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Effects recycling of rice straw 2009 09 23-v 07-2011


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Reycling of rice straw as an entry point to sustainable rice production, effects on soil, climate and farmers' incomes.
Author: Winfried Scheewe

Published in: Education, Technology
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Effects recycling of rice straw 2009 09 23-v 07-2011

  1. 1. Recycling of Rice Straw <br />- an entry point to sustainable rice production<br />Effects on soil, climate and farmers’ livelihoods<br />2nd ECHO Asia Agricultural Conference<br />September 21-25, 2009<br />Chiang Mai, Thailand<br />Winfried Scheewe<br />DED-Cambodia/CEDAC<br />Phnom Penh, Cambodia<br />
  2. 2. Does rice straw have any value?<br />Burning of rice straw is a common sight during the harvest period in many parts of South and Southeast Asia. <br />Farmers are unaware: Straw from one hectare contains 25 to 40 kg N. = Farmers are burning money. <br />Yet, the energy (carbon) contained in the straw may be even more important. <br />
  3. 3. Biomass open burning – Global overview<br />Burning of rice straw and other biomass is practiced in most Asian countries <br />
  4. 4. Overview<br /> We will look here at some details of the recycling of rice strawby scattering it equally in the field or mulching. <br />Effects on soil <br />Effects on the atmosphere <br />Effects on farmers’ livelihoods <br />will be discussed<br />
  5. 5. Why do farmers burn the straw?<br />Straw was traditionally used as fodder <br />Mechanization less animals needed<br />Additional cropping cycles<br />straw disturbs land preparation  waste<br />Availability of fertilizers<br />To supposedly prevent further spread of diseases<br />Concept: clean field, (variation of slash & burn)<br />
  6. 6. Why farmers should NOT burn it?<br />1 ton of straw contains:<br />5 to 8 kg nitrogen<br />1.2 kg phosphorous<br />20 kg potassium<br />40 kg silica<br />400 kg carbon<br />Per hectare, about 5 tons of straw are left<br />
  7. 7. What happens if the straw is burnt?<br />400 kilogram of carbon go back to the atmosphere<br />93 % of the nitrogen goes back to the atmosphere, = 30 to 40 kg N/ha <br />25 % of the phosphorous and 21 % of the potassium disappear <br />Silica is left, but the heat makes it insoluble.<br />Straw burns with temperatures up to 700◦ C<br />
  8. 8. What can farmers do instead?<br />Just leave the heap- do nothing (straw will slowly decay in one spot, much of the carbon will be lost)<br />Set up a compost pile (controlled composting) <br />Distribute the straw equally in the field <br />
  9. 9. Mulching – some considerations (1)<br />Scatter the straw equally soon (immediately) after threshing in the field<br />The straw is left for about 4 weeks on the surface to decompose before plowing<br />This allows bacteria involved in the decomposition to fix nitrogen from the atmosphere <br />
  10. 10. Mulching – some considerations (2)<br />Ideally combined with a green manure crop<br />If possible, the straw should be only shallowly incorporated to decom-pose more for several days under aerobe condition before further land preparation for the next planting<br />
  11. 11. What are the effects on the soil?<br />Nitrogen and other nutrients recycled<br />Additional N-fixed<br />Part of the carbon is incorporated into the humus (SOM) content of the soil <br />Nutrient deficienciesminimized<br />Iron (and other) toxicities reduced<br />
  12. 12. A closer look at Nitrogen<br />One tonne of rice grains absorbs about 12.5 kilogram N.If the yield is 4.5 tons, the grain contains approx. 56 kg N. <br />The straw contains about 30 kg N.<br />Grains 56 kg NStraw 30 kg N-------------------------------------Requirement 86 kg N<br />
  13. 13. Several farmers obtained yields of over 4 t/ha over many years without additional inputs.<br />Question:If no synthetic fertilizer was applied, where did the nitrogen come from?<br />- From the straw (per ha) 30 kg - N-fixation associated with the decomposition 25 kg- N-fixation by soil-borne micro-organisms 27 kg- Rain 4 kgTotal 86 kg N/ha<br />Several kind of orga-nismsare involved in natural processes which provide nitrogen to the crop.<br /> All need energy which the carbon of the straw supplies.<br />
  14. 14. Humus content<br />Over time, humus content increases<br />pH level ↑<br />Nutrient supply more balanced<br />Plant health improved<br />Insect problems less likely<br />Soil structure improved<br />Water retention increases<br />Nutrient deficiencies corrected<br />
