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Effects on soil, climate and farmers’ livelihoods 2 nd ECHO Asia Agricultural Conference September 21-25, 2009 Chiang Mai, Thailand Winfried Scheewe DED-Cambodia/CEDAC Phnom Penh, Cambodia - an entry point to sustainable rice production

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

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Page 1: Effects  recycling of rice straw 2009 09 23-v 07-2011

Effects on soil, climate and farmers’ livelihoods

2nd ECHO Asia Agricultural ConferenceSeptember 21-25, 2009Chiang Mai, Thailand

Winfried ScheeweDED-Cambodia/CEDACPhnom Penh, Cambodia

- an entry point to sustainable rice production

Page 2: Effects  recycling of rice straw 2009 09 23-v 07-2011

Does rice straw have any value? Burning of rice straw is a

common sight during the harvest period in many parts of South and Southeast Asia.

Farmers are unaware: Straw from one hectare contains 25 to 40 kg N.

= Farmers are burning money.

Yet, the energy (carbon) contained in the straw may be even more important.

Page 3: Effects  recycling of rice straw 2009 09 23-v 07-2011

Biomass open burning – Global overview

Burning of rice straw and other biomass is practiced in most Asian countries

Page 4: Effects  recycling of rice straw 2009 09 23-v 07-2011

OverviewWe will look here at some details of the recycling of rice straw by scattering it equally in the field or mulching. Effects on soil Effects on the

atmosphere Effects on farmers’

livelihoods

will be discussed

Page 5: Effects  recycling of rice straw 2009 09 23-v 07-2011

Why do farmers burn the straw? Straw was traditionally

used as fodder Mechanization

less animals needed Additional cropping cycles

straw disturbs land preparation waste

Availability of fertilizers To supposedly prevent

further spread of diseases Concept: clean field,

(variation of slash & burn)

Page 6: Effects  recycling of rice straw 2009 09 23-v 07-2011

Why farmers should NOT burn it?

1 ton of straw contains: 5 to 8 kg nitrogen 1.2 kg phosphorous 20 kg potassium 40 kg silica 400 kg carbon

Per hectare, about 5 tons of straw are left

Page 7: Effects  recycling of rice straw 2009 09 23-v 07-2011

What happens if the straw is burnt? 400 kilogram of carbon

go back to the atmosphere

93 % of the nitrogen goes back to the atmosphere, = 30 to 40 kg N/ha

25 % of the phosphorous and 21 % of the potassium disappear

Silica is left, but the heat makes it insoluble.

Straw burns with temperatures up to 700◦ C

Page 8: Effects  recycling of rice straw 2009 09 23-v 07-2011

What can farmers do instead?

Just leave the heap- do nothing (straw will slowly decay in one spot, much of the carbon will be lost)

Set up a compost pile (controlled composting)

Distribute the straw equally in the field

Page 9: Effects  recycling of rice straw 2009 09 23-v 07-2011

Mulching – some considerations (1) Scatter the straw equally

soon (immediately) after threshing in the field

The straw is left for about 4 weeks on the surface to decompose before plowing

This allows bacteria involved in the decomposition to fix nitrogen from the atmosphere

Page 10: Effects  recycling of rice straw 2009 09 23-v 07-2011

Mulching – some considerations (2)

Ideally combined with a green manure crop

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

Page 11: Effects  recycling of rice straw 2009 09 23-v 07-2011

What are the effects on the soil?

Nitrogen and other nutrients recycled

Additional N-fixed Part of the carbon is

incorporated into the humus (SOM) content of the soil

Nutrient deficiencies minimized

Iron (and other) toxicities reduced

Page 12: Effects  recycling of rice straw 2009 09 23-v 07-2011

A closer look at Nitrogen

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.

The straw contains about 30 kg N.

Grains 56 kg NStraw 30 kg N-------------------------------------Requirement 86 kg N

Page 13: Effects  recycling of rice straw 2009 09 23-v 07-2011

- 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 kg Total 86 kg N/ha

Several farmers obtained yields of over 4 t/ha over many years without additional inputs.

Question: If no synthetic fertilizer was applied, where did the nitrogen come from?

Several kind of orga-nisms are involved in natural processes which provide nitrogen to the crop.

All need energy which the carbon of the straw supplies.

