1. Manure Use in Grain Production Systems
Josh McGrath
&
Edwin Ritchey
Soil Management Specialists

2. The 4R’s of Number Two
Rate – lower rate might provide higher N return and limit P risk
Timing – Fall applied manure provides little N value
Placement – Surface application has potential to lose nutrients, tillage has potential to lose soil
Source – Still working on this for manure

3. Manure N is all about the N cycle

4. Nitrogen Cycle NH3 N2 NO N2O Thermal N2 Fixation
Atmospheric Deposition
Legumes
Volatilization
Deposition of plant and animal residue
Symbiotic BNF N2
NH3
N2O
Denitrification
Nitrogen Cycle NO
Plant Uptake
Deprotonation
Non-Symbiotic BNF
NO2-
Protonation
Organic N
NO3-
NH4+
Mineralization
The nitrogen cycle is complex with many forms and rapid transformation between soil pools – many are biologically mediated and therefore hard to predict – spatially and temporally variable
Nitrification
Immobilization
Leaching
Sorption
Desorption
Fixed NH4
(2:1 clays and organic matter)

5. Manure Nitrogen Cycle Manure contains organic N Some as urea
Inorganic N
Mostly ammonium
Some nitrate
Manure Application
Manure Nitrogen Cycle
Urea
Organic N
NH4+
Manure N is mostly organic. Dry manures have some ammonium and little nitrate. Liquid manures and biosolids might have more nitrate.
During storage manure N is relatively stable – especially dry manure like poultry litter
Urea and uric acid in poultry litter make up a large portion of the readily available N.
Poultry litter can have 10 – 20 lbs NH4-N/ton. If surface applied some of this will volatilize (depends on temperature, moisture, and wind speed)

6. Urea in the presence of urease (already in the manure) rapidly hydrolyzes to form ammonium
Manure Application
Manure Nitrogen Cycle
Urea
Urease
Organic N
NH4+
Mineralization
In the presence of urease, above ~45 degrees F, urea is rapidly converted to NH4+ N. Really doesn’t get going until about 60F I think.
Immobilization

7. NH3
If not incorporated (rain, tillage, injection) the ammonium can quickly volatilize as ammonia gas
Volatilization
Manure Application
NH3
Manure Nitrogen Cycle
Deprotonation
Urea
Protonation
Urease
Organic N
NH4+
Mineralization
When surface applied the NH4-N in the manure and from urea hydrolysis can deprotonate, forming NH3, and volatilize. Incorporation of manure through rainfall, tillage or injection minimizes this loss. Wet manures are subject to much more volatile N loss than dry manures. In coarse textured soils some N can volatilize if only incorporated a couple inches.
The objective of manure management is to retain as much N as possible on the soil CEC as NH4
Immobilization

8. NH3
Ammonium can be rapidly converted to nitrate depending on moisture and temperature
Volatilization
Manure Application
NH3
Manure Nitrogen Cycle
Deprotonation
Urea
Protonation
Urease
Organic N
NO3-
NH4+
Mineralization
Nitrification is temperature and moisture dependent. Nitrifying bacteria mediate the process.
Nitrification
Immobilization

9. Manure Nitrogen Cycle Nitrate readily leaches NH3 Volatilization
Manure Application
NH3
Manure Nitrogen Cycle
Deprotonation
Urea
Protonation
Urease
Organic N
NO3-
NH4+
Mineralization
Once N is in the NO3 form it can move with water in the soil profile. Where leaching is a concern this can result in significant loss of N.
Nitrification
Immobilization
Leaching

10. Manure Nitrogen Cycle Nitrate readily leaches and denitrifies NH3 N2NO
N2O
Nitrate readily leaches and denitrifies
Volatilization
Manure Application N2
NH3
N2O
Manure Nitrogen Cycle
Denitrification NO
Deprotonation
Urea
NO2-
Protonation
Urease
Organic N
NO3-
NH4+
Mineralization
In anaerobic environments denitrifying bacteria start stealing O from the nitrate and the N can be converted to a gas and lost.
Nitrification
Immobilization
Leaching

