Mass Balance

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Mass Balance

• Use Phosphorus
• (Other nonvolatile elements are similar)

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Concept of Mass Balance

• Elements are neither created nor destroyed.
• Elements which enter a system either exit the
  system or are stored.
• The composition of animal productsmeat, eggs,
  milk, etc. is not significantly affected by what
  the animal eats. (Diet can control flavor, odor,
  etc.)

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Some Exceptions

• Bones are influenced by mineral intake
• Calcium, Phosphorus, for example.

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Farm Produced Feed
Gases
Ration
Manure
Mineral Supplements
Milk
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How much P was in the manure?

• We know how much P was in the supplement
• We know how much P was in the feed
• We know how much milk was produced
• The P content of milk is constant0.09
• There is no gaseous phase in P
• Hencewe know how much P is in manure

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Phosphorus in Manure

• P manure P feed P milk
• P feed P farm feed P supplement
• P milk Total milk x 0.009

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Example

• A mature dairy cow consumes 55 lb of dry matter
  per day. It is 0.42 P.
• She produces 70 lb of milk per day.
• P manure 55 x 0.0042 70 x 0.0009
• P manure 0.17 lb P

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Tradeoffs in Nutrient Balance

• Some phosphorus is exported
• the animals either gain weight which is some
  fraction P and are marketed
• Or they produce a product which is some fraction
  P and it is marketed
• If more P is imported in supplement and/or
  fertilizer, there is net import of P.

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Enterprise Level BalanceDairy

• Phosphorus
• Dr. Beede exampledaily intake of 100 g
• 32 g goes to milk
• 68 g goes to manure (assume no growth)
• 68 g/d x 365 d x (454 g/lb) 54.67 lb (P)
• 124.3 lb (P2O5)

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Differences with other Elements

• Carbon
• Some is respired as CO2
• Nitrogen
• Can evolve as ammonia, N2, or NOx
• Is stored in protein
• Some other elements have a gaseous phase

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Enterprise Level BalanceDairy

• Carbon
• Where does it go? (Beede, p. 27)
• Heat 40
• Manure 35
• Milk 20
• Methane 5

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Carbon, cont

• Daily DM intakeabout 50/d
• Annual intake18,000
• Assume all corn silage
• Yield at 24 T/A
• You need
• (18,000)/(24 x 2,000) 0.375 A
• By the waythats about 300 lb of methane!

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There is a Difference Among Animals

• The biggest difference is in digestive systems
• Ruminantscan process fiber
• Non-ruminantscant
• Because of differences in systems
• There is a difference in conversion of feeds
• There is a difference in ability to use natural P

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Ability to Convert Feed

• Feed ConversionFeed to gain ratio (FGR)
• Numbers to memorize
• 1 Fish
• 2 Poultry
• 3 Swine
• 4 Cattle

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Ruminants and Non-ruminants

• Ever had the joy of releasing gas produced in the
  rumen of a cow?
• Chewing is the first step in processing the
  feed. This is no small task as the cow makes
  40,000 to 60,000 jaw movements per day as it
  chews and rechews regurgitated feed. Then it
  passes down a 2 1/2 to 3 foot tube called the
  esophagus into a large fermentation vat of 40 to
  50 gallon capacity. Here digestion of feed goes
  on by 500,000 billion bacteria and 50 billion
  protozoa living and multiplying there. These
  small organisms have several unique
  characteristics which allow the cow to thrive in
  situations which would be impossible for other
  animals to live. They digest fiber found in hay,
  silage, and pasture for energy, make protein from
  nitrogen, and synthesize B vitamins for their
  host, the cow.

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Ability to Utilize Natural P

• P naturally occurs in feed
• Some of it is in phytic acid form, some isnt
• Ruminants have an enzyme (phytase) that makes the
  non-available stuff available
• Phytase is available to add to feed, and it will
  make more P available. Not all phytase is equal.

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Dairy P continued

• Assume 24 T/A silage production
• Uptake (MWPS-18, p 10.3)62.5 lb/A
• 124.3 lb/ 62.5 lb/A 2 A per cow
• Its obvious that there is great savings for
  reducing P feeding.
• Dr. Beede example would imply that we could
  reduce P feeding 30 IF we could improve
  availability

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Dairy P continued

• Reduce P intake by 30. Now feed 70 g/d.
• Milk is still 32 g/d
• Manure is now 38 g/d
• Required land is now
• 38 g/d x 365 d / 454 g/lb 30.55 lb P
• 69.4 lb P2O5
• 69.4 lb/62.5 lb/A 1.11 A per cow.

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Enterprise level balanceSwine

• Lets assume a relatively simple operation
  growing feed (corn and soybeans), feeding
  finishers, and applying manure.

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Odor
100 Pigs
Water
Products
Waste
Feed
Chemicals
Fertilizer
Rain
Nutrients
Ration
Land Application
Corn
Soil 10 A
Supplement
Soybeans
Runoff
Drainage
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P based manure application

• Following NRC P recommendations
• 150 hog needs 12.42 g P daily (5.03 g available)
• average over 50 to 250 lbs is 11.56 g
• Assume a 25 soybean meal, 75 corn ration
• Assume 46 bu beans and 148 bu corn

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Feed and Nutrients per Hog

• From 50 to 250, hog will consume 510 of feed.
  
• The feed will include 2.264 lb P
• The hog will retain 1.053 lb P
• The balance--1.211 lb goes back to the land
• The crop will take up 0.432 lb
• The balance--0.779 lb requires more land
• 0.22 A soybeans OR 0.16 A corn OR 0.17A in
  proportion

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Quick Check on Area Needed
Animals per Acre Animals per Acre
Type Best Poss Likely
Finishing Hogs 15 10
Finishing Spaces 5 3.3
Farrow to Finish (per sow) 0.5
Lactating Cow w/ heifers 1.0 0.67
Lactating Cow w/o heifers 0.5 0.33
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Corn uptake N/PversusN/P of manure

• Corn Manure
• N/P 2.5 1.32 (fresh)
• 0.66 (field)
• Overall result is if we apply based on crop
  uptake of actual field N, we will overapply P
  by Corn 2.5/0.66 3.8
• Thats an excess of about 150 lb/A!

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Why 75 Corn, 25 Soybean

• My Theory
• Corn soybeans rotation
• 148 bu corn is 8288 lb corn per acre
• 46 bu soybeans is 2760 lb soybeans per acre
• Corn is 8288/(82882760) 75
• Soybeans are 2760/(82882760) 25
• The Outcome is the same for a 3-crop
  rotationcorn, soybeans, wheat, e.g.

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County Level Balance

• Look at crops as a use (removal) of nutrients
• Look at manure as a source of nutrients
• Supplement as necessary
• It tells you Michigan farmers ignore the nutrient
  value of manure

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The State of Michigan
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Whats the take-home message?

• Give credit for nutrients in manure.
• Apply additional fertilizer as needed AFTER
  giving credit.
• Put the manure where its needed, not where its
  easy to get rid of.