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The political and territorial reintegration strategy that had been implemented in Cambodia to establish peace and order in the late 1990s caused the degraded evergreen forestlands to be allocated to the demobilized Khmer Rouge families in the western regions of the country. The increasing regional demand for cereals and tubers and the highland saturation in central rice areas have driven massive immigration of smallholder farmers. Almost half a million hectares of those forestlands were thus converted in less than 15 years for annual upland cash crops development. This dramatic expansion of agricultural area, without any plan for sustainability, has exerted tremendous pressures on the natural forest resources and on biodiversity. Its effects rapidly spread on the water and soil resources of Cambodia. With conventional practices and more frequent flooding and incidents of drought, smallholder farmers could hardly sustain their livelihoods, which are mainly based on annual upland farming. Farmers with investment capacity have shifted to planting tree crops and/or to animal production in order to cope with the hazardous phenomena. This case story presents the collaborative R&D program between farmers and researchers in Battambang and Kampong Cham provinces in Cambodia. The program aimed to restore soil fertility and build the resilience of smallholder farmers to the effects of climate change while improving crop productivity and profitability of the smallholder farmers. Using the Diagnosis, Design, Assessment, Training and Extension (DATE) methodology, the project implementers designed, tested, and evaluated crop production systems that are grounded on the principles of conservation agriculture (CA). DATE is a multi-scale, multi-stakeholder participatory approach. It integrates scientific and tacit knowledge, and is composed of four components: agrarian systems diagnosis, field experiment, on-farm assessment, and pre-extension. A number of CA-based cropping systems have been designed and validated in the program: (1) mono-cropping of maize in association with pigeon pea or mungbean as relay crops, (2) biannual rotation cropping of maize with soybean or cassava, and (3) intensified cropping of maize and cassava. Synergizing this with the benefits of CA, each system has the capacity for climate change adaptation and mitigation, to retain soil fertility, and to increase smallholder farmers' profitability. Based on the results, pigeon pea is the most suitable crop for mollisols used with maize since it can improve the water retention capacity of the soil, reduce soil evaporation, and reduce mineral nitrogen inputs. Moreover, its grain can be sold or used as animal feed to augment farmers' income, a characteristic that smallholders look for in an agricultural production system. Likewise, shifting mungbean to be sown by hand broadcast after harvesting early maize significantly reduces farmers' risks and costs, thereby improving their productivity. Shifting to CA-based cassava production (a key annual crop) using chisel to operate strip tillage on planting rows after the early maize harvest also enables farmers to significantly minimize risks and costs. These risks and costs are estimated to be about USD (United States Dollar) 300–400 per hectare and USD 200 per hectare, respectively. Designing CA-based cropping systems based on the DATE methodology presents clear benefits. DATE is a holistic approach for identifying technical, socioeconomic, and institutional elements for a sustainable and more inclusive intensification of smallholder farmers' agricultural production systems. However, designing such innovative techniques is a combination of context-specific and context-generic features. These issues need to be taken into account should such innovation be replicated in other regions. In addition, this action-research program should be a continuous process; the agro-technical performances of the introduced cropping systems should be continuously validated in multiple locations and for several years. The outcomes of the cropping systems should also be continuously monitored such that their impacts on natural resources (e.g., soil organic carbon, nutrient cycles, xenobiotic dynamic, etc.) can be determined and measured accurately.

The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass-C input and its biodiversity under no-till (NT) drives soil restoration of degraded agro-ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow-based conventional tillage (CT) on soil organic carbon (SOC) stock vis-à-vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0_58 and 0_67MgCha_1 y_1 in the 0- to 20-cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0_59 for the PG site and ranged from 0_48 to 1_30MgCha_1 y_1 for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14_2%at the PGsite and ~20_5% at the LRV site. The SOC resilience index ranged from 0_29 to 0_79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline.

