Keywords

1 Introduction

Southeast Asian (SEA) countries have demonstrated a comparative advantage in their rate of expansion, resulting in sizable gains in global market shares for key food and agricultural products. The challenge for SEA is to pursue economic development without placing additional pressure on natural resources and the environment. The degradation of agricultural resources is a major hurdle in improving the global situation of agriculture in the region. Natural resources upon which agricultural production depends are deteriorating due to land degradation, forest loss, and poor agricultural practices. The intrinsic fragility of soils, the rate of organic matter decomposition, and increased population pressure have led to yield declines (Dierog et al. 2001; Lienhard et al. 2013a)

The negative impacts of conventional agricultural practices—land degradation, soil erosion (Fig. 12.1), declines in biodiversity, pollution, desertification, etc.—are well known. Added to these are the dramatic social implications of famine, poverty, out-migration, etc. Global food needs are rising with population growth. Agricultural production needs to increase to fulfill these pressing needs. Agricultural systems capable of meeting this challenge must now be productive, profitable, and sustainable. Production and quality must be improved to boost farmers’ incomes while preserving natural resources and the environment. Through many positive impacts in the field and for the environment, conservation agriculture (CA) and ecological intensification can effectively meet these substantial challenges in both developing and developed countries. The principal identified route to feeding an increasing population while mitigating climate change, in particular in developing countries, is assisting smallholder farmers in agricultural development and especially with the promotion of agroecological farming practices (De Schutter 2011) .

Fig. 12.1
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Soil erosion after plowing in North Laos

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2 History of CA in Southeast Asia

CA is any cropping system, which integrates the three principles of minimal soil disturbance, permanent soil cover, and crop rotations (FAO 2007), and is not dissociable from conservation tillage, defined by Lal (1989) as any tillage system that reduces loss of soil or water relative to conventional tillage. Both approaches have similar objectives (e.g., soil erosion control, soil fertility improvement) , promote to some extent similar tools (e.g., use of cover crops, soil mulching, reduction/cancellation of soil tillage, integration of the landscape dimension), and face similar constraints regarding their broad adoption (e.g., opportunity cost of land and labor, field protection against communal grazing, management skills).

In recent decades, agrarian landscapes and livelihoods in the uplands of SEA have undergone dramatic changes. Farming households have had to adapt to the mounting influence of global drivers such as demographic changes, market forces, and government policies that have led to the rapid expansion and intensification of agriculture (Castella 2012) . The need to buffer the negative consequences of these land-use changes (e.g., deforestation, land degradation) has rapidly emerged .

Experiments and the promotion of soil and water conservation practices started in the early 1970s (Garrity 1996) and included various technical packages, including contour hedgerows systems, agroforestry practices, natural vegetative strips, and managed fallows. Contour hedgerow systems were developed in the Philippines in the early 1970s and are based on the principle of growing field and permanent crops in 3–5-m-wide bands between double-contoured hedgerows of nitrogen-fixing trees. These leguminous trees are regularly pruned and the cuttings are placed in alleyways to serve as organic fertilizers (MBLRC 2004). Contour hedgerows were widely promoted during the 1980s and 1990s in several SEA countries (e.g., Indonesia, Myanmar , Thailand, Vietnam, and Philippines) to reduce soil erosion and maintain soil fertility . These were the first experiments in SEA showing interest in soil mulching. Two main constraints were identified for their broad diffusion (Garrity 1996) : (1) the tendency for perennial pruned-tree hedgerows to compete for growth resources and hence reduce yields of associated annual crops planted in adjacent rows and (2) the enormous amount of labor needed to prune and maintain hedgerows. The diffusion of contour hedgerow systems has also been hindered by the increasing pressure on land to increase and sustain agricultural production (Lal 2005) , with smallholders confronted more and more with the opportunity cost of growing hedgerows where staple or cash crops may be grown. Competition between main and relay crops, labor requirements, labor difficulty and, above all, the opportunity costs of land and labor are similar constraints experienced for CA diffusion in SEA, with the main challenge for smallholder farmers being how to make the best use of limited resources (land, labor, and capital).

Considerable agronomic studies were conducted in SEA countries in the 1990s to improve the benefits of fallowing through the establishment and management of leguminous species during fallow periods of less than 2 years. Experiments were based on the use of herbaceous, fast-growing legume cover crops (von Uexkull and Mutert 1995) , shrubby legumes (Roder and Maniphone 1998), or forage legumes (Garrity 1996) . All studies pointed out the benefits of using legume species in short-term fallows to accelerate soil fertility regeneration, weed suppression, and/or provide a possible source of other economic benefits. The main constraints highlighted for the greater diffusion of cover crops use were: field protection from communal grazing, protection from dry season fires, and a dependable seed supply, all of which are common constraints in CA diffusion.

CA is much more recent with less than a decade of on-field experiments in SEA. The first projects, which included a CA component, were located in continental SEA (Cambodia, Laos, and Vietnam) and have been mainly supported by the French Development Agency (AFD) with technical support from the French Agricultural Research Centre for International Development (CIRAD) . More recently, new institutions (US and Australian universities, ICRAF) supported by other donors (United States Agency for International Development, USAID, AusAid, Australian Centre for International Agricultural Research, ACIAR) have similarly initiated work on CA in continental (Cambodia, Vietnam) and insular (Philippines) SEA.

