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FORMS OF PHOSPHORUS IN THE SOIL

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Title: FORMS OF PHOSPHORUS IN THE SOIL


1
FORMS OF PHOSPHORUS IN THE SOIL
  • Inorganic (50-70 of soil P)
  • Bound (Fixed)
  • Bound to Al, Fe and Ca cations on soil clay
    particles
  • Dependent on soil pH
  • Binding cations Optimum pH
  • Al, Fe
    4 - 5
  • Ca
    7 8
  • Most P in soil
  • Binding occurs rapidly when any P is applied
  • Most fixed in the upper 2 5 inches of soil
  • Less P fixed in sandy or peaty soils with high
    infiltration rates
  • Bound P is unavailable to plants
  • Primarily pollutes water sources with soil
    erosion
  • Available P (Labile)
  • P that is not fixed or has been released from
    bound P
  • Forms
  • Orthophosphate (HPO4, H2PO4)
  • Usually present in very low amounts
  • Dependent on

2
  • Conversion of bound P to soil available P is a
    slow process
  • Most soil tests measure available P, not total P
  • Available P is water soluble
  • May move with subsurface water flow to surface or
    subsurface water resources
  • 60 90 of the P in animal manure is in an
    inorganic available form
  • Organic P
  • Bound
  • P that is immobilized by microbial conversion of
    organic P into more resistant and stable forms of
    organic P
  • Increases with increasing CarbonPhosphorus
    ratios
  • Greatest at CP ratios gt 3001
  • Transported with soil erosion to water sources
  • Available
  • P in undecomposed plant residues and microbes
  • Must be converted to inorganic P by microbial
    mineralization before being used by plants
  • Available organic P is often water soluble
  • Sources of dissolved organic P
  • Decaying plant material
  • Manure
  • Transported with run-off or subsurface water

3
FORMS OF PHOSPHORUS IN SOIL
4
P FERTILITY
  • Discussed as P2O5
  • Calculated by multiplying P by 2.29

5
P TRANSPORT IN THE ENVIRONMENT
  • Forms
  • Sediment P
  • Includes
  • Fixed inorganic
  • Bound organic
  • Transported with sediment associated with soil
    erosion
  • Primary form lost from cultivated land or from
    stream bank erosion in pastures
  • Slowly supplies P for algae growth in water
    sources
  • Dissolved P
  • Includes
  • Available inorganic P
  • Available organic P
  • Amount increases with increasing P content of
    soil
  • Transport by
  • Surface run-off
  • Subsurface flow and tile
  • Primary form of P in run-off from land covered
    with vegetation
  • Immediately available for algae growth

6
P TRANSPORT IN THE ENVIRONMENT
7
EFFECTS OF P ON ENVIRONMENTAL QUALITY
  • Eutrophication of surface water sources
  • Primary cause of eutrophication of fresh water
    sources
  • Algae in fresh water sources can use atmospheric
    N2 as N sources
  • P limits algae growth
  • Recently identified as the major cause of the
    hypoxic (dead) zone in the Gulf of Mexico
  • Effects
  • Excessive growth of undesirable algae and plants
  • Results in O2 shortage as algae and plants die
    and decay
  • May result in blooms of cyanobacteria and harmful
    algae like Pfiesteria piscida.
  • Results
  • Summer fish kills
  • Taste, odor and treatment problems in water
  • Increased water turbidity
  • Decreased recreational use
  • P levels
  • Eutrophication
    .02 mg/l
  • Plant growth .2
    - .3 mg/l
  • Water quality standards
  • Streams entering lakes
    .05 mg/l (50 ppb)

8
P CONCENTRATION IN IOWA LAKES (2001)
9
CHANGE IN THE CONCENTRATION OF P IN MAN-MADE
LAKES IN IOWA
10
LIVESTOCK AND LOADING OF P IN THE ENVIRONMENT
  • Concentration of livestock production
  • 31 of farms in US have inadequate land to apply
    P from the manure produced
  • Manure from these farms represents 70 of the
    excess manure P produced
  • 5 of the counties have inadequate land to apply
    P from the manure produced
  • Manure from these counties represents 23 of the
    excess manure P

