Soil Biology. Susan Samson-Liebig & Beth Burdolski USDA-NRCS Bismarck, ND. North Dakota Teacher Workshop August 7, 2013 USDA-NRCS

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1 Soil Biology Susan Samson-Liebig & Beth Burdolski Bismarck, ND North Dakota Teacher Workshop August 7, 2013 USDA is an equal opportunity provider and employer

2 Presentation Overview Brief overview of soil biology Discussion of the slake test results Methods to assess soil biology Question/Answer

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4 Life in the Soil Bacteria Fungi Protozoa Nematodes Arthropods Earthworms

5 Life in the Soil Pop Quiz: How many soil microorganisms are in one heaping tablespoon of a healthy soil?

6 Bacteria Total number of individual bacteria in a gram of soil ranges from millions to billions depending soil health Decompose pesticides/other chemicals Feed on organic matter that is easy to breakdown Store and cycle nitrogen Nodules formed where Rhizobium bacteria infected soybean roots

7 Fungi Up to 3,000 species in cultivated soil Saprophytes feed on organic matter difficult to breakdown, such as crop residue Parasites attack foliar and root plant material, other fungi, nematodes and micro and macroarthropods Mutualistic Fungi (Arbuscular Mycorrhizal Fungi - AM ) obtain nutrients (primarily P, but also Cu and Zn) from beyond depletion zones around roots (about 100 meters of fungal hyphae per g of soil) Store nitrogen in hyphal bodies and release nitrogen by decomposition

8 Glomalin Is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi that acts like a glue that holds soil particles together. (SEE DEMO) One benefit of glomalin is increased aggregate stability, leading to better soil structure and improved air and water transfer through the soil. Dr. Kris Nichols, ARS, Mandan, ND

9 Protozoa Paramecia Protozoa include: amoebae, ciliates, flagellates Consume bacteria, fungi, and algae Are an important part of the nitrogen cycle Number in the thousands per gram soil Ciliate Sarcomastigophora Amoeba

10 Nematodes Fungal feeders, bacteria feeders, root feeders, predators and omnivores Most are non-pathogenic An important part of the nitrogen cycle About individuals/gram of soil Affected by management: pesticides, soil organic matter, tillage

11 Microarthropods Mites and springtails Approximately 5 to 20 per gram of soil Decompose & shred organic matter An important part of the nitrogen cycle Tillage and pesticides are harmful!

12 Earthworms Help cycle nutrients and assist in aggregate stability Burrowing through lubricated tunnels forces air in and out of soil Earthworm casts contain 11% of the humus and 7X the nitrogen, 11X the phosphorus, and 9X the potash than surrounding soil

13 Space Air Water Food What Do Soil Organisms Need? Rose & Elliot

14 Soil Organic Matter - A food source for soil biology

15 Soil ph and Microbial Processes Group/Process Range Optimum Bacteria Nitrification / Denitrification Sulfur oxidation Methane oxidation Fungi Actinomycetes Protozoa 5-8 >7 After Smith and Doran (1996).

16 Salinity (Electrical Conductivity) Soil microorganisms differ considerably in their tolerance to salt. Fungi and actinomycetes more tolerant than most bacteria. Halophilic bacteria possess a high tolerance to salt.

17 Little surface cover Jay Fuhrer, NRCS

18 Plenty of surface cover Jay Fuhrer, NRCS

19 Soil Respiration Soil Food Web analysis Microbial DNA analysis Enzymes What s living in the Soil? Biological Indicators

20 CO2-BURST : (also called the Haney-Brinton Method) Dried, weighed samples of soil are moistened triggering a flush of carbon dioxide. The burst is measured in ppm and is proportional to microbial biomass and potential carbon and nitrogen mineralization (how much is potentially available to plants). Data usually not provided on conventional soil test. BASAL RESPIRATION: Fresh, field-moist soil is evaluated for background or basal CO2 respiration in the lab by filling the test jar to volume or in the field by using a 3 cylinder inserted in the soil. The results indicate general soil health (biological activity) and carbon dioxide emissions per surface area.

21 Self Education Resources The Nature and Properties of Soils 14th Edition, Nyle C, Brady, Ray R. Weil Buffalo Bird Woman s Garden, Gilbert Wilson (Google PDF) Agroecology, Gliessman The One Straw Revolution, Masanobu Fuhuoka (Google PDF) Managing Cover Crops Profitably 3rd Edition, Sustainable Agriculture Network Guns, Germs, and Steel, Jared Diamond Soil Biology Primer, Dr. Elaine Ingham*(Soil Food Web to Rodale)

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