3 Current Status of CA in SEA

Since the history of CA in SEA is short (less than a decade), its development has been driven more by the research sector than extension. The main success stories of CA system adoption are with maize cropping due to the expansion of this crop in the region over the past decade (Lestrelin and Castella 2011) . Maize cultivation under zero tillage with prior crop residue management and/or relay association with a legume (beans, forage, or shrubby legumes) is the most popular CA system. After 6 years of research and 4 years of extension support, adoption estimates of maize-based CA systems in the south of Sayabouri province (Northern Laos) in 2008 were 1500 ha implemented by 1100 smallholders (Slaats and Lestrelin 2009) and 5000 ha in 2011 (Panyasiri et al. 2011) . However, only a limited (~10 %) and highly variable percentage of these areas were implemented in association or rotation with a legume (Slaats and Lestrelin 2009) . Maize associated or intercropped with legume crops are the main systems tested and promoted in northern Vietnam (Tuan and Doanh 2008; Hauswirth et al. 2011; Nicetic et al. 2011) , Yunnan province (Tao et al. 2008), and the Philippines (Mercado et al. 2011) , while in Cambodia, they are mainly based on maize and/or cassava (Manihot esculenta) associated with stylo legume (Stylosanthes guianensis CIAT 184; Boulakia et al. 2008, 2012a) with about 500 ha of experiments conducted and evaluated with farmers (Chabierski et al. 2011) .

4 CA and Ecological Intensification: An Alternative to Traditional/Conventional Farming Systems

Feeding an increasing population and mitigating climate change through promotion of agroecological farming practices is how the CIRAD and its national partners (National Agricultural Research Institutes) have come together over the past 10 years to develop CA systems, particularly in Brazil, Cambodia, Cameroon, Laos, Madagascar, and Vietnam.

In these countries, CA systems are evaluated according to the main objectives assigned to agricultural food systems (De Schutter 2011) which include the need to: (i) increase agricultural production (to respond to future needs), (ii) increase farmers’ incomes (to reduce poverty), notably smallholders’ incomes , and (iii) sustain resources, which support agricultural activities.

There are limited published works on CA in SEA with most of the information coming from grey literature (reports, technical leaflets, and communications to congress), which is accessible on the following websites:

4.1 Economic Returns of CA Systems at Field and Farm Level (Economic Impact)

In the absence of government subsidies for the agricultural sector and/or payment for environmental services, clear economic benefits must be apparent for smallholders to change from conventional to CA. The effects of CA on economic returns—calculated as value of production minus operational costs per unit area—vary according to its effect on the main grain or tuber yield of crops and the implementing costs. The economic valorization of the additional biomass produced by cover crops is important in the short term when used for animal production while the medium- to long-term effect is important for soil fertility; however, for farmers during CA development and dissemination, it is not an argument for changing their farming system (Lienhard 2013b) .

In productive lands, subsistence agriculture and extensive systems, the operational costs associated with CA systems are generally higher than under conventional slash and burn systems (Fig. 12.2) with additional outlays for secondary crop seed, minimal fertilization and/or pesticide use, and fencing materials. Economic gains therefore rely on productivity gains, which can be substantial (Husson et al. 2001) , modest (Nicetic et al. 2011), or nil (Affholder et al. 2009) depending on the system tested (diversified rotational system vs. mulching) and the years of experimentation (short to medium term).

Fig. 12.2
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Slash and burn traditional practice in mountainous area

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On productive land engaged in a process of intensification and marketization of agriculture (mountainous area, newly connected to market areas), farmers often practice high-input cultivation without adequate knowledge (Nicetic et al. 2011). Improved crop and input management and intercropping with legumes can significantly improve maize production and increase profits (Nicetic et al. 2011) .

On degrading land with commercial intensive monocropping, 5-year experiments with 2-year rotation of maize with rice bean under tillage significantly increased economic returns (from 20 to 50 % depending on the year) compared to maize monocropping due to less production costs for land preparation and weed control and associated increased maize yields (Tran Quoc et al. 2008) . In Laos, the fee-for-service requested for disc plowing with a tractor under conventional tillage is higher than the cost for rolling and herbicide spraying under CA (Tran Quoc et al. 2008; Slaats and Lestrelin 2009; Lienhard unpublished) . In addition, land preparation costs are significantly higher under the conventional system when herbicides are needed before sowing to supplement tillage for effective weed control, which is the common situation after several years of monocropping under tillage (Bounthong et al. 2005; Tran Quoc et al. 2008) . The reduction in production costs is the main reason (28 % of answers) given by farmers for expanding their cultivated surface under CA in the south of Sayabouri province (Lestrelin et al. 2012b) . Despite no significant differences in grain yields, the differences in costs for land preparation and weed control led to significant differences in economic returns (10–15 % higher profits for maize continuous cultivation under no-till and crop residue management compared to conventional monocropping under tillage; Tran Quoc et al. 2008; Slaats and Lestrelin 2009) and explained the rapid and large diffusion of this cropping system .