11
  • The low NP ratio of manure relative to crop
    needs
  • Crop NP2O5 needed Livestock NP2O5
    excreted NP2O5 available
  • Corn grain 2.5 Swine (G-F)
    1.15 .88 (Slurry)
  • Soybeans 4.26 Beef feedlot
    1.41 .75 (Scraped)
  • Alfalfa 4.5 Lactating dairy
    cow 2.45 .88 (Slurry)
  • Bromegrass 3.88 Layer
    1.15 .88 (Slurry)
  • Corn silage 1.95 Turkey
    1.17 .75 (Litter)


  • w/ incorporation
  • Results in excess P accumulation in soil if N is
    applied at the agronomic rate
  • Problem is enhanced by N volatilization

12
  • Low P retention

  • retained
  • Growing cattle
    21
  • Growing swine
    27
  • Poultry
    21
  • Grazing cattle
  • Little P removed by grazing cattle
  • Most P is recycled to the soil
  • Pastures generally are not good places to
    repeatedly fertilize with swine and poultry
    manure unless periodically baled
  • Stream bank erosion
  • Poorly managed grazing may remove vegetation from
    stream banks allowing soil erosion
  • With increasing soil erosion, P pollution of
    streams will occur

13
FUNCTIONS OF P IN LIVESTOCK
  • Bone structure
  • 80 of the bodys P
  • Bound to calcium as hydroxyapatite crystals
  • Ca10 x(PO4)6(OH)2(H3O)2x
  • CaP ratio 21
  • Serves as a reserve source for Ca and P for other
    functions
  • Energy metabolism
  • Adenosine triphosphate (ATP)
  • Creatinine phosphate
  • Genetic structure
  • Nucleic acids
  • Cell membranes and organelles
  • Phospholipids
  • Phosphoproteins
  • Acid-base balance
  • Microbial growth and digestion in the rumen of
    ruminant animals

14
P DEFICIENCY SYMPTOMS
  • Bone abnormalities
  • Weak, bent, easily broken
  • In young animals, rickets
  • In adult animals, osteomalacia
  • Loss of appetite or depraved appetite
  • Animals eat unusual materials like pebbles,
    metals etc.
  • Behavior does not represent a sense for P in
    feeds
  • Unthrifty appearance and loss of growth
  • Reduced milk production
  • In swine, paralysis of the hind limbs
  • In cattle, reduced fertility
  • Questionable concern
  • Only occurs when cattle are fed very low P levels
    (lt .2P) for long periods of time
  • May be the result of impaired feed digestion by
    not meeting the microbial needs

15
P IN FEEDS
  • P concentration in feeds
  • P concentration in most feeds except mature
    forages is moderate to high.
  • Livestock species Total P reqt. Feed
    class Feed P, DM
  • Dairy cow
  • Lactating .40
    Energy conc Corn .30
  • Dry .25
    Oats
    .40
  • Beef
    Cottonseed
    .60
  • Finishing steer .24
    Protein conc Soybean meal .71
  • Lactating cow .22
    Meat and bone 4.73
  • Dry cow .12
    Grain Wheat mids
    1.02
  • Swine
    processing Distillers grains
    .83
  • Growing-finishing .4 - .6
    byproducts Corn gluten feed1.00
  • Sow .6
    Forages Corn silage
    .28
  • Poultry
    Alfalfa hay
    .31
  • Layers .4
    Grass hay
    .30
  • Broilers .4
    Grass pasture
    .40
  • Turkeys .6
    Corn stalks
    .09

16
  • Availability of P in feeds
  • 60 75 of P in grains, grain by-products, and
    oilseed meals is bound to form phytate
  • Phytate-phosphorus is unavailable to monogastric
    animals
  • Phytate-phosphorus is degraded by the enzyme,
    phytase, produced by the rumen bacteria in
    ruminant animals

17
  • P availability

  • Swine and poultry Cattle

  • ( available)
  • Corn and corn byproducts 15
    70
  • Wheat
    50 70
  • Soybean meal
    25 70
  • Meat and bone meal
    67 -
  • Forages
    - 64
  • Dicalcium phosphate
    100 70
  • Defluorinated phosphate
    95 70
  • Must compensate for the low availability of
    phosphorus from plant sources in monogastrics by
    supplementing mineral sources
  • Results in increase P excretion

18
P DIGESTION AND METABOLISM IN NONRUMINANTS
  • Small intestine
  • Phytate-P
  • (60-75 of plant P)

  • Excess Ca or high pH
    Feces
  • Inorganic P
  • Passive
    Active

  • absorption transport

  • Circulating P
    1,25(OH)2vitamin D


  • kidney
  • Bone

    (Low blood Ca or P)
  • Soft tissue
    25 (OH) vitamin
    D

  • Excess (Circulating
    in blood)


