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Montane Paddy Rice: Development and Effects on Food Security and Livelihood Activities of Highland Lao Farmers
Abstract
Rice, the staple crop in northern Laos, has traditionally been grown in shifting cultivation systems (upland rice). Government policies and increasing population pressure have resulted in declining productivity of this system. Farmers need alternative and sustainable rice production systems to meet their rice needs. One alternative is the production of rice in flooded, terraced fields (montane paddy). This option is not new; however, farmers are developing these montane paddy fields much more now than in the past. The objectives of the study were to understand why farmers have begun developing montane paddy, the effect of paddy rice production on farmer livelihood activities, and the economics and costs associated with developing paddy land. The survey focused on 9 highland villages in northern Laos. In all villages, farmers reported declining upland rice yields. Between 1998 and 2002, the paddy area in these villages increased by over 240%. The main reasons cited for developing new paddy area were higher yields and less labor involved in paddy rice production. Paddy farmers had better rice security, grew more cash crops, owned more livestock, and had higher income. A cost–benefit analysis of developing paddy area suggests that paddy development is a good investment. Further research is required in identifying suitable areas for continued development, and accessing the environmental and social impacts of paddy development.
... In these regions, rice (Oryza sativa) as a staple food has been traditionally grown in S&B systems by resource-poor subsistence farmers (Linquist et al. 2007). Traditional upland rice cropping still accounts for half of the total rice area in the north, yielding 1.7 t ha -1 on average (Ministry of Agriculture Forestry 2004). ...
... Unstable production has been attributed to environmental heterogeneity, as well as insufficient and irregular rainfall (Roder 2001, Linquist et al. 2006, Saito et al. 2006b). Furthermore, rapid population growth combined with government policies for forest conservation no longer support traditional S&B agriculture with long fallow periods, which has consequently resulted in fallow shortening from 40 years in the 1970s to 5 years by 1992 (Roder et al. 2001), and then to 2 to 3 years in the 2000s in some areas (Linquist et al. 2007). Under short fallow conditions, soil degradation proceeds and thus crop productivity can rapidly decline. ...
... The poor adaptation of japonica varieties to low-yielding conditions was the result of reduced grain numbers per panicle and a decreased grainfilling ratio, but these parameters were well maintained by indica varieties, as was previously reported by Asai et al. (2009b). The superiority of indica varieties was also consistently confirmed under unfavorable upland conditions in past field trials conducted in Luang Prabang Province, where yield levels were within a range of 0.5 to 1.8 t ha -1 (Linquist et al. 2007, Sengxua et al. 2007, Asai et al. 2009b. As was observed in this study, indica varieties in the tropics had in common vigorous tillering traits with small-sized grains (Takahashi 1984). ...
Adaptability to a wide range of environmental factors is a key for achieving stable production in the slash-and-burn (S & B) agriculture of mountainous Laos, where soil varies widely in productivity. Adaptability assessment based on the genotype by environment (GxE) interaction of grain yields in this study entailed an investigation of the yield performance of maize, Job's tears, and seven varieties of upland rice including improved variety B6144F-MR-6-0-0 (B6144), at eleven locations under rainfed upland conditions. Across the eleven locations, the mean yields of upland rice ranged widely from 56 to 583 g m⁻². While the GxE interaction was significant, one improved indica variety (B6144) produced high grain yields at all eleven locations. Under low-yielding conditions (56 to 205 g m⁻² of upland rice), four indica varieties consistently performed with more stable yield performance than three tropical japonica varieties, the poor adaptation of which was attributed to reduced grain number per panicle and the grain-filling ratio. Under moderate- and high-yielding conditions (284 to 583 g m⁻²), two semi-dwarf varieties - Tampi (tropical japonica) and B6144 (indica) - exhibited the highest productivity due to a higher harvest index (0.40-0.41) compared with the others (0.28 - 0.34), but B6144 likely exhibited lodging signs under fertile soil conditions, where the mean yields were above 360 g m⁻². The GxE interaction effect was highly significant among the three upland crops; relative to upland rice, maize was particularly better adapted to moderate-and high-yielding conditions, whereas Job's tears adapted better to low-yielding conditions. Job's tears exhibited stable yield performance across all eleven locations. In contrast, maize had higher yield compared with all upland rice varieties under the adapted conditions, although the upland rice varieties had higher yields compared with maize under unadapted conditions. In conclusion, Job's tears or indica varieties are recommended for growth under low-yielding conditions, and maize or semi-dwarf cultivars are recommended under high-yielding conditions. And with possibly more lodging resistance, the improved indica variety B6144 could be the ideal variety adaptable to a wide range of soil fertility.