Cambodian rainfed areas engaged in intensive market-oriented agriculture for some time (Chabierski et al. 2011) had greater economic returns under CA systems than conventional tillage systems for maize (15–25 % under CA) and cassava (20–35 % under CA) production, due to substantial gains in productivity. However, these increases in productivity were associated with higher investments, which represent the main constraint for broader diffusion of CA (Chabierski et al. 2011) .

In degraded acidic and weathered savannah soils of northern Laos, grain and forage production was significantly improved with significant gains in economic returns, but required higher initial investments (machinery, fertilizers) when compared to traditional tilled and unfertilized production systems (Lienhard et al. 2008) . In highly degraded, poor, and acidic sandy soils (derived from sandstone with a pH of around 4–5 and often aluminum toxicity), CA techniques of no tillage, rice direct seeding, and rotation with legumes and gramineaes forages increased paddy rice production from 2.5 to 4.6 t/ha (3-year average) with the same level of fertilization. Forage production of Brachiaria humidicola and Stylosanthes guianensis in rotation (3 years) with rice (3 years) allowed beef-fattening activities during the rainy season. Beef weight gain was around 650 g day−1 with meat production of around 500–600 kg ha−1 (Legoupil 2013) .

4.2 CA Systems Impact on Soil Fertility and on Environment

4.2.1 Effect on Soil Erosion

Soil erosion is deemed a key reason for CA promotion in SEA sloping areas (Bounthong et al. 2005; Tuan and Doanh 2008; Mercado et al. 2011) . Valentin et al. (2008) found that mulching significantly reduced runoff and total sediment yield in different catchments in Laos, Thailand, and Vietnam. Lestrelin et al. (2012b) identified soil conservation issues as an important reason for farmers to experiment with CA systems (12 % of answers) and/or to expand their cultivated land under CA (9 % of answers).

4.2.2 Effect on Soil Physicochemical Properties

CA has had a positive effect on soil aggregation, which plays a key role in soil organic turnover and soil susceptibility to erosion. Tivet et al. (2008) observed a significant increase (up to 60 %) in the mean weight diameter (MWD) of aggregates in field top soils (0–10 cm) under no-till management (maize monocropping with residue management and 2-year rotation of maize and rice bean) compared with conventional tilled and maize monocropping systems. Lienhard et al. (2013d) had similar results for a 3-year rotation of rice, maize, and soybean cultivated under no-till management with cover crops prior to and with main crops, or under conventional tillage. Lienhard et al. observed a significant decrease in C and N contents in top soil (0–10 cm) in a Laos savannah grassland under conventional tillage compared to CA management (11 % difference after 2 years’ cultivation). Despite similar amendments, the sum of exchangeable bases was 1.5-fold higher under CA systems than under conventional tillage.

4.2.3 Effect on Soil Biodiversity and Biological Activity

Several regional studies have shown a significant positive effect of CA systems on soil macrofauna diversity (Husson et al. 2003; Boyer et al. 2008; Boulakia et al. 2012b) , density, and biomass (Husson et al. 2003; Boyer et al. 2008; Tivet et al. 2008) . All studies notably mentioned the positive effect of CA on earthworm populations with increased earthworm biomass (up to 80 %) under CA compared to conventional burn and/or tillage systems.

Husson et al. (2003) observed similar microbial communities (as estimated by FAME—fatty acid methyl ester—profiles) under a 2-year managed fallow of ruzi grass and a 10-year natural fallow. Boyer et al. (2008) observed significant (30 %) increases in microbial respiration under no-till systems with mulch when compared with bare soils. Lienhard et al. (2013a, c) , showed a significant decrease (− 20 %) of soil microbial molecular abundance (as estimated by soil DNA extracts quantification) under a conventional tillage compared to CA systems .

4.3 Climatic Change Impact and Carbon Sequestration

The joint process of deforestation , new land extension, and agricultural intensification often leads to vast soil erosion and gradual soil exhaustion. Crop residues are at a minimum, organic matter in the soil decreases, and carbon sequestration becomes minimal. In terms of greenhouse gas (GHG) emissions, these traditional systems are polluting the atmosphere since they are based on burning fallow biomass. Alternatives need to be created and developed that reconcile economic viability, social balance, environmental conservation, and climate change adaptation . These are crucial for the long-term improvement of smallholders’ living conditions and poverty alleviation.

Analysis of long-term climatic conditions in SEA clearly showed that climate is variable (Lefroy et al. 2010), and is a critical issue for agricultural production. Using projections, the analysis predicted that by 2050 the minimum and mean temperatures will increase by up to 2 °C and the maximum by up to 5 °C. The predictions for rainfall suggest less in May and more in April and October.

4.3.1 Resistance to Climate Change

Resistance is the tendency of a system to remain stable in the face of external perturbations . CA improves resistance to climate change as CA has beneficial effects on soil fertility, water management, and water-use efficiency. With an increase in soil organic matter and root density under CA, water infiltration and water holding capacity improve, making water more available throughout the farming cycle (Ricosy and Saxton 2007). Surface mulch and improved soil pore structure also increase infiltration and absorption capacity, while reducing evaporation . These benefits help reduce the risk of erosion and flooding during heavy rains, which contributes to aquifer recharge and makes more water available to crops (Hobbs 2007; Derpsch 2008; Verhulst et al. 2010). Together, these CA characteristics increase crop resistance to drought and tend to reduce yield fluctuations between dry and wet years compared to conventional farming practices .