La connaissance des différentes unités agronomiques au niveau d'un terroir et leur utilisation par les agriculteurs est indispensable si l'on veut adapter les propositions de systèmes SCV aux contraintes du milieu. Ces unités agronomiques sont définies de manière à constituer des ensembles homogènes, pour lesquels les systèmes de cultures que l'ont peut proposer sont identiques. Ainsi, l'origine d'un sol n'est pas vraiment discriminante (il ne s'agit pas d'unités pédologiques), mais on s'attache avant tout à prendre en compte les caractères discriminant les possibilités de culture. Dans la zone agro-écologique de moyenne altitude, avec longue saison sèche, la différenciation agronomique des sols se fait sur la base de leur niveau de fertilité, de leur compaction, et de leur régime hydrique (en saison et en contre-saison). Ainsi, les pratiques agronomiques peuvent faire évoluer une parcelle d'une unité à une autre. Par exemple, un sol compacté sur lequel on installe des plantes de couvertures au système racinaire très puissant, peut ainsi évoluer en quelques années vers un sol non compacté. De même, la fertilité du sol peut évoluer, dans un sens ou dans un autre. En pratique, on peut distinguer ces unités en se basant sur la couleur du sol, la flore en place et les performances des cultures conduites par les paysans.

The production of annual cash crops (soybean, maize, cassava) in upland rainfed agriculture has been practised for more than 60 years in Cambodia. Today it is an important dimension in the development of smallholder agriculture on the western and northern pioneer fronts. Current tillage-based cropping systems induce soil depletion, weakening the production systems. A 9-year R&D program, initiated in 2004, has implemented the DATE methodology (Diagnosis, Design, Assessment, Training and Extension) to adapt direct-sowing mulch-based cropping alternatives for the sustainable production of soybean, maize and cassava on-farm, with and for farmers. The cropping systems that have developed integrate cover crops for biomass input to allow a rapid improvement of production capacity, even when instituted on severely degraded soil, setting the technical basis for sustainable agriculture that needs limited inputs of agrochemicals and that is adapted to smallholders conditions.

Les pratiques agricoles modifient les propriétés physiques et chimiques des sols, qui à leur tour peuvent affecter les micro-organismes qui y vivent avec des conséquences sur le fonctionnement biologique et la qualité de ces sols. Nous connaissons cependant peu de choses sur les interactions entre les pratiques agricoles, les propriétés physico-chimiques et les communautés microbiennes des sols. Peu d'études ont notamment été conduites dans les savanes herbacées des zones tropicales, fortement acides et lessivées, alors que ces espaces représentent des réservoirs importants de terres agricoles, aujourd’hui peu mis en valeur, alors qu’ils pourraient répondre, dans de bonnes conditions d’exploitation, au besoin local et régional d’augmentation et de pérennisation de la production agricole. Dans cette étude, nous nous sommes intéressés à l’impact de pratiques culturales (avec ou sans labour) sur les propriétés physiques, chimiques et microbiennes des sols d’une savane herbacée acide du nord-est laotien. Une rotation triennale riz/ maïs/ soja a été initiée en 2008, conduite selon 4 modalités culturales : 3 systèmes « zéro-labour » de semis direct sur couverture végétale (SCV) se différenciant par les plantes de couvertures associées avant et avec les cultures principales, et un système conventionnel (CONV) basé sur un labour annuel. L’impact de ces pratiques a été évalué deux ans après la conversion de ces terrains en terre agricole, en référence au pâturage naturel environnant (PAS). Malgré un nombre limité d’années de culture, nos résultats montrent un effet rapide des pratiques sur les caractéristiques des sols : contrairement à CONV, les SCV s améliorent les caractéristiques physico-chimiques des sols (stabilité structurale, matières organiques des sols et capacité d’échange cationique) ainsi que l'abondance microbienne (biomasse totale, densités bactérienne et fongique). Nous avons également observé des différences significatives de structure génétique des communautés bactériennes du sol entre SCVs, CONV, et PAS. De façon intéressante, l'abondance et la diversité bactérienne sont apparues différemment influencées par les changements d'environnement du sol: alors que la densité bactérienne a été affectée par la quantité et la diversité des résidus de récolte restitués au sol, à la teneur en carbone organique du sol et à la somme des bases échangeables du sol, la structure génétique bactérienne de sol a, de son coté, été principalement déterminée par la teneur en aluminium, le pH, la capacité d'échange cationique et le rapport C /N du sol. Cette étude, qui représente l’une des évaluations environnementales de pratiques agricoles les plus complètes en milieu tropical acide, nous amène à recommander les systèmes de semis direct sans labour avec restitutions élevées en résidus de récolte afin d'améliorer les propriétés physiques, chimiques et microbiennes des sols acides tropicaux et de contribuer ainsi à la durabilité de l'agriculture dans ces écosystèmes.

