Sustainable Intensification of Drylands Agriculture: Prospects for Improved Varieties and Crop Management Technologies in SSA

Transcription

1 Sustainable Intensification of Drylands Agriculture: Prospects for Improved Varieties and Crop Management Technologies in SSA Tom Walker with colleagues from ICRISAT and ICARDA

2 Agro-climatic challenges: Dry Spells Early season drought 40 days to plant in the southern Sahel 80 days in the more rainfall-assured Guinean Zone Seedlings succumb to high soil temperatures Differences in India and West Africa s SAT Early season drought variable in West Africa Termination of the rainy season more variable in India Early onset means a longer growing season in West Africa Chronic drought in West African in the 1970s and 1980s partially led to the demise of groundnut exports to Europe

3 Differences in cereal production and rainfall from their mean levels between 1960 and 2000 in Burkina Faso

4 Agro-climatic challenges: Poor Soils Low native soil fertility Relics of 2 billion year old granites Volcanic soils richer, but fix P Severe micro variation within and across fields Farmers strategy to intensify on fields near home Soil fertility gradient from near to far fields Far fields become infertile with shortening of fallows N and P Macronutrients most lacking 80% of soils deficient in available P N supplied continuously; P managed as a stock 80% rock phosphate in Africa Nutrient mining okay sometimes Mineral fertilizers rarely damage the soil Both mineral fertilizers and manure are needed Evidence for land degradation: Cassava in Malawi

5 Composition of rainfed crop area by Aridity Index Classes, length of growing season, and rainfall in SSA circa 2000 Type of rainfed area Aridity Index Classes Average length of growing season (days) Average rainfall (mm) Share of rainfed cropped area (%) Dryland Dryland Dryland Dryland Rainfed wet Source: Constructed from the HarvestChoice database

6 Frequency distribution of maize yields weighted by area, by aridity index category n 10,204 n 21,910 n 22,745 n 23,780 n 40,635 n 120,128 Constructed from HarvestChoice database, 2014

7 Frequency distribution of maize yields weighted by elevation 1 = masl; n = 49,292 2 = masl; n = 31, masl; n = 29,472 4 = masl; n = 6,835 5 = masl; n = 1,910 6 = > 2500 masl; n = 941 Constructed from HarvestChoice database, 2014

8 Percent of dryland of total cropped area by commodity grouping Constructed from HarvestChoice database, 2014

9 Prospects for Genetic Improvement 1. Maintaining and accelerating the pace of varietal change 2. Introducing new varieties well-adapted to the drylands of SSA 3. Improving the availability of cereal hybrids in West Africa

10 Coverage of the DIIVA Project (Diffusion of Improved Varieties in Africa) 20 crops in 30 countries 152 crop by country observations; 65 are the same as in the Evenson and Gollin study 7 CGIAR centers Over 200 participating scientists, mainly from national programs 17 nationally representative surveys 4 impact assessment case studies Project duration: December 2009 to August 2013

11 DIIVA: Key findings by the numbers 1,300 FTE scientists; 3,500 released cultivars; 1,150 improved varieties and hybrids adopted 35% area in MVs in % MV adoption for continuing crops implies an annual gain of 1.45% 14 years: average varietal age 35% area in MVs declines to 31% if surveys were used instead of expert opinion CGIAR share in adoption 65%; released varieties 40%

12 Varietal output in SSA by crop and decade

13 Food crop adoption in SSA in 2010

14 Change in estimated level of adoption of improved maize and cassava varieties between 1997/98 and 2009/10 Maize Cassava Zambia Benin Zambia Malawi Guinea Uganda Zimbabwe Mali Cameroon Nigeria Tanzania Togo Kenya Ethiopia Angola Togo Mozambique Malawi Nigeria Cote d Ivoire Guinea Angola Benin DR Congo Ghana Uganda Cameroon Tanzania Burkina Faso Ghana Kenya Zimbabwe Senegal DR Congo

15 Improving availability of cereal hybrids in West Africa Almost no access to cereal hybrids in West Africa presently Advantages of hybrids higher yield potential more yield stability private sector incentives to fill the sub-regional profile with hybrids and seed Indian farmers strongly prefer hybrids to improved varieties in sorghum and pearl millet: the recent penetration of hybrids into Rajasthan Drawing on the experience of maize hybrids in ESA Recent development of Guinean hybrids in sorghum in Mali ICRISAT s hybrid parents research consortium (HPRC)

16 Introducing new varieties well-adapted to the drylands (CRPs) Dryland Grain Legumes 1. Drought and low phosphorus-tolerant bean, cowpea, and soybean 2. Short-duration, drought-tolerant, and aflatoxin-free groundnut 3. Insect smart production systems in chickpea, cowpea, and pigeonpea 4. High nitrogen-fixing chickpea, common bean, faba bean, and soybean 5. Pigeonpea hybrids and management practices

17 Farmer showing Striga-damaged sorghum Photo source: ICRISAT Happenings, 2012

18 Collaborative lab work at ICRISAT Photo source: ICRISAT Happenings, 2012

19 Striga-resistance results Photo source: ICRISAT Happenings, 2012

20 Partners in Research: ICRISAT ASARECA BeaC BMZ KARI Kenya IER-Mali University of Hohenheim National program: SUDAN (ARC), Eritrea, Kenya, and Mali Photo source: ICRISAT Happenings, 2012

