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Early Soil Scientists?!. Topics Covered Today:. Soil Ecosystem/Food Web Dynamics Portraits of the Soil Organisms Impact of Soil Management. Key Ideas: Ecosystem is microscale Name the types of organisms Organisms break down larger molecules into plant avail. nutrients.
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Topics Covered Today: • Soil Ecosystem/Food Web Dynamics • Portraits of the Soil Organisms • Impact of Soil Management • Key Ideas: • Ecosystem is microscale • Name the types of organisms • Organisms break down larger molecules into plant avail. nutrients
THE SOIL FOOD WEB A GOOD SOIL Is A LIVE SOIL USDA Natural Resources Conservation Service
When are soil organisms active? • Daily • Seasonally
Where are the soil organisms? • Rhizosphere • Litter • Humus • On & around soil aggregates
Microbial Biomass with Depth • And other soil organisms!
Components of Soil Organic Matter Living organisms <5% Fresh residue <10% Stabilized organic matter (humus) 33% - 50% Decomposing organic matter (active fraction) 33% - 50% (Mites on leaf)
FOOD WEB & SOIL HEALTH Mite feeding on springtail INTERACTIONS!!!
Two Bugs are Better Than One • Effects of bacteria and bacterial-feeding nematodes on blue grama grass growth
Nitrogen-fixing Bacteria • Nodules formed where Rhizobium bacteria infected soybean roots.
Actinomycetes • Bacterial cells • Grow like fungal hyphae
Fungi and Soil Quality • Decompose carbon compounds • Retain nutrients in the soil • Bind soil particles • Food for the rest of the food web • Mycorrhizal fungi • Compete with plant pathogens
Bacteria vs. fungi Fungidominatein Forests Bacteriadominatein Grasslands& Ag Lands
Mineralization and Immobilization Organisms consume other organisms and excrete inorganic wastes. Organic nutrients are stored in soil organisms and organic matter. Inorganic nutrients are usable by plants, and are mobile in soil. Organisms take up and retain nutrients as they grow.
Cyanobacteria – N fixing Diatoms ALGAE Lichens (fungi+algae)
Soil-Dwelling “Vampires” • Amoebe eating through fungi
NEMATODES Bacterial-feeding nematode Fungal-feeding nematode
Predatory Nematodes - Root-feeding nematodes Lesion nematode Root-feedingnematode
Nematode Trappers • Fungal hyphal rings constrict when a nematode swims through.
Types of Arthropods • Shredders • Predators • Herbivores • Fungal-feeders
Shredders Millipedes Pillbugs
Springtails (fungal feeders) • Abundant in many soils. • Feed on some disease-causing fungi. • Jump by slamming their tail down.