Microdose fertilisation : a step on the ladder towards crop intensification in the Sahel?

Transcription

1 Microdose fertilisation : a step on the ladder towards crop intensification in the Sahel? Charles Bielders UCL Total millet production, millet grain yield and harvested area in Niger Yield Area Production 1

2 Productivity Productivity Pathways to sustainable intensification Vanlauwe et al., 2010 Soil fertility / quality of natural resource base Pathways to sustainable intensification Vanlauwe et al., 2010 Soil fertility / quality of natural resource base 2

3 Productivity Productivity Pathways to sustainable intensification Integrated Soil Fertility Management (ISFM) Long-term fallow Vanlauwe et al., 2010 Soil fertility / quality of natural resource base Pathways to sustainable intensification ISFM Vanlauwe et al., 2010 Soil fertility / natural resource status 3

4 Productivity Agricultural intensification in the Sahel: «The ladder approach» Microdose (12-60 kg fertilizer / ha) Demand on capital, labour, Market integration, policies, Aune and Bationo, 2007 Microdose fertilisation Two main characteristics: Localised placement of fertilizer : at sowing, thinning, booting, ; mixed with seed or not Micro-dose : small doses of essential nutrient(s). 2 to 6 g fertilizer / hill. 4

5 Microdose fertilisation in the Sahel Focussed on the main limiting nutrient (P), but N generally also supplied Typically (for hills/ha): 2 g DAP( )/hill = 4 kg P/ha and 3,5 kg N/ha 6 g NPK( )/hill = 4 kg P/ha and 9 kg N/ha Millet yields multiplied by a factor of Buerkert et al.,

6 Microdose fertilisation demonstration trials (Millet) Yield Control (kg/ha) Yield gain (%) Range yield increase (kg /ha) Fertilizer Country Ref. 305?? % 118% 116% 61% 90% < DAP, 2g <0-900 DAP or NPK Niger (1) Burkina (2) % DAP, 2g Niger (3) 571 ( ) 83% (4% 125%) DAP, 2g Mali (4) % 130% 76% 144% 123% DAP, 2g NPK, 4g NPK, 4g Mali Burkina Niger (5) Niger (6) Not specified ? Niger (7) (1) Buerkert et al., 2001; (2) Tabo et al. 2011; (3) Hayashi et al., 2008; (4) Camara et al., 2013; (5) Bagayoko et al., 2011; (6) Aune et al., 2007; (7) Bationo et al., 2005 Microdose fertilisation Microdose = step on the intensification ladder? Based on average yield response, yes! BUT «Does one size fit all?» : Are blanket recommendations recommended, irrespective of : Resource base (soil fertility)? Management (Manure, planting dates, )? Climate? 6

7 Microdose fertilisation (Millet) Yield Control (kg/ha) Yield gain (%) Range yield increase (kg /ha) Fertilizer Country Ref. 305?? % 118% 116% 61% 90% < DAP, 2g <0-900 DAP or NPK Niger (1) Burkina (2) % DAP, 2g Niger (3) 571 ( ) 83% (4% 125%) DAP, 2g Mali (4) % 130% 76% 144% 123% DAP, 2g NPK, 4g NPK, 4g Mali Burkina Niger (5) Niger (6) Not specified ? Niger (7) (1) Buerkert et al., 2001; (2) Tabo et al. 2011; (3) Hayashi et al., 2008; (4) Camara et al., 2013; (5) Bagayoko et al., 2011; (6) Aune et al., 2007; (7) Bationo et al., 2005 Demonstration trials 279 on-farm trials, 3 years Millet, local land race Fertilizer treatments: Control, 2 g DAP, 6 g NPK per hill 5 Manure management levels Farmer s management : sowing density, sowingweeding-harvest dates Soil, rainfall, corralling 7

8 Yield difference microdose vs. control (kg/ha) Difference in grain yield between microdose and control plot (kg ha -1 ) Difference in grain yield between microdose and control plot (kg ha -1 ) Difference in grain yield between DAP or NPK microdose plots and the control plots, as a function of yield in control plots No manure Manure Millet grain yield in control plot (kg ha -1 ) Millet grain yield in control plot (kg/ha) Bielders and Gérard, 2014 Difference in grain yield between DAP or NPK microdose plots and the control plots, as a function of yield in control plots No manure Manure Millet grain yield in control plot (kg ha -1 ) Bielders and Gérard,

9 Cumulative probability (-) VCR = 1 Cumulative probability (-) 1.00 Risk analysis Cumulative probability distribution of microdose value-cost ratios for three different classes of millet grain yields in control plots kg/ha kg/ha > 400 kg/ha Value / Cost Ratio 1.00 Risk analysis Cumulative probability distribution of microdose value-cost ratios for three different classes of millet grain yields in control plots kg/ha kg/ha > 400 kg/ha Value / Cost Ratio 9

10 Square root (Yield) Microdose by Sowing date interaction on millet grain yield (kg/ha) Control : y = x ; R² = 0.05 DAP : y = x ; R² = NPK : y = x ; R² = Linéaire (Control) Linéaire (DAP) Linéaire (NPK) ~May 1 ~July 15 Sowing date (DOY) Bielders and Gérard, 2014 Conclusions Advantages of microdosing Fertilizer input reduced by a factor 3-4 compared to recommended broadcast fertilization Self-adjusts to plant density Low initial financial investment Often substantial yield increases, on average! Higher water use efficiency than farmer practice May help mitigate yields losses due to late onset of rainy season 10

11 Cumulative probability (-) Microdose fertilization: a reliable step on the intensification ladder? Ladder : «A series of ascending stages by which someone or something may progress» kg/ha kg/ha > 400 kg/ha Value / Cost Ratio Best to target those fields (or parts of fields) where low productivity is expected. To be confirmed! Conclusions Microdose fertilization By no means an end in itself Short-term productivity boost to increase yields and biomass production, must be accompanied by optimal recycling of organic resources Open issues: nutrient mining arrested? Need for enabling markets and policies 11