  • Liver

  • Kidney Vitamin D

  • (Diet or
    sunlight)


19
  • Factors affecting P absorption from the gut
  • Phytate
  • High phytate reduces P absorption
  • CaP ratio
  • CaP should be between 11 to 1.251
  • Intestinal pH
  • High intestinal pH reduces P absorption
  • Vitamin D
  • Vitamin D deficiency reduces P absorption

20
STRATEGIES TO LIMIT P LOADING OF THE ENVIRONMENT
BY NONRUMINANT ANIMALS
  • Increase availability of dietary P
  • Degrade phytate-P
  • Feed microbial phytase
  • Enzyme produced by fungus, Aspergillus sp.
  • Treatment
  • 200 to 1000 units/kg
  • 500 units 90 gm/ton
  • Effects
  • Decrease P excretion by 30 to 50
  • Increases availability of some other minerals and
    amino acids
  • Most activity occurs in stomach or gizzard
  • Optimal activity occurs at pH lt4.0
  • Effectiveness decreased if
  • Excess Ca is fed
  • Vitamin D is deficient
  • Phytase is applied before pelleting feed
  • Temperatures greater than 140 F destroys
    enzyme
  • Effectiveness improved if
  • Fed as an enzyme cocktail with phosphatase,
    protease, citric acid, and pectinase

21
  • To reduce P excretion when using phytase, rations
    must be balanced to meet the available P
    requirement
  • Phytase can reduce the amount of inorganic P
    supplemented in swine and poultry diets by .1
    unit or 25
  • Example (Swine)
    1000 head Farrow-finish

  • P in phases Manure P (lb P2O5/yr)
  • Normal diet .60,
    .55, .50, .45 13,000
  • Phytase-treated .50, .45,
    .40, .35 8,900
  • Economics of using phytase
  • Cost of phytase cost of dicalcium phosphate
    saved
  • Genetically modify crops to contain phytase
  • Successful in corn and soybeans
  • Limitations
  • Susceptible to destruction from heating during
    processing
  • Difficulty in separating genetically modified
    crops from other varieties

22
  • Genetically modify swine to have phytase in
    saliva
  • Gene from Escherichia coli has been inserted into
    swine
  • Phytase secreted in saliva of GM pigs
  • Stable at pH 2.5
  • Resistant to pepsin
  • Decreases P excretion by 60
  • Limitations
  • Variable response
  • Regulator and consumer concerns with GMO foods
  • Possible allergenicity to E. Coli proteins
    that are resistant to digestion in the stomach
  • Genetically modify crops to decrease phytate
    content
  • Reduces phytate content of corn and soybean meal

  • Phytate-P, of total P

  • Normal Low phytate
  • Corn
    75 35
  • Soybeans
    70 24
  • Increases P bioavailability

  • P bioavailability,

  • Normal Low phytate

23
  • Limitations of low phytate crops
  • Low germination rates
  • 4 23 reduction in seed weight
  • Difficulties in separating grain hybrids
  • Addition of vitamin D metabolites
  • 1,25(OH)2 vitamin D increases P transport across
    intestinal wall
  • Has additive effects with phytase
  • Feeding 1,25 (OH)2 vitamin D and phytase can
    replace .2 units or 50 of the inorganic P added
    to chick diets
  • Limitation
  • Excess vitamin D may be toxic
  • Addition of probiotics
  • Probiotics are microbial cultures dosed or fed to
    establish a population of favorable bacteria
  • Feeding Lactobaccillus-based cultures increase P
    retention by 22 in chickens

24
  • Balance diets closer to the P requirements
  • Limit safety margins
  • Swine industry commonly feeds P at 120 155 of
    the NRC requirements
  • Swine diet
    Manure P, lb/pig
  • .5 P
    2.5
  • .6 P
    3.5
  • Current actual requirements for poultry are 40
    less than recommended by NRC
  • Phase feeding
  • P requirement (as a of diet) decreases as
    animals grow
  • Increasing number of phases to 4 or 5 or more
    will reduce P excretion by 10
  • Limitation
  • Feeding and handling more diets
  • Separate sex feeding
  • P requirements for males gt P requirements for
    females
  • Accurate real-time feed composition
  • Book values are inaccurate
  • Wet lab analysis of P and phytate-P is slow and
    expensive
  • Near infrared reflectance spectroscopy (NIRS)
    technology may help

