The following is a quick summary of why should growers and crop
consultants measure pH in their soils during the course of the
year.
Soil pH is an important consideration for farmers and gardeners
for several reasons:
- Many plants and soil life forms have a preference for either
alkaline or acidic conditions, affecting the choice of crop or
plant that can be grown without intervention to adjust the pH
- Diseases affecting plants also tend to thrive in soil with a
particular pH range
- The pH can affect the availability of nutrients in the
soil.
Factors affecting soil pH
The pH value of a soil is influenced by the kinds of parent
materials from which the soil was formed. Soils developed from
basic rocks generally have higher pH values than those formed from
acid rocks.
Rainfall also affects soil pH Water passing through the soil
leaches basic nutrients such as calcium and magnesium from the
soil. They are replaced by acidic elements such as aluminum and
iron. For this reason, soils formed under high rainfall conditions
are more acidic than those formed under arid (dry) conditions.
Soil life and pH
A pH level of around 6.3-6.8 is also the optimum range preferred
by most soil bacteria, although fungi, moulds, and anaerobic
bacteria have a broader tolerance and tend to multiply at lower pH
values. Therefore, more acidic soils tend to be susceptible to
souring and putrefaction, rather than undergoing the sweet decay
processes associated with the decay of organic matter, which
immeasurably benefit the soil. These processes also prefer
near-neutral conditions.
pH and plant diseases
Many plant diseases are caused or exacerbated by extremes of pH,
sometimes because this makes essential nutrients unavailable to
crops or because the soil itself is unhealthy (see above). For
example, chlorosis of leaf vegetables and potato scab occur in
overly alkaline conditions, and acidic soils can cause clubroot in
brassicas.
Measuring Soil pH
Simple mistakes when measuring soil pH will leave you with
results that can ruin your farming operation. Don't get
caught in not following simple process rules.
Do not test cold soil. Cold inactivates bacteria, resulting in a
false reading. Wait until soil temperature (not air temperature)
has been above 60 degrees for at least two weeks, then test.
When measuring soil pH, don't neglect the subsoil, unless you
are the lucky owner of a four-foot-deep black prairie loam. We
forget that if surface soil is only six to ten inches deep, most
roots of many crops will grow through that upper layer and get the
majority of their nourishment from the subsoil.
Precision Plant Systems offers pH testers with stainless steel
probes that makes the measurement process much easier to manage and
record.
http://www.cropiq.com/products/cropiq-field-instruments.aspx