Effects of Soil Management on Soil Organisms Mary Barbercheck Dept. of Entomology Penn State University

In 1 teaspoon of agricultural soil there are…  Bacteria 100 million to 1 billion  Fungi 6-9 ft fungal strands put end to end  Protozoa Several thousand flagellates & amoeba One to several hundred ciliates  Nematodes 10 to 20 bacterial feeders and a few fungal feeders  ArthropodsUp to 100  Earthworms5 or more

Elliot & Coleman Ecol. Bull. 39: 23-32

Some Goals of Soil Management Manage system for productivity and beneficial processes Improvement in abiotic and biotic properties of soil Improvement of plant health Conservation of beneficial organisms Suppression of pests

Crop Rotations Reduce Pest Habitat Provide Beneficial Habitat Know Your Pest Minimal Pesticide Use Above-Ground Diversity to Favor Beneficials Pest and Disease Suppression Minimal Use of Synthetic Pesticides & Fertilizers Minimize Tillage to Conserve OM Crop Rotations Add Organic Matter Below-Ground Diversity Healthy Soil

Effects of Agricultural Management on Soil Arthropods Densities are much lower than in unmanaged systems, regardless of level and types of inputs Favors bacteria over fungi Soil arthropods tend to consume fungi Predators 10% of consumers) Consumers 10% of producers) Producers Energy Pyramid (After Moldenke, 2002)

Implication of Bacterial Dominance in Soil Typical Ratio B:F >10:1 (After Moldenke, 2002) Predatory Arthropods (0.0001x) Predators of BFN (0.001x) BF Nemas (0.01x) Protozoa (0.1x) Bacteria (x) Predatory Arthropods (0.01x) FF Invertebrates (0.1x) Fungi (x) Bacterial-based Fungal-based

Some Factors Affected by Tillage Soil Moisture Soil Temperature Range of Temperature and Moisture Fluctuations Surface Residue Soil Fauna Abundance and Diversity Plant Diversity Favors Bacteria > Fungi

Tillage Effects on Soil Arthropod Abundance & Diversity in Corn Goldsboro, NC No TillConv. Till No Richness Simpson Shannon Evenness Richness: No. of taxa Simpson’s: probability that 2 species selected at random will be the same; 0 to 1; diversity decreases as index increases Shannon’s: uncertainty in predicting identity of organism chosen at random; equals zero when only 1 species present Evenness: 1=all taxa in similar numbers, as approach 0, divergence from evenness, some taxa more dominant

Effects of Tillage on Entomopathogenic Nematodes in Maize S. carpocapsae S. riobrave H. bacteriophora Millar & Barbercheck, 2002

Effects of Tillage and Cover Crops on Pest & Beneficial Arthropods in Soil Peachy et al Applied Soil Ecology 21: 59-70

Effects of Cover Crop Rye Management in Reduced Tillage Corn Clark et al J. Entomol. Sci. 28: a ab bc c

Effects of Cover Crop Rye Management in Reduced Tillage Corn Clark et al J. Entomol. Sci. 28: a a ab b a a b a b b

Effect of Organic & Mineral Fertilizers in Alfalfa Fratello et al Agric. Ecosyst. Envt. 27:

Effect of Compost Type on Microbial Biomass N and Soil Arthropods Gunadi et al Eur. J. Soil Biol. 38: Vermicomposts Trophic Groups

Systems Experiment Microarthropods Cumulative Average Barbercheck, unpubl.

Systems Experiment EPN & EPF Cumulative Average Barbercheck, unpubl.

BMP for Management of Soil Organisms Systems effects can arise from very complex direct and indirect interactions Minimize compaction Provide continuous energy (e.g., cover crops) Reduce tillage to favor fungal-based food webs Provide refuges for mobile predators Rotate crops to reduce pest organisms Reduce use of biocides Cosmochthonius (Oribatida) D. Walter

Web Resources Soil Biodiversity Portal Soil Biology Primer USDA Soil Quality Institute Appropriate Technology Transfer for Rural Areas Earthworms: The agriculturist’s friend

The End Photo by M. Greenwood