Contributions of Tillage, Root, and Rhizosphere Investigations to Contemporary Research On Nutrient Environmental Behavior.

Land management practices directly affect the behavior and plant availability of the applied crop nutrients, in particular phosphorus (P) inputs.  In no-till production systems, fertilizer , crop residues, animal manure P, and organic residue-derived carbon accumulate at the surface and in the near-surface zone (Allmaras et al., 1999).  Dr. Allmaras’s early work on plant root growth and root activity has shed much light on rhizosphere processes.  Among those developments, the discussion will be focused on how plant roots (Duff et al., 1994; Ma et al., 2009) and rhizosphere microorganisms (Greiner et al., 2000; Dao and Hoang, 2008) synthesize and release extracellular metabolic enzymes to effect nutrient turnover, P transformations, and transport.