1. Fertilizers: Form & Function

2. Fertilizers – Basic Definition
Has a guaranteed analysis.
This is the minimum level of fertilizer nutrients expressed as a percentage.
Also tells us the source of the fertilizer nutrients.
Contains fertilizer nutrients.
Not a growth amendment or stimulant.

3. Classes of Fertilizers
Soluble
Slow Release
Chemically Slow Release
Physically Slow Release
‘Stabilized’ N Sources
Those that are Slow-Release via Mineralization (Organic)
Other fertilizers – bioenhanced, microbially mediated, etc. Those derived from proteins?

4. Soluble Fertilizers Immediate nutrient release
Rapid turfgrass response
Possibility of turf burn
Tend to be inexpensive
Examples: urea, (NH4)2SO4
Most often our foliar
sources, too.

6. Other Soluble N Sources
Ammonium sulfate (21-0-0)
Calcium nitrate
Potassium nitrate ( )
Sodium nitrate (16-0-0)

7. Establishment of Hybrid Bermudagrass as Affected by N Source
Day/Month/Year
7-9-02
shoots per cup cutter
Ca(NO3)2
76 a
127 b
147 a
NH4NO3
74 a
137 a
145 a
7-6-04
88 a
96 a
98 a
90 a
109 a
100 a

8. Slow-Release Fertilizers
Physically slow-release
Slow release via a physical coating around a soluble prill
Technologies have been around since the 1950s, others newer (80s and 90s)
SCU
PCU, resin-coat, multi-coat
Chemically slow-release
Slow release by their manufacturing method (homogeneous) – 1950s
Ureaformaldehyde/Methylene urea
IBDU

9. Chemically Slow-Release
Slow release due to a chemical reaction.
Nitrogen must be made plant available by bonds being broken.
Methylene ureas (urea formaldehyde).
Isobutlyidene diurea (IBDU).
Slower, more consistent N release.
Higher cost than soluble.

10. (7.8 g N m-2)

11. Physically Slow Release
Coated with wax, sulfur or plastic to make slow-release.
Typically urea, but also may be K2SO4.
Consistent, slow N release.
Length of release varies with coating thickness and other coating characteristics.

14. 6.8 g N m-2 2x
6.8 g N 2 x
4.9 g N 4 x

15. 6.8 g N m-2 2x
6.8 g N 2 x
4.9 g N 4 x

16. There are MANY different types:
Penn G-2 color as affected by slow-release N source, Farmlinks GC, 2007

17. 2016 Prill damage study, Auburn.
Estimated Days for N Release
days after application 1
Percent Nitrogen Release
Traffic
None
P-value 45
7.0
2.6
0.04 90
13.0
6.7
0.09
120
6.3
1.9
0.24
180
3.2
0.3
0.97
Estimated Days for N Release
%N release
Traffic
None
P-value 45 13
7.8
0.15 90 11
7.5
0.34
120
6.3
4.8
0.44
180
5.0
4.4
0.71
2016 Prill damage study, Auburn.

18. Total Percent N Volatilized by Source5 10 15 20 25 30 35 40 45 50
Urea
SCU
Polyon
Methx AN
Milorganite
N Source
% N Volatilized

19. ‘Stabilized’ Nitrogen Fertilizers
Urea with the addition or either a nitrification inhibitor (dicyandiamide), urease inhibitor (N-(n-butyl) thiophosporic triamide), or both.
Inhibits the enzymes urease and ammonium mono-oxygenase.

20. Volatilization (Urease) Inhibitors
Maleic itaconic co-polymer – Nutrisphere-N®
Ca-Heteropolysacharides Cl and Ca-Aminoethylpiperazine Cl – NStay®, Stay-N®
Calcium polymer blend – NZone
N-(n-butyl) thiophosporic triamid- UMaxx, Uflexx, Hydrexx

21. Volatilization Lab Method
Loss of N to atmosphere as ammonia gas. Big issue in manure application. Common with urea or urea-based products. Irrigation lowers N loss.
Lab Method

23. Passive Micrometerological Technique – Field Study
10 foot aluminum mast
Wind vane
Oxalic acid-coated tubes inserted perpendicular to mast at 5 heights

25. How to prevent volatilization losses?
Don’t use urea (still an issue on high pH soils, however)
Water in
Slow-release sources
Foliar
Volatilization inhibitors

26. 3.2 mm
6.4 mm
12.7 mm
25.4 mm

27. Nitrification Inhibitors
In agriculture, we try to slow this ammonium to nitrate conversion using nitrification inhibitors.
Have been around for 40 years, but are coming back into the market again with new products.

28. Nitrification – Conversion of ammonium into nitrate, done by nitrifying bacteria. Incubation study. Effect of addition of dicyandiamide.
+ inhibitor
urea
urea
+ inhibitor
control
control
Extractable soil ammonium
Extractable soil nitrate

29. Fertilizer

30. Urea versus Urea + additive
1 lb N/M
0.8 lb N/M
Never a significant difference between the two treatments.

31. Organic Fertilizers and Biofertilizers

32. Organic – at its simplest, it means that the product contains carbon.
Organic Fertilizer - a material that is derived from plant or animal-based materials.

33. Let’s take a closer look at that….
Dissolved organic N (ppm)
Microbial biomass N (ppm)
Soil organic matter (%)
Control
104 c
4.51 b
Organic (216)
134 a
4.95 a
Organic (216) + post-herb
128 ab
4.55 b
Mineral (219)
106 c
4.44 b
Mineral (98) + pre/post herb
100 c
4.37 b
Mineral (245) + pre/post herb + fung
110 c
4.63 b
Mineral (171) + pre/post herb + insect
107 c
October, 2004 data collection
Long term application of organic fertilizers resulted in a significantly higher soil microbial biomass.
Cheng et al., 2008

34. Penn G-2 bentgrass putting green
N at 4.9 g N m-2 (1 lb N/M)

35. Crystal Green
Crystal Green is sustainably produced by Ostara using nutrient recovery technology that combines phosphorus, nitrogen, and magnesium into pure crystalline granules.
Crystal Green is virtually water insoluble and releases only in response to organic acids produced by growing roots.
Phosphorus content in wastewater can be reduced by recovering a portion of the phosphorous as a crystalline product called struvite.
Struvite is relatively easy to dry and handle and shows potential as a slow-release fertilizer. Struvite is the common name for magnesium ammonium phosphate hexahydrate (MgNH4PO4 · 6(H2O)).

36. Percent establishment of Tifway hybrid bermudagrass as affected by P source. Auburn, AL, 2014.
Bermudagrass was sprigged on June 25th 2014.
All P applied at 2 pounds P2O5 per 1,000 ft-2 (9.8 g P2O5 m-2) 1 wk prior to sprigging.

37. (9.8 g P2O5 m-2)

38. (9.8 g P2O5 m-2)