... The theoretical basis for AP draws on concepts from input-output analysis, an economic method originally devised to quantify and assess interdependencies between producers and consumers in large-scale economies (Leontief, 1966). In AP, water flows within a hydrologic system are conceptualized as carrying 'embedded' or 'dissolved' productive value, analogous to an aqueous solution in the field of chemistry. ...
... This agricultural catchment covers approximately 3.5 km 2 and land use is dominated by rice production (Fig. 9). Similar to areas throughout upland Laos (Linquist et al., 2007;Roder, 2001), rice is produced in two distinct agroecosystems: upland rice is directseeded on unbunded fields on hillslopes within the traditional shifting cultivation system, while paddy rice is produced during the wet season in flooded conditions on bunded fields established in two low-lying areas. Paddies are irrigated from the Hom stream that drains the catchment. ...
... This example demonstrates this capability, and though livestock and cash crops are important livelihood components in upland Laos, only rice production aspects are considered and results thus represent the aqueous productivities for rice production only. Relevant production and economic data were acquired from both primary and secondary sources (Linquist et al., 2007;Pandey and Bhandari, 2010;Roder, 2001) and are shown in Table 2. ...
... The Lao government has implemented policies to reduce shifting cultivation and promote more permanent cultivation systems to prevent deforestation and degradation of the mountainous areas. However, such land use intensification has led to declining agricultural productivity (Linquist, Trösch, Pandey, Phouynyavong, and Guenat 2007) as yields have declined (Saito et al. 2006) and labor requirements, particularly for weeding, have increased (Roder 1997). One alternative is to develop more paddy area in the mountainous areas to increase rice production in a sustainable way (Souvanthong 1995;Linquist et al. 2007), but it is unclear whether sufficient suitable land is available. ...
... However, such land use intensification has led to declining agricultural productivity (Linquist, Trösch, Pandey, Phouynyavong, and Guenat 2007) as yields have declined (Saito et al. 2006) and labor requirements, particularly for weeding, have increased (Roder 1997). One alternative is to develop more paddy area in the mountainous areas to increase rice production in a sustainable way (Souvanthong 1995;Linquist et al. 2007), but it is unclear whether sufficient suitable land is available. Many of the large flat areas (at least 10 ha) in Laos have been converted to paddy through large-scale irrigation schemes but further research is needed to identify other (smaller) areas for paddy cultivation (Linquist et al. 2007). ...
... One alternative is to develop more paddy area in the mountainous areas to increase rice production in a sustainable way (Souvanthong 1995;Linquist et al. 2007), but it is unclear whether sufficient suitable land is available. Many of the large flat areas (at least 10 ha) in Laos have been converted to paddy through large-scale irrigation schemes but further research is needed to identify other (smaller) areas for paddy cultivation (Linquist et al. 2007). ...
