Farming in Sub Sahara Africa: too little science, too many myths

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1 Farming in Sub Sahara Africa: too little science, too many myths Lecture 4: Concepts of Integrated Soil Fertility Management in Africa common sense or revolution R. Merckx Francqui chair UCL-LLN 25/4/212 1

2 Content Introduction: the pendulum swings The ISFM components Germplasm Fertilizers Inorganic/organic interactions Local adaptation Validation of the ISFM concept by meta-analysis Conclusions 2

3 Period Paradigm Role of fertilizer Role of organic inputs Experiences 196s and 197s 198s 199s 2s External Input Paradigm 1st Paradigm Organic Input Paradigm Sanchez Second Paradigm Integrated Soil Fertility Management Use of fertilizer alone will improve and sustain yields. Fertilizer plays a minimal role. Fertilizer use is essential to alleviate the main nutrient constraints. Fertilizer is a major entry point to increase yields and supply needed organic resources. Organic resources play a minimal role. Organic resources are the main source of nutrients. Organic resources are the entry point; these serve other functions besides nutrient release. Access to organic resources has social and economic dimensions. Limited success due to shortfalls in infrastructure, policy, farming systems, etc. Limited adoption; organic matter production requires excessive land and labor. Difficulties to access organic resources hampered adoption (e.g. improved fallows). On-going; several success stories (see below). 3

4 Relative increases in yield/ae LOW HIGH QUADRANT C - Low - high Tree and herbaceous improved fallows Alley farming with cereals Biomass transfer systems Slash and burn, shifting agriculture Fortified composting Transfer of agro-industrial by-products QUADRANT A Low - low -Earthworm composting - Bio-solids and municipal wastes - Alley farming with root crops in sandy soils -Live fences in small farms Insert [Technology and Adoption potential under development] ISFM for cassava - based systems ISFM for NERICA Integration of ISFM in conservation agriculture Large - scale u se of phosphate rock QUADRANT D High - high Fertilizer micro - dosing ISFM and soil and water conservation in semi-arid - areas Dual purpose grain legume - cereal rotations with fertilizer targeted to different phases of the rotation Improved cereal - legume intercrops with adjustments in row arrangement QUADRANT B High - low Germplasm and fertilizer Crop residue or manure utilization Domestic composting Grain legume-cereal rotations or Intercrops without fertilizer N-efficient cereals, germplasm tolerant to low soil acidity Great potential but at present limited knowledge Relative adoption potential and effectiveness to contribute to soil fertility improvement for various SFM interventions. LOW Adoption potential HIGH 4

5 The ISFM components Dealing with variability Focus on Agronomic Efficiency Fertilizer and Improved Germplasm Combined application of organic and inorganic inputs Adaptation to local conditions 5

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7 Variability within a farm is as huge as within the entire continent Area Organic C (g kg -1 ) Total N (g kg -1 ) Available P (mg kg -1 ) Exchangeable K (mmol kg -1 ) Agro-ecozones (-2 cm) Equatorial forest NA* NA Guinea savanna NA NA Sudan savanna NA NA NA NA Fields with in a village Home garden Village field Bush field

8 Crop yield Focus on agronomic efficiency AE = (Y F -Y C )/F appl Linear response? 8 5 kg/ha Capture efficiency Conversion efficiency Nutrient application rate 8

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10 7 6 (a) grain yield 8 Yield (kg ha -1 ) AE 2 1 N-AE (kg (kg N) -1 ) Fertilizer N applied (kg N ha -1 ) AE constant in the linear part Then decreases non linearly to zero 1

11 Yield with fertilizer (kg ha -1 ) (b) A B C grain yield AE N-AE (kg (kg N) -1 ) Yield without fertilizer (kg ha -1 ) Three zones: - poor, less responsive soil (A) - maximal yield increases (B) - good, less responsive soils (C) 11

12 crop yield yield from ISFM yield increase from improved AE yield from fertilizer alone yield increase from additional nutrients increase in AE nutrients in fertilizer fertilizer equivalency organic inputs nutrients applied 12

13 maize grain yield [t ha -1 ] Some examples of different AE s 7 6 home field outer field AE=15 Maize response to SSP fertilizer application and AE in home and outer fields Murawe, Zimbabwe (Zingore et al. 27) AE=12 AE=85 AE= P applied [kg P ha -1 ] 13

14 Yield with fertilizer (kg ha -1 ) Agronomic efficiency (kg kg -1 ) 3 (a) Kibungo-Bugesera Umutara Yield without fertilizer (kg ha -1 ) 12 (b) Kibungo-Bugesera Umutara Grain yield of common beans with DAP and AE in function of grain yield w/o fertilizer - Farmers fields - Eastern Province of Ruanda -3 Yield without fertilizer (kg ha -1 ) 14

