Sunday, May 15, 2011

Getting to know your soil, Gardening 101b

     You have picked your spot, rolled your sleeves up and are ready to take the plunge into the world of gardening. As you put your spade or trowel into the ground, here are a few things to know about your soil.

     Is your soil sandy, silty or clay?  What does loamy mean? What is humus? (No it isn't a dip) What are pH values? How does it affect my plants? Why do I need to bother with any of this?

     The last question is the easiest to answer. Knowing about your soil will help to avoid problems during the growing season. Gardening is a labour of love but it is labour, sometimes a lot of labour. Knowing about the earth you are planting in will help to avoid disappointment and frustration later on. Here is your quick and easy explanation to many of your soil questions.

     Soil is typically described by particle size. Sand is the largest, clay the smallest and silt somewhere in between. Your earth usually is identified by the highest concentration one of the three above.

     Sand as the largest drains water easily, is well aerated and roots spread quickly and easily. On the negative side, very poor water retention and usually low nutrient count. A plus or minus depending on your point of view, it is easy to uproot plants grown in sandy soil. All sand is not created equal. Gardening sand or sharp sand is exactly that. Rough and used to break up heavier soil. Builder's sand, used in construction is smoother, will compact more and has a tendency to bind with heavier soil rather than break it up, the bane of the urban gardener.

     Clay is the finest particle. It usually has a high nutrient count and retains water well. It compacts making for poor aeration of the soil and it is difficult for roots to spread. Because it compacts so much, when dry it can become a water barrier, negating it's water retention properties.

     Silt being in the middle as far as size goes, is a combination of both of the above, not really outstanding in any one area nor does it have any really negative properties.

     Loam describes earth that is a combination of all three in roughly equal amounts. It is the ideal growing medium, the best of all worlds. All you need is a generous helping of humus and you are almost ready to grow.

     This is a vast oversimplification of soil conditions, but does provide a starting point for identifying what you have in your garden. Two quick soil tests; wet your soil (damp not soaking). Rub a little between your thumb and forefinger. If it is gritty like sandpaper, sandy, smooth and a little slippery, silty and if it is sticky and tacky, clay. You can also squeeze it into a ball in your hand. If it falls apart, sandy, if it holds together but crumbles easily, silty and if it sticks together in clumps, clay.

     Humus the end result of organic/vegetable matter decay. It is what you are aiming for when you compost. Typically dark in colour, it is relatively light when dry and has a rich "earthy" smell. Humus is loaded with nutrients, a great food source for your plants. "Black Earth" is a form of humus usually made from peat.

     The easiest way to change or amend your soil be it heavy or light is to incorporate organic matter or humus. It helps break up clay and sandy soil gets a boost in nutrients and water retention. Changing your soil condition is a continuous process, even good earth gets depleted when you are growing things. Your ideal growing medium for most plants is about a foot to 18 inches of loamy, humus rich soil with a neutral pH value of around 7.

     What does the pH value indicate, the acidity or alkalinity of your earth. It is measured on a scale of 0 to 14. The lower the number, the more acidic the higher, more alkaline or basic. Neutral is the half point range on either side of 7, roughly 6.5 to 7.5. Neutral is where most of your plants will fall but things like blueberries or heather thrive in more acidic conditions with lilac and clematis preferring more alkaline.  

   So what?  The pH of you soil determines how nutrients are made available to your plants. If it is off you will get stunted or no growth. It isn't absolutely necessary to test your pH unless; you are trying to diagnose poor performance from last year or you just want to be pro active and avoid any problems in this area. Almost any garden centre should have a simple pH test you can use at home.

     It is relatively easy to "fix" a pH problem. Lime will raise it and sulfur or green compost will lower it. Ask your garden centre how to use lime or sulfur correctly.

     There it is, the dirt on ... Dirt.

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