This document discusses fertilizer use efficiency. It defines different types of efficiency like recovery efficiency and agronomic efficiency. It discusses how efficiency is defined differently for nitrogen versus phosphorus and potassium. Maintaining optimum soil test levels for P and K is considered 100% efficient. The document also outlines opportunities to improve nitrogen efficiency through balanced nutrition, precision agriculture, and better fertilizer management practices. Improving efficiency will impact future fertilizer demand differently for nitrogen versus P and K.

1. MUHAMMAD FAHAD ANSARI
12IEEM 14
Characteristics
& efficient Use
of fertilizers

2. Characteristi
cs &
efficient Use
of fertilizers
Potash & Phosphate Institute/Potash & Phosphate Institute of Canada

3. Fertilizer Use Efficiency:
An Old Topic but With New Importance
 International Nitrogen Initiative (INI)
 Goal: to optimize N’s beneficial role in sustainable food
production and minimize N’s negative effects on human health
and the environment resulting from food and energy production.
 Will focus attention on improving fertilizer N efficiency at a global
scale
 Multiple Level Nutrient Management
 NRCS program under development to subsidize farmer
practices that improve nutrient use efficiency
 Will test our collective understanding of nutrient use efficiency
for N and P

4. Traditional Nutrient Efficiency Terms
 Recovery efficiency (RE) = Increase in
uptake per unit nutrient added usually expressed
as %
 Agronomic efficiency (AE) = Crop yield
increase per unit nutrient added such as
bu/lb or kg grain/kg nutrient

5. Agronomic efficiency of fertilizer N used
on corn grain in the U.S., 1964-2002
75
70
Kg grain per kg N .
65 59
60
55
43
50
45
40
35
30
1960 1965 1970 1975 1980 1985 1990 1995 2000
39% increase in N efficiency
Since 1975: 12% increase in fertilizer N per ha
40% increase in corn yields

6. N fertilizer recovery efficiency using
on-farm measurements
Opportunity for improvement
Crop Region Number Avg N Recovery,
of farms rate, %
kg/ha
Maize NC USA 56 103 37
Rice Asia-farmer 179 117 31
Asia-researcher 179 112 40
Wheat India-poor weather 23 145 18
India-good weather 21 123 49
Cassman et al., 2002

7. Areas of opportunity for improvement
in fertilizer N efficiency
 Continued improvement in cropping
system management
 Realisticestimation of attainable yield
 Yield potential protection – pest management
and other cultural practices
 Balanced nutrition

8. Balanced nutrition in the U.S.
 Ohio State University – dryland corn
 80 ppm soil test K 45% N recovery
 139 ppm soil test K 80% N recovery
 Kansas State University – irrigated corn
 No P applied 35% N recovery
 45 kg ha-1 75% N recovery

9. Balanced nutrition in China
Treatment
Reference Crop N NPK
N recovery by crop,%
Zhu, 1994 Barley 28 51
Jin, 2001 Wheat (11 yrs) 31 70
Corn (5 yrs) 35 66

10. Areas of opportunity for improvement
in fertilizer N efficiency
 Continued improvement in cropping
system management
 Use of site-specific precision ag
technologies

11. Site Specific Management:
Accounting for spatial variability

12. Spatial variability in fertilizer N efficiency
Year 1 Soybeans Year 3
Uniform N rate In year 2 Variable N rate
11.1 t/ha average yield 11.3 t/ha average yield
Indiana; two
N rates based
on soil type
N Efficiency,
kg grain/kg N
28-39
39-50
50-62
62-73
Murrell and Murrell, 2002

13. Variable N rate contributed to increased N
efficiency
40 ha field divided into 10 zones
9
8 Whole field year 1, 47 kg grain/kg N
8
Frequency of zones
7 Variable rate year 3, 53 kg grain/kg N
6 13% increase in
fertilizer N efficiency
5
4
4
3
2 2 2
2
1 1
1
0
0
28-39 39-50 50-62 62-73
N use efficiency, kg grain/kg applied N
Murrell and Murrell, 2002

14. Areas of opportunity for improvement
in fertilizer N efficiency
 Continued improvement in cropping system
management
 Use of site-specific precision ag technologies
 Better prediction of soil N mineralization
 Improved timing of N application
 Improved manure management and crediting
 Improved fertilizers
 Biotechnology?

15. Is the concept of fertilizer use
efficiency the same for P and K as it
is with N?

16. The result of applying the definition of
agronomic efficiency for N to P
 The highest “efficiency” occurs when inadequate amounts
are applied at low soil test levels
 Building soil test levels to optimum reduces “efficiency”
120
 “Efficient” P use means reduced profitability, water use
P use efficiency, kg corn/kg P
100 * efficiency, N use efficiency, and land use efficiency
80
60 **
40
20
0
** *
5 10 15 20 25
Bray P-1, ppm Low High

17. We need to view P and K efficiency
as different than N efficiency
 A.E. Johnston and P Poulton
“The difference method (RE) is appropriate for N … but
is less useful for P and K where plant available
reserves of these nutrients can accumulate in the soil
from past applications of fertilizer.”
 Sustainable efficiency (for P&K) – Nutrient
input needed to sustain the system at optimum
productivity expressed as a removal to use ratio

18. P and K Sustainable Efficiency in N. America
 Review current crop removal to use ratios
 Review current soil test levels
 Combine the two to assess efficiency
Information Sources:
• Soil Test Levels in North America, PPI/PPIC/FAR Technical Bulletin
2001-1.
• Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR
Technical Bulletin 2002-1.

