Method of reducing nitrous oxide emissions from a plant growth substrate
Inventors
Kloepper, Joseph W • Calvo Velez, Pamela • Torbert, III, Henry Allen • Watts, Dexter B • Ames, Robert Norman
Assignees
Auburn University • US Department of Agriculture USDA • Tenfold Technologies LLC
Publication Number
US-9266786-B2
Publication Date
2016-02-23
Expiration Date
2032-10-16
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Abstract
A method of modulating and in particular, reducing nitrous oxide emission from a substrate for growing on or more plants by applying a microbial based soil additive and a fertilizer blend to the substrate.
Core Innovation
The invention provides a method for modulating and reducing nitrous oxide emissions from a substrate used for growing one or more plants by applying a microbial based soil additive in combination with a fertilizer blend comprising ammonium nitrate. This microbial soil additive is Trichoderma-free and includes mixtures of at least four microbial strains or filtrates, supernatants, or extracts thereof, applied in amounts effective to reduce nitrous oxide emissions. The substrate can be various mediums such as soil, vermiculite, pearlite, gravel, clay, sand, peat moss, ground up wood, pine bark, or other plant growth supports treated with fertilizers.
The background highlights the issue of increased greenhouse gas emissions, particularly nitrous oxide (N2O), from agricultural soils primarily due to nitrogen fertilization, which accounts for 60 to 80% of global anthropogenic N2O emissions. Given the necessity of nitrogen fertilization for optimal crop yields, there is a pressing need to develop crop management practices that reduce N2O emissions. Microbial interactions in soil significantly influence nitrogen cycling processes, including nitrification and denitrification, which are sources of N2O emissions. Therefore, a method employing application of beneficial microbial inoculants such as plant growth-promoting rhizobacteria, particularly Bacillus species, is proposed to modulate soil microbial communities and reduce N2O emissions in fertilized soils.
Claims Coverage
There are ten main inventive features pertaining to a method combining fertilizer application and microbial soil additives to reduce nitrous oxide emissions.
Method for reducing nitrous oxide emission from soil
A method comprising applying a fertilizer composition containing calcium ammonium nitrate, urea ammonium nitrate, or urea to soil, then applying a Trichoderma-free microbial based soil additive in an amount effective to reduce nitrous oxide emission, measuring the N2O amount, and determining reduction compared to untreated controls.
Applicable soil compositions
The soil composition can be agricultural soil or non-sterile soil in pots, or substrates such as soil, vermiculite, pearlite, gravel, clay, sand, peat moss, ground up wood, or pine bark.
Microbial based soil additive composition
The microbial additive comprises a mixture of spore-forming plant-growth promoting rhizobacteria including isolates of Bacillus pumilus, Bacillus subtilis, Bacillus safenis, and Lysinibacillus xylanilyticus. Another embodiment includes Bacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Rhodococcus rhodochrous, with a pH between about 8.0 to about 8.5.
Adjustment of moisture level
The method may further include adjusting the moisture level of the soil composition to promote microbial function and plant growth.
Ratio of microbial additive to fertilizer for granular fertilizer
The ratio of microbial based liquid soil additive to granular fertilizer is about 1.5 L (1.5 kg) to about 7.5 L (7.5 kg) per metric ton of granular fertilizer.
Ratio of microbial additive to liquid fertilizer
For liquid forms, the ratio of microbial based soil additive to liquid fertilizer composition is from about 1:1 to about 1:50 by volume.
Concentration of microbial additive
The microbial based soil additive contains between about 1×10^3 to about 5×10^6 colony forming units per milliliter.
Fertilizer application rates
The fertilizer is applied at a rate sufficient to provide between about 50 mg to about 100 mg of fertilizer per kg of soil composition, adequate for nitrogen nutrition for growing plants.
The claims cover a method that combines applying specific fertilizer compositions with a microbial soil additive comprising defined microbial strains in effective amounts and ratios, optionally adjusting soil moisture, to reduce nitrous oxide emissions from various soil or growth substrates.
Stated Advantages
The microbial based soil additives significantly reduce nitrous oxide emissions from soils treated with calcium ammonium nitrate and urea ammonium nitrate fertilizers compared to untreated controls.
Filtered microbial additive products containing microbial metabolites also reduce nitrous oxide emissions, indicating metabolites contribute to emission reduction.
Benefits include modulation of nitrous oxide emissions in both plant-containing and plant-free soil systems.
Documented Applications
Modulating and reducing nitrous oxide emissions from agricultural soils and non-sterile soils in pots using microbial soil additives combined with ammonium nitrate-containing fertilizers.
Application to various plant growth substrates including soil, vermiculite, pearlite, gravel, clay, sand, peat moss, ground up wood, and pine bark for growing plants with reduced greenhouse gas emissions.
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