Page 14: Effects  recycling of rice straw 2009 09 23-v 07-2011

Humus contentOver time, humus

content increases pH level ↑ Nutrient supply more

balanced Plant health improved Insect problems less

likely Soil structure improved Water retention increases Nutrient deficiencies

corrected

Page 15: Effects  recycling of rice straw 2009 09 23-v 07-2011

Nutrient deficiencies corrected Farm of Isidro Prado

After 15 years of conventional cultivation Zinc deficiency became a problem

Yield declined by 60 to 70%

Straw application within two years, yield back to normal levelsof over 4.5 t/ha(40 sacks from 0.38 ha)

Page 16: Effects  recycling of rice straw 2009 09 23-v 07-2011

Iron toxicity corrected In some places iron

toxicity is a problem due to strongly reducing

conditions in the soil and/or low pH

low and unbalanced crop nutrient status

Causes stunted growth, extremely limited tillering.

These conditions can be corrected just by returning the straw

Page 17: Effects  recycling of rice straw 2009 09 23-v 07-2011

Straw management and climate (1) Burning releases carbon

Philippines: 3.26 million tons C per year (= 12 million tons CO2)

Total emissions 2006: 8.4 Giga-tons carbon

Burning causes pollution (including polycyclic aro-matic hydrocarbons, some are toxic)

Incorporation may add to releases of methane

Page 18: Effects  recycling of rice straw 2009 09 23-v 07-2011

Straw management and climate (2) The main sources of greenhouse

gases emissions in agriculture

Million tons CO2 -eq

Agriculture contributes between 17 and 32% of all global human-induced green house gases.

Of this, 12% is caused by biomass (incl. rice straw) burning

Cool Farming: Climate impacts of agriculture and mitigation potential, www.greenpeace.org (2008)

Page 19: Effects  recycling of rice straw 2009 09 23-v 07-2011

Straw management and climate (3) Decomposition under

anaerobe condition: Methane emissions ↑

If synthetic N is applied Nitrous Oxide emissions ↑

Synthetic N requires energy (~1.4% of the world's annual energy supply)

causes CO2 emission

Generally:Recycling of straw minimizes releases of CO2 + other green house gases from rice fields

Carbon (humus) in soil ↑

Page 20: Effects  recycling of rice straw 2009 09 23-v 07-2011

Straw management and climate (4) Soils can serve as carbon

sinks

Generally, soils have lost carbon due to clearing and cultivation

Claim by IRRI scientists: Irrigated soils still high in humus (or SOM)

Rainfed rice fields provide different conditions than irrigated fields

Page 21: Effects  recycling of rice straw 2009 09 23-v 07-2011

Effect on farmers’ livelihoods (1)Comparaison MASIPAG (Organic) vs. Conventional (2003)

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.

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.

However, the cost-benefit analysis did not include cost 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.

Page 22: Effects  recycling of rice straw 2009 09 23-v 07-2011

Effect on farmers’ livelihoods (2)Mr. Isidro Prado:

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)

Later he needed to borrow only PHP 2,000.00 for which he paid a much lower interest rates (= 3,750.00)

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

STOP burning rice straw Need to raise

awareness Many NGOs promote

sustainable practices Many provinces and

municipalities have issued ordinances prohibiting the burning of rice straw

Page 24: Effects  recycling of rice straw 2009 09 23-v 07-2011

STOP burning rice straw (2)

Group of Advocates for Sustainable Agriculture, Inc.

Tandag, Surigao del Sur

Ang Paggamit sa Uhot

sa malungtarong agricultura

(The use of rice straw for

sustainable agriculture)

Page 25: Effects  recycling of rice straw 2009 09 23-v 07-2011

STOP burning rice straw (3)

CITY ORDINANCE NO. 229, S-2006 (TAGUM City)

d. Agricultural Areas:

1. Agricultural wastes, e.g. rice straws, corncobs, must not be burned but be stockpiled in a proper location and composted.

Page 26: Effects  recycling of rice straw 2009 09 23-v 07-2011

Tribute 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.

Mr. Jose had learnt about this from the late Masanobu Fukuoka, a Japanese farmer and philosopher. He first published his ideas about natural farming in his book The One-Straw Revolution.

Mr. Masanobu Fukuoka. He died in 2008 in the age of 95 years.

Page 27: Effects  recycling of rice straw 2009 09 23-v 07-2011

Thank you !

The recycling of rice straw by scattering it in the field follows nature’s way.

It is a simple way to recover and maintain soil fertility.

Some progress has been made to address this “burning” issue.

Obviously more efforts are needed to inform farmers about the benefits!

Conclusion