4.3.2 Resilience to Climate Events

Resilience refers to a system’s ability to recover quickly from damage or change. Climate change is reflected in the increasing number of extreme weather events. The use of agroecological techniques can significantly reduce the negative effects of these events because resilience is enhanced by the implementation and promotion of agricultural biodiversity at the production system level. It is expected that droughts and floods become more frequent and severe. CA based on species diversity is better able to cope with both weather risks.

4.3.3 Carbon Sequestration and Reduction in the Greenhouse Effect

Storing carbon in the soil is an agricultural (enhanced physicochemical and biological soil properties) and environmental (reduced atmospheric CO2) challenge. CA systems were initially developed to fight soil erosion, but they appear to also favor C storage in soils. It is well-known that agriculture is responsible for substantial atmospheric GHG emissions and these could be reduced by implementing CA cropping techniques. In CA, the balance is markedly in favor of carbon sequestration. The use of direct seeding reduces fuel consumption (less mechanized work) thus reducing CO2 emissions from tractors. CA also promotes carbon fixation in organic matter accumulated in the soil. By implementing CA, anywhere from 0.5 to more than 3 t ha−1 per year of carbon can be fixed over a period of at least 10 years. It is not clear whether this would have a positive effect in the fight against greenhouse emissions because it is unknown if these systems promote further significant emissions of GHG such as CH4 and N2O. At two well-structured, clayey sites in Brazil and Madagascar, CH4 and N2O emissions were almost negligible (Seguy et al. 2006) .

5 Challenges and Strategies to Develop and Disseminate CA in SEA

5.1 Restoration of Soil Fertility in Degraded Areas

Land degradation refers to land which, due to natural processes or human activity , can no longer sustain economic function and/or the original natural ecological function due to causes such as deforestation , inappropriate agricultural practices, or overgrazing (GEF 1999). Land degradation involves two interlocking and complex systems: the natural ecosystem and the human social system. Land degradation takes various processes and forms such as soil erosion due to water and wind, physical deterioration (compaction, sealing), chemical deterioration (soil fertility decline, salinization, acidification), or vegetation degradation. Figure 12.1 shows land degradation due to erosion in northern uplands of Laos.

Trends indicate that accelerated land degradation and related environmental problems will continue to impede economic and social development in SEA. One major challenge is to achieve sustainable economic growth in a way that alleviates rural poverty without jeopardizing the quality of the environment.

Unfortunately, the rate of degradation is accelerating in most regions of the world (Table 12.1) and particularly in most countries of the southeast subregion. Some countries face more serious challenges than others do. This is partly due to differences in the rate of overall population increase or the rate of urbanization. Land degradation is also due, in large part, to the failure to engage land users in the mitigation effort. Most soil and water efforts are stand-alone interventions that are not attractive to rural households. Poor farmers have little or no money to invest in conservation measures and have no incentive to change their land use if this increases the risk of not producing enough food for their families.

Table 12.1 Humid tropical forest deforestation areas (in 106 hectare (ha) and degradation rates (in % of the initial areas). (Source: Achard et al. 2002)
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Water erosion covers all forms of soil erosion by water, including sheet and rill erosion , and gullying. Human-induced intensification of land sliding is caused by vegetation clearance, road construction, etc. Wind erosion refers to loss of soil by wind, which occurs primarily in dry regions. Soil fertility decline is a catchphrase to refer to what is more precisely described as deterioration in soil physical, chemical, and biological properties. While a decline in fertility is indeed a major effect of erosion, the term covers forms of degradation other than erosion. The main processes involved are:

  • Lowering soil organic matter with an associated decline in soil biological activity.

  • Degradation of soil physical properties such as structure, porosity, and water-holding capacity, due to reduced organic matter.

  • Deficiency in soil nutrient resources, including reduced availability of major nutrients (nitrogen, phosphorus, potassium) , onset of micronutrient deficiencies, and development of nutrient imbalances.

  • Acidification of soils, including aluminum toxicity; these “acrisols” are common in mountainous areas. Acidic soils can exist in rice plains where soils have developed from sandstone.

  • Salinization is a term used in its broad sense to refer to all types of soil degradation brought about by increased salts in the soil. It thus covers salinization in its strict sense, the buildup of free salts, and the development of dominance of the exchange complex by sodium.

The key issues in terms of environmental degradation and the main reasons for these soil degradations are explained in Table 12.2. As far as agricultural soils are concerned, the main cause of degradation is soil erosion due to rainfall occurring on bare soil either after slash and burn or after land plowing on steep soils mainly where commercial monocropping is practiced. Plowing on steep slopes and foothills is largely practiced as it is often included in a global package proposed by traders in which credit, hybrid seeds, and chemical inputs are supplied in exchange for grain production.

Table 12.2 Key environmental issues and degradation causes in ASEAN zone. (Source: 4th ASEAN State of the Environment Report 2009)
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The vulnerability to and impact of climate change are major concerns for SEA. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2007) mentioned that warming of the climate system is evident from observations of increasing global average air and ocean temperatures. Since IPCC’s first assessment report in 1990, assessed projections have suggested that global average temperatures will increase anywhere from about 0.15 to 0.3 °C from 1990 to 2005.

