Soils Final Exam

Presentation takeways- Soil biota diversity

(smallest to largest) archea, bacteria, protists, fungi (macrofungi and mycorrhizal fungi), microfauna, mesofauna, macrofauna, megafauna

Presentation takeaways - Geographic and temporal distribution

scales from vertical, horizontal, and temporal distribution. There is diversity on the aggregate scale, and it’s important to note this whole area as the critical zone, critical for all life on earth (right above soil and into parent material). Climate, vegetation, salinity, and soil texture affect soil biodiversity

Presentation takeaways - ecosystem functions and services

soil and soil biota provide ecosystem services: provisioning (transporting of nutrients and water to plants), regulating (decomposers decomposing orgo material), supporting (soil ages and habitats), cultural (colors, religion, etc.)

Presentation takeaways - threats

most are results of human activity, pollution, land degradation, climate change, effects from agriculture, etc.

Presentation takeaways - intervention

main goals are to increase biodiversity in biota and plants, remediate soils and work to inc. biodiversity in small scales, and change agricultural practices to protect soil biota

Presentation takeaways - policy, education, and outreach

recently there’s increased curiosity in soil organisms, and education and awareness can help us be more sustainable in management practices

Technical report writing - soil orders:

capitalized

Technical report writing - cardinal directions:

not capitalized (unless proper noun) ex. northwest, Northern Illinois University, North Carolina, etc

Technical report writing - no _ person writing or _ language

1st, subjective

Technical report writing - referencing figures

Don’t reference figures in a separate sentence (ex. Figure 3 shows this by…), cite them at the end of a sentence (Figure 3).

Technical report writing - units

metric (cm/m)

Technical report writing - street names (after a number)

not capitalized (7th avenue)

Technical report writing - nutrients

not capitalized (nitrogen)

Technical report writing - paragraph indents

not needed. don’t indent paragraphs

Technical report writing - dashes

en dash (—), not - or —- (use 2 dashes)

Technical report writing - numbers and units

include a space between number and metric (30 cm)

What is permafrost? Spatial patterns?

permanently frozen ground that is below 0 degrees C for 2 consecutive years. Found primarily in the high Arctic in Canada, Alaska, Russia, and Greenland

Why is the Arctic warming faster than other regions of the planet?

Albedo effect/ positive feedback loop

Active layer

the ground that thaws in the summer and freezes in winter. It is where microbial activity is present. The active layer is increasing as permafrost thaws

Thaw vs. Melt

permafrost is comprised of soil, rock, AND ice, and cannot melt because it doesn’t have a fully liquid form. Permafrost thaws as frozen meat does

Thermokarst

pockets in the ground when ice in permafrost melts. water often seeps through them

Yedoma

extremely carbon rich Arctic permafrost with less ice content than others

Consequences of thawed permafrost

road/building/infrastructure collapse, increased release of GHG at an accelerated rate

How does Carbon Dioxide release from the soil?

CO2 is released in dry conditions with oxygen

How does methane release from the soil?

Methane is released in wet soils without oxygen (gley, marshes)

Why is the Arctic vulnerable?

Albedo effect makes the problem worsen, permafrost thaw affects entire ecosystems and destroys infrastructure, positive feedback makes it warm much quicker

The Arctic as a carbon source rather than a sink… how/why is this happening?

The active layer is slowly increasing, which increases microbial activity, both through heat activation and “opening the buffet” to digest stored carbon within the permafrost. The carbon that was originally being stored in the “sink” is now being released as a source. Wildfires and logging are also contributing.

Impacts of abrupt thaw

causes a LOT of carbon to be released at once, can be increased with climate change, difficult to model in climate change predictions

Schurr (2016) article: The Permafrost Prediction

5 to 15% of stored carbon can escape from permafrost within this century, calculated through field work and computer modeling 

2024 NOAA State of the Arctic chapter on soils

The arctic is becoming a source instead of a sink. Permafrost temperature is increasing in all of the arctic, but especially in the high arctic

Horwath et al. (2008) “Spatial and temporal distribution of soil organic carbon in non-sorted striped patterned ground of the High Arctic”

Cryoturbation plays a large role in soil and SOC storage/distribution. Much of the stored carbon is below 25 cm, not what was previously thought

Schurr et al. (2015) Review article “Climate change and the permafrost

carbon feedback”

There is a lot of uncertainty about the magnitude of carbon release, as most existing research focuses on gradual release and not abrupt thaw. This can be a long term amplification, regardless of what humans do

 How are soils connected to climate change via the carbon cycle?

Soils are a carbon sink, storing a lot of carbon, but with warming can release carbon, becoming a carbon source (seen in the Arctic)

How can soil carbon loss accelerate global climate warming?

