The ecology of nutrientsKey terms Cycles Flows Stocks
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
Source of plant nutrient (% of total)Nutrient Deposition/fixation Weathering RecyclingNitrogen 7 0 93Phosphorus 1 < 10 > 89Potassium 2 10 88Calcium 4 31 65Data from (Whittaker et al. 1979)
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 solutionweatherableminerals
Nutrient ecology in agroecosystems What’s missing?
Environmental losses are sometimes larger How big is this arrow normally? than crop removalDissipation into the surroundingenvironment via erosion, leaching, volatilization…
N budget for Rothamsted wheat experiment From the To the atmosphere atmosphere Crop 50 10-50 Fertilizer uptake 200 200SOM - 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
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
"The most effective managementstrategy will be one that recognizes thepattern of nitrogen demand by thecrop and the nitrogen releasecharacteristics of all important nitrogen sources to provideadequate, but not excessive levels of soil nitrogenthroughout the growingseason." Peak uptake = 5-10 lbs(Doerge, 1991) of N/ac/day
Timing of N availability has a big impact on uptake vs. losses Crop uptake (Dinnes et al., 2001)
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
Where do eroded nutrients go? Most are relocated to lower landscape positions but do *not* end up in water bodies!
Nutrient pollution(Eutrophication)Excess nutrientspromote algal blooms inaquatic ecosystemscreating unusually highbiological oxygendemand when the algaedies and begins todecompose.Conventional wisdom:Nitrogen is the most limiting nutrient in marinesystems. Reality is more complex.Phosphorus is the most limiting nutrient in freshwaterecosystems
In 2002 5,549 miles (out of 15,491) of Illinois streamsdid not meet IEPA water quality standards.
Understanding the “Dead Zone” There are a ~ 400 recurring dead zones world wide! Almost the entire eastern seaboard hasrecurring dead zones
“Geologic evidence shows that dead zones were not a naturally recurring event in the Chesapeake Bay or mostother estuarine ecosystems” says Diaz. "Dead zones were once rare. Now theyre commonplace”.
Understanding Hypoxia Layer of nutrient rich fresh Fresh water water over salt water is less dense than salt water
What is causing the hypoxic zone in the Gulf ?
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 Nwhere agriculture is the dominant source!
Is the Dead Zone in the Gulf increasing in size ? Yes… but not consistently. Yes... but there is lots of variability!
The location of hypoxic zones is dynamic! Frequency of Occurrence 1985 - 1999 Rabalais, et al.Distance Paris to London = 490 km 28
N and P levels in the Mississippi and all significant tributaries are monitored
Why does so much N get into Illinois’ rivers ???
Artificial drainage in the United States % of land drained~ 40% of IL cropland has been tiledhttp://www.ars.usda.gov/SP2UserFiles/Place/36251500/TheExtentofFarmDrainageintheUnitedStates.pdf
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 ppmThe EPA drinking water standard is 10 ppm NO3-N
Why is nutrient pollution a persistent problem if…
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
IL Agronomy Handbook - maintenance rates of P2O5 and K2O
P balance for IL in 2008606,500 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
High fertilizer prices in fall of 2008 = less applicationP 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 cropsAccording to IDOA records, only 3250 tons of P2O5 were purchased (fall 2008/spring 2009)
Soil test P levels are dropping in the Corn BeltChange between 2005 and 2010 % of samples below critical level
The U of I recommends a build and maintenance approach for P and K Critical Level
In contrast with P, N inputs and outputs are currently ~ balanced in IL Units are 1000 metric tons N / yr M.David
Back in the sodbusting days, IL was losing over 500,000 tons of N/yr ! Units are 1000 metric tons N / yr M.David
Mining Prairie N Net anthropogenic inputs M.David
N inputs to IL soils (alfalfa and other forage legumes)Mg = 1 x 106 g = 1000 kg = 1 metric ton1 metric ton = 2204.6 pounds1 metric ton = 1.1023 US tons M.David
Photo: MARGARET BOURKE-WHITE So where do the nutrients in IL grain end up?Aerial view of Cargill grainelevator w. barges lined up on thebank of the Chicago River in 1951
Surplus P and NState P N --Million of lbs in excess--DE 7.3 14.6MD 10.4 19.6NJ 0.9 1.8NY 3.3 4.2PA 23.7 33.8VA 24.8 42.3(Source: USDA, 2001)
Redistribution of nutrients in the Mid-Atlantic region excess Counties with large excesses have the most livestockIs it possible to send these excess nutrients back to the Corn Belt??
