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Agriculture carried out in the mountainous areas of Southeast Asia is intensifying rapidly, driven as it is by economic growth, policy changes, the introduction of new technologies and population growth. Rice, the dominant crop, is giving way to a greater variety of cash crops such as maize, vegetables, fruits, flowers and rubber. Building on a long-term interdisciplinary research project run by the University of Hohenheim over the period 2000–2014, in collaboration with various universities and research institutes in Thailand and Vietnam, we discuss three interrelated problems that tend to accompany land use intensification in mountainous areas, these being rapid land degradation, increasing levels of pesticide use and pollution, and persistent poverty. We set the framework for this book by introducing these problems and discussing how research into the development, testing and adaptation of innovations, as well as the development of knowledge on mountainous land use systems, has contributed to more sustainable land use and rural development among the mountainous areas of Southeast Asia.

The information available in relation to soils in Southeast Asia’s (SEA) mountainous regions is still limited, and so our research tried to rectify this situation in two key ways. The first approach was to gather soil information in order to help develop a soil database for parts of mountainous SEA. This approach also included two further issues important to soil knowledge in SEA, as reported in this study: Savanna regions with underlying limestone are unique to SEA, resulting in specific soil landscapes with soils of various degrees of weathering. Non-sustainable agriculture affects soil fertility in the uplands of SEA, in particular the frequent problem of soil erosion at hill slopes adversely affects both soil physical and chemical properties. The second approach was to develop and progress methods so as to improve soil research and soil analysis. These approaches included (1) gamma ray spectrometry to retrieve airborne and ground-based data on natural radioactive isotopes of potassium, thorium and uranium in soils, as proxies for rock and soil formation, (2) an inter-comparison of state of the art soil mapping approaches in an development oriented context, and (3) the evaluation of ethnic soil knowledge systems, those considered useful in the identification of local soil distribution patterns, though not suitable for transfer to a larger scale.

The mountainous ecosystems of Southeast Asia have experienced a tremendous increase in human activity over the last few decades. An integral part of land use change and land use intensification in the area is the changes in water and matter cycling that have taken place, a situation which calls for increased attention to be paid to resource management, particularly given the environmental vulnerability of the region. Building on four case studies that describe the consequences of such change and provide implications for resource management with regard to flooding, nutrient stocks and fluxes, and the fate of pesticides, we develop a general perspective on current matter and water related issues. This perspective will require us to integrate (1) knowledge on water and matter related processes, (2) the spatial and temporal scales on which they are active and through which they connect inside a watershed, and (3) their physiographic (site and land use specific) domains.

A change in land use from the growing of upland rice to the cultivation of cash crops has increased the level of use of synthetic pesticides in the mountainous areas of Thailand and Vietnam. Although this increase has occurred generally across both countries, it has been especially prevalent in mountainous areas. The objective of this chapter is to describe the challenges faced when wishing to reduce the risks caused by the use of agricultural pesticides in mountainous areas, both from an economic and a biophysical point of view. Building on case studies from Thailand and Vietnam, we show how the potential risk of pesticide use is related to the limited experience farmers have in handling pesticides, and the hydrological relationships between highland and lowland areas.

In the mountainous regions of Southeast Asia, smallholder farmers are both victims of and actors in the degradation of natural resources, as a result of their agricultural activities. Addressing sustainable development thus requires a good understanding of the agriculture-poverty-environment nexus – defined as the set of complex linkages between agriculture, poverty and the environment – and of the economic incentives that drive the natural resource use of smallholder farmers in vulnerable areas. The objective of this chapter is to improve our understanding of the extent and nature of these linkages across different settings in Southeast Asia – namely northern Vietnam and northern Thailand, and to derive policy recommendations that can contribute towards the enhancement of sustainable development in these regions. The chapter draws on empirical research conducted in northern Vietnam and northern Thailand between 2007 and 2011.

With higher fruit exports from Thailand, the importance of irrigated fruit production has increased over recent years and, as a consequence, water resources have become more and more scarce. At the same time, farmers in northern Thailand are being increasingly confronted with weather anomalies. Scheduling based on plant stress avoidance or the exploitation of stress signals can optimize water use efficiency and the profitability of irrigation under changing climatic conditions. Traditional irrigation through the use of water hoses is a common management practice in northern Thailand; however, this method is inefficient, labor intensive and relatively inflexible. The introduction of micro-irrigation systems is one important component in the development of water saving irrigation practices, with cost-benefit analyses showing that investment in a micro-sprinkler system can be beneficial. As with improved irrigation, the marketable fruit yield can be increased substantially during drought years; thus, it is worthwhile changing from traditional to modern, water efficient and flexible irrigation systems. The emphasis of irrigation research is placed on increasing water use efficiency (WUE) and deficit irrigation strategies, in particular, partial root-zone drying (PRD) were found to increase WUE substantially. Under PRD only one side of a tree row is watered, while the other is left to dry-out to a predetermined level before next being irrigated. Stress responses in general decrease water consumption and vegetative growth while yield decline is usually minor. In on-station experiments, PRD treated mango and longan trees maintained yields when compared to well-watered trees. Sophisticated deficit irrigation strategies can only be applied when robust stress monitoring methods are available, and thermal imaging is one such new, non-invasive method. In the research study outlined here, the use of this method was investigated under field conditions, with our findings showing that it has the potential to be used within future irrigation scheduling systems.