Soil carbon is released through microbial activity, which is activated in heat. This creates a positive feedback, releasing more carbon into the atmosphere at an accelerated rate

Amount of carbon in soils vs other pools. SOC in permafrost versus other pools of Carbon.

Lots of carbon in soils that often gets overlooked, over double the amount of carbon in soils vs. the atmosphere. There is a lot of SOC in the Arctic/Gelisols, as the Arctic is cold and wet, which slows decomposition and traps SOC

What is the name of the federally administered conservation program that removes cropland from production and plants it to grasses?

Conservation Reserve Program

The hypoxic zone in the Gulf of Mexico is created by excess __ from agricultural and urban runoff into the Mississippi River

Nitrates

Conventional tillage technique that produces the most vulnerability to erosion.

moldboard plow

Soil conservation technique typically used in urban areas.

Silt fence

Test to assess aggregate stability

slake

Wind erosion conservation technique

linear tree planting (wind break)

As earthworms digest organic matter they leave expelled fecal evidence on the surface called casts. T/F

true

Organisms like ants and rodents are often considered ecosystem engineers in the way that they alter the soil environment. T/F

True

Crayfish create _________ at the surface as they burrow through the soil to reach the ______.

chimneys, water table

The pedologic name for an in-filled animal burrow is a

krotovina

Mycorrhizal fungi have symbiotic relations with plants in which the fungi supply key nutrients to the plant, and the plant supplies sugars and exudates to the fungi. T/F

True

What are some of the connections between the decline of past human civilizations and soil erosion?

Intensive agricultural practices such as deforestation, intensive farming, the plow, etc. result in soil erosion and reduced soil fertility. This reduces crop yields, and people starve

What are erosion processes?

detachment, transportation, and deposition

Water erosion examples

Sheet - smallest level of erosion, from rain droplets (soil looks like mushrooms)

Rill - middle level of erosion, forms small channels

Gully - largest level of erosion, forms severe, deep channels

Wind erosion examples

Saltation - “jumps”, detaches soil and bounces it around

Creep - rolling along a surface

Suspension - small particles carried through wind and come down

How do we quantify/measure levels of soil erosion

RUSLE: Revised Universal Soil Loss Equation

What is RUSLE

A = R x K x LS x C x P

RUSLE: A

predicted Annual soil loss

RUSLE: R

Rainfall erosivity

RUSLE: K

soil erodibility

RUSLE: L

slope Length

RUSLE: S

slope gradient or Steepness

RUSLE: C

Cover and management

RUSLE: P

erosion-control Practices

Why is it critical to understand site specific concerns/needs when examining RUSLE

Soil erosion is not universal across all landscapes; it is very site specific based on specific factors, and RUSLE helps to get a quantifiable number to measure soil erosion for a specific site

What is a way to control soil erosion in urban areas

Silt fence. this retains soil on disturbed land, protecting from erosion using thin fabric to trap soil

Conservation tillage

(erosion control), stepping away from conventional agriculture like the moldboard plow, using strip tillage and no till to reduce disturbance to the soil, resulting in less displacement of soil and erosion 

No-till

planting directly into residue of previous year’s crop (erosion control). Doesn’t till at all, not disturbing the soil

Terraces

slows downside water movement and prevents transport of soil (erosion control). Ridges alongside hills for agriculture

Cover crops

(erosion control and nutrient management), provides living roots throughout the entire year to uptake nutrients, water, and stabilize soil

Grassed waterways

channels to divert runoff are lined with grasses which clean water quality and catch sediments (nutrient management)

Riparian buffer

(both nutrient and erosion control), water flow is slowed, nutrients (phosphorus from ag runoff, nitrogen from water) are taken by vegetation, and erosion is slowed by a vegetated buffer alongside streams

Grassed or conservation buffer

permanent vegetation on the edge of a cropped field, reduces water flow and sediments, and mitigates compaction (erosion and nutrient management)

Bioreactor

buried trench on the edge of a field that filters drainage tile water through woodchips to remove nitrates (nutrient management)

Saturated buffer

reduces nitrate levels from agricultural drainage entering waterbodies (Nutrient management). Drainage tile water passes through vegetation using pipe technology to reduce nutrient loss.

Prairie strips

(both nutrient and erosion control), acts as a sponge to soak up nutrients and reduce soil movement

Strip cropping

planting alternating crops in strips parallel to the slope, slowing water as it goes downhill, creating rougher surfaces (erosion and nutrient control)

How are conservation measures connected to soil health? How is soil erosion control connected to nutrient management and healthy soils?