To meet the growing demand for rice and to ease the pressure on mountain ecosystems in northern Laos, it has been proposed to reduce upland rice cultivation and to expand the area under paddy rice. We used Random Forest, a classification and decision-tree-based method, to characterize the areas currently under paddy cultivation, and to predict which areas are suitable for paddy. Topographic variables and accessibility to villages and roads were the most important predictors for the presence of paddy cultivation. There appears to be much land available that is suitable for expanding paddy areas in central and southern Laos but not in the north, where more than 40% of the rice area is on sloping land, and much less area is suitable. We conclude that expanding paddy-based rice production will be difficult in most parts of northern Laos.
... With declining upland rice yields, farmers must find alternative means of growing rice. Linquist et al. (2007) compare traditional upland production systems with terrace-based paddy production in the uplands (Table 10.5). We assume a 30-year project cycle and adjusted cost and farmgate price of rice to 2017 with a GDP deflator. ...
... 5 Assumptions for Benefit-Cost Analysis of Terrace-Based Paddy ProductionSource:Linquist et al. 2007. ...
The Environmental Challenges for Green Growth and Poverty Reduction in the Lao People’s Democratic Republic report reveals strong linkages among environmental quality, economic growth, and social wellbeing of the nation’s 7 million inhabitants. This report is a comprehensive presentation prepared after two years of targeted diagnostic research and analysis of issues and conditions within Lao PDR. The analysis was conducted by an international team of World Bank researchers in cooperation with counterparts in lead government agencies in Lao PDR. Information from the Ministry of Health, the Ministry of Natural Resources and Environment, and others, provided an initial basis for the assessments, and this was complemented by other international information. The results can be regarded as a state-of-the-art contribution of information to decision makers in Lao PDR having an interest in achieving sustainable growth consistent with the 2019 National Green Growth Strategy. The report’s scope includes consideration of impacts on key economic sectors and on risk factors influencing the health of the population. The assessments encompassed the economic costs of degradation in the forestry, agriculture, fisheries, mining, and hydropower sectors. The report identifies solid waste management and plastics as an important priority to which the Government of Lao PDR has already pledged its support in regional and global initiatives. Within the context of the Mekong River and its watershed, this report addresses climate-change impacts including increased risks of flooding.
https://openknowledge.worldbank.org/handle/10986/36266
... In the mountainous area of Laos, upland rice is traditionally grown as a staple food under swidden agriculture (Linquist et al., 2007). Political efforts enacted countrywide in Laos and elsewhere include liberalization of trade and the market in the 1980s and the implementation of land allocation programmes in the 1990s to promote cash crop production and control swidden agriculture with agricultural intensification (Fujita, 2006;Fujita and Phanvilay, 2008;Lestrelin et al., Trop. ...
... Although data on labour productivity remain scarce and it can be difficult to compare parameters among studies (Hunt, 2000), the labour productivity observed in the study area was greater than the values reported in other areas of Laos (5.0 kg-rice man-day -1 ) (Roder, 2001) and in other Southeast Asian countries (3 to 16 kg-rice man-day -1 ) (Hunt, 2000;Nielsen et al., 2006). The performance was comparable to those of lowland rice systems in Laos (13.1 to 28.7 kg-rice manday -1 ) (Linquist et al., 2007;Roder, 2001) and Thailand (46 to 55 kg-rice man-day -1 ) (Hunt, 2000). Furthermore, superiority was also confirmed in comparison with offfarm employment for construction labour in this village, which ranged from 50000 LAK day -1 (6.25 USD) to 60000 LAK day -1 (7.5 USD). ...
To assess the impact of labour-saving practices on farming management and its economic rationality in swidden agriculture of Laos, field surveys were conducted in a rural village in which herbicide application, outsourcing services in threshing and harvesting and late-maturing varieties for efficient harvesting during the dry season have rapidly expanded. With the enhanced labour efficiency, upland farmers extended the field size and produced a large volume of upland rice far exceeding consumption demand. The extent of swidden agriculture and the dependence on labour-saving practices were higher in the farmer group with field parcels in remote areas (F R) than in the farmer group with field parcels in non-remote areas (F NR). Irrespective of the higher production cost, the F R group represented approximately 70% of total upland farmers and achieved higher upland rice production and higher labour productivity than the F NR group. These findings suggest that the high demand for cash income is a causal factor for the emergence of labour-saving practices, and its wide acceptance could be attributed to its high economic rationality. However, the labour-saving farming strategy for large-area cultivation, together with the increasing population density due to immigration inflow during a past decade, resulted in deforestation and forest degradation at the village scale. For a sustainable development, a gradual shift in cash income sources from swidden agriculture to sedentary agriculture must be achieved by employing the labour force made available by labour-saving practices in new alternatives to field-size extension.
