An information search on commercial field production cost of planting sweet sorghum for ethanol indicates that our above cost estimate of $178.01 per acre is comparable to other cost estimates which are in the range of ~$150 per acre.
The continued production goal of Homeland Agricultural Fuels at the Bartow Ethanol facility (a nameplate capacity of 5.4 million gallons per year) is to produce ~600 gallons of ethanol per acre from sorghum (in line with what is currently achieved in Brazil using sugarcane).
As much of the U.S. digs out from freezing weather and snowstorms, Florida's extended growing season allows Farmers to still be growing and harvesting crops like sweet sorghum for ethanol feedstock. A late fall/early winter crop rotation for sorghum takes a little longer to mature (approximately 105 to 110 days from planting) compared to warmer months (where plant maturity occurs in ~90 days) -- due to the reduced amount of daylight hours. Also, while the sorghum's brix (sugar content) appears to be consistent at ~18 throughout all yearly rotations, yields during the fall/winter rotation can be ~40% less than warm weather months primarily because of reduced rainfall (as we do not field irrigate our sorghum). Ratoon yields of our sorghum is extremely poor, as we are using commercial hybrids.
Because of this extended growing season, it is believed that the typical agriculture plan for growing sweet sorghum can be three (3) crop rotations per year on the same acreage (allowing for cyclical soil resting/building to reduce plant disease/pests by rotating in crops like soil nitrogen building white clover legumes).
In early December we conducted sweet sorghum harvesting trials using the newly developed John Deere 3520 cane harvester (developed primarily for the sugar cane industry in South Florida, Louisiana, and Brazil). The capital cost of the Deere 3520 is ~$310,000 with the ability to harvest between 8 and 10 acres per hour (or around +100 acres per day).
The first two pictures below show the Deere 3520 and its total 9 foot width, and 3 foot cutting area dimensions:
The next two pictures shows the sorghum product of the Deere 3520 Harvester -- a 4 to 6 inch billet which is blown into a trailing hay wagon.
The Deere 3520 provides for flexibility in field row planting configurations (18, 24, 36 inch centers) allowing for single pass, two row and even 3 row cutting. The below schematic illustrates the row planting configuration that we use.
Pigweed Control: An issue that continues to plague farmers here in Florida and the Southeast is glyphosate resistant weeds, specifically Palmer Amaranth. A technical service representative for Syngenta, suggest farmers apply a fall weed control treatment now in order to get a head start for next year’s crop. We've had decent control using Dual Magnum
Dry Weather: With little rainfall in recent weeks, meteorologists from the South Florida Water Management District (SFWMD) reported that last month was the driest October in South Florida since record keeping began in 1932. The low monthly rainfall total, coupled with seasonal forecasts of exceptionally dry conditions, underscores the risks of farming, especially on non-irrigated lands where our sweet sorghum yields are all over the map -- ~40 green tons per acre per harvest, to ~20 green tons per acre per harvest.
Ergot in Sweet Sorghum: A major misconception of Farmers and non-Farmers (especially here in the Southeast and Florida) is that growing sweet sorghum for ethanol feedstock will be a "piece of cake". This belief is based primarily on the success of growing forage sorghum for decades. But as more field experience develops, farmers will be shocked that forage and sweet sorghum are very different crops. One very serious problem is a plant disease called ergot, which attacks the unfertilized ovaries in the sorghum heads. In our field experience, we've seen Brix (sugar content) go from ~18 in healthy plants to 0 in just 5 days. Ergot can hit with either high humidity, cooler temperatures, or a combination of the two. We are working with seed producers, farming equipment companies (i.e., John Deere), and applying weed control to near-by Johnsongrass (and also Cogongrass) areas to address this devastating problem.
Soil Micro-Nutrients: This is a good lesson in never really trusting anybody for advice unless they have "dirt underneath their fingernails" -- which are typically the "Old Timers". In walking our fields with typically ~15 foot height sorghum, we always saw what we describe as "crop circles" -- circular or oblong shaped areas where the sorghum was dwarf of a couple of feet tall. After extensive soil testing, we added a micro-nutrient pack to our fertilizer (N) regiment, but the problem still remained. Talking to an "Old Timer" who had worked similar fields, we applied a foliar manganese application -- problem solved!