11. Manure Nitrogen Cycle Crops utilize the nitrate and ammonium pools NH3NO
N2O
Crops utilize the nitrate and ammonium pools
Volatilization
Manure Application N2
NH3
N2O
Manure Nitrogen Cycle
Denitrification NO
Plant Uptake
Deprotonation
Urea
NO2-
Protonation
Urease
Organic N
NO3-
NH4+
Mineralization
Crops can utilize N as NO3 or NH4.
Advantage: Because organic N in manure is constantly mineralizing during the growing season there are some advantages to manure in that it matches crop uptake requirements.
Disadvantage: Because organic N is constantly mineralizing it continues to supply mineral N that can be lost after the growing season is over or before crops start taking up N rapidly.
Disadvantage: It’s difficult to predict manure N mineralization. It varies across the field and across time because it’s dependent on soil microbes, soil chemistry, and weather.
Nitrification
Immobilization
Leaching

12. Spreader calibration

13. The tarp method is okay – gives general idea
The tarp method is okay – gives general idea. You should do a couple passes using centers you are planning on using

14. Spreader Calibration – Distribution is important
-Using pans gives you the rate and distribution. Helps you understand what centers you should use

16. With manure, splitting might be more important
Applying total N with manure will jack up soil P concentrations
More complete mineralization of manure N occurs with lower rate
The bugs are hungry so they chew on the tough meat
Fertilizer at sidedress helps the mineralization process
Sidedress allows you time to assess growing season and tweak rate
PSNT
PSU Agronomy Guide 12
-Applying manure to meet total crop N needs might result in application of 3 – 5 times more P than the crop will utilize. Over time this can result in significant soil P accumulation. P is rather immobile in soil, but once a soil reaches the point of P saturation high dissolved P losses can occur. In addition, P can be lost through erosion of soil particles, which in fields with high STP results in high total P losses.
-There is some evidence that with lower manure rates a higher percentage of the total N becomes available in the growing season. This might mean lower total N being available, but it means more efficient use of the N that is applied.
-Reserving a portion of the total N planned for an inorganic side-dress application gives you a chance to assess how much N you are getting from your manure. Probably a better estimate than just a pre-application manure test. PSNT
-Side-dress also encourages microbial activity resulting in higher mineralization rates and more efficient conversion of manure N to plant available forms.

17. Pre-sidedress Soil Nitrate Test (PSNT)
On fields with a history of manure use or forage legume, early season nitrate is proportional to N availability later in season
soil is sampled to a depth of 12 inches
corn is 6” to 12” tall
portable, easy-to-use meters allow local analysis of soil and rapid delivery of results
widely used across NE and Midwest, though interpretations differ by state

18. 0.93 critical level for response
25 mg/kg critical range
Magdoff, F.R., W.E. Jokela, G.F. Griffin, and S.D. Klausner Predicting N fertilizer needs for corn in humid regions: Advances in the Northeast. p In Predicting N fertilizer needs for corn. Bulletin Y-226. National Fertilizer and Environmental Research Center, Tennessee Valley Authority, Muscle Shoals, AL.

19. Sidebar on plant sampling

20. Determining the right rate and timing
You’ve got to have a plan…even if it’s not a good one

21. AGR-146 Plant available N estimates
Accounts for ammonia volatilization
-UK provides estimates of the proportion of total N in manure available (mineralized) in a growing season.
-These estimates account for volatilization.

22. AGR-146 Plant available N estimates
Accounts for denitrification and nitrate leaching
-UK provides estimates of the proportion of total N in manure available (mineralized) in a growing season.
-These estimates account for volatilization.
-And for nitrate leaching and denitrification losses
-All of these transformations are very difficult to predict
-The longer the manure sits out there the less accurate these estimates are (e.g. fall application)
-There are other ways to predict “plant available N”
-With fall application or not incorporated you might get much less than what these say
-These are just estimates don’t bet on them.
-Ultimately adaptive management is required – come up with a plan, assess it, and adjust – constantly

23. AGR-146 Don’t forget the carry-over
-Residual N from previous manure applications is often overlooked, but very important…this is really hard to predict because of the amount of time that has passed since application. PSNT, LCM, check strips, and cornstalk nitrate test all provide means to assess – adaptive management

24. Field management
Managing manure NUE

25. Methods: Tillage Implements

26. Management versus source
Cumulative P at load from four different tillage practices in SAME corn field Wye Research and Education Center (2006)
One field, four tillage treatments, three replicates
Same manure rate
Same soil test P
Same hydrology and slope
Very different results
Soil Test P = 65 mg kg-1

27. BMPs are spatially and temporally variable in efficacy
Surface applied poultry litter provided a strong P signal in runoff immediately after application in 2006
In subsequent years non- runoff producing rain events preceded first runoff event and there was no treatment effect
Tillage on steeper slopes would have likely increased total P loading

28. Poultry Litter Subsurfer
USDA-ARS, Booneville, AR
Dale Bumpers Small Farms Research Center

29. How it works Opening discs open slot
Pulverized litter (internal patented mechanism) is delivered to the slot
Closing wheels seal the soil surface
Can be adjusted to meet a variety of rates
Greater accuracy and precision across a range of rates

30. Auger delivery system
This picture shows pellets- they work fine. We’ve had engineering challenges using poultry litter with wood shaving bedding. Currently working on new design that is more “field-read.”

