I. INTRODUCTION
Dryand agriculture in Indonesia is an important
livelihood for a significant proportion of the population living in the tropical
savanna climatic zone. Most areas in Eastern
Nusa Tenggara Province fall under the tropical savanna climatic zone with long
dry season where 90% of the population rely on agriculture as their main
livelihood.
The changing climate, abnormal changes in air
temperature and rainfall, increases in frequency and intensity of drought and
flood events have long-term implications for the viability of agricultural
ecosystems (FAO, 2007). People living in marginal areas such as drylands face
additional challenges with limited management options to reduce impacts (FAO,
2007) where climatic pressures on land have existed before the onset of climate
change. Considerable resources needed to
increase agricultural ecosystem resilience are lacking in small scale farming
households facing negative consequences of the changing climate.
The ENSO (El-Nino Southern Oscillation) is the
main driver of inter annual climate variability in NTT. It has significant
impact on seasonal rainfall as well as on the onset and the end of the rainy
seasons (Fox 1995). Boer and Faqih’s (2013) analysis on temporal
and average annual rainfall show greater deviations in the last few decades
which are related to increases in the frequency of El Nino Southern Oscillation
(ENSO) episodes. As a result, most areas in the eastern
part of Indonesia will experience more climate extremes (Boer and Faqih, 2013).
The Indian Ocean Dipole (IOD) and
Madden-Julian Oscillation (MJO) also influence the increase in the episodes of
extreme climates (e.g. the extraordinary drought in 1997/98 which occurred in
conjunction with El Nino and IOD positive).
Studies have confirmed impacts of the changing
climate: the unpredictability of planting seasons, decreased soil fertility
(Sari et al., 2007), failed harvest, degradation of agricultural land
resources, increased frequency, area, and intensities of drought, and increased
intensities of pests (Las, et al., 2008), and decreased crop yields (Setiyanto
and Irawan, 2013).
Droughts as often experienced during El-Nino
periods, cause crop losses in lower hills and alluvial plains while rainstorms
linked to typhoons lead to damage to corn and other crops in the highlands4. In the 2002/2003
El-Nino for example, the production loss in NTT due to drought was about 130
billion rupiahs (equivalent to 16 million US$). Losses varied between districts
of the order of between 0.5 and 5.0 million US$ (NTT Provincial Agriculture
Office, 2004). More recently, the El Niño in 2006/07, for example, caused low rainfall and prolonged
crop failure on the northern coast of the province (Muslimatun and Fanggidae, 2009); while the latest 2015/2016 El Nino had also caused
“Long” to “Extreme “ drought in most areas of eastern Indonesia, including Nusa
Tenggara (Food Security Monitoring Bulletin, 2015). On the other hand, extreme wet season such as experienced during La Nina (Cold ENSO) cause extreme
leaching of especially nitrogen, wind and water damage which mostly damage corn
and sorghum while other crops also tend to experience micro-nutrient
deficiencies.
There are strong indications that changes in rainfall patterns are already
occurring: over the last decade, there has been a growing number of years with
a ‘false’ start of the rainy season, floods and droughts both during dry and
rainy season, and high winds. Historical data analysis indicates that extreme
rainfall has increased during the last half of the 20th century when comparing
1901-1950 with 1951-2000. Climate change projections prepared up to 2050 for
NTT province suggest a likely decrease in September-November rainfall by 2050,
with greater decreases likely in the western parts of the Province. There is also a consistent
indication that rainfall will increase during March-May, suggesting a shift of
the rainy season (a later start and later end) (UNDP, 2011). Prediction on the delayed onset of rainy season in Indonesia’s southern
islands (which include NTT) is also stated by the Netherland Commission for
Environmental Assessment (2015).
Small scale farmers in the dry land are facing
multiple inter-related challenges—affecting their well
beings and sustainabilities—which are
compounded by the changing climate. Technical obstacles concern the
accessibility of appropriate agricultural inputs and techniques; economic
obstacles are related to inadequate capacity to mobilise adequate finances for
appropriate agricultural inputs and unfavourable agricultural product value
chain. Geography concerns with accessibility (thereof, the lack of).
