By Dennis Pennington
Standing in front of photoperiod sensitive sorghum grown in 2012 at the Great Lakes Bioenergy Research Center plots at the Kellogg Biological Station.
Background on sorghum and biofuel crop research
Sorghum is a C4 grass that has potential as an annual biofuel crop. Sorghum has typically been planted in Michigan as a forage crop. Very little sorghum is grown for seed production. Varieties adapted to be direct chopped multiple times per season are the most common. New varieties are being developed specifically for biofuel purposes. The purpose of this study was to evaluate two newer hybrids (ES 5200 and EJ 7281) compared to a long established hybrid (M81E).
EJ 7281 and M81E are sweet sorghum hybrids that derive their name from the high levels of sugar in the sap of the plant stems. In the mid-south, these hybrids are grown and the plant sap extracted to make molasses. ES 5200 is a photoperiod sensitive (PS) hybrid that will continue growing vegetatively until the day length reaches 12 hours and 20 minutes. In central Lower Michigan, that occurs on September 19, much later in the season than conventional hybrids. The benefit of PS hybrids is that they devote their energy to producing more biomass, even after conventional hybrids have switched over and have diverted their energy to producing seed. This usually translates into more biomass.
The study
Small research plots (15 ft by 40 ft) were established at MSU’s Kellogg Biological Station near the Great Lakes Bioenergy Research trials (Lat: 42°23’45.4"N, Long: 85°22’35.9"W). Plots were arranged in a completely randomized design with four replications. Plots were planted June 2, 2014 and harvested on October 27, 2014. Plant population was set at 60,000 seeds per acre. Fertilizer application consisted of 120 pounds of nitrogen, 40 pounds of phosphorus and 40 pounds of potassium applied prior to planting and incorporated. Herbicide: 1.33 pints of Dual II Magnum was applied at planting prior to emergence. Some hand weeding was conducted at V4-V6 growth stage to reduce weed competition prior to canopy closure.
Data
All three sorghum hybrids had high moisture content at harvest time (70-75% moisture). Yield of EJ 72181 and ES 5200 were not statistically different from each other at 6.54 and 6.44 tons of dry matter (DM) per acre respectively. M81E did have statistically lower yield at 4.97 tons of DM per acre.
Figure 1. 2014 KBS Energy Sorghum Trial Data Summary Data |
|---|
Hybrid | % Dry Matter | Yield DM Tons/Acre | |
|---|
EJ 7281 | 30% | 6.54 | a |
ES 5200 | 30% | 6.44 | a |
M81E | 25% | 4.97 | b |
Discussion
Newer hybrids have great potential as biofuel crops. It was expected that the PS hybrid (ES 5200) would have higher yield than the other two hybrids. Plots were harvested with a seven foot wide Kemper harvester and the whole plant was cut at 6 inches above the soil surface. The material was chopped and weighed. The PS hybrid was taller, but had no seed head. The other two hybrids had seed heads. High moisture content may cause problems in the harvest and storage of sorghum for biofuel purposes. High moisture biomass is more expensive to transport and difficult to store without degradation and heating, which leads to spoilage. In the future, methods to reduce moisture content at harvest should be conducted. Perhaps a burndown herbicide application will allow the plant to dry down further in the field prior to harvest.
Source:msu.edu