Oklahoma State University

Sweet Sorghum

Sweet Sorghum

N-Rate by Hydrid:
Locations: Lake Carl Blackwell (LCB) Irrigated Est 07: LCB Dryland Est 08: Chickasaw Est 09. Concluded 2010.
This trial is designed to tell us what the N needs of this new Bio-fuel crop will be when grown in Oklahoma. N applicaiton timing is also being evaluated.

Sweet Sorghum N Study Results.


The first observation that must be noted is that in all years, sites, varieties, and treatments’, lodging was an issue. Every year just prior to antheisis a wind/rain storm would pass through causing severe lodging. However, in all cases the plants survived and continued growth until maturity. As was stated in the introduction, this trial was not designed to specifically identify optimal economic N rate; however, it was designed to test some common management suggestions identify general practices that will lead to the highest economical return. This study at least indicated that the low input sticker placed on grain sorghum may not be completely valid. Yes large quantities of biomass and juice may be produced with very little input but there is still significant economical benefit for the addition of fertilizer rates at or over 112 kg N ha-1. While these rates may not be considered high by producers in the corn belt of the US, they are as high or higher than the traditional practices of the monoculture winter wheat producers of Oklahoma. Other observations that can be made from this data is that it is beneficial to split apply nitrogen as the 168 kg N ha-1 rate was on the average significantly lower in yield and profit. In addition, the 56 -56 kg N ha-1 rate resulted in higher yields and profits than the 112-0 kg N ha-1 rate. The conclusion of this study is that as an agronomic recommendation for the nitrogen fertilization of sweet sorghum produced in central Oklahoma is a split application of 112 to 168 total kg N ha-1 including residual soil test N. Additional research is needed to identify specific optimum N rates.




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