Page 18 - Griffin Gazette Fall 2016
P. 18
Alkalinity Control
with Acid Injection
Image: Begonia with iron deficiency
By Rick Yates, GGSPro Technical cases, technical or reagent-grade sulfuric stock container. For this reason, it’s extremely
Services Manager acids are recommended by GGSPro. These important to always add acid to water and to
forms are effective, relatively inexpensive, never add water to concentrated acid. When
This is an excerpt from the 4th Edition and complement most fertility programs. preparing stock solutions, first fill the stock
GGSPro Technical Reference Guide. tank with the appropriate amount of water,
Chapter 8, Water Quality and Crop Nutrition, When handling acids, care must be taken and then add the acid to the larger volume
contains this and much more grower- to protect worker safety. Workers can be of water.
friendly information including: water and soil injured by direct contact with acid liquids
testing, diagnosing and treating; nutritional or vapors formed by some acids, including Growers that inject acid generally do so
problems; building fertilizer programs based nitric acid. Acids should only be handled in a continuous manner. Injectors used
on water quality and injector calculations. in well-ventilated areas. Inhalation or in this way should be selected to provide
ingestion of acids in liquid or vapor form lasting, reliable service and should be
It is strongly recommended to treat highly should be avoided. Direct contact of acid approved for use with acids. Multi-head
alkaline water sources with acid to neutralize with exposed skin and eyes can cause injectors are convenient to use with acids
the alkalinity to a low level, making the water serious injury. Lightweight, casual clothing and allow complete separation with other
more suitable for production by reducing does not provide adequate protection form injected materials. Growers can combine
its ability to raise soil pH. There are several the corrosive action of acids. Fortunately, acid and fertilizer stock solutions for many
options for acid injection, including sulfuric, acids can be handled safely with proper fertilizer types. However, calcium-based
phosphoric, nitric and citric acid. protective gear. fertilizers should not be mixed with acid
stock solutions as a precipitate will form
The characteristics of the various acids make Well-maintained protective gear should and cause the injector to clog. Examples
them more or less suitable for greenhouse include the following items: of calcium-containing fertilizer formulations
use, depending on specific situations. include, but are not limited to, 15-0-15, 15-
Nitric acid is the most caustic option. For • Acid-impervious gloves, suit and boots 0-0, and 13-2-13.
this reason, it’s generally avoided in most
production settings. The use of phosphoric • Goggles or face shield The amount of acid used to neutralize acidity
acid results in the addition of significant equates to a very dilute solution at the end
amounts of phosphorus to the irrigation • NIOSH/MSHA-approved full-face respira- of the hose, which is completely safe for
water. Since growers generally desire low tor for vapor-forming acids contact with plants and people. However,
levels of phosphorus in their water, most elect this water is not considered potable
to avoid injection of phosphoric acid. For Acids react with water in a strongly and should not be used as or added to
organic growers, some forms of citric acid exothermic manner, meaning the reaction drinking water.
are preferred due their OMRI status. In most between water and acid releases much
energy. This can cause the solution to boil
and lead to acid being dispelled from the
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