  15. 15. Nutrient deficiencies corrected<br />Farm of Isidro Prado<br />After 15 years of conventional cultivationZinc deficiency became a problem<br />Yield declined by 60 to 70%<br />Straw application  within two years, yield back to normal levelsof over 4.5 t/ha(40 sacks from 0.38 ha)<br />
  16. 16. Iron toxicity corrected<br />In some places iron toxicity is a problem due to <br />strongly reducing conditions in the soil and/or low pH<br />low and unbalanced crop nutrient status <br />Causes stunted growth, extremely limited tillering.<br />These conditions can be corrected just by returning the straw<br />
  17. 17. Straw management and climate (1)<br />Burning  releases carbon<br />Philippines: 3.26 million tons C per year (= 12 million tons CO2)<br />Total emissions 2006: 8.4 Giga-tons carbon <br />Burning causes pollution (including polycyclic aro-matic hydrocarbons, some are toxic)<br />Incorporation  may add to releases of methane <br />
  18. 18. Straw management and climate (2)<br />The main sources of greenhouse gases emissions in agriculture<br />Million tons CO2 -eq<br />Agriculture contributes between 17 and 32% of all global human-induced green house gases.<br />Of this, 12% is caused by biomass (incl. rice straw) burning <br />Cool Farming: Climate impacts of agriculture and mitigation potential, (2008)<br />
  19. 19. Straw management and climate (3)<br />Decomposition under anaerobe condition: Methane emissions ↑<br />If synthetic N is applied Nitrous Oxide emissions ↑<br />Synthetic N requires energy (~1.4%of the world's annual energy supply)<br /> causes CO2 emission<br />Generally:Recycling of straw minimizes releases of CO2 + othergreen house gases from rice fields<br />Carbon (humus) in soil ↑<br />
  20. 20. Straw management and climate (4)<br />Soils can serve as carbon sinks<br />Generally, soils have lost carbon due to clearing and cultivation<br />Claim by IRRI scientists: Irrigated soils still high in humus (or SOM)<br />Rainfed rice fields provide different conditions than irrigated fields<br />
  21. 21. Effect on farmers’ livelihoods (1)<br />Comparaison MASIPAG (Organic) vs. Conventional (2003)<br />In the year 2003, the Philippine NGO TCSAI compared yield and income 10 pairs of farmers with adjacent organic and conventional fields irrigated fields and 12 pairs with rainfed fields.<br />The organic farmer, who recycled the straw had a almost 10 percent higher net income than their conventional neighbors. They had less costs for inputs, but therefore higher labor costs.<br />However, the cost-benefit analysis did not includecost for the capital necessary to purchase inputs. Commonly, loans for rice production are obtained from informal lenders. Thus, most conventional farmer have significant deductions from their income due to higher capital costs.<br />
  22. 22. Effect on farmers’ livelihoods (2)<br />Mr. Isidro Prado:<br />Before recycling rice straw he needed to borrow 4,000.00 Pesos and paid up to 3,500 Pesos for each PHP 1,000.00 (=14,000.00)<br />Later he needed to borrow only PHP 2,000.00 for which he paid a much lower interest rates (= 3,750.00) <br />
  23. 23. STOP burning rice straw<br />Need to raise awareness<br />Many NGOs promote sustainable practices <br />Many provinces and municipalities have issued ordinances prohibiting the burning of rice straw<br />
  24. 24. STOP burning rice straw (2)<br />Group of Advocates for Sustainable Agriculture, Inc.<br />Tandag, Surigao del Sur<br />AngPaggamitsaUhotsa malungtarongagricultura<br />(The use of rice straw for sustainable agriculture)<br />
  25. 25. STOP burning rice straw (3)<br />CITY ORDINANCENO. 229, S-2006 (TAGUM City)<br />d. Agricultural Areas:<br />1. Agricultural wastes, e.g. rice straws, corncobs, must not be burned but be stockpiled in a proper location and composted. <br />
  26. 26. Tribute<br />The idea to recycle rice straw in the field was among others propagated by the late Lorenzo P. Jose, a pioneering organic farmer in Central Luzon, Philippines.<br />Mr. Jose had learnt about this from the lateMasanobu Fukuoka, a Japanese farmer and philosopher. He first published his ideas about natural farming in his book The One-Straw Revolution.<br />Mr. Masanobu Fukuoka. He died in 2008 in the age of 95 years.<br />
  27. 27. Conclusion<br />The recycling of rice straw by scattering it in the field follows nature’s way. <br />It is a simple way to recover and maintain soil fertility.<br />Some progress has been made to address this “burning” issue. <br />Obviously more efforts are needed to inform farmers about the benefits!<br />Thank you !<br />