Na­ture Trail

Bray People - - NEWS - WITH JIM HUR­LEY

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

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