15 Example 1: 12 on-farm trials in west Kenya: Recommendation from Ministry of Agriculture (MoA) is compared to 3 ISFM practices. ISFM compensates for reduced fertilizer rates with higher AE, greater yields and profits Management fertilizer input Maize yield Net return benefit:cost ratio AE kg /ha kg/ha $/ha kg/kg Maize-bean intercrop none na w/ MoA recommendation 59 N & 13 P w/ P replenishment 38 N & 33 P w/ 2 t rock P fortified compost 29 N & 6 P Staggered intercrop w/groundnut (Mbili) 25 N & 13 P

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17 maize maize legume legume maize maize MBILI intercropping system Sampling positions 1m.5m X X X X X X X X X X Selected maize plant 17

18 aboveground biomass yield (t ha -1 ) MBILI intercropping Ordinary 1:1 intercropping y = 1.69X + 29 r 2 =.17** d 13 C ( ) 18

19 15 ordinary 1:1 intercropping system MBILI intercropping system root density (m m -2 ) 1 5 SED (-2cm) SED (2-5cm) -2cm 2-5cm 19

20 Conclusions of the Mbili trial - No differences in δ 13 C signatures in any of the seasons despite wide variations in rainfall amounts and distribution. - Benefits of the MBILI system unlikely related to improved WUE. - Mbili system entails better NUE or reduced photosynthesis costs for roots 2

21 Example 2: Management of Striga, in Kenya Over 22 * 1 6 ha of cropland infested in SSA Management fertilizer Maize net benefit:cost AE 2 input yield return ratio kg /ha kg/ha $/ha kg/kg Recommended hybrid H N & 5 P Push-pull with Desmodium 24 N & 5 P Tolerant OPV KSTP N & 5 P Herbicide resistant hybrid 24 N & 5 P Striga infested farms (< 1 Striga seeds ha -1 ) Maize yield without fertilizer is 1483 kg ha -1 21

22 Integrated Soil Fertility Management (ISFM) to bridge yield gaps A set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs and improved germplasm combined with the knowledge on how to adapt these practices to local conditions, aiming at maximizing agronomic efficiency of the applied nutrients and improving crop productivity. All inputs need to be managed following sound agronomic principles Vanlauwe et al., 21 22

23 Yield/ Agronomic efficiency Increase in knowledge A C B Responsive soils Poor, less-responsive soils Current practice Germplasm & fertilizer Move towards ISFM Germplasm & fertilizer + Organic resource mgt Germplasm & fertilizer + Organic resource mgt + Local adaptation Full ISFM 23

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25 Grain yield (kg ha -1 ) Grain yield (kg ha -1 ) Concepts of Integrated Soil Fertility Management in Africa: common sense or revolution Component 1: Improved germplasm + fertilizer 6 6 without without fertilizer fertilizer with with fertilizer fertilizer 5.6 SED* SED* (variety (variety effect) effect) VCR 4 4 SED** SED** (fertilizer) (fertilizer) kg P 6 kg N 25 kg K sites Kasaï Kasaï Kuleni KuleniBH14 BH14BH54 BH54 Performance of OPV maize varieties in Sud-Kivu, DR Congo 25

26 Component 1: Improved germplasm + fertilizer Local variety, severely affected by CMD CMD = cassava mosaic virus disease Improved variety (Nsansi), resistant to CMD Performance of improved cassava varieties in Bas-Congo, DR Congo 26

27 Component 1: Improved germplasm + fertilizer CIALCA trials in Kabamba, Sud-Kivu, DR Congo. without fertilizer with fertilizer (2 bags of NPK ha -1 ) 27

28 Bush bean grain yield (kg ha -1 ) Component 1: Improved germplasm + fertilizer Fertilizer response in Eastern Rwanda Significant responses to N and P Importance of appropriate fertilizer management 3 control 25 a FYM ab DAP 2 b DAP+FYM 15 c with DAP control 1 5 a a a a Murambi Nyakigando Sole DAP was applied at 2 bags per ha, and FYM at 5 t DM ha -1. Mixture combines DAP at 1 bag per ha and FYM at 2.5 t DM ha

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30 maize grain yield (t ha -1 ) Component 2: Organic matter management Strategic use of farmyard manure 8 without fertilizer with fertilizer AE = 7.9 AE = 6.3 AE = 8.8 kg kg -1 kg kg -1 kg kg -1 without FYM FYM, broadcast FYM, in holes 3

31 Component 2: Organic matter management Organic matter generation through dual-purpose legumes maize grain yield (kg ha -1 ) control 3 with fertilizer SED1 SED2 2 1 maize local CB improved CB local SB improved SB preceding crop 29 B 31

32 Component 2: Organic matter management Inoculation and application of P fertilizer to maximizebnf control +Pfert +ino +Pfert+ino 32

