Have you thought about adding chloride to your fertility management program?
Sandra L. Wick, Crop
Production Agent
Well winter is still here, even though we
occasionally get a “tease” from spring that isn’t too far away! It soon will be time when you will be in
field planting corn, soybeans and grain sorghum. So it isn’t too early to start thinking about
your fertility program.
Of course your first step with any cropping
system is soil testing. This component
is critical and is the cornerstone of your fertility program. This will help provide you with the needed analysis
of your soil to determine the nutrients that need to be applied depending on
your crop choice. K-State Research and
Extension does offer this service through the Soil Testing Laboratory, but
there are also several soil commercial laboratories in the state of Kansas that
are also available to producers. So we
highly encourage you to include soil testing as part of your fertility
management program.
“Chloride is one of the essential micro-nutrients
that you may have not thought about to include in your fertility program,”
according to Dr. Dorivar Ruiz Diaz, K-State Research and Extension Soil
Fertility specialist. It is normally
present in the soil in sizeable quantities, however, evaluations in Kansas
indicates fairly low soil chloride levels. A critical role of chloride is in
the oxidation of water in photosynthesis and as an activator of several
enzymes. In addition, chloride application has been shown to suppress or reduce
the effects of numerous diseases on a variety of crops.
Ruiz Diaz points out that physical symptoms of
chloride deficiency in plants vary and are not always consistent. In wheat,
some varieties show a characteristic leaf spotting, best described as random
chlorotic spots on the leaves The spots resemble tan spot lesions, but are
smaller and do not have the characteristic “halo” at the edge of the spot. On
low-chloride soils in Kansas, some varieties consistently show the leaf
spotting, while other varieties never spot. Other research indicates no obvious
visual deficiency symptoms which occurred on corn or grain sorghum, even where
chloride fertilization increased yields.
Summaries of soil test data in Kansas show a
majority of the samples had chloride levels below 40 pounds per acre, with a
significant number of samples less than 10 pounds per acre (on 0- to 24-inch
samples).
As an anion, a negatively charged ion, chloride
is not readily adsorbed on the soils exchange complex and is subsequently not
attached. Because of this, chloride moves readily with soil water. Chloride is
quite leachable, even more so than nitrate.
Kansas State University Soil Testing Laboratory
and most commercial labs offer a chloride soil test. Ruiz Diaz emphasizes that
because of the leaching potential of chloride, it is recommended to sample to a
depth of 24 inches to best assess soil chloride status (just like nitrogen and
sulfur). When testing for pH, phosphorus (P), potassium (K), organic matter,
and zinc, a 0- to 6-inch sample is recommended. When testing for the mobile
nutrients (nitrogen, sulfur, or chloride) a 0- to 24- inch sample is
recommended.
Ruiz Diaz points out that potassium chloride
(KCl) is the most common and readily available chloride-containing fertilizer
in Kansas. On an elemental basis, KCl fertilizer is 53 percent potassium and 47
percent chloride. For ease of calculating, assume a ratio of roughly 50 to 50
potassium to chloride. For example, if 50 pounds of KCl fertilizer is applied,
about 25 pounds of chloride would be furnished. Since P and K in fertilizer are
reported on an oxide basis (P2O5 and K2O), it can be confusing because many
fertilizer dealers know potassium chloride as 0-0-60 or 0-0-62. For ease of
calculating chloride application, just remember the product is about 50 percent
chloride. Research in Kansas has
evaluated all sources of chloride and results show each of these fertilizers to
be equally effective in supplying chloride.
Research indicates the likelihood of a response
to chloride fertilizer is directly related to soil chloride levels. So to start
incorporating chloride fertilization, a soil test is highly recommended to
determine if a chloride application might benefit your crop. When soil tests indicate a need for chloride,
the recommendation is to apply 10 to 20 pounds of actual chloride per acre,
depending on soil test chloride level.
Considerable research with chloride fertilization
has been conducted in Kansas on wheat, corn, and grain sorghum. Positive yield
responses have been noted on these crops. To date, response to chloride
fertilization on other crops such as soybean has been limited. Remember, response at any given soil chloride
level in a specific year may vary with several factors, including variety,
disease pressure, timing of moisture or temperature stress relative to the
effect of chloride on plant development, and soil chloride distribution
relative to crop root distribution.
A more detailed research summary, with yield
response data, can be found in the recently updated KSRE publication MF2570,
“Chloride in Kansas: Plant, Soil, and Fertilizer Considerations”: https://www.bookstore.ksre.ksu.edu/pubs/MF2570.pdf.
The Post Rock Extension District will be hosting
a “Spring Crops Update Meeting” on
Thursday, March 14, in Lincoln at the Finch Theatre starting at 10:00 a.m. and
concluding at approximately 12:30 p.m. A
FREE lunch will be served following the program, sponsored by The Bank of
Tescott. Pre-registration is requested by Monday, March 11, either ONLINE at www.postrock.ksu.edu or to your local office of our Post Rock
Extension District in Beloit, Lincoln, Mankato, Osborne or Smith Center. A minimum of 10 participants are needed to
hold the meeting. Hope to see your
there!