The IPCC reported that without further action to reduce GHG emissions, the global average temperature is likely to rise by a further 1.84 °C this century, or up to 6.4 °C in the worst-case scenario. This projected global warming is likely to trigger serious consequences for humankind and other life forms, including a rise in sea levels of between 18 and 59 cm, which would endanger coastal areas and small islands, as well as a greater frequency and severity of extreme weather events. SEA is highly vulnerable to climate change as a large proportion of the population and economic activities are concentrated along coastlines. The region is heavily reliant on agriculture for livelihoods and the level of extreme poverty remains high.

About 21 % of the lands in SEA (91 M ha) is used for agriculture. Of this, approximately 36 % (33 M ha) is classified as lowlands and 64 % (58 M ha) as uplands (Dierog et al. 2001) . These uplands represent the greatest potential for agricultural production despite the fact that most have acid soils (Table 12.3). Due to their low fertility status, only 20 % of the uplands are presently being used for agriculture and are characterized by diverse unstable agricultural systems. These areas often have poor infrastructure that limit farmers’ access to necessary agricultural inputs to improve productivity.

Table 12.3 Extent of acid soils in Southeast Asian countries in ’000 ha. (Source: Dierog et al. 2001)
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5.2 CA Practices to Restore Soil Fertility in Degraded Areas

Soil erosion control in sloping areas is a major issue in SEA, notably when land preparation is based on soil tillage. Of the existing conservation tillage technologies (e.g., mulching, contour hedgerow systems, natural vegetative strips, strip tillage), crop residue retention requires the least labor (Garrity 1996) with a significant impact on reducing runoff and sediment yields (Valentin et al. 2008) . In sloping and soil tillage-based areas, no tillage and crop residue retention are alternatives to tillage for limiting soil erosion.

The 10-year experiment in SEA with CA confirmed that soil organic carbon content was directly linked to land preparation (less C mineralization under no tillage) and the quantity of biomass returned to the soil (Lienhard et al. 2013) . A basket of CA technologies, including zero and reduced tillage , direct seeding, and residue management, has been developed and tested in different countries. Promising results were obtained in (i) regenerating fertility to degraded soils, (ii) providing livestock with high quality forage, and (iii) increasing soil carbon sequestration. Despite these promising results, dissemination has been limited. Lestrelin et al. (2012a, b) found that the innovation process was hindered by multiple stakeholder strategies that need to be fully understood and disentangled before new practices could be widely adopted.

In degraded acid and weathered savannah soils (northern Laos), significant gains in economic returns were obtained when initial investments in machinery and fertilizers were made (Lienhard et al. 2008) .

In highly degraded, poor, and acid sandy soils of the Savannakhet plain of Laos—with acid soils derived from sandstone, a pH of around 4–5 and often aluminum toxicity—CA techniques of no tillage, rice direct seeding, and rotation with legumes and forage grasses have increased paddy rice production with forage production allowing beef-fattening activities during the rainy season (Legoupil 2013) .

5.3 Providing Alternatives to Slash and Burn—Intensification and Diversification of Existing Farming Systems in the Uplands

5.3.1 Existing Farming Systems in the “Uplands”

Rice is the staple food grain produce in SEA with around 50 % of all agricultural land devoted to its cultivation. Farmers have made great progress during the past decade to improve average rice yields and modestly expand crop areas. However, present food security is highly tenuous given that surplus rice production occurs mainly in lowland areas. The highland regions are still largely deficient in staple food grain production.

Highland areas represent large surfaces in SEA. Most of these areas are subjected to a tropical monsoon climate with two distinct wet and dry seasons; the wet season occurs between May and November. It has been estimated that 70 % of highland areas have a slope greater than 20 %, which precludes its use for permanent agriculture. Most farmers live in subsistence conditions with very little production marketed off-farm. Oilseed, pulses, root crops, fruits, vegetables, coffee, and tea are the other crops.

5.3.2 Rainfed Rice-Based Farming Systems

The traditional highland/upland farming system is called “shifting cultivation” or “slash and burn,” where land is cleared annually of forest or scrub then traditionally planted with rice using a dibble stick (see Fig. 12.2). Historically, rice was grown for a single season on a plot of land cleared from the forest and then left fallow for a long period (10–20 years). For different reasons such as limited allocated land to farmers, demographic pressure, and extension of commercial monocropping, the fallow period has been drastically reduced to 3 years or less leading to erosion, loss of fertility, and declining production. A short-fallow farming system is simply not sustainable. Farming production systems still rely mainly on upland rice production under slash and burn techniques and cattle production (free grazing in forests and fallow areas), but the recent development of monocropped corn at the expense of former upland rice and fallow areas is becoming increasingly important from an economic perspective. A reduction in grazing areas has resulted in less cattle stock. Producers have sold their cattle to develop corn production and other business activities such as agricultural services and transport.

5.3.3 Commercial Monocropping Systems

Despite the government policy to curb slash and burn cultivation to preserve forested lands, the aggregate agricultural land area in the uplands has increased owing to a surge of cash crop cultivation. In the provinces linked with transboundary markets and commercial exchanges, the rural economy is presently based on the production of cash crops. These cash crops are grown under contract for export markets.

