I shared this presentation on nutrient flows and cycles with my Soil Fertility class last week (September 2011).

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. 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. Which forms of nutrients in soil are bioavailable?
All become bioavailable (in natural ecosystems and farm
“active” OM fields) but rates of “flow” vary widely.
humus
exchangeable
ions ions in
solution
weatherable
minerals

5. Nutrient ecology in agroecosystems
What’s
missing?

6. Environmental
losses are
sometimes larger
How big is this arrow normally? than crop removal
Dissipation into the surrounding
environment via erosion, leaching,
volatilization…

7. 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 (lbs/ac= 0.89*kg/ha)
Loss by
leaching
20-100
The total N stocks in soil normally greatly
exceed annual flows

8. 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
More data from Rothamsted Jenkinson

9. "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

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

12. Point source vs. non-point source pollution

13. Average soil loss on IA farms is ~ 5 tons/ac/yr
Total lbs in % of total in
Element 5 tons of soil* 150 bu of corn
N 20 15%
P 2.6 9%
K 150 452%
Ca 92 4600%
Mg 44 550%
S 12 120%
* Average total nutrient levels for US soils
http://pubs.usgs.gov/pp/1270/pdf/PP1270_508.pdf

14. Where do eroded nutrients go?
Most are relocated to lower
landscape positions but do
*not* end up in water bodies!

15. Nutrient pollution
(Eutrophication)
Excess nutrients
promote algal blooms in
aquatic ecosystems
creating unusually high
biological oxygen
demand when the algae
dies and begins to
decompose.
Conventional wisdom:
Nitrogen is the most limiting nutrient in marine
systems.
Reality is more complex.
Phosphorus is the most limiting nutrient in freshwater
ecosystems

16. In 2002 5,549 miles (out of 15,491) of Illinois streams
did not meet IEPA water quality standards.

17. Understanding the “Dead Zone”
There are a ~ 400 recurring dead zones world wide!
Almost the
entire eastern
seaboard has
recurring dead
zones

18. “Geologic evidence shows that dead
zones were not a naturally recurring
event in the Chesapeake Bay or most
other estuarine ecosystems” says Diaz.
"Dead zones were once rare. Now
they're commonplace”.

19. Understanding Hypoxia
Layer of nutrient rich fresh Fresh water
water over salt water is less dense
than salt
water

20. What is causing the hypoxic zone in the Gulf ?

21. Primarily agriculture

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

23. Ammonia cloud over the midwest
Where is all this ammonia coming from ??

24. Animal
manure is
the primary
source

25. Sewage is a major source of P
• 47% of total P in IL rivers
Why is there so much P in sewage?
• 70% for Illinois River, 33% for others in state
Very different than N
where agriculture is the dominant source!

27. Is the Dead Zone in the Gulf increasing in size ?
Yes… but not consistently.
Yes... but there is
lots of variability!

28. The location of hypoxic zones is dynamic!
Frequency of Occurrence 1985 - 1999
Rabalais, et al.
Distance Paris to London = 490 km
28

29. GULF OF MEXICO HYPOXIA MAPPING

30. N and P levels in the Mississippi and all significant tributaries are monitored

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

33. Artificial drainage in the United States
% of land drained
~ 40% of IL cropland
has been tiled
http://www.ars.usda.gov/SP2UserFiles/Place/36251500/TheExtentofFarmDrainageintheUnitedStates.pdf

34. Optimizing N availability for crops while maintaining
water quality is a serious challenge!
Nitrogen uptake by corn
220 lbs of N / 4 million lbs of water = 0.000055
55 ppm
The EPA drinking water standard is 10 ppm NO3-N

35. Why is nutrient pollution a persistent problem if…

36. Agroecosystems are not factories!

37. http://nanc.ipni.net/articles/NANC0005-EN
Aver
Actual nutrient removal may vary by
30% or more depending on the specific
growing conditions of the crop such as
soil fertility level, yield, soil moisture,
crop vigor, and limiting nutrients
(interactions) as well as the actual crop
variety and fertilizer program. Changes
to soil fertility may differ from the
amount removed by the crop

38. IL Agronomy Handbook - maintenance rates of P2O5 and K2O

39. P Balance in IL
M. David

40. P balance for IL in 2008
606,500 tons of P2O5 removed in grain
2.23 billion bu of CORN
404,700 tons P2O5
428 million bu of BEANS
179,760 tons P2O5
74 million bu of WHEAT
22,080 tons P2O5
398,607 tons of P2O5 applied as fertilizer
Manure + Biosolids < 30,000 tons P2O5

41. High fertilizer prices in fall of 2008 = less application
P balance for McDonough County in 2009
crop P2O5/unit lbs of P2O5
corn 28576000 bu 0.38 10,858,880
soybeans 5657600 bu 0.84 4,752,384
wheat 58800 bu 0.6 35,280
misc-hay 7020 tons 15 105,300
alfalfa 26790 tons 12 321,480
8037 tons of P2O5 removed in crops
According to IDOA records, only 3250 tons of P2O5
were purchased (fall 2008/spring 2009)

42. Soil test P levels are dropping in the Corn Belt
Change between 2005 and 2010 % of samples below critical level

43. The U of I recommends a build and maintenance
approach for P and K
Critical Level

44. In contrast with P, N inputs and outputs are currently ~ balanced in IL
Units are 1000 metric tons N / yr M.David

45. Back in the sodbusting days, IL was losing over 500,000 tons of N/yr !
Units are 1000 metric tons N / yr M.David

46. Mining Prairie N
Net anthropogenic inputs
M.David

47. 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

48. N outputs from IL soils
M.David

49. 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

50. Surplus P and N
State P N
--Million of lbs in excess--
DE 7.3 14.6
MD 10.4 19.6
NJ 0.9 1.8
NY 3.3 4.2
PA 23.7 33.8
VA 24.8 42.3
(Source: USDA, 2001)

51. Redistribution of nutrients in the Mid-Atlantic region
excess
Counties with
large excesses
have the most
livestock
Is it possible to send these excess nutrients back to the Corn Belt??

