Exam 2 Study Guide

List two factors that have resulted in the increased demand for food production

population increase and increased wealth (eating higher on the food chain)

On a global scale how many people are undernourished?

840,000,000

Since mid 1960’s total global acreage devoted to agriculture increased by only 8%, but population increased by _______%.

100%

List 4 causes/reasons of good farm land loss

Desertification, salinization, erosion, urban development

Primary macronutrients

Nitrogen, Phosphorus, Potassium

What is cation exchange capacity and how can it influence groundwater quality?

Sum of exchangeable cations that a soil can adsorb (cmol/Kg). Typically increases with increasing clay and organic matter content. Higher CEC soils can absorb potentially more contaminants such as NH4+ (cations will be held in the soil as soil particles have a negative charge). This means less leaching and runoff.

Common water pollutants associated with agriculture

Nitrogen, phosphorus, sediment, bacteria

Why do well drained soils lose more NO3 than poorly drained soils?

Nitrate leaching, less denitrification

• Well drained soils have a water table below the surface (farther removed from organic matter), negative and negative charges repel, NO3- moves pretty quickly through the soil & less denitrification.

How is phosphorus typically transported to surface waters?

Mainly Erosion (P-attached sediment loss) but may leach if very high P index (all exchange sites in the soil are filled with P), and soluble P in surface layers (was sticking to an iron oxide → oxidized → releases P)

The three processes required for water erosion

Detachment = soil detached when rain drops impact exposed soil

Transport = flowing water carries soil particles

Deposition = water velocity slows and soil particles settle

Why is sediment in surface waters a problem?

Clog drainage ways causing flooding, coat fish gills, prevent light penetration and photosynthesis by Submerged aquatic vegetation, and pollutants attached to sediment (chemical species can sorb to sediment and are often transported with sediment)

Three common agriculture BMPs

• Sediment basin = sediment will fall out in basin (traps it before it leaves the farm; placed in the lowest part of the farm)

• Cover crops = plant during the off-season, provide ground cover, and take up excess nutrients

• Controlled drainage = a flash board riser → dams’ water → forces water levels in the field to the ground surface

Three mechanisms for nitrogen reduction by controlled drainage

• Reduced water outflow = more potential for evaporation

• Denitrification = water table closer to the surface, to get to the ditch and leave → Dissolved oxygen will drop due to organic matter causing anaerobic conditions and then bacteria will break down nitrogen → N2 goes to the atmosphere

• Improved crop yield (soil moisture) = doesn’t allow runoff to leave the farm → helps irrigate the land

Under what conditions will riparian buffers be effective at reducing NO3 loadings to surface waters via denitrification?

Water table close to roots

• anaerobic, saturated, & organic matter & microbes at the tree roots to break down nutrients

Under which conditions will riparian buffers be ineffective at reducing NO3 loadings to surface waters via denitrification?

water table much deeper than roots

How do buffers remove phosphorus?

• Slow runoff so total suspended solids (TSS) & attached P fall out, immobilization (uptake) by organic matter and trees → adsorption of P

• Prevent erosion

Goals related to stream restoration

• Stream sinuosity (snaking) → meandering

• floodplain connectivity- wetland benefits = when water comes out on the banks, want it to stay in the floodplain for wetland vegetation

• ripple and pool complexes- aquatic habitat and DO addition = adding riffles (area where water flow is turbulent and water becomes oxygenated) and root wads (provide stream bank stability and aquatic habitat)

To be considered a wetland, what 3 things must be present?

Wetland soils, wetland vegetation, wetland hydrology

Why isn’t controlled drainage used more in the piedmont?

Slopes too steep – require too many structures

• with that much topography it’s not effective

What are CAFO’s?

Confined animal feeding operations

Where are most hog CAFO’s located in the state?

Coastal Plains, Eastern, NC

What are the components of a typical hog waste system?

• Houses = give the hogs shelter

• Pipe = send liquid waste from hog houses into the lagoon

• Lagoon = where all animal waste is held; solids settle and liquid waste is at the surface

• Spray fields = liquid waste is sprayed on fields as a fertilizer; usually growing hay or Bermuda grass as it can uptake a lot of nutrients (N, P, and water)

What are some typical lagoon wastewater concentrations of TKN (total nitrogen), TP (total phosphorus), and E. coli?

• TKN = 365 mg/L

• TP = 93 mg/L

• E. coli = 6.9 x 10⁴ cfu/100 mL

What are the storage requirements for a hog waste lagoon (what levels are needed beginning with the sludge accumulation to the lagoon berm top)?

From beginning to the top:

• Sludge accumulation

• Permanent liquid treatment = should always be present

• Temporary storage treatment = fluctuates

• 25-yr, 24-hr storage (5-9 inches) = in case we get a bad storm or hurricane

• Heavy rainfall factor = for back-to-back storms

• Freeboard (1 ft)

5 things a CAFO operator must keep in their records

• Permit

• Waste management plan

• Sludge survey

• Calibration of waste equipment records

• Soil sample analysis

Wastewater should be irrigated at rates to maintain soil moisture between ______ and _______.

Field capacity and wilting point

Potential environmental threats related to CAFOs that use anaerobic lagoons

• Over application of waste → causing saturated soil runoff

• Leaking lagoons → mainly old ones

• Ruptured lagoons → during heavy rain events

• Fields with tile drains → pipes that lower the water table in fields → will outlet waste to a ditch then nearby water sources

• NH3 volatilization → if lagoons aren’t covered → respiratory irritant

What materials are lagoon liners made of?

• Clay

• bentonite = an expansive clay

• Plastic

What are some benefits of riparian buffers other than nutrient load reductions?

• Stream shading

• Wildlife and aquatic habitat

• Sediment reduction

• Bank stabilization

Wetlands account for what % land area in the lower 48 states?

5%

Wetlands account for what % land area in NC?

17%

Reasons wetlands are important

• Nutrient reduction

• Carbon sequestration = Pull in carbon from the atmosphere, buried in the soil, plants grow over it, and trap it → good for reducing greenhouse gas emissions

• Aquatic habitat

• Recreation and tourism

What % of US population lives in coastal areas?

> 50%

Common wetland communities in NC

• Wet flat

• Swamp forest

• Shrub swamps

• Marshes

• Bottomland hardwood forest

Examples of major anthropogenic (man caused) wetland destruction/alterations

• Deforestation/filling/draining for construction (building roads and urban development)

• Clearing/draining for agriculture = #1 historically

• Urban stormwater runoff and eutrophication

• Wastewater loading and eutrophication         

What is the difference between wetland restoration and wetland creation?

• Restored wetlands were once wetlands = land was modified but now we want to bring back the land to its original hydrology

• Created wetlands were not = we provide the conditions for it to be a wetland

Two federal agencies that regulate wetlands

1. US EPA

2. Army Corps of Engineers

Two state agencies that regulate wetlands

1. NC Division of Water Resources

2. NC Division of Coastal Management (for the 20 coastal counties)

Two examples of primary indicators of wetland hydrology

• Water marks = common on woody vegetation, mark highest extent of recent inundation

• Sediment deposits = plants often have thin layers, coatings of mineral or organic matter on them after inundation

*Only need one to confirm wetland hydrology*

Two examples of secondary indicators of wetland hydrology

• Crayfish burrows = can only live in water

• Saturation of land visible on aerial imagery

*Must have two to confirm*

Facultative wetland plants (FACW) usually occur in wetland ___ to ____ % of the time

67 - 99%

A property (or portion of property) contains wetland plants when greater than ______ % of plants are Facultative Plants (FAC) or wetter

50%