The Nitrogen Requirement and Use Efficiency of Sweet Sorghum Produced in Central Oklahoma.

          As the need for the production of bio-fuels becomes greater so does the need to better understand the appropriate practices needed for maximum production.  A careful balance must be meet as a desire for maximum yields could lead to a mismanagement of nitrogen (N) fertilizer to the point that the benefits of the bio-fuel that’s grown is off set by the N lost to the environment. 

           On the other hand for Oklahoma famers the allure of bio-fuel production is quite great as both switch grass and sweet sorghum are promoted as being good choices for marginal ground and both are said to lack the high nutrient requirements of other high yielding crops. Many may be tempted to skimp on N fertilizer and lose out on yield.  For the producers of Oklahoma research was needed to evaluate the yield potential of sweet sorghum grown in the central Great Plains and to validate the N requirements of a crop that has been reported reach to maximum yields at inputs of 45 kg ha to 168 kg ha dependent upon source and location. 

            This study was designed to measure the response of sweet sorghum grown in Oklahoma under both dryland and irrigated systems to N rate and timing. 

The project was initiated in the spring of 2007 and since then 5 site years have been harvested.  Each trial consisted of 7 N rates and timing combinations replicated in two hybrids.   Treatments were randomized in an RCBD replicated 3 times.  The two timing tested were pre-plant and side-dress at V8.  Sub-samples were collected at multiple times throughout the growing season.  Total biomass was recorded and samples juices through a screw press.  Squeezing totals were also recorded and sub-sample collected for further analyses.