The early integration to markets led farmers to clear most of the communal forest areas and mobilize land more than 20 years ago (private land ownership and land titling process) and develop these new farming systems based on cash crop production. As a result, most of the forest areas have disappeared and the development of extensive livestock production systems is thus limited by a minor extension of the remaining forest areas, as forests are also used as grazing areas. These farming systems are completed by legumes, cassava, and Job’s tears with mainly paddy rice systems in the lowland areas and some upland rice production for farmers who have little or no access to paddy fields.

As a result of increasing demand for land to produce both staple food grains such as rice and export products such as crops, rubber, or timber, the total forest area has significantly declined. The absence of diversification as well as the use of mechanized tillage practices has gradually resulted in decreased levels of soil fertility and soil degradation. The development of legume production systems in association or in rotation with cash crops has always been limited by market demand and labor constraints. More recently in some areas, farmers have developed other cropping systems such as that based on cassava, which are more adapted to poor soils.

The development of farming systems based on cash crop production has been facilitated by the development of a private sector with traders supplying seeds, inputs, services such as land preparation, credit, and marketing. This dynamic has led farmers to often depend on traders to deliver these services. Some farmers are now engaged in a cycle of debt and de-capitalization due to high interest rates, which range from 30 to 40 % per annum. As a result, this farming system has generated a high level of socioeconomic differentiation, despite increases in average rural incomes, based mainly on:

  • Access to equipment (tractors, trucks, and two-wheel hand-tractors)

  • Level of financial capital for covering the production costs

  • Livestock capital

5.4 CA Practices to Intensify and Diversify Conventional Farming Systems

In order to overcome problems related to soil degradation and reduced soil fertility linked to the traditional slash and burn system, and the recent development of monocropping cash crops, since 2002 some projects in Laos, Vietnam, and Cambodia have developed alternative techniques based on CA (Slaats and Lestrelin 2009), including direct seeding, management of crop residues, and crop diversification through legumes production in association or rotation with corn. These projects have produced interesting results at the farm level in terms of adopting these techniques as well as economic and ecological benefits.

Farming systems that successfully integrate crop and livestock enterprises stand to gain many benefits, which can in turn have a direct impact on an entire agricultural production. CA practices require critical levels of crop residue and cover crops to maintain or enhance soil chemical, physical, and biological properties as well as prevent land degradation. Crops and livestock compete for the same resources and require proper management to meet CA objectives. Farming systems that successfully integrate crop and livestock enterprises stand to improve synergies that directly impact production and agroecological efficiency offering numerous advantages such as income diversification through animal products such as milk, meat, fiber and manure, weed control, soil erosion control, increased yield of main crops, and incomes during the “start-up” period for tree crops (Sanchez 1995).

The appropriate management of livestock is a key issue for improved grain production and even for livestock itself, by improving the sources and quality of feed, and indirectly by improving the soil. In order to achieve this, the following practices are emphasized:

  • Do not overstock; keep some animals according to land availability and forage production capacity which will balance biomass production and consumption throughout the year, avoid overgrazing, and maintain adequate soil coverage

  • Increase land-use intensity by establishing fenced areas for production of grasses and legumes for different uses such as cutting, grazing, silage, hay and for corrals

  • Control grazing with rest periods, which allows pasture recovery. However, the investment for pasture division and rotational grazing is a real constraint

Unfortunately, the dissemination of these new techniques is slow and a significant number of farmers have abandoned these systems due to several constraints: (i) lack of access to credit, suitable equipment, and markets for legumes; (ii) lack of technical support from government; and (iii) lack of farmer or village crop and animal management organizations. On the other hand, an example of a “development fund for sustainable agriculture” has been implemented in Sayaboury, Lao PDR. Based on a tax of 10 Lao Kip kg−1 on exported corn, the fund provides financial and technical support to farmers. This initiative has facilitated the establishment of a favorable socioeconomic context through strong links between farmers and traders for credit, markets, and equipment access, which are essential for the development of similar adoption dynamics for more sustainable cropping systems using direct seeding techniques and promoting diversified production.

5.5 Developing Human Resources to Address the Needs of CA Development and Dissemination Groups

5.5.1 The Present Context

Training is a central issue for CA and agroecology. The development of farming systems that are more intensive and more respectful of natural resources and the environment requires acquisition of new stakeholder knowledge and skills to trigger these changes. The lack of resources and training managers on these issues is often mentioned as a key sticking point to further development.

Ongoing research and development projects have specific objectives to transfer the knowledge and know-how gained during project implementation to existing national institutions. To be effective, this transfer simultaneously requires a capacity-building program in the area of professional training and communication. Different groups such as farmers, extension agents, researchers, and technicians from national organizations must gain competence to efficiently manage new professional responsibilities. Capacity-building is a long process, which requires adequate human resources and financial means.

This training strategy is not only an accumulation of training sessions, field visits, and other activities. It is a permanent attitude aimed at acquiring and assimilating knowledge and know-how. This will result from three types of actions: (i) facilitating information access; (ii) creating and supporting collective thinking during all the steps of program implementation; and (iii) organizing training sessions to cover the technical, management, and legal aspects of CA implementation.

