Chapter 5: Proper Applications of Waste Products

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Chapter 5 Proper Applications of Waste Products
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Proper Application of Waste Products

• Proper waste application involves knowledge of
  the
• waste application system
• soils and crops
• the required buffers that must be adhered to
• This chapter will explain the required buffers
  and all other factors that must be considered
  when you are trying to determine when and how
  much animal waste to land apply.

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What Buffers Are Required When I Make Land
Applications?

• There are three different sets of buffers you
  should consider when land applying animal waste
• perennial streams
• groundwater wells
• good neighbor buffer

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BuffersPerennial Streams

• Under the existing 15A NCAC 2H.0200 Nondischarge
  Rules, you can not land apply animal wastes
  within 25 feet of perennial streams.
• Perennial streams are defined as streams
  indicated by a solid blue line on a United States
  Geological Survey map.
• Effective October 1, 1995 for new or expanding
  swine farms, you may not apply waste within 50
  feet of perennial streams.

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BuffersGroundwater Wells

• A 100-foot buffer is required around wells for
• location of lagoons
• other waste treatment facilities
• land application sites
• Even on a properly managed site it is best to
  maintain the buffer to reduce the potential for
  problems.

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BuffersGood Neighbor Buffer

• Maintain a minimum distance of 200 feet from any
  homes or other buildings frequented by people.
• Do not make land applications on days with
  excessive wind. Drift on these days may irritate
  neighbors or pollute surface waters.

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Proper Application of Waste ProductsIrrigation
Scheduling

• Proper land application of lagoon liquid involves
  the use of water management strategies to best
  achieve a balance between
• optimizing the timing of nutrient application to
  match crop uptake
• maintaining adequate storage in the lagoon to
  handle extreme rainfall without overtopping
• applying water at a rate and amount such that no
  direct surface runoff or percolation below the
  root zone occurs

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Irrigation SchedulingDecision Making

• Do I need to irrigate?
• How much water should I apply?

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Irrigation SchedulingDetermining When to
Irrigate

• Ask yourself
• Do I have an actively growing crop (or will a
  crop be planted or actively start growing within
  30 days)?
• Do I have a nitrogen deficit remaining for this
  crop cycle?
• Is the liquid level in my lagoon above the
  minimum storage depth?
• Are my land application fields dry enough to be
  irrigated?
• Do I have a waste analysis within 60 days of this
  irrigation?
• If the answer to all five questions above is yes,
  then you should schedule an irrigation.

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Irrigation SchedulingBasic Soil-Water
Relationships

• Saturation - all soil pores are filled with water
  and conditions are undesirable for good crop
  growth or wastewater irrigation.
• Field capacity - the soil has had time to drain
  away excess water, but still remains in a very
  moist condition.
• Permanent wilting point - plants cannot remove
  water from the soil.

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Irrigation SchedulingBasic Soil-Water
Relationships

• Gravitational Water - gravitational water is
  computed as the volume of water in the soil
  between saturation and field capacity.
• Plant-Available Water (PAW) - the difference
  between the water content at field capacity and
  the permanent wilting point. Irrigation should be
  scheduled to maintain the water content of the
  soil between these two extremes.

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Irrigation SchedulingEstimating Soil-Water
Content

• There are three practical methods of determining
  if the field is dry enough to be irrigated -
  these include
• a subjective method that involves feeling the
  soil
• objective methods utilizing soil-moisture
  measuring devices
• an accounting approach (checkbook method) to
  estimate soil-water

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Irrigation SchedulingDetermining How Much to
Irrigate

• Irrigation should be scheduled and timed so that
• no surface runoff occurs during the irrigation
• the root zone is not completely saturated at the
  conclusion of the irrigation
• the irrigated water does not leach below the root
  zone

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Irrigation SchedulingDetermining How Much to
Irrigate

• The amount of wastewater that can or should be
  applied during any single irrigation cycle is
  dictated by how much water the soil can soak
  up.
• This varies from day to day and is influenced by
• rainfall - when and how much it last rained
• crop maturity - water uptake rate of the crop
• soil type - texture, structure, depth, and cover
• effective root depth
• evapotranspiration - which is influenced by
  temperature, wind, and relative humidity

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Approximate Water Infiltration Rates for Various
Soil Textures and Slopes
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Irrigation SchedulingOperational Considerations

• Discharge rate - the volume of water exiting a
  sprinkler per unit of time.
• Precipitation rate - normally expressed as unit
  depth of water (inch) per unit of time (usually
  hour).
• Total application volume - computed based on the
  amount of time the system operates at a given
  rate on a given field.

