Posted by Tom Thomas on Fri, Mar 19, 2010 @ 06:01 PM
What is soil pH, and why is it important for my garden?
Some gardeners say that adjusting the soil pH is the single most important thing you can do to ensure healthy plants. It may be a matter of life and death for your garden. So what's the big deal about pH, anyway?
The scoop on soil pH
The acidity or alkalinity of your soil is measured by pH, which stands for potential Hydrogen ions. Alkaline soil is known as "sweet" and acidic is known as "sour." In humid climates, soil tends to be acidic, and in dry climates it tends to be alkaline.
pH is measured on a scale from 1 to 14:
pH less than 7: acidic soil
pH greater than 7: alkaline soil.
pH of 7 exactly: neutral (neither acidic nor alkaline)
How soil pH affects plants
pH affects the availability of nutrients in the soil to plants, and a proper pH level helps prevent soil-borne diseases.
Each plant has its own recommended range for soil pH, which you can research through a quick online search. Sweet potatoes, for example, prefer more acidic soil (4.5 - 6.0). Tomatoes, however, prefer more acidic to neutral soil (6.0 - 6.5) and asparagus prefers more neutral to alkaline soil (6.0 - 8.0).
Testing your soil pH
Check your soil pH regularly, at least twice per year. It's easy to find out the pH of your soil using a kit available at most garden stores, hardware stores, and online. A good garden center will most likely test a soil sample for you.
Test kits normally contain a test tube, solution, and a color chart. You place your soil in the tube, add a few drops of solution, shake up the tube, and let it settle for about an hour. Then match the color of the tube's contents to the chart.
A creative way to test your soil pH is to plant a hydrangea. If your soil is acidic, the blooms will be blue. If the soil is alkaline, on the other hand, the blooms will be pink.
Adjusting your soil pH
Before you use chemical products to adjust your soil pH, make sure you've read the instructions and wear protective gear, such as gloves and a dust mask.
It's generally easier to make your soil more alkaline than it is to make it more acidic. (Fortunately, nature tends to make soil acidic.) To make your soil more alkaline by increasing the pH, add hydrated lime to your soil, less for sandy soils and more for clay and peaty soils. Bone meal, ground limestone, chalk, and crushed marble all contain significant amounts of lime.
Making your soil more acidic by lowering the pH takes time and is best done over a growing season, or even several seasons. You may want to consider building a raised garden bed and filling it with neutral soil.
If your soil is already slightly acidic but you want to increase the acidity, add peat or iron sulphate to it. For a more dramatic increase in acidity, use ground rock sulfur mixed thoroughly with the soil before planting. To ensure the effectiveness of the sulfur in the root zone, the most crucial area affected by pH, apply Great Big Plants Organic Liquid Compost along with this mixture. The beneficial microbes contained in Great Big Plants react with the bacteria in the sulfur to create minor amounts of sulphuric acid. It is possible that you have enough sulphur in your soil already, but have a sub-optimal microbe population. Additions of Great Big Plants should remedy this condition.
Finding the pH balance
Adjusting soil pH is not a one-time task, but rather a regular process. Over time, nutrients will be leached from the soil, and the pH will shift. Keeping tabs on it at least twice per year will encourage your plants to grow efficiently and beautifully.
Posted by Tom Thomas on Thu, Feb 11, 2010 @ 09:29 AM
Did you know that there are millions of soil microorganisms in just a handful of healthy garden soil?
The microorganisms living in your soil - including protozoa, fungi, bacteria, arthropods, and beneficial nematodes - are essential to keeping soil fertile so that plants can grow. Though too small to be seen by the naked eye, they work together to power the nutrient cycle that plants need to grow.
Plants can't feed on soil organic matter (dead leaves, plants and animals) directly, as animals do. They need this material to be broken down and bio-chemically converted into simple forms that are microscopic and water soluble so the plants can take them up through the roots.
That's where microorganisms come in. Without them, organic matter would simply contaminate soil, and plants wouldn't be able to extract the nutrients they need.
These are just some of the tasks that microorganisms perform:
- Decompose soil organic matter, such as leaves and minerals
- Extract and convert nutrients, such as carbon, from the decomposed material
- Provide the plant with nutrients such as nitrogen and phosphorus in a converted and plant usable form
Chemical fertilizers are not an effective substitute for a thriving microorganism population. These fertilizers still need to be converted to a plant usable form and do not supply bio-chemicals and exudates which are part of the healthy interaction between plant roots and microorganisms.
Carbon is the preferred food of microorganisms. To boost the population and activity of microorganisms try adding a little carbon, especially in or near the root zone. The carbon to nitrogen ratio, C:N, is important to the conversion and availability of nitrogen in the plant root zone.
Fortunately, it's not hard to attract microorganisms. They somehow manage to find their way into soil naturally, and then it's up to you to care for them. Nourish these tiny creatures with the basics: food, water, and air. Feed them soil organic matter by adding compost, ensure that the soil stays moist, and keep it aerated, and they will keep doing their jobs.
Be aware that healthy soil is teeming with little creatures who simply need basic care to do what they're genetically programmed to do: to power the nutrient cycle. If you keep these microorganisms alive and help replenish their population, in turn, they'll help your plants thrive.
Posted by Tom Thomas on Tue, Jun 09, 2009 @ 07:06 PM
Is a picture worth a thousand words or what? I came across this picture of increased root mass due to the effects of Humic Acid. (Source: Sustainable Agriculture Reserarch and Education; www.sare.org) We have found that many people are not acquainted with this substance and its benefits. So, in spite of the picture, here are a thousand words anyway. (Well, maybe not that many.)
Humic acid is a term that refers to the combined humic and fulvic acid content found in naturally occurring decomposed plant and animal residues dating back thousands of years or more. Leonardite coal deposits have been found to possess the most bio-chemically active form of humic acid.
Humic acid can help improve soil structure. When applied to clay soils, humic acid can help break up compacted soils, allowing for enhanced water pentration and better root zone growth and development. When applied to sandy soils it adds essential organic material necessary for water retention thus improving root growth and enhancing the sandy soil's ability to retain and not leach out vital plant nutrients.
Humic acid also plays a critical role in the ability of the plants to uptake nutrients from soil. It is especially beneficial in freeing up otherwise unavailable nutrients in the soil so that they are made available to the plant as needed. For example, humic acid can separate aluminum and phosphorus molecules, making the phosphorus available for the plant. Humic acid helps chelate mironutrients, increasing their bio-availability to plants.
Soil microbial activity is stimulated by humic acid by virtue of providing the indigenous microbes with a carbon source for food. As we know, soil microbes are responsible for solubilizing nutrients such as nitrogen and phosphorus so that they can be available for the plant's roots. Microbes continue to break down soil organic matter which increases humus and ultimately adds to the humic acid base of the soil.
So just imagine if you could easily add humic acid, benefical microbes and minor nutrients directly to the plant root zone all at the same time. Hmm....