5.5.2 International CA Training Cooperation with Brazil

At the regional level, there are no academic or even technical offers in terms of agroecology and/or CA. Several years ago, a training offer was made by the University of Ponta Grossa (UEPG-Brazil). This initiative has been supported by various Brazilian research and extension organizations. The UEPG benefits from the university structures and has been developing specific curricula on CA and direct seeding since 1984. Six international training sessions were organized between 2006 and 2011 thanks to support from the “Multi-Country Project for Agroecology—PAMPA.” To date, these courses have trained 78 agronomists, researchers, and academics involved in the field of CA. These researchers came from 12 countries, including Cambodia, China (Shanghai and Yunnan), Laos, Thailand, and Vietnam.

5.5.3 Technical Training in Laos

To meet the challenges of sustainable agricultural intensification in Laos, the Centre for Research and Training in Conservation Agriculture (CERFAC) in Ban Poa (Xieng Khouang Province) was created in 2007 (Fig. 12.3). The aims of the CERFAC Ban Poa Centre are:

Fig. 12.3
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Technical training in North Laos

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  • Training and awareness for a wide audience of students, technicians, farmers, and policy makers. The center began to assume a regional role of exchanges in the framework of the CANSEA network. In 2011, 7 Chinese technicians from the Yunnan province and in 2012, 12 Vietnamese technicians received general training in CA-direct seeding mulch-based crop system (DMC) techniques

  • Conducting innovative research to support the training program, including development of ecologically more intensive innovative farming systems based on CA principles.

6 Problems and Constraints Encountered in Scaling-Up/Out CA

The factors influencing farmers’ decisions to adopt (or not) CA practices are both highly context-specific (e.g., biophysical characteristics, involvement of local elites, extension staff motivation, and capacity; Lestrelin et al. 2012b) and fast changing (e.g., market opportunities, land degradation stage, and/or production costs changes).

General constraints learned from this decade of CA experiments in SEA include those specific to CA systems (e.g., local unavailability of suitable equipments, relay crop, and residue management) and, more importantly, those common to all innovations dealing with agricultural intensification in the uplands and with smallholders (e.g., lack of land tenure security, communal land-use plan, poor public resources and support, unadapted credit access).

6.1 Lack of Availability of Suitable Implements Locally

The lack of availability at a local level of suitable equipments for CA implementation, notably for smallholders, is a major constraint already described for other small-scale agricultural contexts (Harrington and Erenstein 2005; Kassam et al. 2009; Johansen et al. 2012) . Manual sowing in a mulch increases labor force requirements (Affholder et al. 2009; Lestrelin et al. 2012b) , drudgery-induced delays in crop establishment with negative impacts on productivity, and increased competition for labor with other farm activities, notably transplanting lowland paddy rice (Lienhard et al. 2008) . Different no-till planters have been introduced from Brazil and tested/adapted in Laos and Cambodia. This equipment has significantly reduced sowing drudgery and improved labor productivity (Lienhardet al. 2013d) . The importation process and cost of such equipment, as well as the local need for equipment maintenance and continuous adaptation, has highlighted the need for increased involvement of local (national/regional) manufacturers in the development and deployment of affordable and effective no-till implements.

6.2 Communal Grazing and Cover Crop Protection

Communal grazing after crop harvest is a widespread traditional territory management rule in SEA mountainous areas (Garrity 1996) . Animals are located far from cultivated areas during the cropping season and brought back after harvest, threatening cover crop development and effective residue management.

Cover crops must provide clear economic benefits for smallholders to shift from conventional monocropping to systems with crop association and/or succession. Most successful stories of CA intercropping systems in SEA are associated with edible or commercial bean production and/or forage use for livestock system intensification.

Fencing is often required to supplement local bylaws on cattle roaming and ensure effective management and share of crop residues and cover crops between in situ recycling, livestock, and energy supply.

6.3 Unadapted Credit System

Regardless of annual production costs , the practice of CA often requires high initial investments hardly affordable by smallholders in the absence of adequate credit support. Credit needs are highly context-specific and depend notably on the cultivation system (manual vs. mechanized), productivity of the land (fairly productive vs. degraded), and local prices of commodities.

The access of smallholders to financial capital is a major issue for CA adoption in SEA. With limited guarantees (e.g., land titles) to support their credit demand, Lao farmers have been shown to encounter difficulties in gaining access to bank loans, which are, in any case, subject to high interest rates and short-term refund periods—hardly compatible with the timeframe required for such investments (Lienhard et al. 2008) .

6.4 Weed Management and Herbicide Use in CA Systems

Changing from a conventional system to CA changes the nature of weeds and weeding patterns (Kassam et al. 2009; Johansen et al. 2012) . The traditional reliance on burning and/or full tillage for initial weed control is not compatible with CA principles of maximum soil cover and minimal disturbance, respectively. Beyond considering soil disturbance, traditional hoeing of weeds during the crop cycle is hindered under CA by the presence of crop residues; and this leads to increased labor requirements.