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Example

• If your target application volume to achieve the
  required annual PAN is 3.0 inches, and you should
  apply no more than 0.5 inch at each irrigation,
  how many times must you irrigate?
• To answer this, use Formula 7

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Typical Layout of a Stationary Sprinkler System
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Stationary SprinklersDetermination of
Precipitation Rate

• Determine the discharge rate (sprinkler flow
  rate) and wetted diameter from manufacturers
  literature.
• Determine sprinkler spacing. Recommended
  sprinkler spacing is 50 to 65 percent of wetted
  diameter.
• Precipitation rate is then computed using Formula
  8

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Stationary SprinklersDetermination of
Precipitation Rate

• Time of operation is computed using Formula 9

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Typical Layout of a Traveling Gun Irrigation
System
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Traveling Gun SprinklersDetermination of
Precipitation Rate

• Precipitation rate is computed using Formula 10

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Traveling Gun SprinklersDetermination of
Application Volume

• Application volume is computed using Formula 11

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Traveling Gun SprinklersDetermination of
Traveling Speed

• Traveling speed is computed using Formula 12

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Irrigation System Calibration

• Calibration involves collecting and measuring
  flow at several locations in the application
  area.
• Any number of containers can be used to collect
  flow and determine the application rate
• rain gauges
• pans
• plastic buckets
• jars

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Irrigation System Calibration

• For stationary sprinklers, collection containers
  should be located randomly throughout the
  application area at several distances from
  sprinklers.
• For traveling guns, sprinklers should be located
  along a transect perpendicular to the direction
  of pull.
• Set out collection containers 25 feet apart along
  the transect on both sides of the gun cart.

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Application Using Spreader Equipment

• Wastes that have a higher solids content than can
  not easily be handled through an irrigation
  system may require land application through a
  pump and haul system.
• The decision process for waste application is
  more related to the stage of crop growth and
  whether the crops need nutrient applications.

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Application Using Spreader Equipment

• One important issue is the trafficability of
  the fields, or how easily your equipment can be
  operated to obtain uniform waste application
  without rutting the field or causing soil
  compaction.
• Once the decision has been made to perform waste
  application, you must be aware of your
  equipments waste application rate. This requires
  the calibration of the land application equipment.

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Calibration of Manure Spreaders

• Applicators can apply manure, bedding, and
  wastewater at varying rates and patterns,
  depending on
• forward travel and/or PTO speed
• gear box settings
• gate openings
• operating pressures
• spread widths
• overlaps

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Calibration of Manure Spreaders

• Calibration defines the combination of settings
  and travel speed needed to apply manure, bedding,
  or wastewater
• at a desired rate
• to ensure uniform application

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CalibrationLiquid Manure Spreaders

• Spread at least one full load of waste,
  preferably in a square or rectangular field
  pattern for ease of measuring, with normal
  overlaps.
• Measure the length and width of coverage,
  recognizing that the outer fringe areas of the
  coverage will receive much lighter applications
  than the overlapped areas.

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CalibrationLiquid Manure Spreaders

• Multiply the length by the width and divide by
  43,560 to determine the coverage area in acres
• Formula 13
• Formula 14

Coverage area (area of rectangle in ft2)
length (ft) width (ft)
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CalibrationLiquid Manure Spreaders

• Divide the gallons of wastewater in the spreader
  by the acres covered to determine the application
  rate in gallons per acre (Formula 15)
• Repeat the procedure at different speeds and/or
  spreader settings until the desired application
  rate is achieved.