Soil Microbiology, Ecology and Biochemistry: An Exciting Present and a Great Future Based On a Solid Past.

Advances in knowledge of plant-microbial interactions, microbial ecology, biodiversity, nutrient flow, biogeochemistry, and soil organic matter dynamics require integrated studies of soil microbiology, ecology  and biochemistry. Humus represents partially decomposed and stabilized plant residues, microbial products and the biota and has long been recognized for soil quality and stability. It has been fractionated for over 200 years, and plays a major role in defining soil horizons -pedology.  Nutrient transformation studies, early in the 19^th century defined nitrogen transformations. The golden age of soil microbiology, at the turn of the century, identified major soil organisms associated with the important nutrient transformations. Tracer studies of the mid 20^th century and the later isolation of soil DNA together with the great improvements in molecular structure analysis for soil organic matter have  paved the way for the exciting breakthroughs leading to new insights and unified concepts capable of answering today’s questions concerning  the  biological, physical and chemical interactions controlling soil organic matter dynamics.  Long term incubation, together with ¹³C and ¹⁴C, identifies pools and fluxes associated with the plant residues, microbial constituents and the soil matrix. Mid infrared spectroscopy and pyrolysis-molecular beam-mass spectrometry  identify the chemical characteristics produced during decomposition and relate them to SOM dynamics. The soil biota contributes to the labile humus constituents, especially N, and is so diverse (as identified by pyrosequencing) with a rapid growth potential that decomposition is not limited at low biomass values after extended incubation.  Silt and clay protect N compounds, largely in the amide form. Multidisciplinary, well coordinated studies that involve modern information handling together with the analytical techniques now available can lead our field to new major, unifying concepts and the scientific knowledge required to answer questions in global change, biodiversity, ecosystem functioning, food security and sustainable fuels now facing society.