This is an updated version of "Nutrient dynamics"

1. The ecology of nutrients
Key terms
Cycles
Flows
Stocks

2. Internal cycling is most important in natural ecosystems
Nutrient inputs • Chemical weathering of rocks
• Biological fixation of atmospheric N
• Deposition of elements from atmosphere
Ecosystem
• Transfer of nutrients
Between plants and soil
Between organic and inorganic forms
Internal cycling • Changes in ionic forms
• Biological uptake
• Interactions with mineral surfaces
• Leaching
• Gaseous emissions
• Wind and water erosion
• Fire
• Harvest
Nutrient losses

3. Nutrient budget for Hubbard Brook Forest
Source of plant nutrient (% of total)
Nutrient Deposition/fixation Weathering Recycling
Nitrogen 7 0 93
Phosphorus 1 < 10 > 89
Potassium 2 10 88
Calcium 4 31 65
Data from (Whittaker et al. 1979)

4. Elemental concentrations in soil vs. earth’s crust
0.001% 0.01% 0.1% 1% 10% 100%
crust
soil
Adapted from Essington (2003)

5. Which forms of nutrients are bioavailable?
All participate in biogeochemical cycles
“active” OM
but rates of “flow” vary widely.
humus
exchangeable
ions ions in
solution
weatherable
minerals

6. Nutrient ecology in agroecosystems
What’s
missing?

7. Unfortunately
environmental losses are
sometimes larger than
How big should this arrow be?
nutrient removal in harvest
Dissipation into the surrounding
environment via erosion, leaching,
volatilization…

8. N budget for Rothamsted wheat experiment
From the To the
atmosphere atmosphere Crop
50 10-50 Fertilizer uptake
200 200
SOM - N
4000 160 80
NO3- + NH4+
Microbial
Biomass N
#s = kg/ha (0.89*kg/ha = lbs/ac) Loss by
leaching
20-100
The total N stocks in soil normally greatly
exceed annual flows

9. Without fertilization, N is often a limiting nutrient
(i.e., N mineralization is often much slower
than potential crop uptake)
Peak uptake
~ 3 lbs of N/ac/day
Potential
N uptake by
wheat pasture
Mineralized soil N
Jenkinson

10. "The most effective management
strategy will be one that recognizes the
pattern of nitrogen demand by the
crop and the nitrogen release
characteristics of all important
nitrogen sources to provide
adequate, but not excessive
levels of soil nitrogen
throughout the growing
season." Peak uptake = 5-10 lbs
(Doerge, 1991)
of N/ac/day

11. Timing of availability has a big impact on uptake vs. losses
(Dinnes et al., 2001)

12. Weathering, deposition and recycling often supply
trace elements at rates which are not limiting
Total stocks in prairie soil A horizons
low high average
element (mg/kg) (mg/kg) (mg/kg) lbs/ac- pl*
B 11 92 45 90
Cu 65 140 24 48
Mn 100 3907 480 960
Mo 0.4 6.9 2 4
Zn 20 770 65 130
* assumes 1 acre- plow layer = 2 million lbs w/ average conc.

13. Acre-plow layer stocks of trace elements
expressed as years of removal by corn, soybeans and alfalfa
lbs removed lbs removed lbs removed
Total by 150 bu by 60 bu by 6 ton
element lbs/ ac-pl corn yrs soybeans yrs alfalfa yrs
B 90 0.16 563 0.1 900 0.3 300
Cu 48 0.1 480 0.1 480 0.06 800
Mn 960 0.3 3200 0.6 1600 0.6 1600
Mo 4 0.008 500 0.01 400 0.02 200
Zn 130 0.27 481 0.2 650 0.24 542

14. Average annual deposition of
Saharan dust in the Amazon basin
exceeds 10 million tons or
> 150 lbs/ac
Dust leaving
Swap et al. (1992) concluded that the Sahara
the productivity of the Amazon rain
forest is dependent upon trace
elements contained in dust
originating in the Sahara.
“As soils develop in humid environments,
rock-derived elements are gradually lost,
and under constant conditions it seems that
ecosystems should reach a state of profound
and irreversible nutrient depletion. We show
here that inputs of elements from the
atmosphere can sustain the productivity of
Hawaiian rainforests on highly weathered
soils. Cations are supplied in marine
aerosols and phosphorus is deposited in
dust from central Asia, which is over
mg dust/m2/yr 6,000km away.” ( Chadwick et al, 1999)

15. Total Ammonia Emissions by County (1995)
Where is all this ammonia coming from ??

17. Deposition of biological available N
1990s
50 lbs N/acre

19. N inputs to IL soils
(alfalfa and other forage legumes)
Mg = 1 x 106 g = 1000 kg = 1 metric ton
1 metric ton = 2204.6 pounds
1 metric ton = 1.1023 US tons
M.David

20. N outputs from IL soils
M.David

21. Crop specific harvests of N
M.David

22. Net N inputs
Net input = Gross inputs - outputs
1993
M.David

23. Mining Prairie N
Anthropogenic N inputs
M.David

24. -523,000 tons of N/yr !
Units are 1000 metric tons N / yr M.David

25. +1 ton of N/yr !
Units are 1000 metric tons N / yr M.David

26. Why does so much N get into Illinois’ rivers ???

27. Approximately 40% of IL fields
have artificial drainage

28. Yield maps have
made drainage
problems
more obvious
↓
more artificial
drainage
↓
more nutrient
pollution

29. Photo: MARGARET BOURKE-WHITE
So where do the nutrients
in IL grain end up?
Aerial view of Cargill grain
elevator w. barges lined up on the
bank of the Chicago River in 1951