Soil erosion control often keeps in other nutrients, including mineral rich topsoil that doesn’t get disturbed. Reducing erosion allows more organic matter to build, roots are strengthened, and carbon is stored in soil, creating a healthier ecosystem

Key takeaways from SWCD employee visit

SWCD offers multiple programs (such as the conservation reserve program) to farmers to implement BMP on their farms, generally in a 10-15 year contract, done by renting land and farmers promising not to till/erode, plant pollinator habitat, implement BMP, etc. Many acronyms for different programs, but they generally follow this method

Nitrates vs. phosphorus

Nitrate - soluble, to mitigate: focus on reducing movement of water to combat nitrate pollution

Phosphorus - adheres to soil particles (“sticky”), focus on SLOWING movement of water to reduce erosion

Soil Health

continued capacity of soil to function as a vital ecosystem for biota 

Soil biotic diversity and soil health

different organisms provide different functions to the soil, so working to improve biodiversity is vital for growing soil health. This replicates historic land with increased organic matter, more nutrients, and more, increasing soil health.

Glomalin

soil protein produced by mycorrhizal fungi, helps sequester carbon, reduce erosion. Very strong, resistant to decay, doesn’t dissolve in water, really only tillage disrupts it. Acts as the “glue” in soil and strengthens aggregates

Who cares about soil health?

we should care because we eat food. Applying BMP to our soil takes care of our plants, which we use for provisioning ecosystem services

Why do we need to think about soil health

soil health influences our crop yields. Healthier fields = healthier farms = more yields = more money. It’s also cost effective to think about soil health, as farmers will spend less on pesticide and synthetic fertilizer, having a more self reliant soil

What are some ways we can increase carbon content in agricultural soils?

No till farming, reintroducing livestock and mob grazing, always have something living in the soil 

Carbon Cowboys Key Takeaways

Reintroducing mob grazing for cattle increased soil health, letting the healthier “better” plants grow, removing from monoculture which also brings pollinators. These diverse plants make the nitrogen and capture carbon to put into soil, losing the need for synthetic fertilizers

Mycorrhizal fungi

Form glomalin, and have a mutualistic relationship with plants (solubilize nutrients for plants, and plants provide simple carbohydrates to feed fungi). They have almost a very complex root system made up of thread like hyphae. Not all plants have mycorrhizal relationships, but many do

What is regenerative agriculture and how is that connected to soils?

regenerative agriculture - working with nature, not against it. This includes prioritizing soil health and nature based principles to improve soil health

Field trip to Monte Botten’s farm, Grateful Graze (Botten’s Family Farm)

Key takeaways: 5 soil health principles → minimize disturbance, keep soil covered, maximize diversity, have something growing all the time, integrate livestock. This is done to mimic historic land. Slope does affect many agricultural practices, such as erosion, infiltration, aspect, etc. Although he is doing many regenerative agriculture practices, he still struggles with effects of conventional agriculture; runoff from his neighbors fields end up in his ponds and pollute his farm

What important roles do soil fauna play?

soil fauna modify, transport, and form soils through turbation, excrement, organic matter, etc

How do crayfish modify soilis?

crayfish create chimneys through upward biotransfer as they try to reach the water table deep within the soil

How do gophers modify soil?

gophers are able to create mounds when they can’t physically dig deeper into soil. they also are large biomixers

How do ants modify soil?

ants create intricate nests within soil, and bring soil to the surface in the process (upward biotransfer)

How do termites modify soil?

they create giant mounds above soil surfaces using upward biotransfer, being a mix of soil, saliva, and fecal matter

What is the connection between the field of ichnology and modern soil fauna?

Ichnology - study of trace fossils, which helps us be able to see historic bioturbation

How is Charles Darwin involved with the topic of soil fauna

Darwin wrote about earthworms and the processes of mixing and moving soil in a novel (The Formation of Vegetable Mould)

Soil microbiota: decomposers

bacteria and fungi, degrade plant residues and organic compounds (bacteria degrade simpler compounds, while fungi work on more complex compounds)

Soil microbiota: grazers

protozoa and nematodes grade on bacteria/fungi, as they do so they release plant-available nutrients

Soil microbiota: transformers

arthropods shred and consume plant litter, making it more accessible for composers through feces and increased surface area of litter. Ants, termites, and earthworms are ecosystem engineers, changing soil habitat by burrowing and chewing

Soil microbiota: mutualists

mycorrhizal fungi have a mutualistic relationship with plants: the fungus provides nutrients (and sometimes water) to plants, and the plant provides food to the fungi

Upward biotransfer

moving fine fraction particles from the lower biomantle into and/or onto the biomantle

biomixing

organisms burrow, wriggle, mix, and/or churn mainly within the biomantle (moving within the soil)

Cratering

creating craters, depressions, hollows, etc. in the soil as dens