25
  • Minimize feed variability
  • Natural variability
  • Processing
  • Pelleting may reduce P bioavailability
  • Proper weighing and mixing
  • Minimize feed waste
  • Each 1 increase in feed waste .04 lb/pig
    increase of P in manure
  • Total potential for using available tools
    (phytase, low phytate corn, phase feeding,
    vitamin D)
  • Decreases P excretion by 40 to 60 in poultry
  • Decreases P excretion by 50 to 60 in swine

26
P DIGESTION AND METABOLISM IN RUMINANTS
  • Rumen
    Small intestine
  • Phytate-P
  • Inorganic-P Undegraded
  • Degraded
    Very little
    Feces


  • (95-98 of
  • Inorganic P

    excreted P)


  • Microbes
    Passive Active

  • absorption transport

  • Circulating P
    1,25(OH)2vitamin D


  • kidney (Low Ca
  • Recycled to digestive Bone

    or P)
  • tract via saliva

    25(OH)vitamin D
  • (Supplies P to rumen Soft
    tissue
  • microbes if diet is deficient

    liver
  • 80 of total P excreted)
    Excess


27
FACTORS AFFECTING P ABSORPTION IN RUMINANTS
  • Amounts of P consumed
  • High P intake reduces P absorption
  • CaP ratio
  • Optimum is 21
  • Excess amounts of Al, Fe, Mg, Mn, K, and fat
  • Reduce P absorption by producing indigestible
    complexes
  • Intestinal pH
  • Lower intestinal pH increases P absorption
  • P source

  • P availability,
  • Forages
    64
  • Energy and protein concentrates 70
  • Mineral supplements
    70
  • Forage P concentration
  • High soil P increases forage P concentration
  • High forage P concentration reduces P absorption
  • Forage maturity
  • Forage P concentration decreases with maturity
  • Forage fiber digestion decreases with maturity
    decreasing P absorption

28
STRATEGIES TO REDUCE PHOSPHORUS LOADING OF THE
ENVIRONMENT BY RUMINANTS
  • Do not overfeed P
  • Dairy

  • P in DM Manure P, lb/cow/lactation
  • Industry average
    .52 64.9
  • NRC requirement
    .32-.42 42.2
  • Adequate
    .35 34.8
  • Dry cow
    .25 -
  • Reasons for excess feeding
  • Belief that P supplementation will improve
    reproductive performance
  • Studies show no improvement in reproduction above
    .25 P
  • Aggressive marketing of P supplements
  • Beef feedlot
  • Steer (600-1200 lb)
    Diet P, of DM
  • NRC requirement
    0.20 0.30
  • Adequate in experiments
    0.14 0.16
  • Reasons for excess feeding
  • NRC requirement based on 1950 dairy cow data
  • High grain diets contain 0.3 and require no
    supplement

29
  • Beef cows
  • Common P,
    Physiological P reqt,
  • Season feed of DM
    state of DM
  • Spring-summer Pasture 0.37-0.44
    Lactating 0.22
  • Fall Corn stalks 0.09
    Early gestation 0.12
  • Winter Grass-legume hay 0.26-0.34 Late
    gestation 0.16
  • Implications
  • Phosphorus only need to be supplemented when
    grazing or fed very mature grass forages or crop
    residues
  • However, most producers supplement P year-round
  • Reasons for excess P feeding
  • Belief that continuous P supplementation is
    needed for reproductive performance
  • Ease of supplementing minerals free choice to
    provide safety margin
  • Results of feeding excess P
  • Increases amount of P excreted
  • Increases the solubility of the P excreted
  • Amount of P lost in run-off increased 4 times if
    dairy cow diets contain .5P vs. .4P

30
  • Difficulty in lowering P in ruminant diets
  • High concentration of P in grains and grain
    by-products
  • Grains contain adequate P (0.3) to meet
    requirements of feedlot cattle without supplement
  • Grain by-products
  • Contain high concentrations of P

