As I have mentioned in the previous publications, the pH as a concept, was proposed by the Danish chemist Søren Peter Lauritz Sørensen in 1909, in whose theoretical understanding he referred to the pH, as "the negative logarithm of the hydrogen ion (H+) concentration that a solution possesses", or what is the same, property that allows to know the concentration of hydrogen ions in a solution, from the practical point of view the pH, serves as guide to determine the degree of acidity, neutrality or basicity of diluted aqueous solutions.
Fig. 2 pH as an agricultural parameter, serves as a guide to determine the degree of acidity, neutrality or basicity of soils. Image of public domain, Author: Pinus, 2017
Besides the practical interpretative sense, it is important to indicate that in Agricultural Chemistry, the pH functions as an indicator that allows to know the transformations that the matter experiences, either in organic or inorganic state, by means of a scale with range between 0 and 14, representing the value 7 the concentration NEUTRA (acid and base concentration in equilibrium), while the values lower than 7 constitute the section ACID, and the values higher than 7 the fraction BASIC/ALKALINE.
However, the pH as an ideal agricultural variable is located in an oscillatory range between 5 and 7, a category used to weigh soils in relation to active hydrogen suitable for crops, for example, in agronomic research, the pH value is usually determined, this to know the concentration of hydrogen ions in the soil, and then infer the mobility of physical, chemical, microbiological processes that occur in a given area of land.
Particularly the concentration of hydrogen ions in the soil, as an agricultural variable represents the following values; acid soils those that register high concentrations of hydrogen, either by poor water drainage (sedimented soils resulting from excessive rainfall), or those with high values of iron sulfide.
Fig. 3 The concentration of hydrogen ions in the soil is determined by agricultural laboratory methods. Image of public domain, Author: Jarmoluk, 2017
In relation to the soils with alkaline (basic) values, these orient on high concentrations of sodium carbonate to the detriment of hydrogen. Hence the reason that in agriculture is considered the pH range, to establish programs of planting, management and harvest of a particular crop, taking into account that plant species, respond to dissimilar pH values for optimal growth, development and production.
BIBLIOGRAPHICAL REFERENCES CONSULTED:
 Oshunsanya S. Introductory Chapter: Relevance of Soil pH to Agriculture. Soil pH for Nutrient Availability and Crop Performance Publisher: Intech Open access. 2019. Article: Online access
 Lauchli A., and Grattan S. Soil pH Extremes. Plant Stress Physiology (pp.194-209)Chapter: Soil pH Extremes Publisher: CAB International Editors: S Shabala. 2012 Article: Online access
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