21 Prospects for crop and land management technologies and for enhancing livestock interactions Conservation agriculture Micro-dosing fertilizers Improved intercropping systems Soil conservation and land management Animal traction

22 Conservation agriculture (no till, zero tillage) Extent Over 100 million hectares in dryland conditions mainly in the Americas and Australia Emerging interest in SSA since 1995; Very limited in India Principles Minimal soil movement Permanent soil cover with crop residues Crop rotations Characteristics Mulching with cereal straw Mechanical field operations limited to planting Limited traffic zones Weed management with herbicides

23 Plow Pan Damage Photo source: Haggblade, MSU, 2009

24 Crop Residue Retention Photo source: Haggblade, MSU, 2009

25 Minimum Tillage using a Hand Hoe Photo source: Haggblade, MSU, 2009

26 Potential beneficial outcomes Increased water infiltration into the soil Increased soil organic matter resulting in better soil structure, higher cation exchange capacity and nutrient availability, and greater water-holding capacity Increased and more stable crop yields Reduced production costs Increased biological activity in both the soil and the aerial environment leading to more biological control of pests

27 CIMMYT s experience in Malawi Eight years in nine communities Low livestock densities Rainfall infiltration improved by 24-40% Yield advantage 22-24% over control plots Yield advantage greater in dry areas Conclusion: CA can be practiced in diverse environments from sandy to clay soils, nutrient rich to infertile soils and from low to high rainfall areas as long as adequate inputs (fertilizer, herbicides and labor) are available with good extension support to farmers, especially in the initial years (Thierfelder et al. 2013, p. 147)

28 The Heretics View (Ken Giller and his colleagues) Site specific: Termites ate the mulch in Mozambique General: Benefits may be smaller and the costs greater than proponents expect in the drylands of SSA. Mulching materials have a high opportunity cost Yields may actually be lower in the near term CA practices may be more labor intensive The empirical evidence for improving soil organic matter, soil fertility, and below-ground biological processes and for reducing soil erosion is scanty CA as extended by NGOs and other agencies may not include fertilizer, and, when fertilizer is included, CA may require a higher dose to maintain yields on a par with those obtained through conventional tillage. The feasibility of introducing legume rotations on a large scale is questioned

29 Adoption research and meta-analysis Zambia - Conservation farming with planting basins Reportedly on about 100,000 hectares Positive benefits experimentally More labor but less labor seasonality Diligent and disciplined cotton farmers who cultivate about 1 ha by hand and desperately need fertilizer and herbicide No adoption in Mozambique (Too much labor and fertilizer diverted to potatoes from maize) Meta-analysis Brighter prospects in dryer environments Need well-drained soils No yield response in wetter environments (waterlogging with mulch) Need high input levels especially N

30 Micro-dosing Fertilizers Small amount of fertilizer is added to the planting hole at time of sowing Photo source: ICRISAT Impact Brief, 2012

31 Micro-dosing Fertilizers Began in the late 1990s A bottle cap of fertilizer per plant (6 grams) N or P; basal or top-dressed Solid evidence for response (Zimbabwe) 60,000 farmers participated 17 kg per ha N or 25% recommendation kg of grain yield per kg of N Often applied in subsidized conditions Generalizable research protocol that works Computer-based fertilizer response model On-farm trials prior to pilot extension program The perfect should not be the enemy of the good

32 Conclusions: Is the past prologue? What needs to be done to translate prospects into reality? 1. Investing in agricultural research National programs: Need more and younger scientists in cowpea, groundnut, pearl millet, and sorghum improvement CG centers: Need to recover from the doldrums of the late 1990s and early 2000s when staff strength was halved and regional crop networks discontinued (The B&M Gates Foundation)

33 2. Efforts need to be redoubled where adoption of improved varieties is lacking Lagging countries (e.g., Angola and Mozambique in maize) Lagging crops (e.g., pulses and durum wheat in Ethiopia) 3. Improving seed availability in grain legumes in general and groundnut in particular 4. Improving access to cereal hybrids in West Africa Liberalized seed and varietal release policies Training programs in hybrid seed production to demonstrate proof of concept Public provision of hybrid parental lines needed initially

34 5. Assessing the size of the opportunities afforded by marker-assisted selection, conservation agriculture and micro-dosing fertilizer Marker-Assisted Selection 6. Adoption of new varieties in old backgrounds 7. Scope for use of established protocols in other important traits Conservation agriculture: Unraveling its complexity to understand benefits and costs in varying edaphic, agroclimatic, and socioeconomic contexts Micro-dosing fertilizer 8. Labor-saving innovations

35 9. Adoption studies on acceptance of fertilizer in general and micro-dosing in particular 10. Expanding the prospects for intensification Mitigating Trypanosomiasis Accelerating the spread of Bt cotton 11. Sub-regionally targeting crop management and land and water management technologies for intensification Population density Market demand Soils 12. Targeting elevation in East & Southern Africa and length of the growing season in West Africa