil particles together. Another contributor is plant roots and fungi that serve to push soil particles together as they push through. They also manufacture gummy substances that help to hold particles loosely together.
Other tips for creating and maintaining good soil structure include: Cultivating the soil only when moist (not wet); Applying a layer of mulch to prevent compaction from pounding rains; minimizing roto tilling and other forms of cultivation, both of which will kill off many of your soil organisms and break up the desirable soil crumbs; add compost and/or manures regularly, even growing green manure is beneficial to your soils structure. (Green manure is a crop grown for the primary purpose of turning it under to supply the soil with organic matter.)
Soil amendments are not fertilizers (although some do have fertilizer value). Fertilizers supply nutrients, while amendments serve to improve the soils structure, drainage and aeration as well as improving nutrient and water retention. One thing to be thing to be aware of when choosing a soil amendment is its pH level. Like your soil, soil amendments are either acidifying or alkalizing. If your soil has a high pH (in other words is highly alkaline) you would not want to add wood ashes, which also has a high pH. Rather you would want to choose a more acidic amendment like compost or peat moss.
A few of the soil amendments available to you are: Compost (decomposed plant material . It is usually slightly acidic.) Shredded tree bark ( slightly acidic), Sphagnum peat moss (acidic), Manure (sheep, cow, horse, rabbit, even chicken. Sheep manure tends to be slightly acidic while horse, cow and chicken manure tends to be alkaline). Leaf mold (acidic), Wood ash (highly alkaline), Pine needle (acidic)
Healthy soils are alive and teaming with vast numbers of soil microbes such as bacteria, fungi, protozoa, nematodes, earthworms, and arthropods. One of the principles of organic gardening is to feed the soil microbes, not the plant. By feeding the microbes they will in turn feed your plants. Besides providing plants with nutrients soil microbes help to reduce water requirements, improve the soils structure, help to control soil borne funguses and diseases and aerate the soil. One of the microbes Mycorrhizae Fungi play a particularly large roll in over all plant health.
What do you feed microbes? Organic matter (including organic fertilizers). As the microbes break down organic matter they turn it into nutrients that are easily taken up by the plants. These nutrients are slower to leach from the soil, do not burn the plants or cause a build-up of salty residue.
Soil microbes are more abundant in soils that are moist, contain oxygen, have low tillage, are not compacted and where chemicals are not used.
It pertains to a soils acidity or alkalinity. In some gardening books you may see soil described as being sweet or sour. Sweet soil means a soil is alkaline where as a sour soil means it is acidic.
A soils pH is of paramount importance. It affects soils fertility by controlling how well nutrients are dissolved. You can fertilize all you want but if your soils pH is out of range your plants will be unable to access or utilize that fertilizer. Also while plant nutrients are being rendered insoluble, toxic elements become more soluble and can potentially kill plants or severely damage roots. In addition, beneficial soil bacteria will not grow in either highly acidic or highly alkaline soil and without the help of these guys your soils structure will be poor. Symptoms of excessively high or low pH include plants exhibiting yellowing leaves, lack of proper growth and flowering and in severe cases death of the plant. Certain plants thrive in an acid soil while others prefer a more alkaline environment. Knowing what your soils pH level is will help you to choose suitable plants for your soil. It will also help you to correct any imbalances before they become a real problem. For information on how to test your soils pH and how to help alter it.
Free of Excess Salts
Excess salts can be the result of winter deicing efforts or excess chemical fertilizers. Salt dehydrates plants by pulling water out of the cells. Even though there may be plenty of water in the soil the plants will suffer drought. Excessive salts in the soil can stunt plant growth, burn foliage, even kill plants. Salt leaves a visible white deposit on the soil surface. If your problem area is covered in grass it is a little harder to spot but you will know by the symptoms. To correct the problem (or at least help) add gypsum to the soil and water the area with a deep slow watering in order to flush the salt out of the root zone.
When drainage is slow water replaces air in the soil. Air is vital for root growth and overall plant health. To test your drainage, dig a hole about 1’ deep and 1’ wide. Fill it to the top with water and measure the amount of time it takes to drain. If the hole empties in an hour or less your drainage is good. If it takes longer you will need to take steps to improve the drainage. This is called the percolation test. Adding organic matter and gypsum will greatly improve a soil’s drainage. If the condition is more serious you may need to install drain pipes or tile beneath the soil surface in order to carry excess water away from the area.
Photo credits: all photo slides were created by the author.
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