To replace tillage and/or burning for weed control, CA-based projects have promoted slashing (in place of hoeing), rolling (in mechanized areas), crop rotations, use of cover crops, adjustment of sowing time and methods, use of competitive crop genotypes, planting pattern, adjustment of fertilizer strategy, and herbicides, all of which are part of an integrated weed management strategy (Johansen et al. 2012) .

6.5 High Specialization of Agriculture at Local Level

If local agriculture in SEA is increasingly integrated into market (ADB 2011), they also become more specialized. Lestrelin and Castella (2011) showed that for Laos, total annual maize production increased tenfold between 2000 and 2009 from 117,000 to 1,130,000 t, representing more than 90 % of total rainfed cultivated land in several areas. In Cambodia, Boulakia et al. (2010, 2012a) described highly specialized production systems in the uplands, and the difficulty to introduce crops in rotation with cassava due to the high-selling prices of cassava since 2008 (> US$ 200 Mg−1).

If higher integration to market is truly a chance for smallholders for their increased income (Lestrelin and Castella 2011) , the high specialization of agriculture also limits the development of more ecologically intensive CA systems.

6.6 Limited Public Resources to Ensure Adequate On-field Research, Sensitization, and Technical Support

SEA countries are not equal with regard to public support to research, education, and agricultural extension but many are considered low-income countries with limited means to invest in the agricultural development sector.

CA local adaptation and promotion takes time. Harrington and Erenstein (2005) stated that it is not unusual for CA implement development and adaptation to take at least 10 years of (continuous) research and extension. If CA economic and environmental benefits can be seen quickly at field and farm level, then their assessment at watershed/regional scale requires more resources (human and financial) and time. Low governmental salaries and means are also common constraints leading to limited motivation and effective support from agricultural extension agents.

7 The CANSEA Regional Network

7.1 Introduction: Background of CANSEA

Several research for development (R4D) projects in the subregion have developed and disseminated systems of CA based on DMC-SCV, which contribute to ecological intensification and sustainable diversification . These projects have produced a significant set of results and data on CA farming systems in SEA. The CANSEA was created in September 2009 to address various regional problems of research and development, which cannot be solved at the national level. CANSEA is a structured regional organization aimed at implementing projects of regional interest with regional comparable research designs, harmonized environmental and economic assessment methods, and comparable impact indicators (Legoupil 2013) .

7.2 Organization and Governance of the CANSEA Network

This regional network of research for development is made up of eight institutional partners from six SEA countries.

Eight founding members of the network are:

  • Cambodia: the Ministry of Agriculture, Forestry, and Fisheries (MAFF)

  • China: the Yunnan Academy of Agricultural Sciences (YAAS)

  • Indonesia: the Indonesian Agency for Agriculture Research and Development (IAARD)

  • Laos: the National Agriculture and Forestry Research Institute (NAFRI)

  • Thailand: the University of Kasetsart

  • Vietnam: the Northern Mountainous Agriculture and Forestry Science Institute (NOMAFSI) and the Soils and Fertilizers Research Institute (SFRI)

  • The French “Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD)” which cooperates with all partners in SEA. The CANSEA network is considered by CIRAD as its own platform in partnership for CA development in SEA

The CANSEA network is a regional nonprofit structuring organization for research institutions and/or CA-dedicated groups. Network members agreed to: (i) share experiences and results, (ii) define regional priorities and design corresponding R&D programs, and (iii) research and mobilize funding to implement regional programs. CANSEA allows members to do together what cannot be achieved individually. The network is managed by a steering committee and a regional coordination unit (Vientiane Laos). The organizational structure of the regional network is given in Fig. 12.4 (Legoupil 2013) .

Fig. 12.4
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The CANSEA organizational structure

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Table 12.4 shows how the CANSEA strategy areas link to, and are coherent with, national interests for defining common priority objectives. This demonstrates the clear opportunities and entry points for CANSEA members to cooperate with each other.

Table 12.4 Interactions between CANSEA’s strategic topics and geographical areas
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8 Conclusion

While CA investigations are currently mainly in the research sector, recent field experiences in SEA have indicated their potential as a viable and accepted alternative to plow-based agricultural intensification, even in the context of small-scale farming. Several lessons can be learned from the past decade of in situ CA experiments:

  • Agriculture and cropping patterns in SEA are spatially diverse and constantly evolving. The identification of windows of opportunity for CA, i.e., key moments for intervention along specific agroecological transition pathways corresponding to successive stages of land-use intensification and land degradation, may facilitate the design of appropriate CA technologies and spatially differentiated policies.

  • Agricultural trajectories often repeat themselves in time and space, so that lessons can be drawn from past experiences and/or neighboring countries. The recent CANSEA network may play a key role in facilitating the exchange of results and experiences within the region, and hence in CA diffusion.

  • Increase the participation of the private sector. Undoubtedly, there is a need for higher sensitization and enrollment of the private sector to not only improve local availability of suitable implements but also provide credit facilities and/or technical support to farmers’ groups.

  • Need for long-term active research, training, and technical mentoring on CA. A shift from projects on CA to programs on CA is required at the national and regional level to better capitalize on research results and human resources. Of the research topics related to continuous improvement of CA agronomic, economic, and environmental performances, the question of enhancing the diversification of farming systems and reducing pesticide use are two important ones.