30. Redistribution of nutrients in the Mid-Atlantic region
excess
Counties with
large excesses
have the most
livestock

31. Surplus P and N
State P N
--Million of lbs in excess--
DE 7.3 14.6
Why don’t we
MD 10.4 19.6 send the
NJ 0.9 1.8 surplus
nutrients
NY 3.3 4.2 back?
PA 23.7 33.8
VA 24.8 42.3
(Source: USDA, 2001)

33. Keith Bowers of Multiform
Harvest in Seattle has
developed a system to
remove phosphates from
swine and dairy manure. It
involves changing the
chemistry of the liquid manure
to form struvite, a phosphate
compound that is precipitated
out of the slurry. Struvite,
magnesium ammonium
phosphate, is sometimes
deposited naturally as scale
on wastewater pipes and in
the human body as kidney
stones. It’s in demand as a
slow release fertilizer and
magnesium source.

34. Nutrient depletion in Africa
http://www.fao.org/docrep/006/y5066e/y5066e02.jpg

35. Nutrient budgets on organic farms
a review of published data
N
Most organic farms in developed countries do not
have nutrient deficits even though they don’t use
conventional fertilizers.
P
K
http://www.organic.aber.ac.uk/library/Nutrient%20budgets%20on%20organic%20farms.pdf

37. Daily inputs and outputs of dry matter, P and N
http://edis.ifas.ufl.edu/DS096

38. N P K
20% maintenance 13% maintenance 12% maintenance
20% 27%
13%
60% 60% 75%
urine feces
N 50% 50%
P 10% 90%
K 90% 10%
http://extension.oregonstate.edu/catalog/html/em/em8586/

39. Nitrogen budget for a dairy in Florida (lbs of N/acre)
http://edis.ifas.ufl.edu/DS096

40. Annual manure production and nutrient value for a 100 cow dairy
Manure constituent Lbs/year/100 cows Probable $ value
Raw manure (feces + urine) 5,045,000
Water in fresh manure 4,458,990
Total solids 586,000
Total N (lb) 23,400 $3,5101
Total P (lb) 4,800 $2,8801
Total K (lb) 15,100 $2,2651
TOTAL VALUE of N, P, and K $8,655
1Based on assumed values of $.30/lb N, $.60/lb P, and $.15/lb K; N recovered was 50%
of excretion, thus, 50% volatilized.

42. Concentrated Animal Feeding Operations (CAFOs) in IL
There are ~ 500 “large" CAFOs and ~ 2,700 "Medium" CAFOs in IL.
These CAFOs are required to:
Apply for a National Pollutant Discharge Elimination System (NPDES)
Permit
Submit an Annual Report
Develop and implement a manure and wastewater handling plan
(Nutrient Management Plan).

43. In Illinois, there are actually 3 different types of manure management plans
that livestock facilities may be required to have (NRCS, IL DOA, and IL EPA).
U of I Extension has worked with NRCS, IL DOA, IL EPA to develop one
workbook of forms and instructions that when completed by a producer, will
comply with the requirements of all 3 agencies.

45. Nutrient
Balance
Problem

46. Overview of Hislop farm
1500 sow farrow-to-wean operation
32,000 piglets (with an average weight of 10 lbs)
are sold off the farm each.
1500 acres of crops - 750 acres of corn - 50 %
sold off the farm, 750 acres of soybeans – 100%
sold off the farm.
~ 1300 tons of feed purchased each year.
Manure from the sow operation is applied
exclusively to corn ground. Fertilizer is also
applied to corn ground.

47. Nutrient inputs
Purchased feed
Purchased fertilizer
Biological N fixation

48. Nutrient inputs
How many tons of N, P and K are
in 1300 tons of purchased feed ?
Feed analysis?
N  2% of 1300 tons = ? of N
P  0.8% of 1300 tons = ? tons of P
K  0.4% of 1300 tons = ? tons of K

49. Nutrient inputs
How many tons of N, P and K
are in the purchased fertilizer ?
Fertilizer program? Acres? Fertilizer receipts?
N  750 acres*100 lbs/acre*1 ton/2000 lbs = ? tons N
P  750 acres*25 lbs/acre*1 ton/2000 lbs = ? tons P
K  750 acres*50 lbs/acre*1 ton/2000 lbs = ? tons K

50. Nutrient inputs
Biological N fixation
~ 3 lbs of N fixation per bushel of beans
750 acres of soybeans*50 bu/acre*3 lbs of N fixation/bu

51. Total nutrient inputs
∑ Feed
Fertilizer
Biological N fixation

52. Nutrient outputs
∑ Marketed grain
Marketed piglets
Environmental losses

53. Nutrient cycling on-farm
Nutrients in manure
Nutrients in crop residues
Nutrients in 50% of corn grain

54. You are welcome to analyze
your family’s farm or any
other farm with which you
are affiliated.