Keith Bowers of MultiformHarvest in Seattle hasdeveloped a system toremove phosphates fromswine and dairy manure. Itinvolves changing thechemistry of the liquid manureto form struvite, a phosphatecompound that is precipitatedout of the slurry. Struvite,magnesium ammoniumphosphate, is sometimesdeposited naturally as scaleon wastewater pipes and inthe human body as kidneystones. It’s in demand as aslow release fertilizer andmagnesium source.
Some parts of the world have serious nutrient deficitsLevel of nutrient deficit http://www.fao.org/docrep/006/y5066e/y5066e02.jpg
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.PK http://www.organic.aber.ac.uk/library/Nutrient%20budgets%20on%20organic%20farms.pdf
Nutrient flows can be monitored atdifferent geographic and temporal scales
Typical losses of N associated with consumption of grain and meatGrain What happens to the reactive N that doesn’t make to our dinner plates ? Meat
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
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 K2Oper ton. There can be large variability in the actual amounts of P and especially K in thestover. P content typically varies between 5 and 8 lb of P2O5 per ton, and K content can varybetween 5 and 40 lb of K2O per ton.Sources of variation include growing season conditions, hybrid, general fertility of the soil, andthe time elapsed and amount and frequency of precipitation since the crop reached maturityand the time the stover was removed from the field. While phosphorus (P) in stover has lowmobility because it is present in organic forms, potassium (K) is present in a highly solubleinorganic form. Leaching from stover with rainfall is thus more pronounced for K than for P
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/
Annual manure production and nutrient value for a 100 cow dairyManure constituent Lbs/year/100 cows Probable $ valueRaw manure (feces + urine) 5,045,000 Values would be muchWater in fresh manure 4,458,990 higher if calculated using current fertilizer prices!Total solids 586,000Total N (lb) 23,400 $3,5101Total P (lb) 4,800 $2,8801Total K (lb) 15,100 $2,2651TOTAL VALUE of N, P, and K $8,6551Based on assumed values of $.30/lb N, $.60/lb P, and $.15/lb K; N recovered was 50%of excretion, thus, 50% volatilized.
Concentrated Animal Feeding Operations (CAFOs) in ILThere are ~ 500 “large" CAFOs and ~ 2,700 "Medium" CAFOs in IL.These CAFOs are required to:Apply for a National Pollutant Discharge Elimination System (NPDES)PermitSubmit an Annual ReportDevelop and implement a manure and wastewater handling plan(Nutrient Management Plan).
In Illinois, there are actually 3 different types of manure management plansthat livestock facilities may be required to have (NRCS, IL DOA, and IL EPA). U of I Extension has worked with NRCS, IL DOA, IL EPA to develop oneworkbook of forms and instructions that when completed by a producer, willcomply with the requirements of all 3 agencies.
Optimal nutrient management involves a lotmore than just balancing inputs and outputs!
3 main strategies forConservation better nutrient Augmentation cycling Activation
Nutrient augmentation = add nutrients that are deficientReal nutrient management is more complicated than the law of the minimum!! http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/C77D9DFB6F5F2580852568F000676B0E/$file/98-3p12.pdf Corn yield (bu/ac) N rate (lbs/ac) Availability of one nutrient can increase uptake of another
Biological activation ! Continuous corn with hairy vetch
Cliff Schuette’s farm in S IL Brassicas also help to activate residue decomposition
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 ASapplied 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
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
Most responses raised more questions than answers
Excessive residue clearly can inhibit corn growth! This is not exclusively a nutrient problem!So… What is the best strategy for residue recycling???
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
LIME TO WIN From Farm Journal MediaSoil Acidity Affect on Plant Nutrient AvailabilityBy Darrell Smith, Farm Journal Conservation & Machinery Editor Trying to maximize corn profits without understanding acidity is like building askyscraper without pouring a foundation first—the entire structure will probablycome crashing down. Managing pH levels becomes even more important if you’regrowing continuous corn. “I’ve looked at many yield comparisons trying to figure out why one farmerraises 220-bu. corn and another, with similar soils, gets only 180 bu.,” says FarmJournal Field Agronomist Ken Ferrie. “There could be many reasons, but pH isright up there…. If you have the proper pH, you don’t fight residue because microbesdecompose it. Yields show smaller peaks and valleys because yields in acid soilsfall apart in dry years. Managing pH is a major part of weatherproofing soil”.
Overview of Hislop farm 1500 sow farrow-to-wean operation32,000 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 inputsHow many tons of N, P and K arein 1300 tons of purchased feed ? Feed analysis?N 2% of 1300 tons = ? of NP 0.8% of 1300 tons = ? tons of PK 0.4% of 1300 tons = ? tons of K
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
Nutrient inputs Biological N fixation ~ 3 lbs of N fixation per bushel of beans750 acres of soybeans*50 bu/acre*3 lbs of N fixation/bu
Total nutrient inputs ∑ Feed Fertilizer Biological N fixation