... But these traditional swidden systems based on long fallow periods are no longer viable because of rising population pressure. The fallow period has become shorter in response to increased pressure on the land, resulting in a loss of productivity over time (Maclean et al 2002;Linquist et al 2007). Overall, increasing pressure on the marginal uplands has contributed to environmental degradation as farmers reduce fallow periods even more and exploit fragile sloping land in the forest margins (Valentin et al 2008). ...
... Upland areas in Yunnan are characterized by rugged terrain, poor access to markets, environmental degradation, and high incidence of poverty. Upland rice is typically grown by farmers with inadequate resources in sloping fields under the shifting cultivation or swidden system for subsistence (Maclean et al 2002;Linquist et al 2007). In the shifting cultivation system of Yunnan, the fallowing cycle has become shorter over time in response to rising population pressure and government restrictions on the agricultural use of land (Pandey and Minh 1998;Asai et al 2009). ...
An analysis of the patterns of technology adoption by upland rice farmers in southern Yunnan and of the impact of technologies was conducted using farm-household data collected during 2005. The technologies considered were improved upland rice varieties and terraces. The results indicate that these technologies are now spreading in upland areas. Farmers who have adopted both technology components have been able to increase the upland rice yield substantially. Income from rice production was similarly found to be higher for adopters than for nonadopters. In addition, there was evidence that increased rice yield helped reduce the pressure from intensifying food production in these fragile uplands because farmers were able to meet their food needs from smaller areas. Implications of these findings for sustainable development of uplands in Yunnan and in countries in the region are drawn.
... The coefficient of the area of paddy fields to income diversity was not significant either. A case study in northern Laos reported that local people who had large paddy fields could increase engagement in many income-generating activities (Linquist et al., 2007). However, the current study showed that such fields did not clearly support them to enhance their activities. ...
... However, others have argued that a safety first principle often prevails for subsistence-oriented farmers (Rigg and Salamanca, 2009), and they hesitate to adopt new agricultural practices from the larger societies that have embraced them (Joseph and Richard, 2002). The reasons why these new practices are adopted by some socioeconomic groups but not others are multi-factorial, reflecting a complex combination of individual and environmental factors and events (Linquist et al., 2007;Rerkasem et al., 2002). Thus, Cramb (2000) emphasized that a detailed, all things considered case history approach is needed to understand the mechanisms behind the diffusion of agricultural innovations. ...
... The village territory consists of a narrow strip of lowland fields around the Nam Ma River and the hilly uplands on both sides of the valley. In 2001, the village was subject to the GoL's Land Use Planning and Land Allocation (LUPLA) programme, where village territories were divided between neighbouring communities, and the number of officially permitted upland fields per household was limited (see Ducourtieux et al., 2005;Linquist et al., 2007;Fujita and Phanvilay, 2008;Lestrelin et al., 2012). 24 The succession of settlements and the outcomes of the LUPLA process influence the distribution of land among households in the village today. ...
