BLANKET BOGS are a great feature of the Irish landscape. They take a long time to develop and can grow on formerly fertile agricultural land.
By eating grass and other vegetation, grazing animals remove minerals and nutrients from the soil. Also, rain washes chemicals out of the soil. Both of these natural activities tend to make the ground more acid over time.
The pH scale is used to measure acidity. The scale goes from 0 to 14. Anything that registers between 0 and 6 is called an acid and anything that registers between 8 and 14 is called a base; 7 is neutral, neither acidic nor basic. As one moves away from 7 in both directions acids and bases become progressively stronger.
Water and blood are examples of neutral substances. With pH readings of 5 or 6, urine, acid rain and black coffee are all very weak acids. Being more acidic, orange juice and vinegar give readings of 3 or 4. Stronger again at pH 1 or 2 comes lemon juice, stomach acid and the acid in a car battery.
Going up the basic scale, seawater, toothpaste and baking soda give readings of 8 or 9. With a pH of 10 or 11, Milk of Magnesia, ammonia and washing soda are stronger bases. Soapy water registers about 12, bleach is 13 and caustic soda tops the scale at 14.
But to return to the original point: soil naturally becomes acid over time as both grazing animals and rainfall remove basic minerals and nutrients. On farmland, farmers add chemical fertilisers to replace nutrient losses. However, that accelerates the increase in acidity. To correct that issue lime is added to bring the pH up to suit the crop that is being grown.
If fertilisers and lime are not added and if nutrient inputs from grazing animals and dead vegetation are low in areas of very high rainfall, the leaching effect is such that the nutrient inputs may not be sufficient to stop the slide down the slippery slope towards ever increasing acidity.
Some plants cannot tolerate high acidity; others like mosses and heathers thrive in low pH values. As a result, the composition of the vegetation slowly changes with acid-loving plants gradually taking over. Farming is abandoned.
In time, the soil can become so waterlogged and so acid that the bacteria that cause decay cannot function. Dead plant material ceases to rot and accumulates as peat as the bog matures.
Blanket bogs take a long time to develop and can grow on formerly fertile agricultural land