In the four southern districts (Kenthao, Paklay, Boten, and Thongmixay) of Xayabury province, the current cropping systems are based on cash crop production. Maize is the main crop under rainfed conditions and covers more than 30,000 ha in the region. Land preparation is based mainly on plowing, which degrades soil and destroys infrastructures (paddy fields and roads). These deteriorations result from growing pressure on agricultural systems and farmers' lack of access to affordable labour. This study sought to analyze soil aggregation, soil water-holding capacity, and soil biological activity under tillage and notillage conditions in relation to the cropping sequence. Three cropping sequences were investigated: 1. maize monoculture; 2. two-year rotational sequence, maize - rice bean; 3. two-year rotational sequence, maize + Brachiaria ruziziensis - rice bean.). Each year of the sequence was represented under no-till (NT) and tillage (CT) practices. Independent of depth, soil aggregation was greater under no-till conditions and enhanced by crop rotation and higher dry matter production (maize + B. ruziziensis / rice bean). Soil macrofauna, that is, the number of species and amount of biomass, was increased with no-till and the cropping sequence. Earthworms increased with no-till and for some cropping sequences amounted to more than 50% of the total macrofauna biomass. The cropping sequences produced a limited amount of dry matter. The main challenge was to increase biomass productivity (above-ground and below-ground) to recover ecosystem functions (recycling of nutrients, carbon sequestration, high biological activity, integrated weed and pest management, etc.) in a medium-term process (five years). Generating and adapting intensive cropping sequences (high production of aboveground and belowground biomass combined with a high diversity) under no-tillage systems with smallholders is an essential step in achieving long-term land sustainability, to obtain more reliable harvests and higher farm profits.

Les systèmes à base de maïs (altitude (600 - 1100 mètres d'altitude) avec longue saison sèche (6 à 7 mois). Ils sont particulièrement recommandés au Lac Alaotra et dans le Moyen-Ouest. Ils sont assez bien adaptés au climat semi-aride du Sud-Ouest et même dans le Grand-Sud, en particulier ceux à base de sorgho (Ils sont possibles avec le niébé (Vigna unguiculata) dans toutes ces zones, la variété de niébé à utiliser peut être une variété de cycle long ou de cycle court. La dolique (au dessus de 1200m. Sur les Hautes terres (climat sub-tempéré d'altitude), seul le systèmeMaïs + niébé (de cycle court) est possible et recommandé, mais uniquement en dessous de 1500 m d'altitude. Les systèmes à base de sorgho sont recommandés dans le Sud-Ouest (climat semi-aride) et dans le Grand-Sud principalement. Ils sont possibles et performants au Lac Alaotra et dans le Moyen-Ouest, mais cette culture y est peu appréciée. Zea mays) sont très bien adaptés au climat de moyenneSorghum bicolor).Vigna unguiculata) dans le Sud-Est (climat tropical humide).Dolichos lablab ou Lablab purpureus) et le Vigna umbellata se développent très mal.