Die weltweit steigende Nachfrage nach land-basierten Rohstoffen erhöht stetig den Druck auf Land und Landnutzung, vor allem in ressourcenreichen Frontierregionen. Eine gegenwärtige Erscheinungsform dessen stellen Transnationale Landnahmen dar, die den Landnutzungswandel vorantreiben und die landbasierte Lebensgrundlage insbesondere der ländlichen Bevölkerung in vielen Teilen der Welt massiv bedroht. Ziel dieser Doktorarbeit ist es, ein besseres Verständnis der komplexen Prozesse zu schaffen, die Landnahmen befördern. Erstens untersucht sie die rezente Konjunktur des Bananenanbaus in der Provinz Luang Namtha, Laos, die von Chinesischen Investoren getrieben wird. Zweitens zieht die Arbeit das telecoupling Konzept heran und unterzieht es einer kritischen Diskussion in Bezug auf seinen Mehrwert für die Analyse räumlich entkoppelter sozioökonomischer und ökologischer Wechselwirkungen. Eine mehrmonatige ethnographische Feldforschung und deren qualitative Analyse stellen die Grundlage dieser Arbeit dar. Ausgehend von zwei Bananenplantagen in einer kleinen ländlichen Gemeinde fokussiert die Arbeit die Mechanismen und Prozesse, die die Bananenexpansion befördern. Das telecoupling Konzept dient als Instrument, um zu analysieren, welchen Einfluss die multiplen und ko-konstitutiven Interaktionen auf den Vorstoß des Bananenanbaus haben. Darüber hinaus verdeutlichen die tiefgehenden lokalitätsbezogenen Analysen die verschiedenen Kontexte auf, die dieses Wechselspiel spezifisch lokal verorten und gestalten. Die Fallstudie zeigt auf, wie die räumlich entkoppelten Beziehungen durch ein grenzüberspannendes Netzwerk chinesischer Investoren mit sozialen Verbindungen in die Provinz hinein, sowie auf den (chinesischen) Obstmarkt vermittelt werden. Außerdem stellt die Studie heraus, dass die Strategien der Investoren zur Landgewinnung und der daraus resultierende verheerende Landnutzungswandel einer Entfremdung der Dorfbewohner_innen ‘vom Boden’ gleichkommen. Durch die empirische, methodologische sowie konzeptuelle Auseinandersetzung mit dem telecoupling Konzept verweist die Arbeit letztlich auf den Wert qualitativer Analysen für die schwer greifbaren, ‚immateriellen’ Interaktionen sowie mögliche Feedbackmechanismen, welche Landnutzungswandel in einer globalisierten Welt bestimmen.
... The Government of Laos and several international organizations often mention agricultural intensification as a way to curb the problems linked with resettlements and to increase agricultural productivity in general. Aside from the provision of agricultural extension services in resettled villages [33], a key identified challenge has been the expansion of irrigation, which could contribute to improving yields substantially [38,39]. Understanding to what extent resettlement and the LUPLA come along with effective processes of agricultural intensification could give further insights into the impact of these land policies on forests. ...
This study explores the relationships between forest cover change and the village resettlement and land planning policies implemented in Laos, which have led to the relocation of remote and dispersed populations into clustered villages with easier access to state services and market facilities. We used the Global Forest Cover Change (2000–2012) and the most recent Lao Agricultural Census (2011) datasets to assess forest cover change in resettled and non-resettled villages throughout the country. We also reviewed a set of six case studies and performed an original case study in two villages of Luang Prabang province with 55 households, inquiring about relocation, land losses and intensification options. Our results show that resettled villages have greater baseline forest cover and total forest loss than most villages in Laos but not significant forest loss relative to that baseline. Resettled villages are consistently associated with forested areas, minority groups, and intermediate accessibility. The case studies highlight that resettlement coupled with land use planning does not necessarily lead to the abandonment of shifting cultivation or affect forest loss but lead to a re-spatialization of land use. This includes clustering of forest clearings, which might lead to fallow shortening and land degradation while limited intensification options exist in the resettled villages. This study provides a contribution to studying relationships between migration, forest cover change, livelihood strategies, land governance and agricultural practices in tropical forest environments.
