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Title: Plant Growth-promoting Rhizobacteria Allow Reduced Application Rates of Chemical Fertilizers

Author
item ADESEMOYE, ANTHONY - AUBURN UNIVERSITY
item Torbert, Henry - Allen
item KLOEPPER, JOSEPH - AUBURN UNIVERSITY

Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2009
Publication Date: 11/30/2009
Citation: Adesemoye, A.O., Torbert III, H.A., Kloepper, J.W. 2009. Plant Growth-promoting Rhizobacteria Allow Reduced Application Rates of Chemical Fertilizers. Microbial Ecology. 58:921-929.

Interpretive Summary: Efforts to reduce fertilizer rates while increasing nutrient uptake to maintain high yields are very important due to the increasing cost of fertilizers and their potential negative environmental impacts. Greenhouse studies were conducted to determine if fertilizer application rates for plant production could be reduced with the use of microbial inoculants plant growth-promoting rhizobacteria and arbuscular mycorrhizae fungi (AMF). Results showed that supplementing 75% fertilizer with inoculants produced plant growth, yield, and nutrient (nitrogen and phosphorus) uptake that were equivalent to full fertilizer rates. Lower fertilizer rates supplemented with inoculants produced significantly lower plant growth, yield, and nutrient uptake or inconsistent impacts. Further studies using isotope techniques that will reveal specifics on the interactions and impacts of the inoculants and plant uptake of nitrogen are planned.

Technical Abstract: Efforts to reduce fertilizer rates while increasing nutrient uptake to maintain high yields are very important due to the increasing cost of fertilizers and their potential negative environmental impacts. The objectives of this study were to determine (i) if reduced rates of inorganic fertilizer coupled with microbial inoculants plant growth-promoting rhizobacteria with and without arbuscular mycorrhizae fungi (AMF) will produce plant growth, yield, and nutrient uptake equivalent to that obtained with full rates of the fertilizer and (ii) what minimum level the fertilizer could be safely reduced. We used a two-strain mixture of Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4 as well as a formulated rhizobacterial product and an AMF, Glomus intraradices, in the greenhouse. Results showed that supplementing 75% fertilizer with inoculants produced plant growth, yield, and nutrient (nitrogen and phosphorus) uptake that were statistically equivalent to full fertilizer rates. Lower fertilizer rates supplemented with inoculants produced significantly lower plant growth, yield, and nutrient uptake or inconsistent impacts. Further studies using isotope techniques that will reveal specifics on the interactions and impacts of the inoculants and plant uptake of nitrogen are planned.