The Plain of Jars is an acid, infertile savannah grassland covering an area of about 60,000 ha in the western region of Xieng Khouang Province, northeastern Lao PDR. In this ecology, farming systems are mainly based on lowland rice cultivation and extensive livestock production. An increase in rice production and intensification of the livestock industry are two key components in the Lao government's poverty alleviation strategy for this area. The main agronomic constraints for developing crops and forage systems are related to serious unfavourable soil chemical characteristics. Low pH, along with nutrients deficiencies (in nitrogen, phosphorus, potassium, calcium and magnesium) and high levels of aluminium saturation probably have a negative effect on the growth of upland crops, as well as many pasture species. Moreover, severe phosphorus deficiency generates animal health problems. Since 2004, the Lao National Agro- Ecology Programme (PRONAE) has been working on innovative farming systems based on direct seeding mulch-based cropping system (DMC) principles, as a technical approach, and on a progressive in situ validation process with smallholders as a Research & Development (R&D) approach. The advantages of the methodology are presented through the case of a DMC system developed in 2005 by the project to intensify rice-beef production in the Plain of Jars. The farming system initially proposed was a 5-year rotational sequence where improved pasture land was implemented in the first year, fattening activities conducted in the following three years and pasture regenerated in the fifth year using rice as a cash crop to finance pastureland re- implantation. Costs and benefits of the system were simulated according to the data collected in the creation sites. At the end of the 5 years, an average net income of 160 $US/ year/ha and an average labour productivity of 2.5 US$ per ha and working day were expected. The system was then proposed to 89 families forming 16 farmers' groups in 12 different villages for an in situ validation covering 76 ha. Even though promising results have been described at the creation site, 3-years of continuous validation have revealed several constraints for mass extension. In- field monitoring and interviews with farmers showed the main constraints to be (i) Market channels' constraints or malfunctioning, (ii) Fencing costs and maintenance, (iii) Production costs rising faster than benefits, (iv) Credit access and supply, (v) Technical skills required for good-quality pastureland implementation and management and (vi) Cattle fattening management. This feedback has given rise to development-related discussions and proposals regarding credit access, market channel functioning and training supports to be provided to farmers. This feed back has also given rise to new research topics, such as (i) how to generate higher incomes during the first year of implementation and (ii) how to reduce fertilizer use (main production cost) while maintaining at the same time improved pastureland productivity. New farming systems based on direct sowing of rice associated with forage species on degraded native pastureland have therefore been tested at creation sites and are currently under validation with farmer groups. This rice-beef system "creation- validation" process shows (i) the need to maintain research activities in the development process and (ii) the merits of the "creation site / farmer validation group" system for determining the potential for technology dissemination.

The National Agroecology Programme (PRONAE) and the Southern Xayabury Application Point (PASS) of the Capitalization and Rural Development Support Programme (PCADR) have developed an approach in the provinces of Xayabury and Xieng Khouang that relies on direct sowing mulch-based cropping systems (DMC). This approach has provided relevant alternatives to traditional agricultural practices which can no longer ensure the foundations of sustainable agriculture. In view of the results obtained, be they socio-economic or environmental, the Council of Ministers asked the Ministry of Agriculture and Forestry (MAF) to promote these techniques throughout the country, and called for this approach to be included in university and school courses. It is in that context that the Sector-based Agroecology Programme (PROSA), whose main aim is to define and implement a national strategy for the dissemination of Conservation Agriculture based on agroecological techniques (DMC), operates. This strategy is based on implementing an Agroecology Action Plan relying on the necessary incorporation of natural capital in rural development policies. The plan involves programming activities, setting in place decision-making and operational processes and bringing into play financial, material and human resources on both a central and local level (province, district and sub-district). The finest level of intervention comprises groups of farmers linked to service centres set up by the government within the districts (Kum Ban Pattana). On each level, the agroecology action plan is to arise from an integrated and concerted approach, in which each category of rural development stakeholders is committed to a process in which their needs and skills are acknowledged by all. Likewise, on each level, it is necessary to define, in a concerted manner, the initiatives that have to be taken (diagnosis, planning, implementation, monitoring-appraisal), the tools required (training of the different stakeholders, organization and structuring of the State sector and of the private sector, contractualization between stakeholders) and the fields of involvement (extension, local development funding arrangements, management of natural resources, equipment management, organization of supply and marketing chains, etc.). Each of the two pilot provinces, Xayabury and Xieng Khouang, is in the process of defining its Provincial Action Plan in Agroecology. An initial diagnosis of farming systems and their envi ronmental impacts, along with the needs and contributions of each category of stakeholders, has been completed. The provinces then gave priority to defining decision making and operational processes, and setting in place financial arrangements for the Provincial Action Plans. Initially, two funding tools are under consideration: constitution of a development fund, and agricultural credit. On a central level, the decision-making and operational processes are directly attached to the Ministry of Agriculture and Forestry, notably via the Planning Department. The creation of a Research and Service Provider Centre in support of local and national development is envisaged. Likewise, on a central level, it is a matter of facilitating the implementation of training plans for the different stakeholders. Lastly, the inclusion of agroecology in university and school courses is under way. Also for the educational sector, it is necessary to define a training plan to strengthen the skills and abilities of teachers. The creation of a national, or even regional network associating agricultural faculties and agricultural schools would enable an economy of scale by more effectively taking advantage of complementarities and decentralization to a more functional local level.