... Ziegler et al., 2009). In SEA, the policy of eradicating shifting cultivation practices has led to a dramatic reduction in the cropped area and to a shortening of fallow periods (Linquist et al., 2007), counterproductively resulting in declining crop yields (Lestrelin and Giordano, 2007) and increasing soil erosion (Valentin et al., 2008). From a hydrological point of view, this land degradation has also resulted in changes in the hydrodynamic properties of the soil surface (Ribolzi et al., 2011) and subsurface (Ziegler et al., 2004), and consequently, a change in the partitioning of rainfall between overland flow and infiltration. ...
The extent of faecal contamination in soils and water is still poorly known in rural tropical areas despite its important consequences on both human health and the economy. Here we explore the sources, pathways, and spatio-temporal dynamic of contamination in rivers of a rural tropical area at different spatial and temporal scales. Concentrations of Escherichia coli (E. coli), a faecal indicator bacteria (FIB), were measured in the Nam Khan river, tributary of the Mekong river (North Lao PDR). Measurements were made from the headwaters to the main stream under contrasted hydrological conditions (i.e. during base flow and stormflow) and during the wet and dry seasons in 2011. The results show that E. coli contamination is controlled by both land use (i.e. stock of bacteria brought to the soil surface by the faeces of human and livestock) and hydrology (i.e. contribution of overland flow to the river discharge). Direct point-source contamination is of minor importance in this rural watershed, however, during high discharge the concentration of FIB frequently exceeds 5000 MPN 100 mL-1. The E. coli module of the Seneque/Riverstrahler model was adapted to the context of the Nam Khan river, validated with field observations and used to analyse future scenarios of faecal contamination (changing demographic trends and improvements in wastewater management). We found that the risk of worsening FIB contamination was more related to the predicted future rural exodus and to wastewater management practices rather than to an increase in demographic pressure in these upland systems.
... Previous studies reported that such intensification in lowland paddies reduced land-use pressures on the hillsides in similar mountainous areas of the world. 5,11,15 As the double-cropping of rice was not common in the lowlands of the Tanala region in the 1980s 19 or earlier, 10 this farming practice was probably widely adopted over the past few decades. The introduction of rotating rice and leguminous crops (groundnuts and common beans) was also initiated by a recent USAID-funded project through the Koloharena cooperative. ...
An alternative production system to slash-and-burn cultivation is urgently required to satisfy both increasing subsistence needs and environmental conservation objectives in the rainforest region of Madagascar. This paper investigates the current land-use management practices of smallholder farmers that have faced tight land-use pressures due to rapid population growth and stricter forest protection laws. Spatio-temporal patterns of land use were analyzed for lowland and hillside households by using data obtained from a ground survey of 316 fields. Both household groups retained longer fallowing periods for upland rice cultivation (lasting 5.4 to 6.8 years) than those previously reported (of 3 to 5 years). Recent dynamic changes in the agricultural systems included bottomland saturation with irrigated paddies and a rapid transition of coffee-growing areas into slash-and-burn and terraced paddy areas, in order to meet subsistence needs. A shift in dependence from slash-andburn cultivation to lowland paddies was particularly significant among lowland households due to the expansion of terraced paddies and adoption of a double-cropping system in the irrigated lowlands. The hillside households intensified cassava cultivation in short-term fallowing periods, as also reflected by their high dependence on cassava for caloric consumption. The difference in countermeasures adopted by both household groups to deal with land-use pressures was partly due to the accessibility to extension services. The results suggest that such intervention to promote intensification in lowland paddies was apparently an effective approach to reduce dependence on slash-and-burn cultivation. Given the limited land areas in which to further expand paddy fields, higher crop productivity is needed in the future to achieve a smooth transition to an agricultural system not dependent on slash-and-burn practices.
