This study examined the nutrient content and value of tobacco stalks from different tobacco types as a nutrient source for pastures. Tobacco stalk samples were collected from burley, dark air-cured, and dark fire-cured tobacco crops at two locations. Stalk nutrient content varied by location and type but burley stalks contained approximately 60 lbs of N, 11 lbs of P2O5, and 50-73 lbs of K2O per ton of dry stalk. Dark tobacco stalks contained similar nutrient levels. Plots treated with 3 tons/acre of stalks at ambient moisture levels showed substantial yield increases of 3-4 times that of untreated plots in the first two harvests. The addition of tobacco stalks maintained or

1. Nutrient Value of Tobacco Stalks
R.D. Simpson1, J.L. Gray2, E.L. Ritchey3
1ExtensionAgent, University of Kentucky Cooperative Extension, Central City, KY 42330
2Agronomy Technician, University of Kentucky, Princeton, KY 42445
3Extension Soils Specialist, University of Kentucky, Princeton, KY 42445
University of Kentucky
ABSTRACT Stalk Moisture Content: Moisture content was the most variable parameter Table 4. Calculated nutrient removal by hay and dry matter (DM) yields
A field study was initiated to determine the potential of tobacco stalks as a nutrient measured for this experiment and the most influential (Table 3). It is well for three cuttings of hay at Muhlenberg county. All values are in lbs/A.
source, the nutrient content of burley, dark-air, and dark-fired tobacco stalk, and how known that the duration of curing (time in the barn), curing conditions and
N P2O5 K2O DM DM DM
fescue dominated pasture responded to tobacco stalk additions. Five foot square plots methods, and tobacco type influence stalk weight. This can be confirmed by
were established in Muhlenberg County, KY on a private farm and at the University of simply carrying similar amounts of green stalks and brown or “well cured”
Cut 1 Cut 2 Cut 3
Kentucky Research and Education Center near Princeton, KY. Tobacco stalks were hand stalks for any distance. The moisture content for the MC burley stalks was
spread at 3 tons/acre at ambient moisture content. Tobacco stalk samples were air
Check 13 4.1 14.4 780 2017 937
unusually high compared to other stalks in this and other studies and was
dried to determine moisture content and ground to pass a 2 mm sieve for nutrient possibly inflated. If the former is true then it could be attributed to greater
content. Fescue samples were collected and quantified at the Muhlenberg County moisture retention of stalks with elevated K concentrations. The latter would Burley (MC) 43 11.7 60.0 2533 3133 512
location three times during the growing season. Stalk moisture varied considerably
imply a recording or measuring mistake during the DM determination
between locations and stalk types. The differences in moisture are attributed to curing
procedure. Either way, it was decided to report the MC burley data to make a
time prior to stripping, environmental conditions during storage, and different tobacco Dark-Air (MC) 59 15.3 75.6 3049 3565 571
types. Nutrient content within similar types of tobacco was relatively consistent. On a critical point, moisture matters.
dry matter per ton basis, burley contained approximately 60 lbs N, 11 lbs P2O5, and 50
to 73 lbs of K2O. Dark tobacco contained about 60 lbs N, 12 lbs P2O5, and 47 lbs K2O Table 3. Calculated moisture (%) and nutrient content (lbs/A) for stalks at
per ton of dry stalk. Fescue yield increased significantly with the addition of stalks in their respective moisture contents and a 3 ton/A rate. The yield increase for the treated plots was substantial and was clearly visible
the first and second harvest (burley= 1753 and 1116; dark-air=2269 and 1548 lbs/A for Type N P2O5 K2O Cu Zn % upon inspection (Figure 1). Yields increased between 3- and 4-fold the first
the first and second harvest respectively. (Location) Water cutting and this trend continued for the second cutting. The third cutting was
considerably less than the previous two cuttings with the exception of the
METHODS
Burley (MC) 14 2.8 18 0.01 0.02 92 check, which increased over the stalk treatments. Most likely, grass response
A field experiment was established in Muhlenberg county, KY (MC) in November was due to N and K at the MC location and will again become the most limiting
of 2010 and at the University of Kentucky Research and Education Center (UK- Burley (UK-REC) 144 25.2 113 0.09 0.18 24 nutrients if not properly amended in the future.
