1. Organic Nitrogen Inputs and the Soil Food Web

2. What is the Soil Food Web?
Interaction and combination of all the organisms in the soil.
Made up of an incredible diversity of organisms.
They range in size from the tiniest one-celled bacteria, to small vertebrates, and plants.
Fueled by Carbon, Nitrogen, minerals, water and Oxygen.
Major components are the Nitrogen Cycle and the Carbon Cycle.
Zillions of organisms from one celled bugs to plants and larger animals
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

3. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Who eats Who
Another representation
Show the interconnections
The Soil Biology Primer (Chapter 2): By Elaine R. Ingham
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

4. What do Food Web Organisms Do?
Break down plant residues
Release nutrients through microbial decomposition.
Microbes add stabilized nutrients to both the Active and Stable fraction of the soil.
Fix nitrogen from the atmosphere for the plant’s use.
Fix Carbon and release CO2
How?
Food web organisms break down organic matter, eat it, then release it in a stable from -fixed N
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

5. Why is a diversity of organisms important?
Decomposition of Organic Matter requires diversity.
In this interaction, one organism will break down an organic compound in the soil making the surplus by-products available as nutrients for other organisms.
These organisms will in turn do the same thing and continue the cycle, eventually making the nutrients available to plants and animals.
The microbial concentration and diversity impacts the speed and extent of nutrient cycling.
Jonathan Swift:
Big fleas have little fleas upon their back to bite ‘em and little fleas have smaller fleas ad infinitum.
The Soil Biology Primer (Chapter 2): By Elaine R. Ingham
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

6. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
The Food Web in Short
Zillions of organisms from one celled bugs to plants and larger animals
Jonathan Swift:
Big fleas have little fleas upon their back to bite ‘em and little fleas have smaller fleas ad infinitum.
Organic Matter
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

7. What are the requirements for an active Soil Food Web?
Water
Air
Nitrogen (protein and other Nitrogen compounds)
Carbon ( carbohydrates, i.e. - fuel) – Organic Matter
Stable C:N ratio of below 15:1 - a higher number will cause a deficit of available Nitrogen. (Soil C:N is 12)
The Soil Biology Primer (Chapter 2): By Elaine R. Ingham
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

8. Carbon is in the form of Organic Matter
Organic matter is the vast array of carbon compounds in soil. Originally created by plants, microbes, and other organisms, these compounds play a variety of roles in nutrient, water and biological cycles.
Organic matter can be divided into two major categories:
Active fraction
Stabilized organic matter
The Active fraction is divided into
living organisms
fresh organic residue
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

9. Carbon is the Energy that Fuels the Microbes
Carbon Cycle
Carbon is the Energy that Fuels the Microbes
The Carbon cycle follows the N Cycle
Carbon is required for the Nitrogen Cycle
Stabilized Carbon (humus)
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

10. Components of Soil Organic Matter
Soils with high organic matter content are the most productive, store more water and contribute to a better environment.
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

11. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Active Fraction
Used by living plants, animals and microbes for food.
Most of the Cycling of Nitrogen and Carbon Occurs here.
The Active Fraction” is the “Short Term Bank” where Nitrogen and Carbon are deposited and released quickly.
“Useable Forms”
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

12. Stabilized Organic Matter
After years of decompostion, what remains are large, complex compounds that few microbes can degrade. (Humus)
These hard-to-decompose, or stabilized, substances make up a third to a half of soil organic matter.
The Stabilized Organic Matter is the “Long Term Bank” where Carbon and Nitrogen are in a very Stable Form and are released very slowly by microbial digestion.
Humus
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

13. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Increasing Microbial Activity
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

14. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
The Nitrogen Cycle
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

15. The Organic Nitrogen Fertilizer Input Cycle
Organic Nitrogen Input is applied to the soil.
Macro-organisms start the breakdown. (fungi, protozoa)
The result of this macrobial action is amines and ammonia compounds. (plant food)
A portion of the Nitrogen is bound into insoluble organic matter called Humus
Humus is a ligno-protein residue of microbial tissue.
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

16. The Nitrogen Fertilizer Input Cycle
Bacteria (Microbes vs Macrobes) further break down amines & ammonia compounds into nitrites. (some loss to denitrification)
Plants cannot use this form of nitrogen, so it is further broken down by bacteria into nitrates.
Plants can then absorb this form of nitrogen but this is also the form that is lost to leaching.
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

