Managing Soil Biota-Mediated Decomposition and Nutrient Mineralization in Sustainable Agroecosystems

Figure 1

Decomposition of senescent crop residue on the soil surface of an agroecosystem. The leaf is fragmented biologically, through the action of soil meso- and macrofauna, and mechanically by tillage or agricultural machinery that passes over the soil surface. Physical fragmentation continues as microorganisms colonize the surface of leaf particles and those particles are ingested by soil fauna. As secondary cell walls are penetrated and cell membranes rupture, complex organic molecules like cellulose, lignin and proteins are released into the soil pore water. Extracellular enzymes produced by microorganisms and plants hydrolyse complex compounds into simple monomeric units like sugars, phenols, and amino acids. Monomeric substrates are then absorbed through the cell membranes of prokaryotes (shown) and eukaryotes (not shown), where they undergo intracellular enzymatic hydrolysis, leading to the production of carbon dioxide (CO₂) and other metabolic byproducts.