Environmental challenges are numerous—climatic, agricultural land degradation,
and the decline in healthy biodiversity which support pollination and
prevention of pests and diseases. Some farmers are more prone to one or more of
the above challenges.
Adaptation to climate change includes a set of
actions to moderate harm or exploit beneficial opportunities in response to
climate change (IPCC). Biochar based agriculture is one means to adapt to
climate change challenges, through increasing
water retention/drainage capacity and fertility. In agricultural cropping biochar provides
resilience against both excess of water (due to high intensity rainfall), as
well as lack of water (due to extended drought periods). Biochar also assists
in exploiting beneficial opportunities of climate change which are, its ability
to retain water gained from temporal excess (increased rainfall intensity). Application
of biochar will also increase predictabilities of harvest, and extend the
length of planting time (Scholz et al., 2014). Biochar application can also
take the opportunity to increase arable land by the restoration of marginal
land to increase crop production. The combination of increase in the areas of
arable land and extension of planting time is in accordance to analysis of
Irawan (2013) which states that efforts to overcome impacts of El Nino and La Nina
should be focused in preventing the decrease of harvest area during the
occurence of the former, and to increase harvest area during the latter.
Biochar benefit extend beyond the strengthening
of resilience of agriculture in climate change adaptation. The application of
biochar combines a number of important benefits: i) climate change mitigation: absorption
of carbon dioxide (CO2) in photosynthesis and carbon sequestration through its
stable carbon, and the reduction of other GHG emissions (mainly N2O), ii)
pollutant immobilization, and iii) waste management. In contrast to other
organic materials, most of the biochar matrix is probably stable for hundreds
to thousands of years when mixed into soils, and thus represents carbon that is
actively removed from the short-lived carbon cycle.
An alternative use of biochar is as a clean
energy source. Household burning of traditional biomass is a major health risk
factor in Indonesia (Zhang and Wu, 2012). Indoor combustion of solid fuels
using traditional stoves releases a large amount of particulate matter (PM) and
gaseous pollutants, causing serious health
consequences for exposed populations. IAP emission levels generated by
solid fuels are often 20–100 times those of
clean fuels like liquefied petroleum gases, and often up to 20 times higher
than the maximum recommended levels
suggested by the World Health Organization (WHO) guidelines and national
standards (WHO/UNDP 2009).
Biochar briquettes as fuel in low emission
cookstove has been proven to reduce smoke and harmful gas production from
traditional biomass cooking. The use of biochar from agricultural wastes to
substitute for firewood also contributes to the mitigation of greenhouse gases
(GHG’s). Other benefits that may incur with the substitution of firewood with
biochar for cooking are, time freed from firewood collection and increased
security on cooking fuel availabilities in cases where wood for cooking fuel
are scarce.
Decentralised biomass gasification
electricity generation is also important in overcoming the lack of economy of
scale in extending electricity grid to remote and sparsely populated areas.
Likewise, biochar based clean cooking energy may overcome the lack of economy
of scale in expanding the distribution network of clean cooking fuel such as
liquified petroleum gas (LPG).
I.1. Dryland Agriculture
Areas in Indonesia eastern provinces are
generally less developed and in several regions, have been facing chronic
poverty issue for decades such as Eastern Nusa Tenggara (ENT). The main
livelihood of most villages (> 90%) in NTT is agriculture (BPS NTT, 2014). Agriculture
mainly takes place in the form of subsistence rain fed based agriculture.
Dryland agriculture in the east of Indonesia, is
especially vulnerable to climatic stress and land degradation due to drought
and erosion vulnerabilities. Areas which are dominated by tropical savanna
climate, have a longer dry season than most parts of Indonesia which are mainly
in the tropical wet climate.
In Indonesia, dry agricultural land, is defined as
land that receive precipitation of less than 750 mm/year. Agricultural land in
those areas also receive short period rainy season and have less than 179
planting days. In terms of agricultural land resources, almost 50% agricultural
land in Indonesia is dryland potential to contribute to national food crop
production.
Most of agricultural land in NTT falls into the
categories of dry agricultural land (237,800 ha) and dry agricultural land and
bush (601,600 ha) out of 1,177,115 ha total agricultural land.