REC) located in Princeton, KY in February of 2011 to test the influence of tobacco
stalk additions on grass “pastures” in nutrient deficient soils. Dark-air cured and
Dark-Air (MC) 101 15.6 60 0.08 0.11 58
burley tobacco stalks were utilized at MC on fallow ground dominated by fescue
and orchard grass. At UK-REC, dark-fired and burley tobacco stalks were used on
Dark-Fired (UK-REC) 141 21.1 83 0.07 0.15 41
fallow ground covered predominantly by common bermudagrass. All tobacco
stalks were spread at “barn moisture” at a rate of three tons per acre on 5 foot by
5 foot plots. Treatments were replicated four times per location. Tobacco stalk As seen in tables 1, 2 ,and 3, the K content for the MC burley stalks are almost
samples were collected, weighed, dried, ground, and analyzed for C, N, P, K, Ca, 1% greater (100% increase) on an elemental basis and 24 lbs/A greater on an
Mg, Zn, Cu, Mn, and Fe. Soil samples were collected to a depth of 6 inches at oxide basis than the next closest values, regardless of location or tobacco type.
both locations prior to spreading stalks and collected monthly. Biomass from the When moisture content is considered, the MC burley has the highest calculated
plots were collected to 3 inches, placed in bags, dried, weighed, ground and moisture content at 92%. At 92% moisture, these stalks only contributed 18 lbs
analyzed. No other amendments were added and no treatment was grazed. of K2O per acre, whereas the UK-REC stalks contributed 113 lbs K2O at 24%
moisture for the same 3 ton/acre stalk rate at “barn moisture”. When the Figure 1. Plots as the treatments were spread on 11-22-10 (left) and
RESULTS AND DISCUSSION prior to first grass harvest on 5-12-11 (right)
higher nutrient content favors the drier stalk there is even a greater disparity
Stalk Nutrient content: Stalk nutrient content varied with location and type but between the amount of nutrients in a given weight of stalks. Although possibly CONCLUSION
were near 3% N, 0.25% P, and 2-3% K for burley and 4% N, 0.26% P, and 2% K for an inflated value, this example clearly shows the importance of moisture and its
dark tobacco stalks on a dry matter (DM) basis (Table 1). influence on nutrient content if the full benefits of the stalks will be realized as Utilizing tobacco stalks as a nutrient source on pastures is a practical and
Table 1. Nutrient content of stalk dry matter for both locations. a part of a responsible fertility program. economically favorable practice to employ from a standpoint of stalk disposal,
Type N P K Mg Cu Zn nutrient utilization, and crop response if best management practices are
(Location) (%) (%) (%) (%) (ppm) (ppm) A notable observation was a 1% greater amount of K in the burley at MC followed. This included inside storage or spreading immediately upon stripping
location compared to other types and locations. This may be attributed to and adequate rates based on nutrient and moisture content of the stalks. More
Burley (MC) 2.86 0.26 3.05 0.20 20.4 46.2 sampling procedures, analytical procedures, or an undetermined mechanism data is being collected across KY to obtain a better estimate of stalk nutrient
resulting in enhanced K uptake of the plant. On a DM per ton basis, burley content and methods to estimate moisture content other than gravimetrically.
Burley (UK-REC) 3.16 0.23 2.06 0.15 18.1 40.1 contained approximately 60 lbs N, 11 lbs P2O5, and 50 to 73 lbs of K2O. Dark Field work continues on improved methods of distribution and utilization.
tobacco contained about 60 lbs N, 12 lbs P2O5, and 47 lbs K2O per ton of stalk
Dark-Air (MC) 4.01 0.27 1.98 0.31 31.6 45.6 (Table 2). In addition, detectable levels of micronutrients were also present.
Dark-Fired (UK-REC) 3.98 0.26 1.94 0.23 22.2 43.4
Soil Test Values (STV): Initial soil samples indicated that MC samples were in
Table 2. Nutrient content (lbs/ton) of dry matter for both locations. the high-medium to high range for P and very low range for K ( data not shown).
Conversely, UK-REC was in the medium for P and in the high to very high range
Type N P2O5 K2O Mg Cu Zn
for K. Approximately six months after the stalk application, soil test phosphorus
(Location)
(STP) tended to decrease at both locations, likely due to nutrient uptake and
Burley (MC) 57.2 11.9 73.2 4.0 0.04 0.09 removal as hay. Potassium decreased in the check treatments at both locations,
but increased in all instances except the UK-REC dark-fired. Since considerable
Burley (UK-REC) 63.2 10.5 49.4 3.0 0.04 0.08 nutrients were removed in the hay, a slight to no decrease in STV favors the use
of tobacco stalks as a nutrient source for pastures. For More Information Contact -
Dark-Air (MC) 80.2 12.4 47.5 6.2 0.06 0.09
Grass Yield: Grass was collected at both locations, air dried, analyzed, and Darrell Simpson
Dark-Fired (UK-REC) 79.6 11.9 46.6 4.6 0.04 0.09 reported as lbs/A on a DM basis, but reported for MC only (Table 4). drsimpso@uky.edu