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

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

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

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

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

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

Soil maps & recommendation Malawi 1998 & 2014

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

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

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

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

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

Trend of Effects of lime on exch aluminium

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

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

Balanced nutrition-Uasin Gishu

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

Getting the balance Right The 4R Nutrient Stewardship Pg. 2-7 - 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

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.

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

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

Good agronomy eg weeding at right time is crucial

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

Nutrient Expert

Nutrient Expert

Nutrient Expert Scenario Analysis

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