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Agronomic practices, post harvest handling and management to mitigate for Aflatoxins in grains, Guantai S.M. ACDO/VOCA Kenya
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Agronomic practices, post harvest handling and management to mitigate for Aflatoxins in grains, Guantai S.M. ACDO/VOCA Kenya


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Presentation from the Aflacontrol Conference on Aflatoxins, Food Safety and Food Security, Nairobi, Kenya January 2011

Presentation from the Aflacontrol Conference on Aflatoxins, Food Safety and Food Security, Nairobi, Kenya January 2011

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  • 1. Aflacontrol Pilot Project Conference, Southern Sun Hotel 13 th January 2011 Agronomic practices, post harvest handling and management to mitigate Aflatoxins in grains Guantai S.M. ACDI/VOCA Kenya
  • 2. Food Grains
    • Grains are major staples in the tropics and the developing world.
    • Grains are highly nutritious hence form the bulk of the food eaten
    • Major component of animal feed industry.
    • Important industrial raw material.
    • Good substrate to other organisms.
    • Grown by virtually two in every three farmers in Kenya.
  • 3. Importance of good Planning
    • To achieve good quality in maize grains:
      • Plan ahead and carry out the following:
        • How much land to plant and how to plant
        • Early seedbed preparation; preferably immediately after harvest of previous crop when soil is still wet.
        • Soil testing to get proper guidance on nutrient requirement. (This can be carried after a given period or in stages if land size is big).
        • Acquire certified seeds and other farm inputs on time.
        • Practice crop rotation to avoid pathogen accumulation and to replenish nutrients.
  • 4. Early land preparation
    • Plough to bury trash for ease of decomposition and a clean seedbed.
    • Avoid hard pan and destruction of the soil structure and the flora and fauna.
    • Soil and water conservation practices adopted.
  • 5. Conservation tillage
    • Practice Conservation Tillage to incorporate trash as a cover mulch and add organic matter to soil.
    • Chisel plough to break hard pans and create channels for water percolation.
    • Liming needed in acidic soils to ameliorate the soil. ( Effect usually noticed in subsequent seasons).
    • Use Glyphosate to clear unwanted vegetation.
  • 6. Timely Planting
    • Recommended varieties suited to agro-ecozone
    • Plant certified seed to maximize benefits
    • Plant at onset of rains or just before rains
    • Clean seedbed---- maize best on loamy deep soils, pH 5-7.
    • Check and calibrate all equipment and machinery prior to operations.
    • Remember maize requires at least 500 – 700 mm of well distributed rains during it’s growing period.
  • 7. Seed Selection and Variety
    • Agro climatic suitability of the variety
    • Uniformity in growth
    • Disease and pest tolerant
    • Standability
    • Maturity period
    • Sheathing
    • Drooping ear
    • Yield potential
  • 8. Planting
    • Depth of planting not too shallow or too deep (5-8 cm).
      • desiccation or damage by pests if shallow
      • seed exhaust food before emergence if deep.
    • Planting fertilizer (Phosphate, preferably DAP)
    • Depth of fertilizer application below the seed or to the side of Seed (10 cm deep, or to the side)
    • For soils low in P and K as a starter application 10-15 cm deep is recommended.
  • 9. Fertilizer Application and nutrient requirement
    • Maize requires up to 16 elements for healthy growth. Most of these are required only in minute quantities.
    • The most important nutrients required are Nitrogen phosphorous, Potassium and sulphur and to some extent calcium and magnesium.
    • Nitrogen is required for plant growth and makes up to 1-4 % of the plants dry matter.
    • Phosphorous plays a key role in the transfer of energy and photosynthesis. It is required at planting time.
    • Maize takes up considerable nutrients from the soil and some of them are retained in the stover and the grain after harvest hence the need to replenish.
  • 10. Nutrient deficiencies and crop growth
    • When fertilizer or organic matter is not used there is low nutrients in soil leading to:
      • Stunted plants with poor root formation. Leaves turn purplish. Small cob curved at top (starved of P)
      • Stunted plants, yellowish leaf colour and small cob a result of N 2 deficiency.
        • Easily attacked by fungi and diseases
        • Poor yields lead to temptation to retain suspect grains
  • 11. Emerging seedlings
    • Emergency usually within 7 days of planting after onset of rains.
    • Scouting (check on soil crust, soil pests, poor germination).
    • Gap if needed
    • Carry out first weeding at 3-5 leaf stage
    • Carry out second weeding at Knee high
    • Top Dressing with N 2 (approx..50cm high or 6 - 8 leaf stage. Split N 2 application recommended
    • Dust for stalk borer (recommended spot application).
      • (Poor growth result in weak plants that are easily attacked by pests, diseases and fungi)
  • 12. Control weeds, field pests and diseases
    • Weeds harbour pests, compete for moisture and nutrients and suppress growth.
    • Field pests cause 14% loss or more.
    • They create avenues for disease and fungal infestation.
      • Unhealthy crops easily attached by Fungi and other pathogens, while low yields create temptation to retain poor grains)
  • 13. Field Pests
    • The maize crop is very nutritious and therefore attracts pests. Need for IPM.
    • These are leaf eaters, borers and suckers.
    • Farmers need to scout the field and carry out spot application of the recommended pesticide.
      • Loss in yields result in temptation to retain poor quality grains
  • 14. Maize diseases
    • Diseases creates avenues for other pathogens including fungi
    • Most diseases are managed by use of certified seeds treated with a pesticide and fungicide.
    • Other approaches to control are breeding for tolerant varieties
    • Use of biotechnology to develop herbicide resistant biotypes.
  • 15. Growth to Maturity
    • Within 2-3 weeks the nodal roots begin to develop, followed by rapid growth in the next 4-5 weeks and by V 15 it is about 12 days to silking.
      • Ensure roots not damaged during weeding
    • At maturity the plant will have grown up to 20 leaves
    • From about 2 weeks to tasseling and 2 weeks after maize is very sensitive to moisture stress.
      • Stressed maize is a good candidate for fungal and disease attach
  • 16. Management at silking stage
    • The silking stage is when pollen is captured and fertilization occurs.
    • The number of fertilized ovules determine number of kernels.
    • This is a critical period and any stress will cause poor pollination and seed set.
    • It is a period of high nutrient uptake hence need for a second dose of top dressing
  • 17. Moisture management continued
    • This is the time of high moisture uptake.
    • Drought conditions will lead to high crop damage.
    • Stress will create opportunity for fungal and pathogen infestation
    • (Courtesy of SeedCo)
  • 18. Good Maize crop stand
    • Proper spacing and plant density (about 55,000).
    • Clean crop field.
    • Healthy plants
      • Are an assurance of stress free crop with high yields and grains free of diseases, pests and fungi
  • 19. Harvesting
    • Harvest early at physiological maturity (grain moisture content will be around 26%)
    • Stook maize for two or more weeks to dry on the field (grain moisture will reduce to 18%).
    • De husk and remove from field for shelling, conditioning, further drying to 13.5% m.c. and storage
    • Ensure crop is not left on ground and bare soil.
      • Fungal spores are found on the soil
  • 20. Drying and conditioning
    • The grain must be properly dried (<13.5% M.C).
    • Use tarpaulins or clean paved surface for drying the grain.
    • Cleaned and sieved to remove broken, foreign matter, diseased and rotten grains.
    • Dust for pests (apply the pesticide on cool grains.
    • Weighed and bagged in natural fibre bags for storage.
      • Grain that is broken or with foreign matter attracts moisture and pests leading to spoilage and or fungal growth
  • 21. Storage and management
    • The storage is very important at the farm, trader, transporter, processor and consumer level.
    • Common practice by farmers ---store grain in residential houses
    • Grains stored in pp or plastic bags common
    • Do not commingle new and old stocks or treated and untreated stocks.
    • FIFO and good records
  • 22. Asante
    • With the support of Bill and Melinda Gates Foundation