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34 Component 3: Local adaptation Allocation of nutrient resources to the most responsive fields results in maximized agronomic efficiency at farm level for a limited amount of fertilizer. Heterogeneity within farms Good Medium Poor 34

35 Maize grain yield(t ha -1 ) Component 3: Local adaptation Allocation of nutrient resources to the most responsive fields results in maximized agronomic efficiency at farm level for a limited amount of fertilizer. 8 without fertilizer with DAP+CAN fertilizer Homestead Mid-distance Remote 35

36 Maize grain yield(t ha -1 ) ) Component 3: Local adaptation 8 without fertilizer with DAP+CAN fertilizer Homestead Mid-distance Remote 36

37 Maize grain yield(t ha -1 ) ) Component 3: Local adaptation 8 without fertilizer with DAP+CAN fertilizer 6 4 Maximal yield gain 2 Homestead Mid-distance Remote 37

38 Bush bean grain yield (kg ha -1 ) Component 3: Local adaptation Variability in yield response due to management and soil-related factors Fertilizer response in beans in Eastern Rwanda control a FYM ab DAP b DAP+FYM c a a a a Yield with inputs (kg ha -1 ) FYM (a=1.19, R²=.84) DAP (a=1.36, R²=.75) Murambi Nyakigando 1/2FYM+1/2DAP (a=1.34, R²=.79) Yield without inputs (kg ha -1 ) 38

39 Component 3: Local adaptation Variability in yield response due to management and soil-related factors Fertilizer AE (kg kg -1 ) DAP 1/2FYM+1/2DAP Poly. DAP (Series4) Poly. 1/2FYM+1/2DAP (Series5) Yield without inputs (kg ha -1 ) 39

40 Component 3: Local adaptation Variability in yield response due to management and soil-related factors Fertilizer AE (kg kg -1 ) DAP 1/2FYM+1/2DAP Poly. DAP (Series4) Poly. 1/2FYM+1/2DAP (Series5) Remote -4 or poorly managed fields Yield without inputs (kg ha -1 ) Well-managed homestead fields 4

41 Component 3: Local adaptation Variability in yield response due to management and soil-related factors 12 DAP /2FYM+1/2DAP 1 Fertilizer AE (kg kg -1 ) Poly. DAP (Series4) Poly. 1/2FYM+1/2DAP (Series5) Fertilizer AE (kg kg -1 ) Distance from homestead (minutes walking) Delay in planting (days) AE decreases with distance from homestead AE decreases with delay in planting time 41

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43 Maize grain yield(t ha -1 ) Component 4: Rehabilitation of degraded soils 8 without fertilizer with DAP+CAN fertilizer Homestead Mid-distance Remote What about unresponsive soils? 43

44 Component 4: Rehabilitation of degraded soils Chemical degradation (soil acidity or deficiencies in secondary nutrients) LIME for increasing soil ph (with suitable Ca:Mg ratio!) MODIFIED FERTILIZER BLENDS (e.g., Multi-nutrient blends such as the Mavuno product range from Athi River Mining: Planting blend (N, P, K, Ca, Mg, S + micronutrients) + topdressing (N, Ca, S) FOLIAR FERTILIZERS for application of secondary nutrients SEED COATING with micronutrients (e.g., Zn, Mo, ) (FIPS Kenya) Physical degradation requires investments in soil organic matter 44

45 Component 4: Rehabilitation of degraded soils Degradation by soil erosion Progressive terracing using Calliandra Radical terraces in Rwanda 45

46 Crop production (kg ha -1 ) Cumulated soil loss (kg m -2 ) 4 3 (+22%) (+19%) (+69%) Year 1 Year 4 (+62%) Rehabilitation by terracing? 2 1 control hedgerows fanya juu fanya juu +hedgerows On short term and still after 4 years, control the better treatment for yield. But, considerable less soil loss 4 (+29) Year 1 Year 4 3 (+21) 2 1 (+9) (+6) control hedgerows fanya juu fanya juu +hedgerows 46

47 Rehabilitation with manure? 3 years of high rates of FYM P application (kg/ha) (Zingore et al, 27) 47

48 Meta-analysis Impact of various ISFM components on AE - Proper fertilizer management - Use of improved varieties - Combining organic inputs and fertilizer - Adaptation of input application rates to within-farm SF gradients Validate the realistic basis of conceptual diagram of ISFM? 48

49 Meta-analysis - Only peer-reviewed literature - Only trials that include control yields - Trials with N-fertilizer responses - Maize based cropping systems in SSA - Farm surveys, multi-locational on-farm trials, replicated on-station trials - Exclude data points with low N-AE due to high N rates 49

