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ENVS 204

ENVS 204

Soil loss and degradation: causes, consequences, restoration and conservation efforts

Soil loss and degradation: causes, consequences, restoration and conservation efforts

Chapter 6 soil drainage

Chapter 14—Erosion

Chapter 9 soil acidification soil salinity and sodicity

Chapter 15—Chemical pollutants

General Questions: What types of soil degradation occur, and what are their direct and indirect causes? How are soils’ physical, chemical and biological properties affected by different types of degradation? What strategies do we use to protect soils, and to restore those that have been degraded? Terms to Know: soil acidification invasive species bioremediation other specific terms will come from your classmates’ presentations

Causes of soil degradation?

Soil changes due to degradation

Physical According to Answers.com, there are three causes: •Salinization from chemical fertilizers •Erosion caused by poor land management •Soil compaction caused by farm equipment

Chemical

OTHERS?

Biological http://www.globalchange.umich.edu/globalchange2/current/lectures/land_deg/ land_deg.html

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What are the roots that clutch, what branches grow Out of this stony rubbish? Son of man, You cannot say, or guess, for you know only A heap of broken images, where the sun beats, And the dead tree gives no shelter, the cricket no relief, And the dry stone no sound of water. Only There is shadow under this red rock, (Come in under the shadow of this red rock), And I will show you something different from either Your shadow at morning striding behind you Or your shadow at evening rising to meet you; I will show you fear in a handful of dust. From The Wasteland (T. S. Eliot)

Example—physical (student presentations)

http://www.wehaitians.com/

Note the steep slopes and lack of vegetation in these photos from Haiti

http://flickrhivemind.net/Tags/deforestation,haiti/Recent

Example—Chemical

Example—Physical and Chemical (student presentations)

Soil acidification

• repeated wetting and drying of low humus, Fe oxide-rich soil can lead to formation of plinthite • enhanced rates when soil is warm • can harden irreversibly • concern in areas where rainforest vegetation is removed for agriculture

• • • •

nitric and sulfuric acid in rain, mine leachate overuse of nitrogen-containing fertilizers plant litter low in base cations leaching of base cations

importance of buffering capacity of soil Soil pH and root length in Australian almond orchards

http://www.geo.hunter.cuny.edu/tbw/soils.veg/lecture.outlines/soils.chap.14/soil.taxonomy/ultisols/ultisols.htm

1999 article: http://gains.org.gh/articles/gjas_v32_2_p223_227.pdf

http://www.physicalgeography.net/fundamentals/8h.html

http://growing.australianalmonds.com.au/wpcontent/uploads/sites/17/2014/05/AAA09-Figure-5.jpg

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Example—Biological

Pacific Northwest—clearcut and fire impacts on mycorrhizal fungi

•clearcut sites in southern Oregon first studied in 1980s

http://forest.moscowfsl.wsu.edu/smp/solo/documents/GTRs/INT_280/print/Amara nthus.html

•impact of fire

Iceland—inoculating seedlings with mycorrhizal fungi prior to restoration plantings Folia Geobotanica 38: 209–222, 2003 INOCULATION OF GRASS AND TREE SEEDLINGS USED FOR RECLAIMING ERODED AREAS IN ICELAND WITH MYCORRHIZAL FUNGI Batkhuugyin Enkhtuya, Úlfur Óskarsson, John C. Dodd & Miroslav Vosátka Abstract: The objective of this study was to investigate the response of plant species used for reclamation of eroded areas in Iceland to inoculation with mycorrhizal fungi. In a greenhouse trial, Leymus arenarius and Deschampsia beringensis were grown in pots with volcanic ash collected from a site near the Mt. Hekla volcano in Iceland and were inoculated with arbuscular mycorrhizal fungi (AMF) isolates Glomus mosseae BEG25 or Glomus intraradices BEG75. In two field experiments conducted on volcanic tephra fields near Mt. Hekla,a native soil inoculum or commercial inocula TerraVital-D and Terra Vital-G Ecto Mix were compared for efficacy on L. arenarius and Betula pubescens. After four months of growth, the presence of AMF in the pot experiment significantly increased the capacity of grass root systems to bind soil particles. In the field, inoculation significantly increased the number of L. arenarius plants, which emerged from seed and their subsequent survival and growth. Seedlings of B. pubescens grew best following inoculation with ectomycorrhizal fungal (ECMF) inoculum and a subsequent application of inorganic NP-fertilizer. The additionof native soil inoculum had almost no effect on growth of either grass or trees. Our results indicate that reclamation of eroded areas in Iceland could benefit from the use of appropriate mycorrhizal fungi, which might improve plant establishment and growth and increase soil aggregation and stability.

marlimillerphoto.com

Invasive species and soil nitrogen content

Example—Chemical and Biological Scotch broom—N-fixation Invasive species and soil nitrogen content

Publication co-edited by Sarah Reichard (professor at UW Center for Urban Horticulture http://www.fs.fed.us/pnw/pubs/pnw_gtr694.pdf More on invasive species’ soil impacts in research project presentations!

http://farm4.static.flickr.com/3503/4039029358_3662cc6cca.jpg

http://www.co.whatcom.wa.us/publicworks/weeds/images/Cytsco1.jpg

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Invasive species and soil nitrogen content

Invasive species and soil nitrogen content

Milk thistle—establishing on very high N soils where dairy manure applied Japanese knotweed— much lower C:N litterfall

http://www.ezherbs.net/_borders/milk%20thistle.JPG

http://www.co.thurston.wa.us/tcweeds/weeds/Japanese-Knotweed.htm

Soil Restoration Methods

http://fairfoodfight.com/2011/02/15/know-your-manure-lagoons/manure-lagoon/

Soil Conservation Methods What sorts of things to we do to protect non-degraded soils?

What sorts of things to we do in an attempt to remediated degraded soils? • • • • • •

multiple reasons to add organic matter and/or agricultural lime flushing with water situations where soil is heated bioremediation with plants, fungi, bacteria revegetation time

Conservation districts—national level http://www.nacdnet.org/about/districts King County Conservation District http://www.kingcd.org/

Questions to consider… • in what sort of situations would the soil actually be removed? • source of money to accomplish this? • what combinations of strategies might be most effective?

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