|Torbert, Henry - Allen|
Submitted to: Canadian Journal of Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/23/2008
Publication Date: 10/4/2008
Citation: Adesemoye, A.O., Torbert III, H.A., Kloepper, J.W. 2008. Enhanced Plant Nutrient use Efficiency with PGPR and AMF in an Integrated Nutrient Management System. Canadian Journal of Microbiology. 54:876-886. Interpretive Summary: Fertilization is an essential practice to optimize crop productivity, however, fertilization has also been associated with nutrient contamination of surface and groundwater. A field study was conducted to test whether microbial inoculants could be used to increase plant yield and enhance nutrient uptake, and thereby remove more nutrients, especially N, P, and K from the field. The field trial evaluated a commercially available microbial inoculants, a mixture of plant growth-promoting rhizobacteria (PGPR) with or without arbuscular mycorrhiza fungi (AMF) under differerent tillagae and fetilizer application systems. Results showed that inoculants promoted plant growth and yield. Higher amounts of N, P, or K were removed from the plots with inoculants, potentially reducing nutrient losses to the environment. Further studies should be conducted to combine microbial inoculants with reduced rates of fertilizer.
Technical Abstract: A three-year field study was conducted with field corn from 2005 to 2007 to test the hypothesis that microbial inoculants that increase plant growth and yield will enhance nutrient uptake, and thereby remove more nutrients, especially N, P, and K from the field as part of an integrated nutrient management (INM) system. The field trial evaluated microbial inoculants, a commercially available mixture of plant growth-promoting rhizobacteria (PGPR) with or without arbuscular mycorrhiza fungi (AMF), across two tillage systems (no-till and conventional till) and two fertilization regimes (poultry litter and ammonium nitrate). Data were collected on plant height, yield (dry weight of ears and silage), and nutrient content of corn grain and silage. In addition, nutrient content of soil was determined while bioavailability of soil nutrient was measured with plant root simulator (PRSTM) probes. Results showed that inoculants promoted plant growth and yield. For example, grain yield (kg ha-1) in 2007 for inoculants were AMF 7,717, PGPR+AMF 7,260, PGPR 7,313, Control 5,725, and for fertilizer were Poultry litter 7,470 and NH4NO3 6,537. Nitrogen content per gram of grain tissues was significantly enhanced in 2006 by inoculant and fertilizer as well as their interactions. Significantly higher amounts of each element (N, P, or K) were removed from the plots with inoculants, based on total nutrient content in grain per plot. The results support the overall hypothesis that application of inoculants can lead to a reduction in the build up of N, P, and K in agricultural soils. Further studies should be conducted to combine microbial inoculants with reduced rates of fertilizer.