module 8: open feedlot construction and management for water and air quality protection

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Module 8: Open Feedlot Construction and Management for Water and Air Quality Protection

By Jeff Lorimor


Introduction

Open feedlots are defined as confined areas that are devoid of vegetation or crop residue where animals are held for 45 days per year.


CAFO Definition

Federal regulations define a Concentrated Animal Feeding Operation (CAFO) as a feedlot with capacity equal or exceeding:

1,000 beef animals. 700 dairy cows. 2,500 swine over 55 pounds. Other species of EPA-defined sizes.


NPDES Permit

CAFOS must obtain National Pollutant Discharge Elimination System (NPDES) permits. The permits:

Require capturing feedlot runoff. Require pumping captured liquids onto crops. Prohibit releasing runoff except in very large

storms (25-yr, 24-hr storm).


Other CAFO Requirements Weekly inspection of storm water control

devices Must have depth markers in containments Record-keeping requirements


Nearby Water Feedlots should not have streams running

through them. Feedlots should not drain directly into streams,

ditches, tile intakes, or other waterways leading directly to waters of the state.


Runoff Control and Management

Complete containment Contain all runoff in a basin below the lot. To prevent overflow, land apply (irrigate) the

liquids. Discharge systems

Useful for lots smaller than CAFOs Release after settling solids in a manner that

prevents water pollution.


Diversions Runoff control should start by diverting clean

water away from the lot surface.

Downspouts


Settling Solids All feedlots should have

solids settling basins (debris basins) to capture solids from the feedlot runoff.


Settling Solids (continued) Solids settling basins do not store liquids

permanently. Liquid velocity is slowed, but the liquid is

released. State regulations may determine basin

design. Porous outlets should be unplugged frequently

to enhance liquid release. Solids should be removed frequently.


Nutrients are in Solids Most of the nutrients (>

90%) from open feedlots are found in the solids, not in runoff liquids.


Containment Structures Must have capacity to store runoff from the 25-yr, 24-hr

storm If inadequate capacity exists, pump out the

containment. Maintain the structure in good condition.

Control erosion. Eliminate rodents. Keep mowed. Maintain depth indicator gauge. Keep accurate records.


Air Quality In Western states, dust and odor are bigger

concerns than water quality. They are affected by the moisture content of the feedlot surface. Too dry…dust results Too wet…odor results

In more humid regions, surface runoff is the primary concern.


Between 25%–40% Moisture is Optimum in a Feedlot

01020304050

60708090

100

0 10 20 30 40 50 60 70 80 90 100

Moisture Content, %w.b.

Du

st/O

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r P

ote

nti

al

Dust Potential

Odor Potential


Corral Construction If possible, build on 3%-5% slopes. Avoid pen-to-pen drainage. Build mounds up and down the slope, not across

the slope. Build mounds so cattle have access to them

without going through a pothole. Provide convenient access for manure removal.


Properly Constructed Mounds Stay Dry


Open Lot Maintenance Proper maintenance

is the most important factor in avoiding air and water quality problems with open lots.

Pull blades are better than push blades for maintenance.


Make Mounds of Good Soil–Not Manure

Mounds should run up and down, rather than across, the slope.


Open Lot Dust is a Function of

Loose manure depth on the corral surface.

The moisture content of the loose manure.

Hoof action arising from cattle activity.


Corral MaintenanceKeep the surface as hard, smooth, and dry as

possible.

Minimize hoof prints that can hold water.

Scrape manure to maintain a 1"-2” base of manure above the soil surface.

Frequently inspect and fill holes and depressions.


Stocking density (animals per unit area). Animal bodyweight. Number of days on feed. Corral surface condition (e.g., wallows, “dust

pots”). Manure harvesting frequency.

Dust Emissions

Loose manure depth is a function of…


Loose Manure Depth

Deep and soft Thin and well

compacted


Manure not yet harvested > 2” deep

Manure harvested within previous 3 days < 1” deep


Manure Moisture Content


Moisture from Heat Control Sprinkling lots during hot weather can create wet

conditions in humid areas. Sprinkle only intermittently. Locate sprinklers in areas that will not create

potholes. Sprinklers should provide 0.25”/day or more. Patterns should overlap 50% of the diameter. Do not sprinkle the feed apron.


Stocking Density Increased stocking density adds more moisture

to the lot surface from cattle urination. Texas research showed reduced Pm-10

emission at 75 sq ft/head vs. 150 sq ft/head. Other factors such as cattle performance are

important in determining maximum density.


Manure Moisture ContentF

eed

apro

n

1 2 3 4

Water Trough

High activity; High moisture

Low activity;Low moisture


Dust Control Applying water to the feedyard surface,

passively or actively, helps but is not a cure-all. Frequent manure harvesting (> 1 per turn)

decreases water requirements and increases water effectiveness.

Use the off-season to get ready. Prioritize within the yard and the corral.


Mortality Management for Odor Control Limit exposure to the elements; use rapid

rendering service pickup.

Compost. Perforate or cleave thoracic cavity and cover

carcass with 1'-2' of dry, organic material.

Burial is no longer acceptable in many states.


Summary Preventing water and air pollution from open

feedlots starts with good lot design. Management and maintenance are the keys to

ongoing pollution prevention. Maintain smooth dry lots. Adjust moisture and scrape carefully to

minimize particulate and gas emissions.

module 8: open feedlot construction and management for water and air quality protection

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