50 N-AE (kg kg -1 N) N-AE (kg kg -1 N) y=86 East/Central Africa x=5 <3 kg N/ha 3-6 kg N/ha 6-9 kg N/ha >9 kg N/ha Power function y=88 x=52 East/Central Africa <1. t/ha t/ha t/ha >3.3 t/ha 6 y=4e+12*x y=823*x y=84 9 Southern Africa x= x=52 y=89 Southern Africa 6 y=2e+11*x y=3179*x y=67 x=21 West Africa y=1e+8*x y=61 3 West Africa x=96 y=56596*x Maize yield in the no-input control (kg ha -1 ) Fertilizer N applied (kg N ha -1 ) 5

51 N-AE (kg grain kg -1 N) Average SED 5 Germplasm Local Improved - OPV Improved - Hybrid N-AE for local, improved open pollinating and improved hybrid varieties - Increase in N-AE from 17 to 26 kg.kg -1 N 51

52 N-AE (kg grain kg -1 N) Sole fertilizer Class 1 organic inputs Class 2 organic inputs Class 3 organic inputs Manure or compost (a) SED Pr > F.6 n=366 * * * N-AE affected by mixing fertilizer with organic inputs - Lower N-AE with class 1 or 3 due to different reasons - Class 2 alleviation of other than N constraints - Manure/compost highest N-AE 52

53 Control maize yield (kg ha -1 ) N-AE (kg grain kg -1 N) N-AE (kg grain kg -1 N) 3 25 (a) (b) (c) 2 3 SED 3 SED SED Infield Outfield Infield Outfield High Q Low Q N-AE as affected by targeting within- farm soil fertility gradients - Targeting to infields doubles N-AE from infield to outfield; from lower quartile to higher quartile 53

54 Basic principles well founded - ISFM components improves N-AE 54

55 Conclusion: ISFM? Old wine in new casks? Compare with the Green Revolution 55

56 Fertilizer-based Green Revolution Integrated Soil Fertility Management Approach Feasibility Does the technology work? Accessibility Can the technology reach its intended beneficiaries? Product-led: lost soil nutrients are replaced through the purchase and application of mineral fertilizers. Applying the right type of fertilizer at the required rate results in improved crop yield and increased farm profits but investment in fertilizer increases farmers risk during less favorable growing seasons. Mineral fertilizers are industrial products that must be manufactured, packaged, transported and marketed to farmers who are willing and able to purchase and apply them. Fertilizers may be packaged in ways making them more attractive to farmers. Knowledge-driven: limited farm resources are strategically complimented by purchased farm inputs Combining mineral fertilizers with organic resources and improved germplasm and integrating them into more efficient farming operations improves fertilizer and water use efficiency, crop yield and profits. ISFM requires access to information that builds a set of flexible principles empowering farmers to make better decisions concerning allocation of limited available resources and permitting higher yields from modest investment in farm inputs. 56

57 Fertilizer-based Green Revolution Integrated Soil Fertility Management Scalability Can the technology be adjusted over a wide range of conditions? Some fertilizers are broadly applicable to different soils and crops while others are intended for specific commercial enterprises. Product information and marketing campaigns increase awareness of fertilizers. ISFM techniques can readily spread among farmers engaged in similar enterprises, particularly when backstopped by demonstrations, farmer field days and agricultural officers. Sustainability Does the technology continue to operate without external support? Demand for fertilizers continues when they are efficiently distributed, fairly priced and profitably used. The ability and willingness to purchase additional fertilizers depends upon fair markets for crop surpluses. Fertilizer sales support local business enterprise. ISFM increases demand for fertilizers and improved seed. Robust practices optimize yield and profits during good growing seasons while reducing risks of drought, pests and disease under less favorable circumstances. ISFM practices enhance soil and environmental quality. 57

58 Conclusions ISFM works: AE can increase from 14 to double (Malawi seeds and fertilizer programme!) Need for fertilizer and improved varieties Access to input/output markets and access to credit Farmers schools, appropriate OM management instruction Agrodealer training Enabling environment: markets 58

59 Thanks to many Adrien Cremers Abigael Nekesa Otinga E&ES Benjamin Horemans Bernard Vanlauwe Bruno Delvaux C. Van Moorleghem Daniel Mugendi DGD IAEA Els Buyse Elke Vandamme Erik Smolders Frans Schoovaerts Generose Nziguheba Gerard Govers Gerd Dercon Isabelle Vandeplas Seppe Deckers Jan Diels Jan Feyen Johan Six KAOW Karlien Cassaert Koen Van Keer Ken Giller Kristin Coorevits Kristof Van Oost Laetitia Six Lieven Van Holm Marnik Van Clooster Miet Maertens Monicah Mucheru Nteranya Sanginga Pieter Pypers Paul Woomer Richard Thompson Robert Okalebo Rony Swennen Ruth Njoroge Sofie Bruneel Steven Bouillon UCL-LLn VLIR-UDC 59