ecology of nutrients
DESCRIPTION
This is an updated version of "Nutrient dynamics"TRANSCRIPT
Cycles
Flows
Stocks
Key terms
The ecology of nutrients
Internal cycling
Nutrient inputs
Nutrient losses
• Chemical weathering of rocks
• Biological fixation of atmospheric N
• Deposition of elements from atmosphere
• Transfer of nutrients
Between plants and soil
Between organic and inorganic forms
• Changes in ionic forms
• Biological uptake
• Interactions with mineral surfaces
• Leaching
• Gaseous emissions
• Wind and water erosion
• Fire
• Harvest
Ecosystem
Internal cycling is most important in natural ecosystems
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)
Nutrient budget for Hubbard Brook Forest
100%1%0.1%0.01% 10%0.001%
Elemental concentrations in soil vs. earth’s crust
soil
crust
Adapted from Essington (2003)
Which forms of nutrients are bioavailable?
ions in
solution
exchangeable
ions
“active” OM
humus
weatherable
minerals
All participate in biogeochemical cycles
but rates of “flow” vary widely.
Nutrient ecology in agroecosystems
What’s
missing?
Dissipation into the surrounding
environment via erosion, leaching,
volatilization…
How big should this arrow be?
Unfortunately
environmental losses are
sometimes larger than
nutrient removal in harvest
SOM - N
4000 160 80
200 200
Microbial
Biomass N
NO3- + NH4
+
From the
atmosphere
50
To the
atmosphere
10-50 FertilizerCrop
uptake
Loss by
leaching
20-100
N budget for Rothamsted wheat experiment
The total N stocks in soil normally greatly
exceed annual flows
#s = kg/ha (0.89*kg/ha = lbs/ac)
Jenkinson
Mineralized soil N
wheat pasture
Potential
N uptake by
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
"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."
(Doerge, 1991)
Peak uptake = 5-10 lbs
of N/ac/day
(Dinnes et al., 2001)
Timing of availability has a big impact on uptake vs. losses
elementlow
(mg/kg)high
(mg/kg)average (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
Total stocks in prairie soil A horizons
* assumes 1 acre- plow layer = 2 million lbs w/ average conc.
Weathering, deposition and recycling often supply
trace elements at rates which are not limiting
elementTotal
lbs/ ac-pl
lbs removed by 150 bu
corn yrs
lbs removed by 60 busoybeans yrs
lbs removed by 6 ton 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
Acre-plow layer stocks of trace elements expressed as years of removal by corn, soybeans and alfalfa
Dust leaving
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
6,000km away.” ( Chadwick et al, 1999)mg dust/m2/yr
Average annual deposition of
Saharan dust in the Amazon basin
exceeds 10 million tons or
> 150 lbs/ac
Swap et al. (1992) concluded that
the productivity of the Amazon rain
forest is dependent upon trace
elements contained in dust
originating in the Sahara.
Total Ammonia Emissions by County (1995)
Where is all this ammonia coming from ??
50 lbs N/acre
Deposition of biological available N
1990s
N inputs to IL soils
Mg = 1 x 106 g = 1000 kg = 1 metric ton
1 metric ton = 2204.6 pounds
1 metric ton = 1.1023 US tons
(alfalfa and other forage legumes)
M.David
N outputs from IL soils
M.David
Crop specific harvests of N
M.David
Net N inputs Net input = Gross inputs - outputs
19
93
M.David
Mining Prairie N
Anthropogenic N inputs
M.David
Units are 1000 metric tons N / yr
-523,000 tons of N/yr !
M.David
Units are 1000 metric tons N / yr
+1 ton of N/yr !
M.David
Why does so much N get into Illinois’ rivers ???
Approximately 40% of IL fields
have artificial drainage
Yield maps have
made drainage
problems
more obvious
↓ more artificial
drainage
↓more nutrient
pollution
Photo: MARGARET BOURKE-WHITE
Aerial view of Cargill grain
elevator w. barges lined up on the
bank of the Chicago River in 1951
So where do the nutrients
in IL grain end up?
Redistribution of nutrients in the Mid-Atlantic region
excess
Counties with
large excesses
have the most
livestock
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)
Why don’t we
send the
surplus
nutrients
back?
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.
http://www.fao.org/docrep/006/y5066e/y5066e02.jpg
Nutrient depletion in Africa
Nutrient budgets on organic farms
http://www.organic.aber.ac.uk/library/Nutrient%20budgets%20on%20organic%20farms.pdf
N
P
K
a review of published data
Most organic farms in developed countries do not
have nutrient deficits even though they don’t use
conventional fertilizers.
http://edis.ifas.ufl.edu/DS096
Daily inputs and outputs of dry matter, P and N
urine feces
N
P
K
50% 50%
10% 90%
90% 10%
N
20% maintenanceP
13% maintenance
K
12% maintenance
60%
20%
60%
27%
75%
13%
http://extension.oregonstate.edu/catalog/html/em/em8586/
http://edis.ifas.ufl.edu/DS096
Nitrogen budget for a dairy in Florida (lbs of N/acre)
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
1 Based on assumed values of $.30/lb N, $.60/lb P, and $.15/lb K; N recovered was 50%
of excretion, thus, 50% volatilized.
Annual manure production and nutrient value for a 100 cow dairy
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).
Concentrated Animal Feeding Operations (CAFOs) in IL
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.
Nutrient
Balance
Problem
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.
Nutrient inputs
Purchased feedPurchased fertilizerBiological N fixation
Nutrient inputs
How many tons of N, P and K are in 1300 tons of purchased feed ?
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
Feed analysis?
Nutrient inputs
How many tons of N, P and K are in the purchased fertilizer ?
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
Fertilizer program? Acres? Fertilizer receipts?
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
Total nutrient inputs
∑Feed
Fertilizer
Biological N fixation
Nutrient outputs
Marketed grainMarketed piglets
Environmental losses∑
Nutrient cycling on-farm
Nutrients in manureNutrients in crop residues
Nutrients in 50% of corn grain
You are welcome to analyze
your family’s farm or any
other farm with which you
are affiliated.