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Beneficial Use of ByProducts in Agriculture


Organic matter affects recommended N rate and improves soil physical properties 3.1% - low ... Soil properties need to be considered before application ... – PowerPoint PPT presentation

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Title: Beneficial Use of ByProducts in Agriculture

Beneficial Use of By-Products in Agriculture
  • Carl J. Rosen
  • Dept. Soil, Water, and Climate
  • University of Minnesota

Beneficial Use
  • Land application vs. landfilling
  • Cycling of nutrients
  • Improving soil properties for crop growth
  • Minimal risk to the environment or human health

Key Components
  • Soil evaluation
  • Crop requirements
  • By-product characterization
  • Application rate to meet crop needs

Evaluation of Agricultural Soils
  • Soil testing is essential
  • 6-8 depth for pH, organic matter, P, K,
    micronutrients, texture
  • 24 depth for nitrate

  • Texture sand, silt, clay - leaching risk,
    affects recommendations for timing of N
  • Organic matter affects recommended N rate and
    improves soil physical properties
  • lt 3.1 - low
  • 3.1 to 4.5 - medium
  • 4.6 to 19 - high
  • gt 19 - very high (organic soils)

Interpretations (cont.)
  • Soil pH
  • Affects nutrient availability and microbial
  • 6 to 7 is optimum
  • Lime recommended if pH is less than 6.0
  • Buffer index is needed to determine rate of lime
    to apply

Interpretations (cont.)
  • Soil nitrate test (0-24)
  • Measure of residual nitrate (lbs/N)
  • Reliable on medium to fine textured soils
  • Most useful if manure applications have been used
    or if previous crop was stressed (eg. drought)

Interpretations (cont.)
  • Phosphorus
  • Two test are used
  • Bray P1 pH lt 7.4
  • Olsen P pH gt 7.4
  • lt 25 ppm Bray or 20 ppm Olsen
    potential crop response
  • gt 200 ppm limit for application runoff
  • P index?

Interpretations (cont.)
  • Potassium
  • Ammonium acetate extractable
  • lt 160 ppm potential crop response
  • Boron
  • Hot water extractable
  • lt 1 ppm potential crop response
  • gt 4 ppm potential toxicity

Interpretations (cont.)
  • Zinc DTPA extractable
  • lt 1 ppm potential crop response
  • Soluble salts saturated paste
  • gt 4 mmhos/cm (ds/m) potential problems

By-Product Characterization
  • Tests to consider BEFORE application
  • pH
  • Salts
  • Total C and N (C/N)
  • Inorganic N (nitrate and ammonium)
  • Acid digest for essential elements
  • USEPA 503 elements risk assessment
  • Selected organics risk assessment

By-Product Characterization
  • Inorganic
  • Coal ash, wood ash, sugarbeet lime, water
    treatment lime, dry wall, rock fines
  • Generally low in nitrogen, some can be used as a
    liming agent, may supply calcium, magnesium,
    sulfur, potassium, phosphorus, some micronutrients

By-Product Characterization
  • Organic
  • Biosolids, yard waste, MSW compost, food waste,
    paper mill sludge, cardboard sludge, dairy
  • Will increase soil organic matter content,
    variable nitrogen supply, may also supply other
    essential nutrients (P, K, Ca etc.)

Liming Potential of By-products
  • pH greater than 8.0
  • Calcium carbonate equivalent
  • Particle size
  • Moisture content
  • Effective neutralizing power (ENP)
  • ENP for Ag-lime 50-60

Co-Application of By-products
  • Potential benefits from by-products with
    different characteristics
  • Examples
  • Biosolids ash (OM, N, P, pH, K)
  • Biosolids paper mill sludge (OM, N, P, OM)
  • Economics needs to be considered

By-Products with Liming Potential
  • Benefits of adding lime to acid soils
  • Increases nutrient availability
  • Increases microbial activity
  • Do not apply on soils with a pH greater than 6.5
  • Over-application of lime
  • Affects availability of nutrients - P, Fe, Mn
  • Can affect activity and degradation of some

Organic Matter in By-Products
  • Benefits sandy soils by increasing water holding
  • Benefits clay soils by improving soil structure
    aeration and drainage
  • Difficult to put a monetary value on OM

Fertilizer Value of By-products
  • Nitrogen
  • Organic and inorganic N
  • Only a portion of the organic N will be released
  • Release depends on C/N ratio, moisture,
    temperature, type of by-product
  • N availability estimated from incubation and/or
    field studies

Fertilizer Value of By-products
  • Importance of properly estimating N release
  • Underestimation N deficiency, yield loss
  • Over estimation potential for nitrate leaching
  • Rate of organic by-product to apply based on
  • Estimated N release
  • Crop grown and previous crop
  • Soil organic matter
  • Soil nitrate test

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Fertilizer Value of By-products
  • Phosphorus (mainly from organic by-products)
  • Total P, organic P, acid extractable
  • Most organic by-products applied based on N
  • P comes along for the ride
  • New regulations may limit rate of by-product
    application based on
  • Soil test P, runoff risk (P index)
  • P content of by-product,
  • P removal by crop

Fertilizer Value of By-products
  • Potassium
  • Significant amounts in wood ash by-products
  • Most potassium in the ash is considered available
  • Calcium, magnesium, sulfur
  • Significant amounts in many by-products
  • Available to varying degrees
  • High levels of sulfate may leach
  • Boron, copper, zinc, iron, manganese, molybdenum
  • Micronutrients - low amounts required for plant

Potential Problems
  • Salts saturated paste (mmhos/cm)
  • lt 2 no problems
  • 3-4 problem for sensitive crops
  • 5-7 moderately tolerant crops survive
  • gt 8 most crops damaged
  • Managing high salts
  • Be sure to incorporate in soil
  • Apply in fall before planting
  • Leach before using

Potential Problems
  • Sodium
  • Detrimental to soil structure
  • High levels toxic to plants
  • Limit application to less than 170 lb Na/year
  • Chloride
  • Highly leachable
  • High levels can be toxic
  • Agronomic rates applied with potash fertilizer
    100 to 200 lbs Cl/A

Potential Problems
  • Boron
  • Essential for plants, but high levels toxic
  • Easily leached
  • Do not exceed 4 lb B/A loading
  • Molybdenum
  • Essential for plants
  • High levels can be toxic to ruminant animals
  • Availability increases with increasing pH
  • Agronomic rates 0.25 to 0.5 lb Mo/A

Additional Concerns
  • Odors
  • Dust
  • Pathogens
  • Inerts

Additional Concerns
  • Compaction

  • Each by-product needs to be characterized
    chemically and physically before application
  • Soil properties need to be considered before
  • Requirements of crop should be taken into account
  • Match by-product attributes with soil/crop needs