31. Increased NUE P. Kleinman, USDA-ARS
Broadcast treatments were yield limited. Probably by N that did not mineralize or volatilized
P. Kleinman, USDA-ARS

32. Works in heavy cover crop or pasture
Does pretty well in heavy residue.

33. Injection, Instinct, and UAN
All plots received 90 lbs pre-plant N per acre from one of three sources
Injected ACT with Nitrapyrin
Surface applied normal litter
Surface applied UAN
Side-dressed N at V6 with 0, 45, 90, or 135 lbs/acre
Irrigated
Included 0 N check and high N preplant (270 lbs/acre)
Flat rate of N before planting from three sources. ACT is a “high” N litter. Not much different from standard litter so for point of this example doesn’t matter.
Nitrapyrin = Instinct
Used 5 way streamers to apply UAN
Side-dressed at v6 to get response curve

34. Injection, Instinct, and UAN
Main-plot Treatment
Total N (%)
NH4-N (%)
Organic N (%)
PAN (%)
PAN (lbs/ton or lbs/gal)
Pre-Plant N rate (lbs/acre)
Pre-plant Rate (tons/acre or gal/acre)
1 - ACT
3.32
0.68
2.64
2.00
40.06 90
2.25
2 - Normal
3.19
0.70
2.50
1.94
38.87
2.32
UAN 30
3.25
27.69
OrgN= TN – NH4 = 3.32 – 0.68 = 2.64
PAN = 0.5*OrgN + NH4 = = 2.00%
In the mid-Atlantic we calculate plant available N per ton of manure.
This shows application rates of manure and UAN (gal/acre)
We applied half the N upfront as ACT or normal litter or UAN
We applied the same amount of N upfront, just different amounts of litter
Assumes all the NH4-N and ½ half of the organic N is available in the first year

35. Injection, Instinct, and UAN
Highest N recovery from injected PL with nitrapyrin
Litter surface applied matched UAN
We see a much better response to N with the injected litter and nitrapyrin. Probably early season leaching and more complete mineralization in the soil later in the season. We seemed to run out of N with UAN late in the season.

36. Less N and same yield

37. Sidedress needed @ 245 bu/acre
Normal litter: 126 lb-N/acre
Injected/treated: 42 lb-N/acre
Less N and same yield

38. More yield across all N rates

39. More yield across all N rates
sidedress of 100 lb-N/a
Normal litter: 243 bu/acre
Injected/treated: 259 bu/acre
More yield across all N rates

40. Field Storage of Poultry Litter

41. Basics Litter should be placed high and dry
Push pile up into conical shape
Flat spots or humps collect water and degrade litter
Keep area around pile as clean as possible
Crust formation protects litter
Very little N and P are lost
Salt accumulation under pile can inhibit crop growth after pile removal

42. N loss to soil over time (~100 ton pile)
Using the standard pile size (i.e., 100-ft long and 18-ft wide) and estimated soil bulk densities, it is possible to estimate the loading rate of N into the soil from the poultry litter pile based on length of time the pile has been in place. For each of the time-of-removal treatments (15-day, 30-day, 45-day, 90-day, 120-day, and 150-day), the following amounts of inorganic N were found in the underlying soil: 4.0, 12.0, 7.6, 9.2, 11.7, and 10.4 pounds, respectively in year 1; and the amounts were 3.4, 8.4, 8.7, 16.1, 13.7, and 15.6 pounds, respectively in year 2. These data suggest that maximum N loading was reached in 30 days in year 1 and 90 days in year 2.
Greg Binford, Unpublished

43. Economic Value of Poultry Litter Tool
Calculators available for grain crops and pasture, hay, silage
Tweak management to see cost/value relationship
In reality fall application of poultry litter removes majority of value

44. Summary Know what you are using (test manure)
Know how much you are using (calibrate spreader)
Is it worth the price compared to commercial fertilizer – pencil it out
Proper field storage is far better (economically and environmentally) than fall application

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