is the first of what is hopefully going to
become a regular section in our magazine.
The articles will cover in general terms aspects of the science of
horticultural production. For those who are
familiar with this subject this will serve as a
refresher, and for others an insight of what
might be occurring in your crop. In this first
article we look at the subject of pH which is
often over looked and underestimated in its
effect on plants.
The pH storypH is
the term used to describe or measure the acidity
or alkalinity of a soil or solution. The full
measure or scale is 0-14 with 0-7 being acidic
and 7-14 alkaline. 7 being in the middle of the
scale is neutral, 0 being the extreme in acidic
and 14 the
alkaline or caustic. In agricultural soils or
waters the range is usually between 5 and 8.5.
In scientific terms pH is a measure of the concentration of hydrogen
ions (H+) with the higher the concentration
being reflected by the stronger acidic values,
ie the lower the pH reading.
only measure the pH of the soil growing the
crop, however in horticulture where regular
irrigation is part of the production process,
water pH can play a significant role. Plants
don't just grow in soil, they grow in a solution
combination of soil, water, air and cultural
additives (namely fertilisers) and it is the
resultant combination of pH that we need to be
paying the attention to.
As an example
if we have a soil with a pH of 6.5 a water
source with a pH of 7.6 and an alkaline
fertiliser is used then