19. Partial K budgets for the U.S.
(average of 1998-2000)
Crop Applied Recov. Removal to use
Region removal fertilizer manure* fertilizer fert+man
------- K2O, billion kg ------
U.S. 8.8 4.6 1.7 1.91 1.39
6 corn states 3.0 1.9 0.5 1.62 1.30
* USDA-NRCS, 2000; Due to manure distribution problems relative to crop demand,
this likely overestimates the agronomic contribution.

20. Ratio of K removal by crops to fertilizer
applied plus recoverable manure
BC
AB MB
SK
ON PQ
PEI
WA NB
ME
MT ND NS
OR MN
R/(F+M)
VT
ID NH 0.00-0.89
NY
WI
SD
MI MA 0.90-1.09
CT
WY RI 1.10-1.49
IA
NE
PA 1.50-4.99
NV OH NJ
IL IN MD > 5.00
UT WV DE
CO MO VA
CA
KS
KY
NC
AZ NM OK TN
AR SC
MS AL GA
TX LA
FL

21. Percent of Soils Testing Medium or Lower
in K in 2001
North America
43%

22. Partial P budgets for the U.S.
(average of 1998-2000)
Crop Applied Recov. Removal to use
Region removal fertilizer manure* fertilizer fert+man
------- P2O5, billion kg ------
U.S. 5.2 4.0 1.5 1.30 0.95
6 corn states 2.3 1.4 0.4 1.71 1.33
*USDA-NRCS, 2000; Due to manure distribution problems relative to crop demand
and unavailability of a portion of manure P, this likely overestimates the agronomic
contribution.

23. Ratio of P removal by crops to fertilizer
applied plus recoverable manure
BC
AB MB
SK
ON PQ
PEI
WA NB
ME
MT ND NS
R/(F+M)
OR MN VT
ID NH 0.00-0.49
NY
WI
SD
MI MA 0.50-0.89
CT
WY RI 0.90-1.09
IA
NE
PA 1.10-1.49
NV OH NJ
IL IN MD >1.50
UT WV DE
CO MO VA
CA
KS
KY
NC
AZ NM OK TN
AR SC
MS AL GA
TX LA
FL

24. Percent of Soils Testing Medium or Lower
in P in 2001
North America
47%

25. Viewing removal to use in light of soil
test levels
 Large regional differences exist across North
America in both current removal to use ratios
and soil test levels
 “1” is often not the appropriate removal to use ratio
target for a state or for a field
 Soil test levels < optimum: ratio should be < 1
 Soil test levels > optimum: ratio should probably be > 1
 Starter fertilizer needs are often independent of
soil test levels or removal to use ratios

26. Est. crop removal / (fertilizer + manure use) State level P assessment: R/(F+M)
1.8
1.6 Low and SD IA High but decreasing
1.4 decreasing
WI
1.2
1.0
AR
0.8
0.6
0.4
GA
0.2
Low and increasing High and increasing
0.0
-15 -10 -5 0 5 10 15 20 25
State median soil test level - target level, ppm
Target level = lower end of high category

27. Estimating target removal/use ratio for a field
 Target K test = 150 ppm Current test = 130
 Build: (150 - 130) x 9 kg K2O/ppm = 180 kg K2O/ha
 To spread build over 4 yrs = 180/4 = 45 kg K2O/ha
 Avg crop removal per year = 67 kg K2O/ha
 Total to apply = 45 + 67 = 112 kg K2O/ha
Target removal to use ratio = 67/112 = 0.60

28. Examples of apparent recovery efficiency
of P fertilizer in long term studies
Soil(s) Applied No. of Recovery
P2O5, kg/ha Crops %
Calcareous clay 67 5 F 28
Clay loam, pH 7.3 29 9 F 54
28 soils, pH 6.2-7.9 152 8 GH 74
4 soils, pH 6.7-7.6 230 19 GH 87
Sandy loam, non-calcareous 118 4 F 100
GH = Green house; F = Field.
Fixen, 1992

29. If a field is at its optimum soil test
level, and replacement of the P and
K removed by crops maintains that
optimum level, what is the efficiency
of P or K?
100%
If use must exceed removal to maintain optimum productivity,
soil erosion or fixation are often the cause:
 Reduce erosion losses
 Utilize banding and annual fertilizer application

30. Impact of Improving Efficiency on
Fertilizer Demand
 Critical to properly define efficiency for the
nutrient in question
 Nitrogen
 Good progress has been made in improving
agronomic efficiency
 Will be significant pressure to further improve
agronomic efficiency without sacrificing yield potential
 Research shows there is room for improvement
 Yields will likely continue to increase faster than N
use

31. Impact of Improving Efficiency on
Fertilizer Demand (continued)
 Phosphorus and potassium
 Will be increasing pressure to improve system efficiency
by reducing P levels where excessive
 Sustainable efficiency will translate into increased P and
K demand in some major production regions
 Pressure to improve N efficiency should result in
increased support for balanced nutrition with P and K
 Higher future crop yields could require higher target soil
test levels and temporarily impact demand
 The thermodynamic need to replace P and K removal at
some soil level sets a lower limit for P and K use
 As food needs increase … fundamentals of
natural systems indicate a permanent and
expanding role for fertilizers in food production