We began to harvest the Dale and Theis sweet sorghum varieties on July 24 and completed the harvest on July 25. Only the Dale and Theis varieties were harvested on these dates because they reached harvest maturity before the M81-E and Topper varieties. During the first day of harvest, we began by “trimming-out” drill rows 1, 2 and 4 of each plot. We also “trimmed-out” the third drill row of each plot; however, on this drill row we left a 10-foot section. The 10-foot section served as our data collection sample. If you remember, the objective of this study is to evaluate the ratoon potential and nitrogen (N) requirements of of the different sweet sorghum varieties. For this reason, we did not want to harvest the crop at ground level. We targeted leaving a stubble approximately 6 to 8 inches tall. In the first picture, you can see that we used a weed-eater with a blade attachment to harvest the sweet sorghum. In the second picture, you can see a closeup of the remaining stubble. The harvested sweet sorghum was then removed from the plots (picture 3). The “trimming-out” process took a whole day to complete. By the end of the day only the 10-foot data-collection samples remained (picture 4).
We waited until the following day to harvest the data-collection samples because as soon as the sweet sorghum was harvested, we immediately took the samples to the laboratory for sugar analysis. We were told that the longer the harvested stalks remained unprocessed the more the sugar content would drop. So we had to coordinate our harvest time with the laboratory personnel who conducted the analysis for us. From the 10-foot sample we collected several types of information, including a stand count, total biomass and processable biomass. The processable biomass -- the weight of the stalks with the leaves and heads removed -- represents the actual weight of the material that would be used in the sugar mill. In the fifth picture you can see that we bundled the 10-foot section and weighed the samples in the field using a portable digital scale and a barrel to hold the sorghum in place. We then began to pull off the leaves from the stalks (picture 6), cut off the grain heads (picture 7) and reweigh the remaining stalks (picture 8). The stalks were then rebundeled, tagged and loaded onto a trailer for transport to the laboratory for analysis (picture 9). The whole process was repeated again on August 11 and 12 for the M81-E and Topper varieties.
| | Figure 1. Harvest of the sweet sorghum was accomplished with a weed eater with a blade attachment. |
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