1. Fertilizer and Lime Recommendation in East and Southern Africa: Key Issues
James Mutegi

2. The Consortia Program ESA Consortia mandate region
West Africa Soil Health Consortia-To start soon

3. Outline Background Current fertilizer recommendations
Key gaps in fertilizer recommendations
Management of acidic soils impact on yields
Fertilizer response in context of spatial variability
4R nutrient stewardship
Tools for fine tuning fertilizer reccomendation

4. Background
There is ample evidence that for higher crop yields & incomes in SSA, fertilizers have to be used appropriately
Most of recommendations in ESA are blanket across different soils, climatic conditions and crops
As a result often there is mismatch between crop requirements and the rates/types of nutrients applied
When matching of nutrients to crop nutrient requirement is poor the results are: low FUE, income losses, food insecurity and poverty

5. Recommended blanket fertilizer rates
Country
Maize
Millet
Sorghum
Irrigated Rice
Kenya
N60P30K0 DAP topdressed with CAN
N18P46 as DAP: FYM 5 t/ha at planting
Uganda
50 kg N, 10 kg P (125 kg DAP at planting & 125 kg Urea as top dress)
125 kg/ha AS broadcast when crop is 15 cm high
110 kg/ha of SSP at planting 110 kg/ha CAN as topdress
100 kg/ha Urea
Rwanda
70 kg N/ha, 42 kg P/ha, 42 kg K/ha
Malawi
92 kg N/ha, 22 kg P/ha, 8 kg S/ha
46 kg N, 22 kg P, 8 kg S/ha
83 kg N/ha, 25 kg P2O5, 4.5 kg S

6. Recent recommendations
Revised Fertilizer recommendations for Maize and Rice in the Eastern, Southern Highlands and lake zones of Tanzania 2014
Region/
Tanzania
Crop
Revised rates
P source
Bags of P fertilizer
Bags of N fertilizer source
Morogo
Maize N P
Urea
CAN SA 80 40
TSP
4.0
3.5
6.0
8.0
DAP
2.0
4.5
M. Mazao
9.0
1.5
2.5
Tanga 60 20
3.0
Similar spatially explicit results exist for 9 agricultural regions in Tanzania

7. Soil maps & recommendation Malawi 1998 & 2014

8. Ethiopia soil based fertilizer recommendation
Recommended blends for Tigray
For practical reasons a few blends appropriate for large areas were produced
The reccomed are soil based: IFA grant to IPNI to fine tune them through crop response trials

9. Key gaps in current recommendations
None of these popularly used recommendation has incorporated considerations for
Soil pH-Acidic soils are wide spread in ESA & reduce FUE significantly
Balanced nutrition-Most of these recommendations are not considerate of micronutrient & K deficiency
They don’t consider field to field/within field variability in fertility
The recommendation consider only nutrient source & rate-They are silent on the nutrient application at the right time and place (4R nutrient stewardship)
Excellent fertilizer recommendation require appropriate seed & management to produce good results

10. Maize response to applied nutrients for low, immediate and high productivity soils in southern Malawi
Zingore et al., 2010

11. Soil pH and nutrient availability
Acidic soils: reduce nutrient availability for crop use coupled with increased
Al toxity,
Liming is known to check Al toxicity, increase pH, increase P availability,
improve N efficiency and supply Ca

12. Trend of effect of lime on soil pH
2005
2006
2007
2008
Kisinyo et al 2015

13. Trend of Effects of lime on exch aluminium

14. Fertilizer & lime effect on maize yield in W. Kenya
Treatment
Bungoma
Siaya
Uasin Gishu
Average
Control
0.58
0.52
1.36
0.8
DAP
4.42
3.90
5.42
4.5
Lime alone
4.48
2.32
5.36
4.1
DAP + Lime
5.49
4.52
6.19
5.4
Nekesa et al., 2005, Okalebo et al, 2007

15. Fertilizer & lime effect on soybean grain yield W. Kenya 2012-2013
Trt
Eshirali
Masaba
Nyabed
Eshia
Mean
Control
1.1
0.8
1.3
1.6
1.2
NPK
3.4
1.9
2.4
3.2
2.7
NPKSCaMgZnMo
3.6
1.8
2.8
3.1
NPKSCaMgZnMoLime
4.0
3.0
3.9
3.7
3.5
All applied during planting at application rates recomended to achieve attainable yield
Source: N2Africa_IPNI supported Msc

16. Balanced nutrition-Uasin Gishu

17. Contribution of various nutrient combination in Adama Tulu-Ethiopia
Fertilizer
Treatment
Yield
Control
No fertilizer
15 quintals PK
25 quintals NK
26 quintals NP
30 quintals
NPK
42 quintals
NPKSZnBO
Fertilizer with Micronutrients
Fertilizer available in Ethiopia is UREA, NPS and DAP

18. Getting the balance Right The 4R Nutrient Stewardship
Pg SOURCE, RATE, TIME, AND PLACE are completely interconnected in nutrient management. None of the four can be right when any one of them is wrong. It is possible that for a given situation there is more than one right combination, but when one of the four changes the others may as well. The 4Rs must work in synchrony with each other and with the cropping system and management environment.
IPNI 2011

19. Getting the balance Right The 4R Nutrient Stewardship
1. Supply in plant available forms
2. Suit soil properties
3. Recognize synergisms & interaction among nutrients
4. Blend compatibility
1. Appropriately assess soil nutrient supply
2. Assess all available indigenous nutrient sources
3. Assess plant demand
4. Predict fertilizer use efficiency
1. Assess timing of crop uptake
2. Assess dynamics of soil nutrient supply
3. Recognize timing of weather factors
4. Evaluate logistics of operations
Recognize root-soil dynamics
Manage spatial variability
Fit needs of tillage system
Limit potential off-field transport
The scientific principles of managing crop nutrients are universal.
They underscore the processes relating the use of nutrients to their impact on crops and soils and to their fate.
They give an excellent framework to ensure that none of the known principles of nutrient management are ignored in the development of recommendations.

20. N fertilizer response under variable soil fertility conditions
Clayey soil
Sandy soil
Zingore et al., 2011

21. FUE for poorly responsive sites
Year 1
Year 3
17 t/ha
17 t/ha
50 kg P
50 kg P
Rehabilitation of degraded fields

22. Good agronomy eg weeding at right time is crucial

23. Site specific diagnostic tools
Farm/Field scale variability imply difficulty in developing reccom that are 100% precise for every farm and field
Various diagnostic and reccom tools have been developed for use by farmers and extension workers to improve FUE at a farm level
Lot of validation & calibration for location specificity still needed
The tools include: Optimizer (OFRA tool), Nutrient Expert etc
A number of donors and fertilizer companies have invested in devpt and validation of nutrient expert
Has history in Asia, but working versions have been developed for certain regions in Kenya, Ghana, Zimbabwe & North Africa
Projects are underway to use it to support fine tuning fertilizer recom in Ethiopia, Nigeria, Ghana & Tanzania

24. Nutrient Expert

25. Nutrient Expert

26. Nutrient Expert
Scenario Analysis

27. Conclusion Effective fertilizer recommendation package foe ESA
Consider field scale variability
Take consideration of non responsive soils
Take consideration of huge areas that are characterized by acidic soils
Provide guidance for appropriate agronomy that should go with the recommended rates
Cognizant that FUE would improve when the 4R nutrient stewardship is taken into consideration