17. Understanding the Nitrogen Cycle
Nitrogen Cycling is Dependant on Carbon
Nitrogen Cycling is Dependant on Microbes
Nitrogen Cycling feeds the Soil (microbes) which the Feed the Plant
This occurs Primarily in the Active Fraction of the Soil
The Important point is that BIOLOGY and ORGANIC MATTER is REQUIRED!
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

18. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Examples:
Organic Nitrogen
With No Biology
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

19. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Examples:
Organic Nitrogen
With Biology
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

20. Organic Fertility Goals
Increase the Soil Food Web in order to increase the Activity of the Carbon and Nitrogen Cycles
Increase the Active Fraction of Organic Matter (This where the N mineralized)
Improve the Efficiency of Fertilizer Inputs
Maintain a C:N Ratio of the Soil Below 15:1 so we don’t create a Nitrogen sink.
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

21. Differences in Input Characteristics
Organic Nitrogen Inputs vary dramatically in how they Affect the Soil Food Web and Nutrient Cycling.
They may be Differentiated by the C:N Ratio
C:N Ratio determines how much of the N stays in the Active Fraction and how much goes to the Stable Fraction
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

22. Differences in Input Characteristics
Organic Nitrogen Inputs may be Characterized by their Plant Available Nitrogen ( PAN)
PAN is the amount of Nitrogen that will be Available to the Plant during the Growing Season
In General:
The higher the C:N ratio the lower the PAN
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

23. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Organic Fertilizers
Here isa graphical representation of the information we just looked at showing…
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

24. Plant Available Nitrogen (PAN)
PAN is the quantity of Nitrogen Available during the growing season after a fertilizer is applied.
The amount of Nitrogen Immobilized is dependant on the C:N Ratio.
Higher the C:N Ratio the more N is Immobilized
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

25. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
How to Calculate PAN
Variables:
C: N Ratio of Organic Fertilizer
Percent Nitrogen in Organic Fertilizer
Total Pounds to be Applied
Microbes have 8:1 C:N Ration
Microbes use 25% Carbon for Growth, 75% for Energy
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

26. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
PAN Calculation
Total N =
(Pounds used) x (Percent Nitrogen)
Total Carbon =
(Total N) x (C:N Ratio)
Carbon used for New Tissue =
(Total C) x 25% (microbes use 25% of C for new tissue)
Nitrogen Immobilized =
(New tissue) / C:N Ratio of Microbes (8:1)
PAN =
(Total Nitrogen) – (Total Immobilized)
In-Season Efficiency
(PAN) / (Total Nitrogen)
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

27. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Examples (PAN)
Turkey Litter
4% N, 12.5 C:N, 1000 lb/Acre
Calculate for Total N:
1000 x 4% = 40 lbs
Calculate for Total C:
40 x 12.5 = 500
Calculate 25% Lb New Tissue:
500 x 25% = 125
Calculate N Immobilized,
Using Microbe C:N of 8:
125 / 8 = 15.63
Calculate PAN:
= 24.37
Calculate In-Season Efficiency:
24.37 / 40 = 61%
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

28. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Examples (PAN)
Protein Fertilizer
8% N, 4.0 C:N, 1000 lb/Acre
Calculate for Total N:
1000 x 4% = 80 lbs
Calculate for Total C:
80 x 4 = 320
Calculate 25% Lb New Tissue:
320 x 25% = 80
Calculate N Immobilized,
Using Microbe C:N of 8:
80 / 8 = 10
Calculate PAN:
= 70
Calculate In-Season Efficiency:
70/ 80 = 87.5%
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

29. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Organic Fertilizers
PAN Efficiency
Fertilizing Material PAN Efficiency
Layer Poultry Litter 69%
Broiler Poultry Litter 53%
Feather Meal 88%
Seabird Guano 94%
Liquid Fish 92%
Corn Steep 88%
Molasses Deriv %
Liquid Guano 97%
This data is taken from the previous Efficiency Chart slide
Note there is some variations due to either
Bedding litter content for manures
Type of protein
Degree of hydrolzation on liquid fish products. The more hydrolized – the lower the C:N ratio
What is good to see is that the field research we looked at earlier is confirmed by our math model.
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

