AGR-164
COO PER ATI VE EX T E N S I O N S E RVI C E
UNIVERSITY OF KENTUCKY 鈥? COLLEGE OF AGRICULTURE
Water Quality Guidelines for
Tobacco Float Systems
Bob Pearce and Gary Palmer
W Table 1. Water quality parameters to be Table 2. Recommendations for tobacco
ater quality testing is available
measured by the University of Kentucky float bed water with alkalinity levels be-
through the University of
and desirable ranges for these parameters. tween 100 and 200 ppm CCE.
Kentucky鈥檚 Soil Testing Laboratory
Parameter Desirable Calcium
for farmers using the tobacco float
(units) Range Alkalinity level Recommended
transplant system. Table 1 lists the
(ppm CCE) (ppm) Action
pH 6.0 鈥? 7.5
measurements that will be made and
125 above 38 None
Conductivity (mmho/cm) 0.0 鈥? 0.75
their desirable ranges. It is expected below 38 Use acidifying
Alkalinity (ppm) 50 鈥? 100
that the water provided by most mu- fertilizer
Nitrate-Nitrogen (ppm) 0.0 鈥? 5.0
nicipal water systems will be accept- 150 above 45 None
Phosphorus (ppm) 0.0 鈥? 5.0
able for tobacco transplant produc- below 45 Use acidifying
Potassium (ppm) 0.0 鈥? 5.0 fertilizer
tion. However, some water districts
Calcium (ppm) 40 鈥? 100 175 above 53 Use acidifying
that use ground water sources may
fertilizer
Magnesium (ppm) 15 鈥? 50
have high levels of alkalinity and
below 53 Acidify with acid
Zinc (ppm) 0.0 鈥? 2.0
conductivity. The primary purpose of to 100 ppm CCE
Copper (ppm) 0.0 鈥? 2.0
the water testing service is for those 200 above 60 Use acidifying
Iron (ppm) 0.0 鈥? 2.0
who plan to use water from private fertilizer
Manganese (ppm) 0.0 鈥? 2.0
wells in their float beds. below 60 Acidify with acid
to 100 ppm CCE
Alkalinity
The water quality factor which
will be of most importance to to- Alkalinity will be reported in concentration of total carbonates
bacco producers is the alkalinity. Al- terms of calcium carbonate equiva- (TC) in milliequivalents per liter
kalinity refers to the capacity of the lent (CCE) in parts per million (ppm) (meq/L). Total carbonates in meq/L
water to neutralize acid or to resist a on water test reports. Occasionally, can be converted to alkalinity in ppm
lowering of the water pH. The major alkalinity may be reported as the with the following formula:
contributors to alkalinity in natural
waters are bicarbonates. Alkalinity
influences plant growth by causing total carbonates (meq/L TC)
alkalinity (ppm CCE) =
the pH of the growing medium to in- 0.02
crease. At high pH, some nutrients
become less available, resulting in
Recommended Treatment natural control on the activity of bi-
nutrient deficiencies. High alkalinity
carbonate, so more alkalinity can be
can also contribute to the accumula- for Alkalinity
tolerated in the presence of a higher
tion of ammonia in the growing me- At low alkalinity levels, less than
level of calcium.
dium, causing poor plant growth. 50 ppm, the water has very little ca-
When the alkalinity is greater than
pacity to buffer against a pH de-
200 ppm, it is recommended that the
crease so a non-acid fertilizer is rec-
bicarbonate be neutralized to a level
ommended. If the alkalinity is be-
of 100 ppm. The addition of mineral
tween 50 and 100 ppm no corrective
acids will be necessary to reduce the
action is needed. For alkalinity levels
alkalinity to an acceptable level. The
between 100 and 200 ppm the rec-
amount of acid needed will depend
ommended action will depend on
on the type and concentration of the
the calcium level of the water (Table
acid used.
2). Calcium in the water acts as a
A G R I C U L T U R E 鈥? H O M E E C O N O M I C S 鈥? 4-H 鈥? D E V E L O P M E N T
As an example, assume a sample dealers and auto parts stores have source. In the event that this is not
has an alkalinity of 250 ppm. We battery acid, but you should ask for possible, it is recommended that a
need to neutralize 250 - 100 = 150 virgin battery acid. Recycled battery fertilizer with a lower salt content be
ppm. To calculate the amount of acid acid may contain some impurities used.
needed, you need to know the con- that are harmful to plants. The most
Other Measurements
centration of the acid. Acid concen- common type of battery acid is 9.19
tration is given in units called nor- N (35%) sulfuric acid. The amount to For the other measurements, un-
mality (N). A common source of acid add can be determined: less extreme values are reported no
is battery acid. Many farm implement action will be recommended. High
levels of nitrate, phosphorous or po-
tassium may indicate surface con-
tamination of the water source. This
ppm CCE alkalinity x 2.56
= oz. acid per 1000 gallons water
raises concern that the water might
normality of acid
also contain levels of some pesticides
For the example above: which could cause injury to tobacco
150 x 2.56 = 42 oz. battery acid per 1000 gallons water seedlings. If levels of micronutrients
9.19 over 2 ppm are found, consult with
your county Extension office before
using the water.
If a different type of acid is used select equipment specifically de-
you must substitute the normality of signed for acid injection, since acids
that acid into the equation above. will corrode pipes and equipment.
Note that not all 鈥渂attery acid鈥? is the
Conductivity
same concentration, but the 35%
concentration is most commonly Another water quality factor which
used in automotive type batteries. If Acknowledgment
needs to be considered is the con-
a different type of acid will be used, ductivity. High conductivity indicates Much of the information contained in
please contact your county extension a high level of salts. Conductivity this publication came from: Produc-
office for assistance in determining levels greater than 0.75 mmho/cm (a ing Tobacco Transplants in Green-
the rate of acid to use. reading of 8 on the Dist-4) indicate houses: Water Quality. W. David
The appropriate amount of acid that soluble salts may be high Smith, Gerald F. Peedin, Fred H.
should be carefully added to the float enough to cause injury to young Yelverton, and C. Ray Campbell.
bed and mixed one to two days prior seedlings. The remedy in most cases Published by North Carolina Coop-
to seeding. If you plan to inject acid, will be to suggest a different water erative Extension Service. AG-488-3.
WARNING!
Strong acids will result in very serious burns to the skin and damage to the eyes. When
using any acid be extremely cautious to avoid contact with the material. The chemical
reaction between acid and water can cause acid to splash into eyes or onto skin and
clothing.
Always add acid to water, not the reverse. Add the acid in small portions with complete
mixing before adding more.
Always wear safety goggles with splash guards, rubber gloves and a chemical resistant
apron. Have plenty of clean water available to immediately wash off any acid.Do not use
acids alone. Have someone nearby who can summon medical assistance if necessar y.
Safety information can be found on a material safety data sheet (msds). The msds for
a product should be available from the product鈥檚 manufacturer.
Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability, or national origin.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, C. Oran Little,
Director of Cooperative Extension Service, University of Kentucky College of Agriculture, Lexington, and Kentucky State University, Frankfort.
Issued 2-96, 3000 copies
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