  • P, DM
  • Wheat mids
    1.02
  • Distillers grains
    0.90
  • Corn gluten feed
    1.00
  • A large increase in ethanol plants will increase
    the amounts of distillers grains available
  • 75 of distillers grains are fed to beef
    cattle
  • A diet containing 40 distillers grains will
    contain 0.55 P
  • If by-products are fed, more land will be needed
    to apply at an agronomic rate
  • Strategic use of P reserves in cows
  • Dairy cows may safely mobilize 500 to 1000 g P
    from bone in early lactation
  • Could also be used for intervals in beef cows
  • Ruminants effective at recycling P
  • Mobilized P must be replaced at different times
    of the year

31
  • Feeding ionophores
  • Chemical feed additives that affect mineral
    transport across membrane
  • Common ionophores
  • Monensin (Rumensin)
  • Lasalocid (Bovatec)
  • Reduces P excretion
  • Monitor feed status
  • Analyse feeds
  • Books values are inadequate
  • Condition score cows
  • Measure of cow fatness
  • Scale (1 9)
  • 1 very thin
  • 5 desired
  • 9 very fat
  • If cows lt condition score 5, analyse diet for
    energy, protein and minerals
  • P solubility in feces
  • No soluble P means inadequate P in diet

32
  • Feed high quality forages
  • Immature, high quality forages contain more P
    that is more digestible than mature forages
  • Avoid excess calcium in diet
  • Use improved grazing management practices
  • Properly managed rotational grazing should limit
    P loss in soil erosion from both upland and
    riparian areas
  • Bale some pasture forage to remove P and to keep
    the remainder of the pasture immature
  • Only fertilize pastures with P based on soil
    analyses
  • Strategic supplementation to grazing cattle
  • Only supplement if grazing mature forage on low P
    soil
  • Limit use of free choice mineral
  • In future, may be able to feed grains that are
    genetically modified for a lower P content.

33
POTENTIAL TO DECREASE P EXCRETION BY RUMINANTS
  • Dairy
  • 20 decrease in dietary P
  • 25 30 decrease in manure P
  • 50 decrease in P run-off from land
  • Beef
  • 33 decrease in dietary P
  • 40 decrease in manure P (5.1 lb P/steer)

34
MANURE HANDLING AND STORAGE TO MINIMIZE P LOADING
OF THE ENVIRONMENT
  • Goals
  • Maintain NP ratio
  • Use strategies to minimize N loss
  • Minimize P loss
  • Minimize precipitation run-off
  • P loss from lots and storage facilities is low if
    run-off is minimized
  • Strategies
  • Catch run-off from lots and storage areas
  • Divert clean water from lots and storage areas
  • Minimize the solubility of P in manure
  • Gravity settling and mechanical separators will
    remove 15 to 25 of the P in liquid manure
  • P decreases in the liquid fraction of manure in
    lagoons and increases in the sludge
  • 65 of the P in manure will be in the sludge
  • Addition of aluminum sulfate, magnesium chloride,
    ferric chloride, and some Ca salts will
    precipitate P from liquid manure in the solids
    fraction
  • Enhance manure transport from farm
  • Compost

35
LAND APPLICATION STRATEGIES TO LIMIT P LOADING OF
THE ENVIRONMENT
  • Goals
  • Apply manure to meet crop P needs
  • Apply manure to minimize risk of P transport to
    water sources
  • Considerations
  • Should manure be applied?
  • Application rate?

36
METHODS TO DETERMINE WHETHER MANURE P SHOULD BE
APPLIED
  • Soil tests
  • Measures available P relative to plant response
  • If soil test is high or very high
  • Manure should not be applied or applied only at
    the agronomic rate depending on transport risk
    determined by a P index
  • P index
  • A measure of the risk of P transport to surface
    water sources
  • Required for every field which manure applied on
    it from a CAFO in Iowa
  • Integrates soil, landscape, and management
    factors that influence P transport to surface
    water sources
  • Identifies causes of P delivery and provides
    options to decrease P transport

37
  • Considerations for the Iowa P index
  • Erosion component
  • Gross erosion (Slope, soil type, cover)
  • Sediment trapping (Conservation practices)
  • Sediment delivery (Amounts of sediment and
    distance from stream)
  • Buffers
  • Soil P test erosion (Sediment-bound P loss)
  • Run-off component
  • Run-off (Soil drainage)
  • Precipitation (Annual)
  • Soil P test run-off (Soluble P loss in run-off)
  • P application (Total P fertilization)
  • Subsurface drainage component
  • Precipitation (Annual
  • Flow factor (Presence of subsurface strata)
  • Soil P test infiltration (Soluble P infiltrating
    soil in drainage