Tour of Shanghai region and Chongming Island --- Jiao Tong University (Franco-Chinese ARCUS project). Tour of Southeast Yunnan. Route Kunming -- Wenshan - Mengzi - Kunming - YAAS University. Seen on Chongming Island and areas around Shanghai (Qingpu) : - In the field: Agroforestry work (Dr. Chunjiang Liu), very intensive cropping system. Rice/wheat with tillage, burnt straw, massive use of chemical fertilizers including N (> 240--300 kg/ha/year) on slightly alkaline, hydromorphic alluvial soils with a varying water table. - Jiao Tong University: Multi-disciplinary complex with state-of-the-art equipment and top level scientists. Proposals: ? Improve agroforestry DMC systems to be "as fully ecological as possible". - Convert the existing rice/wheat system into a DMC with management of straw combined with live perennial legume covers planted in the wheat and controlled by irrigation water in the rice - Rapid reduction of chemical inputs to quickly achieve organic rice/wheat production with clean soil and water without productivity loss. - DMC rice/wheat systems set up on farms and on the University campus to serve Franco-Chinese PhD trainings on major biology topics at the heart of DMC operations (carbon sequestration, pertinent global biological indicators, microbial ecology tools, ecology engineering x ecosystem services including phytoremediation, optimization of "genotypes x environments x soil and crop management mode" relationships). Seen in southeast Yunnan (Wenshan) - Mediterranean red soil (fersiallitic) on upland peneplains and on low mountains +/-- leached, active degradation under heavy tillage; mountains farmed from top to bottom, manure carried up on people's backs, 1000 m²/worker. On the plains, irrigated rice farming on the lowest lying zones during the hot season, potato on straw beds (rice straw). Vertisol +/-- saline bordering on red soil on the large upland plains planted with fruit trees (grape vines, Eriobotrya japonica, Punica granatum, Morus alba, various fruit trees) as in the Mengzi region. - On extremely steep slopes + maize intercropped with sweet potato in the hot season (on these soils, rapid fall of organic matter). - On the plain, very intensive system on tilled soil + plastic over vast surface areas, irrigated by small hill reservoirs; maize, pepper, tobacco crops in the hot season (tropical climate), wheat + strong diversification of market garden produce in the cold season. - 5 - Proposals - Enormous work to do with fertility regenerating DMCs, intensive sustainable agriculture with minimal chemical inputs, on both mountain and plain agriculture. ?- Very intensive, very diverse DMCs to be built: On the plains: - DMC on live plant covers (multiple agrosystemic services) with buried drip irrigation (+/- 20 cm) sustaining very diverse associated crops ("mini-forests"). - Under irrigated trellis fruit crops, install plant covers that do not require maintenance and provide extensive ecosystemic services. - On rice paddy fields, beyond the rice-potato system, build very productive DMCs with little chemical inputs, including N towards increasingly biological, ecological DMCs. In the mountains: - Urgent priority: stop tillage; focus instead on protecting soil with cover crops. - Build very intensive DMCs on live and dead covers based on maize + sweet potato (traditional system), maize associated with biodiversity combinations that provide at no cost enormous ecosystemic services which economize inputs and protect the environment (maize + Stylosanthes, maize + Desmodium (uncinatum + intortum) maize + (Finger millet + Cajanus), maize + soya, maize + (oat + vetch); soya + (oat + vetch) etc... and these same crops on perennial legume covers. - As in Chongming-Shanghai, YAAS University has excellent laboratory equipement and young, highly skilled, highly motivated, multi-disciplinary teams. The same major scientific themes cited in the case of Chongming-Shanghai centered on soil biology could be the focus