30. Cost Analysis Including PAN
Organic Fertilizers
Cost Analysis Including PAN
Fertilizing Material $/Ton 0r Gal. $/ lb N
Layer Poultry Litter 4% N $250 $4.55
Broiler Poultry Litter 4% N $250 $5.88
Feather Meal 12% N $750 $3.57
Meat & Bone 8% N $600 $4.44
Seabird Guano 12% N $900 $4.00
Liquid Fish 5% N $4.00 $17.37
Liquid Guano 4.5% N $4.00 $18.35
This data is also derived from the Efficiency Chart
We see here that there is not a huge difference between all the dry sources of PAN until we get to the liquid products
So…. The question is why use liquids?
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

31. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

32. Other Issues Affecting SFW & Nutrient Cycling
Excess Carbon
Excess use of Low PAN Inputs will increase the Soil C:N Ratio creating a Nitrogen deficit that will reduce the effectiveness of soil applied Nitrogen.
This excess Carbon (raw organic matter) is unstabilized and serves as energy for microbes once Nitrogen is present resulting in Nitrogen going to the Stable Fraction.
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

33. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Other Issues……….
What about the mineralization rate of various Inputs?
Inputs have various rates of mineralization
Mineralization rate is affected by the Input, Composition, Temperature, Soil Microbial Activity, etc.
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

34. Crop Demand vs Mineralization
What do we do when the Crop Demand for Nitrogen is less than the mineralization rate of the Fertilizer Input?
Apply more fertilizer BUT How?
What kind of fertilizer?
When should it be applied?
Can the cost be minimized?
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

35. Decision Making Information
Mineralization Rate of Inputs
PAN of Inputs
Soil Nitrogen Levels of Nitrate, Ammonia and Total Nitrogen
Total Nitrogen from all Sources (fertilizer, soil, compost, etc.)
Crop Demand for Nitrogen
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

36. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Organic Fertilizers
To answer that we need to look at how these products mineralize over time and the release rates of PAN
This slide depicts the release of PAN thru mineralization (microbe activity)
Looking at the black dotted line for crop demand we see that the demand does not match the availability or mineralization
Our Choice is to add more fertilizer in the beginning to supply the required PAN (red line) OR
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

37. Nitrogen Input Decisions
Liquid or Dry Fertilizer
Dry Fertilizers have a 6 to 12 week Mineralization Rate depending on the Product
Liquid Fertilizers have a 0 to 6 week Mineralization Rate depending on the Product
In order to Synchronize Availability with Demand higher rates of Dry Inputs compared to Liquid Inputs will be needed due to the Mineralization Rate and PAN
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

38. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Conclusions
The Food Web is the micro-organisms that mineralize organic matter and produce humus for future use and soil stability.
Soil is comprised of Living/Fresh & Active or Stable Organic Matter (Living/Fresh and Active is more available)
PAN is higher for Low C:N ratio Inputs. High C:N contributes Nitrogen to the Stable Fraction (i.e.: not this crop)
Feed the Soil to Improve the SFW
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

39. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Further Conclusions
PAN affects the true cost of a product.
Solubility and Availability is important if you need a fast acting fertilizer.
Use of very low C: N ratio Nitrogen fertilizers is better (feed the crop directly) for short season crops and Peak N demand periods
Synchronizing applications with crop demand is critical for success.
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

40. Organic Fertility Goals
Increase the Soil Food Web in order to increase the Activity of the Carbon and Nitrogen Cycles
Increase the Active Fraction of Organic Matter (This where the N mineralized)
Improve the Efficiency of Fertilizer Inputs
Maintain a C:N Ratio of the Soil Below 15:1 so we don’t create a Nitrogen sink.
Treat short duration deficiencies with low C:N Ratio Soluble liquids containing MINERALIZED Nitrogen to increase PAN.
Organic Matter –
Mixture of carbon compounds created biologically.
Go to next slide
Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI

41. Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI
Thank You!
This presentation will be available at
Tim Stemwedel contact information:
7600 N. Ingram, Suite 121
Fresno, CA 93711
Organic Matter –
Mixture of carbon compounds created biologically.
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Organic Nitrogen Inputs and the Soil Food Web, Tim Stemwedel, COFI