38
  • Ranks risk of application site from 0 to 15
  • Interpretation
  • Very low (0 1)
  • Effects of P losses from a field will be small
  • Low (1 2)
  • Current soil conservation and P management
    practices do not pose threat
  • Medium (2 6)
  • P delivery potential is low, but improved soil
    conservation and P management practices should be
    considered
  • High (6 - 15)
  • Impacts of P on surface water is high. Improved
    soil conservation and P management practices to
    reduce P transport are required.
  • Very high (gt 15)
  • Impacts of P on surface water is extreme.
    Improved soil conservation and P management
    practices to reduce P transport are required.
  • P management plan that may include
    discontinuation of P application must be
    implemented.

39
CALCULATION OF MANURE APPLICATION RATE BASED ON
THE AGRONOMIC RATE FOR P
  • Manure P production or concentration
  • Manure_________
    P2O5, lb/lb animal wt/yr
  • Swine Growing-finishing
    0.13
  • Sows litter
    0.12
  • Sows (gestation)
    0.05
  • Gilts
    0.066
  • Beef 450 750 lb
    0.083
  • Finishing
    0.078
  • Beef cows
    0.10
  • Dairy 50 lb milk/d
    0.087
  • 70 lb milk/d
    0.096
  • 100 lb milk/d
    0.11
  • Dry
    0.074
  • Heifers
    0.033
  • Poultry Layers
    0.26
  • Pullets
    0.20
  • Broilers
    0.28
  • Turkey
    0.23

40
  • Availability of manure P to plants
  • Affected by
  • P retained during storage
  • Type Proportion of excreted P
    available to apply
  • Feedlot
    .95
  • Manure under roof
    1.0
  • Bedded swine
    1.0
  • Liquid/slurry
    1.0
  • Pit beneath slats
    1.0
  • Compost
    .95
  • Anerobic lagoon
    .35 (Remainder in sludge)
  • P solubility in manure
  • Greater in lagoon manure than solid or slurry
  • Application method
  • P retention greater from injection than surface
    application
  • Soil
    incorporation Broadcast Irrigation
  • -- of
    manure P available after application---
  • Scraped manure 80
    70 -
  • Poultry house litter 80
    70 -

41
  • P uptake by crop
  • - Based on realistic yield expectations

  • P2O5 uptake and harvest
  • Corn
  • Grain
    0.36 lb/bu
  • Stover
    9.16 lb/ton
  • Soybeans
    0.88 lb/bu
  • Corn silage
    4.01 lb/ton
  • Alfalfa hay
    10.08 lb/ton
  • Alfalfa silage
    7.56 lb/ton
  • Bromegrass hay
    9.62 lb/ton

42
  • Calculation of manure application based on P
    needs
  • Equations
  • P2O5 needed, lb/ac RYE x P2O5 uptake and
    harvest
  • Manure application, gal/ac P2O5 needed,
    lb/ac/(Manure P2O5 conc x

  • P
    availability)
  • Example
  • Field has a RYE for corn of 180 bu/acre
  • Liquid manure containing 3.5 lb P2O5/1000 gal by
    analysis is applied with irrigation
  • P2O5 needed, lb/ac 180 bu/ac x 0.36 lb P2O5/bu
    64.8 lb/ac
  • Manure application, gal/ac 64.8 lb/ac /(3.5 lb
    P2O5/1000 gal .80)

  • 23143 gal/ac
  • Manure application rate for P will be 25 to 50
    of that for N
  • Manure application should usually be based on the
    P rate
  • New EPA regulations will allow a single
    application of manure to meet multiple year needs
    for P on fields with
  • a low potential for run-off
  • application does not exceed the N-based rate
    during the first year


43
  • Effects of using distillers grains for feeding
    cattle on land base for manure application
  • Assumptions
  • 2500 head feedlot with 2 groups per year
  • Average weight, 975 lb
  • lb P2O5/lb animal weight/year .078 (Corn based
    diet) or .156 (Distillers grains diet)
  • Broadcast application 70 P availability
  • ½ cropground available for land application
  • Corn production, 200 bu/ac
  • Corn P2O5 uptake .36 lb/bu

Corn, 1.9 miles
Distillers grains 2.7 miles
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