According to the Agency for Agricultural Research and
Development, the production of food crops in dryland needs to be increased so
that it can contribute to the national food security (Balitbangtan, 2013). The harvested
land area of dryland crops has increased annualy by 0.34%, which is an
insignificant—compared to those of non dryland harvest area with increase rate
of 1.22% (Balitbangtan, 2013). Furthermore, area planted with agricultural
commodities dominant in the dryland (cassava, dryland rice, and peanut) tend to
decrease or remain stagnant (Balitbangtan, 2013). While there have been
investments made in dryland agriculture, overall investments are much greater
in wetland rice and plantation. Regions with dominant drylands (Sulawesi and
Nusa Tenggara) experience slower or even contraction in the development of
agricultural commodities than regions dominated by wetland rice or plantations
(Balitbangtan, 2013). Generally, investments for dryland agriculture
development is slower than for the wetland. This is reflected by the slow
accumulation of agricultural capital and slow productivity increase in the dryland (Balitbangtan,2013).
I.2. Land Degradation in the Dryland
Land degradation is a reduction in the physical, chemical or biological status
of land, which may also restrict the land's productive capacity
(Chartres, 1987). degraded land in Indonesia can be defined as “critical
land” based on standard as described in the Regulation of Dirjen 4/V-SET/2013
about Technical Guidance of Conducting Spatial Data of Critical Land byThe
Ministry of
Forestry (The Ministry of
Environment and Forestry since 2014). Based on the regulation, critical land is
the land which has been damaged, hence losing or reducing the function up to
the defined or intended level. Therefore, the assessment of critical land in an
area is adjusted with
the area function. The value of critical level of land is acquired from
multiplication of weights and scores value[1] (Prasetyo
et al, 2013).
The area of the degraded land (lahan
kritis) in Indonesia was 24.3 million hectare (ha) in 2013 (MoF). Most of the degraded land are in
the forest and non-forest lands, have become weed infested land, open space,
grassland, and dry agricultural land.
The extent of degraded land in Indonesia is increasing rapidly
especially in the dry areas, in the eastern and central parts (Anwar, 2009), caused mainly by
inappropriate land use and the
lack of soil and water
conservation techniques.
Revitalisation of degraded land is a strategy outlined in the Indonesia
Climate Change Sectoral (Agriculture) Roadmap which serves the need and demand
for development in increasing agricultural areas that can prevent deforestation
and decrease degraded land (BAPPENAS, 2010).
In the eastern parts of Indonesia, which are considerably drier,
climatic factors contribute to the
dryness and arid conditions in various parts of the islands. In East
Nusa Tenggara (NTT) Province, degraded land has reached 1,356,757 ha,
comprising 299,291 ha in forest land and 1 057 466 ha in non-forest land.
The biophysical conditions of NTT Province, which are closely related to
land degradation problems, are characterized here under:
· An island dominated by hilly topography, 26–46
percent slope, with young sedimentary rocks and volcanic parent materials and
high erosion sensitivity;
· Low vegetative cover, low infiltration rate,
high runoff and risk of floods;
· A dry season of nine months and a rainy season
of three months with high erosivity via rainfall;
· Land productivity is very low, thus requiring
many inputs from farmers to maintain production;
· High sediment load during floods; this has led
to mangrove forest degradation, downstream pollutionand other negative
environmental impacts.
I.3. Biochar, Agro-Ecosystem Resilience and Climate Change Mitigation
Biochar, a heterogeneous substance rich in
aromatic carbon and minerals, is produced by
pyrolysis of sustainably obtained biomass
under controlled conditions.
Biochar
contributes to the increase in soil water holding capacity as well as drainage
in flood prone area, the neutralization of soil acidity and to a decrease in
the solubility of phytotoxic metals such as aluminum in soils. In addition,
biochar can bind and release nutrients (N, P, K, Ca) and could therefore reduce
nutrient leaching to the subsoil in weathered, low-cation exchange capacity
soils.
Biochar specific surfaces, being generally
higher than sand and comparable to or higher than clay, will therefore cause a
net increase in the total soil-specific surface when added as an amendment. The
beneficial impact of biochar as soil ammendment tool is because of its cation
exchange capacity (CEC; 40 to 80 meq/100 g, high surface area (51 to 900/m2.g),
which leads to increased soil pH and water holding capacity, and affinity for
micro- and macro-plant nutrients (Lehmann et al, 2006; Laird et al, 2009 and
Lehmann, 2007).