53. 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.

54. Some parts of the world have serious nutrient deficits
Level of nutrient deficit
http://www.fao.org/docrep/006/y5066e/y5066e02.jpg

55. What do you think the nutrient balance
is like on organic farms??
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

56. Nutrient flows can be monitored at
different geographic and temporal scales

57. Typical losses of N associated with consumption of grain and meat
Grain
What happens to the reactive N that doesn’t make to our dinner plates ?
Meat

58. All of the N losses identified on the previous slide
are opportunities for nutrient recycling
Many of these opportunities are already being
realized by innovative farms/agribusinesses

59. What is the nutrient content of corn stover?
At plant maturity, corn stover on average contains 7 lb of P2O5 per ton and 30 lb of K2O
per ton. There can be large variability in the actual amounts of P and especially K in the
stover. P content typically varies between 5 and 8 lb of P2O5 per ton, and K content can vary
between 5 and 40 lb of K2O per ton.
Sources of variation include growing season conditions, hybrid, general fertility of the soil, and
the time elapsed and amount and frequency of precipitation since the crop reached maturity
and the time the stover was removed from the field. While phosphorus (P) in stover has low
mobility because it is present in organic forms, potassium (K) is present in a highly soluble
inorganic form. Leaching from stover with rainfall is thus more pronounced for K than for P

60. 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/

61. 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
Values would be much
Water in fresh manure 4,458,990
higher if calculated using
current fertilizer prices!
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.

63. 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).

64. 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.

67. Optimal nutrient management involves a lot
more than just balancing inputs and outputs!

68. 3 main
strategies for
Conservation better nutrient Augmentation
cycling
Activation

69. Nutrient conservation = minimizing environmental losses

70. Nutrient augmentation = add nutrients that are deficient
Real nutrient management is more complicated than the law of the minimum!!
http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/C77D9DFB6F5F2580852568F000676B0E/$file/98-3p12.pdf
Corn yield (bu/ac)
N rate (lbs/ac)
Availability of one nutrient can increase uptake of another

71. Biological activation !
Continuous corn with hairy vetch

72. Cliff Schuette’s farm in S IL
Brassicas also help to
activate residue
decomposition

74. In a 3-yr field experiment, ammonium sulfate (AS) and urea-ammonium
nitrate solution (28% UAN) were applied to corn residues in November
at 30 lb N/acre. Other N treatments included 100 lb N/acre as AS
applied in the fall and spring and various combinations of spring and fall
N to provide a total of 190 lb N/acre. Initial corn residue amounts
ranged from 5600 to 7000 lb dry matter per acre. In 1999 and 2000,
time and source of N application and residue chopping did not affect N
mineralization, residue decomposition, or soil temperature. In 2001,
residue decomposition measured in June was increased by fall N
treatments, but did not affect N mineralization or soil temperature.
Fall N applications to promote corn residue decomposition did not
improve no-till corn yields and do not appear to be justified.
http://www.soils.wisc.edu/extension/area/horizons/2001/Napp_residuedecomposition.pdf

75. The value of fall applications of N on residue recycling is a hotly debated topic!
Recent discussion on Ag Talk
http://talk.newagtalk.com/forums/thread-view.asp?tid=255365&mid=1953006#M1953006

76. Most responses raised more
questions than answers

77. Excessive residue clearly can inhibit corn growth!
This is not exclusively a nutrient problem!
So… What is the best strategy for residue recycling???

78. There is no single best strategy for recycling residues!
https://www.jungseedgenetics.com/Jung%20Seed%20Genetics%20Agronomic%20Library/agronomic_spotlight_-_managing_the_effects_of_crop_residue_in_continuous_corn_rfs.pdf

79. LIME TO WIN
From Farm Journal Media
Soil Acidity Affect on Plant Nutrient Availability
By Darrell Smith, Farm Journal Conservation & Machinery Editor
Trying to maximize corn profits without understanding acidity is like building a
skyscraper without pouring a foundation first—the entire structure will probably
come crashing down. Managing pH levels becomes even more important if you’re
growing continuous corn.
“I’ve looked at many yield comparisons trying to figure out why one farmer
raises 220-bu. corn and another, with similar soils, gets only 180 bu.,” says Farm
Journal Field Agronomist Ken Ferrie. “There could be many reasons, but pH is
right up there….
If you have the proper pH, you don’t fight residue because microbes
decompose it. Yields show smaller peaks and valleys because yields in acid soils
fall apart in dry years. Managing pH is a major part of weatherproofing soil”.

80. Nutrient
Balance
Problem

81. http://www.misa.umn.edu/prod/groups/cfans/@pub/@cfans/@misa/documents/asset/cfans_asset_287004.pdf

82. 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.

83. Nutrient inputs
Purchased feed
Purchased fertilizer
Biological N fixation

84. 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

85. 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

86. 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

87. Total nutrient inputs
∑ Feed
Fertilizer
Biological N fixation

88. Nutrient outputs
∑ Marketed grain
Marketed piglets
Environmental losses

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

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