This chapter briefly summarizes the causes and consequences of soil erosion, before presenting examples of effective soil conservation technologies (SCT), such as contour-based cropping, cover crops, mulching and geo-textiles, and based on case studies from northern Thailand and northern Vietnam. Depending on site conditions, a soil erosion reduction of 30–60 % in the first year after establishment and up to 72–98 % by the third year was observed in these studies when compared to local farmers’ practices. In north-east Thailand, maize grain yields increased from 1.5 and 3.2 Mg ha, to 3.8 and 5.5 Mg ha under minimum tillage und relay cropping. The study in north-western Vietnam revealed that although the majority of farmers were aware of soil erosion mitigation methods, adoption rates of the promoted soil conservation technologies remained low. These technologies compete for land and labor resources with the main cropping activities, in particular highly profitable commercial maize cultivation, incurring high opportunity costs. Based on these case studies, we conclude that innovative approaches to soil conservation require a change in land use systems, not just the adoption of conventional SCT in the existing systems. The integration of plant and animal production in the uplands should be promoted that allows farmers to benefit from urban-based economic growth on the one hand, such as through the exploitation of niche markets for high-value meat, while being environmentally sustainable on the other. The improved integration of animal husbandry with plant production systems could make feed producing soil conservation options more attractive to farmers, which could be further stimulated by introducing payment for environmental services (PES) schemes.

Aquaculture is an important part of the farming system for ethnic Black Thai farmers in the uplands of Son La province, providing cash income and protein rich food for home consumption. The current aquaculture system, with grass carp as its main fish species, is a feed-based system, with leaf material from banana, maize and cassava as well as weeds and by-products from other farming activities, used as key inputs. As with all other feed-based aquaculture systems, this system depends on a constant flow of water in order to supply oxygen; however, the system is limited by feed and water availability and is threatened by a disease that affects only grass carp. This chapter provides a detailed description of the use of aquaculture within the Black Thai’s farming system, an analysis of the feed resources currently used therein, as well as of those resources that may potentially be used. It also provides an analysis of grass carp diseases as well as a description of innovatory aquaculture practices geared towards replacing the disease susceptible grass carp with common carp, as the main species. These suggested modifications are based on the enhanced production of natural food in ponds and the application of supplemental feeds partly based upon on-farm resources. Finally, the potential for earthworms to be used as a high quality feed ingredient, one which can be produced on-farm from currently not used or underutilized resources, is studied in terms of the production of supplemental feed for the common carp.

Participatory approaches have been discussed as alternatives to and complementary elements of more conventional research on sustainable land use and rural development in upland areas of Southeast Asia. Following a brief overview of the history of participatory approaches (Sect. 9.1), this chapter discusses the potential and limitations of applying Participatory Rural Appraisal (PRA) tools to field research practice in Vietnam (Sect. 9.2) and of involving stakeholders in priority setting, modeling and environmental valuation in the Southeast Asian uplands (Sect. 9.3). Section 9.4 scrutinizes the use of the Payments for Environmental Services (PES) tool, which aims to actively engage smallholder farmers in preserving fragile mountain ecosystems in Southeast Asia by rewarding them in cash or in kind. Section 9.5 provides an example of a successful multi-stakeholder knowledge and innovation partnership in northern Thailand – in the form of a litchi processing and marketing network formed among Hmong villagers, an approach which uses a promising action-research approach towards building sustainable rural livelihoods among ethnic minority groups.

People’s decisions with respect to agricultural land use and management practices have had a major impact on natural resource degradation in Vietnam and Thailand for centuries. In addition to an ever-increasing population density, economic transformation and market integration have exacerbated the pressure on natural resources in the rural areas of both countries, particularly during recent decades. From its beginning, the Uplands Program has sought to address research questions related to the impacts of land use management on natural resource degradation at the landscape level in Southeast Asian countries, as have researchers linked to the Program in the area. Integrated modeling of land cover and land use change, as a means to simulate effects which extend over various spatial and temporal scales or scientific domains, began to play a more prominent role within the Uplands Program after 2006. This chapter highlights modeling approaches and decision support tools used as part of the Uplands Program to investigate various research questions at the human–biophysical interface, and will compare modeling approaches, looking at the issues of land use and management impacts from different angles, whereby the different focuses used by each model have resulted in different levels of detail and precision in various respects.