Increased soil fertility has been reported
in the use of biochar as soil ammendment (Norwegian Research Council, 2014). An
increase of yield was obtained in a
field test in an oxisol soil in Sulawesi. A trial in a compact clay (vertisol)
area in Oebola, West Timor (NTT Province) shows that biochar can help to drain
compact clay soil during heavy rainfall in the monsoon season.
Biochar ability to ammed a degraded soil
was also reported. In Ngatatoro, Sulawesi, biochar which was used to ammend a
degraded oxisol soil with limited nutrient holding capacity (low cation
exchange capacity) increased yield and the length of planting season enabling
two planting seasons (Norwegian Research Council, 2014).
Biochar can
also strengthen communitye’s resilience through increasing access to modern
energy services which are, clean thermal energy for cooking and productive
activities and electricity—which are often lacking in remote areas. Pyrolysis
heat from the production of biochar can be recovered for the provision of low
emission thermal energy. Biomass gasification to generate electricity produces
biochar as the by-product. Biochar made into briquettes can be used as clean
cooking fuel. Access to those energy forms improve living conditions. Electricity
and significant heat energy can also be precursors for economically productive
activities (e.g. food proccessing, agricultural product drying).
Biochar also combines a number of other important
benefits such as: i) climate change mitigation: carbon sequestration and
reduction of other GHG emissions (mainly N2O), ii) pollutant immobilization, and
iii) waste management.
Assessments of the realistic potential for
biochar in carbon abatement have converged on a figure of about 1 Giga ton
Carbon/yr (Lehmann, 2007) presenting a potential wedge for climate change mitigation
(Nsambe, 2015).
Biochar sequester about 40% of biomass
from agricultural wastes that are pyrolised. Biomass which is pyrolysed returns
around half of the biomass carbon into the atmosphere as CO2. Around 40% of
total biomass C is sequestered, i.e. locked up for long periods, as biochar
(the remaining 10% is more labile and degraded). In contrast to other organic materials,
most of the biochar matrix is probably stable for hundreds to thousands of
years when mixed into soils, and thus represents carbon that is actively
removed from the short-lived carbon cycle.
Biochar also
inhibits the emission of the strong greenhouse gas nitrous oxide (N2O), where
up to 90% (lab trials) and 70% (field trials) reductions in the release of the
gas have been reported. The most probable mechanism to explain this is a
combination of a “pH effect”(biochar having an alkalizing effect, see below)
and an additional mechanism such as strong biochar sorption of nitrous oxide
followed by reduction of N2O to N2 with biochar-sorbed
organic molecules serving as electron donor.
Potentially, the
energy generating component of a biochar system can displace carbon-positive
fossil fuel energy and high emission traditional biomass combustion from cooking.
The ability of biochar to maintain soil
fertility can potentially reduce emission from the conversion of forest to
replace degraded agricultural land.
Contamination
of soil with legacy pesticides such as DDT and persistent pollutants such as
PAHs is still a significant problem (a billion-euro problem throughout the
world). Such organic pollutants can be immobilized by strong binding to biochar
added to the soil in small (1-5%) dosages. Studies indicate extremely strong
sorption of hydrophobic organic compounds and pesticides to non-activated
biochar (i.e., biochar that has not undergone a process with steam or chemical
activation to increase pore volume) (Norwegian Research Council, 2014).
Biochar can be
used as one solution to manage agricultural waste, as the are signficant
quantities of wastes that are burnt and disposed indiscriminately, for example
into water bodies. Biochar based system utilize the unmanaged agricultural
wastes, converting the wastes into useful products which are soil ammendment
and also a source of energy.
I.4. Biochar Production Technologies
Rather than a single technology, biochar
is a common thread running through various technological approaches, which can be
varied to emphasize a particular outcome or opportunity (Lehmann, 2007).
Traditional biochar producing technologies
emit greenhouse gases and particles and are therefore non-sustainable. There is
a need to both introduce new environmentally friendly technologies making
efficient use of pyrolysis gases and heat generated by pyrolysis.
Previous phase of the project have tested
a number of technologies which are evaluated based on its social and economic
compatibilities and environmental
performances.
