Soil and its pH

We continued to discover the connections between chemistry and gardens, and found out quite a lot about soil pH. At first, we didn’t think there’d be a way to take the pH of the soil, or if it was even important. After doing some research, we discovered that there are several different ways to take the pH of the soil, some of which are listed below.

• Use an inexpensive pH testing kit based on barium sulphate in powdered form. When a small sample of soil is mixed with water, the color will change according to the acidity or alkalinity.
• Use litmus paper. A small sample of soil is mixed with distilled water, into which a strip of litmus paper is inserted. If the soil is acidic the paper turns red, if alkaline, blue.
• Use a commercially available electronic pH meter, in which a rod is inserted into moistened soil and measures the concentration of hydrogen ions.

Now that you know what to use to discover what the pH of the soil is, you need to know why it’s important! Its main importance is that certain plants can grow the best only at certain pHs. A list of plant pH preferences is listed below.

• pH 4.5-5.0: blueberry, cranberry, orchid, blue hydrangea
• pH 5.0-5.5: parsley, potato, radish, ferns, sweet potato
• 5.5-6.0: beans, carrot, brussels sprout, peanut
• 6.0-6.5: broccoli, cauliflower, cabbage, cucumber, tomato, strawberry
• 6.5-7.0: asparagus, beet, celery, lettuce, spinach, onion
• pH 7.1 - 8.0 lilac, brassica

To increase the pH of the soil (make it more basic), use a process calling liming. To decrease the pH of the soil (make it more acidic), use iron sulphates or aluminium sulphates, ammonium nitrate, decayed vegetable matter, compost, or stable manure.

Be sure to check back at our blog for more information on the incorporation of chemistry in gardens!