Soil Science Flashcards
Microbial activity and population proliferate best in what moisture range
20 - 60%
Microorganisms growing at low temperature below 10C
Psychrophiles
Microorganisms growing well in temperature range of 20C to 45C
Mesophiles
Microorganisms that can tolerate temperature above 45C
Thermophiles
Chief source of energy and food
Soil Organic Matter
Ratios of soil organic matter to detritus to microbial biomass to faunal biomass
1000: 100: 10 : 1
*threadworm or eel worms
*Unsegmented round worms about 4 to 100 um
*Crytobiotic or resting state
*Cycling and release of plant available nitrogen accounting 30 to 40%
Nematodes
*often classified as Protists
*prokaryotes, single-celled organism
*Cells do not have true walls
*Amoeba, ciliates, flagellates
*Most varied and numerous of the soil faunas
*Grow best at 18 to 32C
*Resting body or Cysts
Protozoa
*Eukaryotic
*Equipped with chlorophyll
*Photoautotrophs
*Size ranges from 2 to 20um
*Green Algae (moist but nonflooded acidic soils)
*Diatoms (neutral to alkaline, well-drained, older soil rich in OM)
*Excrete polysaccharides that have very favorable effects on soil aggregation
*Most abundant photosynthetic microorganism
Soil Algae
Prokaryotic and contain chlorophyll, carotenoids, and phycocyanin pigments
Blue-green Algae
*Total biomass probably represent the most important soil microflora
*Reproduce by asexual and or sexual pores
*Eukaryotes with clear nuclear membrane and cell walls
*Heterotrophs
*Aerobic
*Yeast (anerobic), mold and mushrooms (filamentous)
*Hyphae, fruiting bodies
Fungi
Penecillium, Aspergillus, Trichoderma, Verticillium, Fusarium, Paecilomyces, Pestalotia, Monilia, Mucor, Colletorichium, Lasiidiplodia, Thielaviopsis
Genus of Fungi
*Serve to transfer mineral nutrients from fungi to the host plant
*Serve as storage organs of mycorrhizae
*Arbuscules
*Vesicles
*Prokaryotes
*Aerobic heterotrophs
*Actinomycin, neomycin, and streptomycin
*Develop best in moist, warm, well-aerated soil
*Nocardia and Streptomyces
*reduce even cellulose, chitin, and phospholipids to simpler forms
*Very important in the final (curing) stages of composting
Soil Actinomycetes
Earthy-aroma of organic-rich soils and freshly plowed land which is mainly due to actinomyces products called
Geosmins
*most numerous of the microorganisms
*Cocci (round), spirilla (spirillum), and rods (bacillus)
*Majority are heterotrophic
*Grow best under neutral to slightly alkaline conditions
*Prokaryotic
*Size ranges from 0.5 to 5um
*Most important groups in the breakdown of hydrocarbon compounds such as gasoline and diesel fuel
Soil Bacteria
Certain organisms produce these substances that so strongly bind to irons and other organisms and their immunity cannot grow or lack of essential elements
Siderophores
Rapid composting technology was developed by
; Trichoderma harzianum
Dr. Virginia Cuevas
Most favorable temperature for nitrification ranges from
20 to 30C
*correction of soil acidity by the application of what
*Correction of soil alkalinity through
*Correction of soil salinity through
*Liming
*Application of Sulfur then flooding
*lime application and leaching
Electrical conductivity of the soil solution gives an indirect measurement of the salt content
Soil Salinity
Identifies the degree to which the exchange complex is saturated with Na
Exchangeable Sodium Percentage (ESP)
Gives information on the comparative concentrations of Na, Ca, and Mg in soil solutions
Sodium Adsorption Ratio (SAR)
*accumulation of neutral soluble salts
*Salts are commonly brought to the soil surface by evaporating water, creating a white crust (alkali)
*Carbonates, Chlorides and sulfates of Na, Ca, and Mg
*pH < 8.5 (white alkali)
*plant growth reduced due to osmotic effect
*EC = more than 4dS/m at 25C
*Dominate in arid-semi arid regions
*Contain appreciable quantities of chlorides and sulphates of Ca and Mg
Saline Soils
*high levels of exchangeable Na
*Plant growth is constrained by toxicities of Na, OH, and HCO ions
*Black Alkali
*ESP of 15 or more
*Dominate in semi-arid and sub-humid regions
*Capable of alkaline hydrolysis (Na2CO3)
*EC is less than 4dS/m at 25C
Sodic Soils
*high levels of soluble salts and exchangeable Na
Saline-sodic Soils
Critical period of competition (weeds)
1/3 to 1/2 of its life cycle
Allelopathy:
Microorganism to microorganism
Microorganism to Higher plants
Higher plants to higher plants
Higher plants to microorganism
Antibiotic
Marasmin
Koline
Phytoncide
Last stage of plant germination.
Period of independent growth; the seedling is on its way of establishment or ___
Ecesis
Tells when to lime
Present in soil solution
Active acidity
Tells how much lime to apply
Present in soil colloids
Reserve Acidity
N and S: amino acid
N and P: nucleic acid