Technologies that were evaluted previously
are, the Adam Retort Kiln (ARK), Top lift updraft stoves (TLUD), and the Kon
Tiki kiln (KTK).
The development of the Adam retort
kiln and similar devices such as basic steel retort systems introduced the partial
afterburning of pyrolysis gazes. In these retort systems the feedstock wood can be
mixed with dry biowaste materials like prunings, rice husks or maize cobs but a lot of
valuable start-up wood is still needed [Sparrevik et al., 2014; Adam 2009). Such medium-scale improved retort technologies, with
the recirculation of pyrolytic gases produce around 75% lower
deleterious gas emissions (mainly CO, CH4, aerosols) and higher yield than traditional systems.
Household-scale cooking stoves,
so-called TLUDs (Top-Lit Up-Draft stoves) (Manoj
et al, 2013) can generate biochar while using the
energy produced for cooking. Advantages include that they burn cleanly avoiding negative
health effects due to indoor air emissions (Smith
and Mehta, 2003), can use various waste biomasses as
feedstock and are fuel-efficient. Small-scale TLUDs may be applicable for
horticulture or small kitchen gardens but they generate too little biochar (0.5–1 kg per
run for household devices and up to 10 kg for the bigger community stoves) to supply
enough biochar for farming or selling as charcoal. In addition, the stove needs to be
actively quenched after each cycle, which is impractical in daily use (Corenelissen et al., 2016).
A recent development has been the
introduction of the Kon-Tiki flame curtain kiln, designed in 2014 in
Switzerland and rapidly spreading since by open source technology transfer to farmers in
more than 50 countries (Schmidt
and Taylor, 2014).
In contrast to medium-sized retort
kilns, no startup wood is needed for flame curtain kilns. The cost per kiln
varies with design, construction material and country but is within a range of €30 (soil pit
shield) to €5000. The cheapest way is a mere conically shaped soil pit which would essentially be
for free (Corenelissen et al., 2016).
The
Kon Tiki kiln offers multiple advantages (Corenelissen et al., 2016):
1. gas and aerosol emissions are
relatively low (for CO even lower than those of retort kilns)
compared to other small scale
biochar and charcoal production technologies but not to
large-scale processes;
2. no wood is required for
startup;
3. construction and operation is
much easier and more economic compared to retort kilns;
4. pyrolysis is much faster
(hours) than in most traditional and retort kilns (days).
Advantages
and disadvantages of various medium-size kiln types (Cornelissen et al., 2016)
Biochar produciton
technology
|
Application
|
Main advantages
|
Main disadvantages
|
Biochar-generating TLUD cookstove
|
Kitchen gardens, cooking purposes
|
Energy for cooking, Saving firewood, Low gas
emission factors
|
Too small to generate larger amounts of biochar
|
Traditional kilns
|
Agriculture, charcoal making
|
Familiarity, Low investment cost, Complete pyrolysis of thicker
logs
|
High gas emission factors, Slow (4 days)
|
Retort kilns
|
Agriculture (possibly+ energy), charcoal/ briquette making
|
Lower emissions than traditional kilns, High biochar yield,
Energy generation possible with pyrolysis heat, Complete pyrolysis of thicker
logs
|
High investment cost, Startup wood required. Complicated construction and operation,
Slow (2 days)
|
Kon Tiki Kiln
|
Agriculture + heat, charcoal making
(small logs)
|
Relatively low emissions esp. of CO,
No startup wood required, Easy to construct and operate, Fast (3 hours for 1 m3
biochar), Low to zero investment cost, Heat recovery
|
Relatively low biochar yield
(charcoal making), Incomplete pyrolysis of thick logs
|
Power-generating systems
|
Energy + agriculture, briquette making
|
Power generation, Negligible emissions
|
Relatively high investment cost, Low
caloric
content of briquettes
|
[1] There are several
parameters used to determine “critical land” level based on
the regulation No. P.32 / Menhut-II / 2009, including: land cover, soil slope,
soil erosion hazard level, land productivity, and land management. Bulk
density, soil permeability, soil texture, soil
structure, and soil organic carbon are some soil parameters needed in determining
soil erosion hazard using USLE (Universal Soil Loss Equation) method.
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