Importance of soil pH

The pH of soil or more precisely the pH of the soil solution is very important because soil solution carries in it nutrients such as Nitrogen (N), Potassium (K), and Phosphorus (P) that plants need in specific amounts to grow, thrive, and fight off diseases.
If the pH of the soil solution is increased above 5,5, Nitrogen (in the form of nitrate) is made available to plants. Phosphorus, on the other hand, is available to plants when soil pH is between 6 and 7.

Søren Peder Lauritz Sørensen

9 January 1868 - 12 February 1939
Danish chemist, famous for the introduction of the concept of pH, a scale for measuring acidity and basicity. He was born in Havrebjerg, Denmark.
From 1901 to 1938 he was head of the prestigious Carlsberg Laboratory, Copenhagen. While working at the Carlsberg Laboratory he studied the effect of ion concentration on proteins, and because the concentration of hydrogen ions was particularly important, he introduced the pH-scale as a simple way of expressing it in 1909. The article in which he introduced the scale (using the notation pH), described two new methods for measuring acidity. The first method was based on electrodes, while the second included comparing the colours of samples and a preselected set of indicators.
He is also known for the Sørensen formol titration.

pH Tests

The pH plays a highly important role in biochemistry, chemistry and technology since it affects numerous chemical processes. The results of many analytical methods are influenced by the pH of the solvent or buffer. The measurement can be made with a pH meter or with rapid tests, such as pH indicator paper or strips and pH indicator solutions (pH indicator mixtures). The great advantage of Merck’s rapid tests is that this method of determination can be used directly on the spot without requiring any additional help or sample preparation. The high accuracy of the results enables you to take any necessary counter-measures immediately, no matter whether in environmental analysis or the industrial sector as part of in-process controls

There are a lot of ways for finding the pH of some substance. One way is to use litmus paper. The pH paper is able to tell how strong the chemical is, whether it is a stronger acid or a stronger base.

Litmus paper

Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccella tinctoria. It is often absorbed into filter paper. The resulting piece of paper or solution with water becomes a pH indicator (one of the oldest), used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions. Neutral litmus paper is purple. The mixture contains 10 to 15 different dyes. Litmus was used for the first time about 1300 AD by Spanish alchemist Arnaldus de Villa Nova. From the 16th century on, the blue dye was extracted from some lichens, especially in the Netherlands. The main use is to test whether the solution is acidic or alkaline. Wet litmus paper can also be used to test water-soluble gases; the gas dissolves in the water and the resulting solution colours the litmus paper. For example, ammonia gas, which is alkaline, colours the litmus paper blue. Other reactions can cause a colour-change to litmus paper; for example, chlorine gas turns blue litmus paper white – the litmus paper is bleached. This reaction is irreversible and therefore here the litmus is not acting as an indicator.