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Low External Input Sustainable Agriculture (LEISA) approaches to soil fertility management

Low External Input Sustainable Agriculture (LEISA) approaches to soil fertility management. Optimise soil conditions for plant growth Principles timely availability of water, air, nutrients good soil structure appropriate soil temperatures

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Low External Input Sustainable Agriculture (LEISA) approaches to soil fertility management

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  1. Low External Input Sustainable Agriculture (LEISA) approaches to soil fertility management • Optimise soil conditions for plant growth • Principles • timely availability of water, air, nutrients • good soil structure • appropriate soil temperatures • minimise toxicity and / or practices which lead to toxicity

  2. Optimising nutrient availability & cycling Principles

  3. Limit nutrient losses by: • recycling of organic waste • reduce leaching (e.g. by using bedding straw • for cattle to conserve urine) • reduce runoff & soil erosion • reduce burning of stubble • use slow-releasing fertilisers such as rock • phosphate • nutrient pumping by deep rooted spp. • limit nutrient export by producing crops with • relatively high economic value compared to • nutrient content (fruits, nuts, herbs)

  4. Capture / manage nutrients by: • utilising legumes / N-fixing bacteria or blue-green algae • encourage capture of (water and air-borne) sediments • from outside flowing over farm • make maximum use of livestock manure • use green manures

  5. Supplement nutrients by: • use of OM from off farm (e.g. agro-industrial waste); • purchased fodder and/or concentrates Use complementary systems: e.g. .........

  6. Manure handling & improvement • Improve quantity / quality by: • adjusting animal numbers / species • improved feeds (more concentrates, more legumes, • urea treatment of residues) • minimise distances between collection & application • points (but N.B. effect of collection on non-arable land • fertility) • use chicken manure (sheds) • bat droppings ?

  7. Composting • improves quality of organic fertiliser • heaps or pits (latter better in hot climates • - less oxidation) • in situ applications

  8. constraints: • availability of materials • transport • labour • water • cultural taboos • oxidation (mainly where there is a hot dry season; • reduced by decreasing tillage intensity)

  9. Green manures • improve OM and N • other elements translocated to top-soil • cover crops such as yam bean (Pachyrrhizus erosus) & • Mucuna utilis suppress weeds such as Imperata spp. • which may proliferate as a result of shortening or • eliminating fallows

  10. Forms include: • improved fallow (whole year or dry season • pre-planting crop (in rice in India) • alley cropping (prunings used as a mulch or incorporated) • single trees in field • (legumes such as Erythina poeppigiana cut for mulch) • relay fallows (plant dry season green manure fallow • before harvesting main crop, e.g.Tephrosia vogelii, • Sesbania rostrata, Mucuna pruriens • live mulches - food crops sown into cover crops such • as Centrosema pubescns, Pueraria phaseoloides, • Arachis prostrata after strips removed by herbicides or • hand to reduce tillage operations • azolla and blue-green algae

  11. Some green manure exotic species for improving soil fertility include: see table in handout

  12. Criteria for selection of plants for improved fallow :

  13. Problems include: • shortage of land • seasonal migration (India) Can you think of others ...

  14. Use of mineral fertilisers • apply in low to moderate amounts in combination with • organic fertilisers • increase efficiency by control of weeds, crop pests, • diseases, soil erosion, leaching, rotations (shallow then • deep rooted crops), attention to timing (e.g. split • applications for N), applying fertiliser below surface • near roots • use mild fertilisers for preference (e.g. "Thomas slag", • thermo-phosphate, bone-meal) • CAN better than urea better than AS • mineralisation of rock phosphate accelerated by • acidification (e.g. by adding to compost)

  15. Vermiculture • manure + earthworms  less manure (30% reduction) • + vermicompost + more earthworms • surface application • mass of earthworms produced = 5% of manure weight • reduces environmental contaminants in solution • pH becomes more neutral

  16. Examples of indigenous sources of nutrients • termite mounds for sorghum / cowpea in Sudan & Congo • ant refuse for fertilising crops in Mexico • Faidherbia albida / sorghum & millet systems in Senegal : • mulch / shade / recycled nutrients • use of weeds as green manure and mulch in Tanzania

  17. Managing flows of solar radiation, water, air • Principles • Improve micro-climates by: • crops of different heights • shade, wind protection • Improve soil moisture by: • improving soil structure & OM • tillage • mulches • Reduce erosion by: • vegetative measures • physical measures

  18. Mulches • Zero tillage • Wind breaks • Water harvesting • Tied ridging • Strip cropping • Permeable contour-line barriers • Small ponds

  19. Integrated farm systems • Bio-intensive gardening (example) - double dug beds

  20. double dig raised beds 30 to 60 cm • keep covered with crops or mulch • liquid manure (40 kg of weeds & dung in 200 • litre drum; left for 3 weeks; mix liquid 1:3 with water, • apply every 10 days) • many spp. of veg. & fruits

  21. Crop - livestock - fish-farming

  22. Farmer involvement • indigenous knowledge investigations / databases • / self-awareness • encouraging farmer to farmer spread / training • farmer experimentation • participatory technology development (PTD) • exposure visits

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