Effects of Tile Drainage on Nitrogen Transformations Regulated by Soil Biota Sources: Jane Frankenburger Purdue University and Gary Sands, University of Minnesota Ammonia loss NH 3 Nitrous Oxide N 2 O Elemental N N 2 Inorganic N–ammonium + nitrate NH 4 + NO 3 -N Nitrate NO 3
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Effects of Tile Drainage on Nitrogen Transformations … · nitrous oxide (N 2O) Denitrification, Nitrous oxide (N 2O) ... Principles and Applications of Soil ... franzen workshop
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Effects of Tile Drainage on Nitrogen Transformations Regulated by Soil Biota
Sources: Jane Frankenburger Purdue University and Gary Sands, University of Minnesota
Ammonia loss NH3
Nitrous Oxide N2O
Elemental N N2
Inorganic N–ammonium + nitrate NH4 + NO3- N
Nitrate NO3
Soil a Living System Soil organisms (biota) carry out a wide range of processes that are important for soil health and fertility in agricultural. Soil contains all forms of life and elements on earth! For more information on the Soil Biota/ Soil Food web see link to http://www.nature.com/scitable/knowledge/library/the-soil-biota-84078125
and algae), soil animals (protozoa, nematodes, mites, springtails, spiders, insects, and earthworms) and plants living all or part of their lives in or on the soil(Soil Quality Institute 2001).
• Soil biota release nutrient elements & cycle them back for use again in plants and animals
Factors Controlled with Tile Drainage that Effect Rates of Microbial Transformations
• Moisture• Salinity
• Removal of moisture increases temperature effecting plant and
microbial growth/ activity• Removal of salts also improves
the soil environment for plant and microbial growth
Soil Habitat
• What physical, chemical, and abiotic factors constitute the soil habitat of microorganisms?
• How does the soil habitat and the microorganisms in it affect soil quality, particularly nitrogen cycling?
What Constitutes Soil Habitat?
Soil is a complex habitat for microbial growth.
It is a heterogeneous medium consisting of:
- Solid, liquid and gaseous phases
Varying in properties across the landscape and with depth
Soil a Mantle of Weathered Rock -What does it Contain?
http://www.canolacouncil.org/contact-us/
Interaction of Mineralogy with Microbiology
• Quantity & type of clay influence drainage, water filled pore space & air as pointed out in other talks
• The interaction of clays such as montmorillinite & vermiculite (minerals) with NH4
+ can temporarily or permanently reduce available ammonium
Soil Fauna, Habitat & Soil Structure
• Availability of habitat for soil fauna is dependent upon soil structure and texture factors that determine pore size and soil water content
• Soil fauna and microorganisms affect soil structure
Interaction Between Soil Minerals & Microorganisms
Soil Fauna Habitat & Soil Structure
• Pores may be filled with water or air
• The proportion of water to air will vary
• Aerial and aquatic communities shrink or expand with soil water potential
Soil FaunaCommunity Habitats
• Aquatic soil fauna live in water-filled pores e.g. protozoa and nematodes
• Aerial soil fauna live in air-filled pore spaces e.g. microarthropods
• Organisms that engineer their own spacee.g. earthworms
Soil Aggregate• made up of sand, silt, clay, organic
matter, root hairs, microorganisms and their "glue" like secretions mucilages, extracellular polysaccharides, & hyphae(filaments) of fungi as well as pores
Balancing the Size of the Pipe and the Size of the Holes: Denitrification
• N2O is an intermediate step in denitrification, and can be all or none of the final product
• Oxygen, pH and ratio of NO3 to available C control proportion of N2O evolved
Balancing the Size of the Pipe and the Size of the Holes: Denitrification
• Low pH N2O, reduction to N2
• Denitrification as O2 but the proportion of N2O produced
• Similar to nitrification, the O2 concentration that maximizes N2O production from denitrification is about 1%
• When NO3 an electron acceptor is in excess of organic C , denitrifiers partially reduce NO3to N2O instead of reducing it to N2
Nitrification vs. Denitrification as a Source of Nitrogen Gases
• Nitric oxide (NO) is consumed by abiotic and biotic sources little NO released from soil
• The primary source of NO is nitrification
• N2O is less reactive and can diffuse from wet soil, source nitrification and denitrification
• Largest N2O flux is probably denitrification
Net Production of Each Gas Occurs at Different Percent Water Filled Pore Spaces
• Nitric Oxide (NO) maximum at ~ 50%
• Nitrous Oxide (N2O) maximum at ~ 70%
• Elemental Nitrogen (N2) at 100%
• Soil microorganisms key players in terrestrial N cycling that includes mineralization, nitrification & denitrification
• Tile drainage affects N cycling on short & long-term scales by modifying water drainage that controls air to water filled pore spaces
• Tile drainage also has a long-term affect on N cycling due to increases in soil quality parameters such as infiltration and microbial activity
• Tile drainage has the potential to improve N cycling by leaching salts from the soil profile particularly when coupled with amendments such as gypsum where appropriate
• Improvements in infiltration and aggregation should increase air filled pore space and reduce excess water, conditions that favor gaseous loss of N and nitrate leaching
References• Bernhard, A. (2012) The Nitrogen Cycle: Processes, Players, and
Human Impact. Nature Education Knowledge 3(10):25.
• Fortuna, A. (2012) The Soil Biota. Nature Education Knowledge 3(10):1
• Mengchang He, Jinghuan Zhang, Ying Wang, Lixia Jin. Effect of combined Bacillus subtilis on sorption of phenanthrene and 1, 2, 3-trichlorobenzene onto mineral surfaces. Journal of Environmental Quality, 2010, 39(1): 236-244. doi:10.2134/jeq2009.0113.
• Sylvia, M., J.J. Fuhrmann, P.G. Hartel, D.A. Zuberer. 2005. Principles and Applications of Soil Microbiology, 2/ED Prentice Hall, Upper Saddle River, NJ. ISBN-10: 0130941174 • ISBN-13: 9780130941176.