Sweet sorghum is a high-value crop that grows well
in Kentucky and has very few pest problems. During
2005-07 we included sweet sorghum as part of the crop rotation in
organic demonstration plots at the Kentucky State University Research
Farm. We found that sweet sorghum is easily compatible with organic
production systems.
In 2005 and 2006
we seeded sorghum on June 6th, using an Earthway row
seeder fitted with a 'radish' seed plate. Rows were spaced 30" apart to
allow space for a roto-tiller. We planted a half acre of 'Dale' in 2005
and a quarter acre of 'Della' in 2006.
The crop grew well
without irrigation, even in the unusually dry summer of 2005. Sorghum
out-competes most weeds by growing rapidly and exuding toxic chemicals
from its roots (allelopathy).
We used a single pass with a roto-tiller to control weeds between rows.
August
September
Our biggest weed
problem was Johnsongrass, which is closely related to sorghum. Like
sorghum, it grows quickly and uses toxic chemicals to weaken
competitors. The weed was difficult to distinguish from the crop when
it was small enough to hoe, so we hand-pulled any Johnsongrass plants
still in the sorghum rows in August, removing as much of the rhizomous
root as possible.
By September the
crop was more than 10 feet tall and formed a dense canopy that shaded
out remaining weeds (shown here beside our 12-foot high tunnel).
September-October
Juice
extraction (October 19, 2006)
We experienced severe lodging of our crop during the
late summer storms of 2006. In 2005 one person was able to cut half an
acre of sorghum in a single September afternoon with
a sicklebar
mower. The lodging in 2006 made
it necessary to cut individual stalks by hand with tobacco knives,
taking about 20 man-hours to harvest a quarter acre of sorghum.
Lawrence Jenkins
brought his mule-driven extractor to the KSU farm in 2005. Dr. Morris
Bitzer brought his portable PTO-driven extractor in 2006 (above). We
extracted juice from stalks that had been stripped of leaves
(left) or had not been stripped (right).
To
strip or not to strip?
Cooking
the juice
Stripping the
leaves had no effect on the amount of juice extracted from the stalks:
100 stalks produced about 6.5 gallons (25 liters) of juice either way,
with no obvious difference in quality or sugar content. The bucket in
the foreground contains juce from 50 stripped stalks; the bucket in the
background contains juice from 50 unstripped stalks.
We cooked 50
gallons of juice over propane
burners in a big stainless steel pan. We stirred constantly,
removing the froth from the surface, and monitoring the temperature and
sugar content. The syrup was ready when the temperature reached 230
ºF (110 ºC) and the sugar content was 80
ºBrix.
Syrup!
The
final product
50 gallons of juice
made about 5 gallons of syrup.
Dr. Bitzer pronounced it excellent syrup. High
praise indeed!
Thanks to:
The 2006 harvest crew (Larry Bomford, Norris Burkhead,
Eddie Reed, Tony Silvernail, Hank Schweikart, and Steve
Skelton)
The extractors and processors (Lawrence Jenkins in 2005
and Morris Bitzer in 2006)
