Abstract
Commercial fertilizer (particularly nitrogen) costs account for a substantial portion of the total production costs of cellulosic biomass and can be a major obstacle to biofuel production. In a series of greenhouse studies, we evaluated the feasibility of co-applying Gibberellins (GA) and reduced nitrogen (N) rates to produce a bioenergy crop less expensively. In a preliminary study, we determined the minimum combined application rates of GA and N required for efficient biomass (sweet sorghum, Sorghum bicolor) production. Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1 optimized dry matter yield (DMY) and N and phosphorus (P) uptake efficiencies, resulting in a reduction of N and P leaching. Organic nutrient sources such as manures and biosolids can be substituted for commercial N fertilizers (and incidentally supply P) to further reduce the cost of nutrient supply for biomass production. Based on the results of the preliminary study, we conducted a second greenhouse study using sweet sorghum as a test bioenergy crop. We co-applied organic sources of N (manure and biosolids) at 75 and 150 kg PAN ha−1 (representing 50 and 100% N rate respectively) with 3 g GA ha−1. In each batch of experiment, the crop was grown for 8 wk on Immokalee fine sand of minimal native fertility. After harvest, sufficient water was applied to soil in each pot to yield ∼1.5 L (∼0.75 pore volume) of leachate, and analyzed for total N and soluble reactive P (SRP). The reduced (50%) N application rate, together with GA, optimized biomass production. Application of GA at 3 g ha−1, and the organic sources of N at 50% of the recommended N rate, decreased nutrient cost of producing the bioenergy biomass by ∼$375 ha−1 (>90% of total nutrient cost), and could reduce offsite N and P losses from vulnerable soils. Keywords: gibberellinsmanurebiosolidsN and P uptakeleaching lossesdry matter yieldsweet sorghum ACKNOWLEDGMENTS This study was funded by State of Florida Federal Stimulus Funds. We wish to express appreciation to Drs. Y. C. Newman and L. E Sollenberger of the Agronomy Dept, University of Florida for their collaboration, and to Mr. Richard Fethiere of the Forage Evaluation Support Lab., University of Florida, and Mrs. Judith Dampier of the Agronomy Dept, University of Florida for their assistance in plant tissue analyses.
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Claims 5
Claim · model-written summary
Co-applying 75 kg N ha-1 (half the recommended rate) with 3 g GA ha-1 optimized dry matter yield and N and P uptake efficiencies in sorghum.
- Treatment
- Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1e0
- Outcome
- dry matter yield (DMY) and N and phosphorus (P) uptake efficienciese0
- Direction
- optimizede0
SorghumNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1 optimized dry matter yield (DMY) and N and phosphorus (P) uptake efficiencies”
Claim · model-written summary
The same co-application of 75 kg N ha-1 and 3 g GA ha-1 resulted in a reduction of N and P leaching.
- Treatment
- Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1e0
- Outcome
- N and P leachinge0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1 optimized dry matter yield (DMY) and N and phosphorus (P) uptake efficiencies, resulting in a reduction of N and P leaching”
Claim · model-written summary
In the second greenhouse study, the reduced (50%) N rate together with GA optimized biomass production of sweet sorghum.
- Taxon
- sweet sorghume1
- Treatment
- reduced (50%) N application rate, together with GAe0
- Outcome
- biomass productione0
- Direction
- optimizede0
Not reportedComparator
Verbatim
e0“The reduced (50%) N application rate, together with GA, optimized biomass production”
e1“sweet sorghum as a test bioenergy crop”
Claim · model-written summary
GA at 3 g ha-1 with organic N sources at 50% of the recommended N rate decreased the nutrient cost of producing the sorghum bioenergy biomass by about $375 ha-1 (>90% of total nutrient cost).
- Taxon
- sweet sorghume1
- Treatment
- Application of GA at 3 g ha−1, and the organic sources of N at 50% of the recommended N ratee0
- Outcome
- nutrient cost of producing the bioenergy biomasse0
- Direction
- decreasede0
- Value
- ∼$375 ha−1e0
Not reportedComparator
Verbatim
e0“Application of GA at 3 g ha−1, and the organic sources of N at 50% of the recommended N rate, decreased nutrient cost of producing the bioenergy biomass by ∼$375 ha−1 (>90% of total nutrient cost)”
e1“sweet sorghum as a test bioenergy crop”
Claim · model-written summary
The authors state that GA with organic N at 50% of the recommended rate could reduce offsite N and P losses from vulnerable soils.
- Taxon
- sweet sorghume1
- Treatment
- Application of GA at 3 g ha−1, and the organic sources of N at 50% of the recommended N ratee0
- Outcome
- offsite N and P lossese0
- Direction
- reducee0
Not reportedComparator
Verbatim
e0“Application of GA at 3 g ha−1, and the organic sources of N at 50% of the recommended N rate, decreased nutrient cost of producing the bioenergy biomass by ∼$375 ha−1 (>90% of total nutrient cost), and could reduce offsite N and P losses from vulnerable soils”
e1“sweet sorghum as a test bioenergy crop”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.