Microbial Soil Management By James M. Peterson Paul Hay University of Nebraska-Lincoln Extension Educators

Soil Composition Organic Matter (<1% to circa 10%) Air (circa 25%) Water (circa 25%) Mineral Matter (circa 45%)

Soil Life and Functions Processes Photosynthesizers Decomposers Grazers/Predators Shredders Parasites/Pathogens Mutualists/Symbiants Organisms Bacteria Flagellates Amoeba Ciliates Fungi Nematodes Algae Annelids Arthropods

Soil Microorganism Habitat Not uniformly distributed through soil Each species exists where appropriate space, nutrient and moisture are found Normally in top few inches of soil Have been found as deep as ten miles

Soil Microorganism Habitat Commonly found around roots of plants Bacteria feed on sloughed-off plant cells and proteins and sugars released by roots Protozoa and nematodes graze on bacteria Litter and humus of soils Only fungi can make some enzymes needed to degrade the complex compounds in humus. Fungi populations are very large in these areas

Decomposers Types Bacteria Arachaea Fungi Water Molds Slime Molds Functions Break down matter Transform and transport nutrients Mobilize or immobilize nutrients Facilitate soil aggregate formation Facilitate nutrient cycling Function Structure

Mutualists/Symbionts Types Bacteria Fungi Functions Enhance Plant Growth Fix N2 Mobilize P and H2O Immunization/ Resistance Function

Soil Bacteria Thirteen different main groups of soil bacteria. Enzymatic decomposition of soft tissues” (sugars, proteins, and pectins). Function Structure

Soil Fungi Decomposition of “intermediate tissues” (cellulose and hemicellulose) Structure

Soil Actinomycetes Actinomycetes (bacteria) -- Responsible for soil odor -- Decomposition of “tough tissues” (lignin). -- Antibiotic producers Pattern

Nitrogen Retention Microorganisms can immobilize or retain nitrogen when the crops are not rapidly growing Example – Nitrogen in the form of soil organic matter or organism biomass Less mobile and less likely to be lost or leached Nitrate – Inorganic form is susceptible to loss by leaching

Bacterial Feeding Nematodes Increase Productivity Ingham, R. et al. 1985. Ecological Monographs 55:199-140.

Fungal Feeding Nematodes Increase Nitrogen Mineralization Chen, J. and H. Ferris. 1997. Journal of Nematology 29:571.

Benefit to Soil Structure Soil Organisms are involved in formation of soil aggregates. Soil bacteria, organic matter and clay interact to create micro-aggregates. These, in turn, are bound together by fungal hyphae and root hairs to produce very stable aggregates.

Benefit of Complex Soil Web Contains organisms that compete successfully with disease-causing organisms. Can suppress many diseases Prevent soil pathogens from establishing on plant surfaces Prevent pathogens from getting food Feed on pathogens Generate metabolites that are toxic to pathogens.

Benefit of a Complex Soil Web Consume or degrade a wide range of pollutants Role of soil in purifying water Reduced need for pesticides as disease suppression improves

Changing of Microorganism Complexity Change to a two or four year rotation from monoculture. Change from conventional tillage to conservation or no-tillage Reduction of high levels of pesticide

Future to Agriculture May more precisely predict the effect of management decisions May choose practices to make changes to the composition of the soil food web. May choose practices to increase the amount of carbon sequestered as soil organic matter.

Soil Development Practices Crop Rotation Nutrient Sources Farm Generated Supplemental Organic Matter Tillage

Holistic System Management Change from production management to system management Change the primary focus from NPK to CARBON Incorporate new understanding of Microbial Soil Management Incorporate new understanding of Soil mineralization Truly understand the factors of increased yield following alfalfa, cowpies, rotation of crops, and tillage or non-tillage responses

Rotations Crop plants Conditioner plants “A well thought out crop rotation is worth 75% of everything else that is done, including fertilization, tillage and pest control.” (Firman Bear, Rutgers Univ.)

What is the Impact of No-till vs Conventional Methods on Crop Yields? Crop Stubble # fields Conventional Till # fields No-till Corn Corn 40 98.3 19 96.0 Corn Soybean 115 114.2 179 110.2 Corn Milo 14 84.5 6 79.2 Corn Wheat 47 109.0 39 121.5

University of Nebraska Tillage Study - Soybean Yields

Conditioner Crop Benefits N Source (hairy vetch, red clover, berseem clover, crimson clover) Soil Builder (rye grass, rye, sorghum-sudangreass, sweet clover) Erosion Fighter (oats, rye, ryegrass) Subsoil Loosener (Sorghum-sudangrass, sweet clover, alfalfa) Weed Fighter (berseem clover, ryegrass, rye, oats) Pest Fighter (rye, sorghum-sudangrass) Specialists (fodder radish, mustards, buckwheat) Selection for goal, rotation, timing and management.

For Questions or additional Information Contact: Paul C Hay, Extension Educator University of Nebraska-Lincoln Extension 1115 West Scott Street Beatrice NE 68310 phay1@unl.edu phone: (402) 223-1384 fax: (402) 223-1370