... In hilly regions of Southeast Asia, upland rice is traditionally grown under slash-and-burn systems, where farmers rely on extended fallows to restore soil fertility and reduce pest and weed infestations (Kyuma and Pairintra, 1983;Roder, 2001). Although slash-andburn systems are sustainable when population densities are low enough to allow for long fallows (Kyuma and Pairintra, 1983), rapid population growth in these regions has resulted in the increase of the cropping intensity, defined as the frequency of croppings for a given period of time (Hayashi et al., 1993;Van Keer, 2003;Linquist et al., 2007). Due to intensive cultivation of upland rice without appropriate agronomic practices, the systems become unsustainable as soil fertility declines, weed infestation increases and yields decline (Funakawa et al., 1997;Roder, 2001;Saito et al., 2006a). ...
... Email: quyengret@yahoo.com landscape compartments (Jourdain et al., 2014;Linquist et al., 2007). The introduction of a second crop cycle -'spring crop' -in irrigable fields before the main summer rice crop each year takes part of this strategy. ...
In mountainous areas of Continental South East Asia, double cropping in the irrigable valleys and terraces is often promoted as a way to increase farmers’ income while alleviating the pressure of agriculture on fragile slopes. However, cold temperature and low global radiation may constrain this strategy. Lethally cold events may occur, and increases in crop cycle length may jeopardize the correct timing of the main rice crop, taking place in summer. The model PYE (potential yield estimator) simulating the impact of temperature and radiation on the development and yield of annual crops was adapted to account for the range of temperature occurring in the area under study. It was calibrated against experimental data for the three crops that are most often considered as spring crops in the irrigable land of the northern mountains of Vietnam: rice, soybean and maize. Then a virtual experiment was designed in order to simulate various scenarios combining crop species and sowing date with climatic data accounting for variability of climate across years, location and elevation. Completed with a sensitivity analysis, it allowed to define favourable ‘sowing windows’ for non-water limited environments, based on the three following criteria: high average yield, low incidence over years of lethally cold events and low incidence over years of delays in the maturity of the spring crop. The length of this sowing window varied greatly across the scenarios tested. The widest was obtained for the case of soybean whatever the location and elevation, which makes it the less risky of the tested options. The approach followed proved effective to identify favourable and unfavourable environments in order to help better targeting the policy in support to the introduction of a spring crop in the mountains of Vietnam.
... References: Linquist et al. 2007;Souvanthong et al. 2009 In the sparsely populated sloping uplands of northern Lao PDR, traditional livelihoods rely on shifting cultivation (swidden agriculture) of upland rice and other crops, with farmers also dependent on forest products and grazing livestock. Growing populations and government policy to eradicate shifting cultivation, combined with moves to protect forestlands, have limited areas where farmers can grow crops. ...
... These hills are used predominantly for shifting cultivation (Hett et al. 2011;Roder et al. 1997). Various case studies have reported that in northern Laos, especially in the provinces of Luang Namtha, Oudomxay, and Luang Prabang, shifting cultivation is still widespread (Inoue et al. 2010(Inoue et al. , 2007Leek 2007;Linquist et al. 2007;Roder 2001;Saito et al. 2006;Yamamoto et al. 2009;Yokoyama 2004) A good road network connects provincial and most district capitals in northern Laos. However, away from these major transport networks accessibility, in terms of practicable transportation, decreases and travel time to these centers thereby increases. ...
The rotational nature of shifting cultivation poses several challenges to its detection by remote sensing. Consequently, there is a lack of spatial data on the dynamics of shifting cultivation landscapes on a regional, i.e. sub-national, or national level. We present an approach based on a time series of Landsat and MODIS data and landscape metrics to delineate the dynamics of shifting cultivation landscapes. Our results reveal that shifting cultivation is a land use system still widely and dynamically utilized in northern Laos. While there is an overall reduction in the areas dominated by shifting cultivation, some regions also show an expansion. A review of relevant reports and articles indicates that policies tend to lead to a reduction while market forces can result in both expansion and reduction. For a better understanding of the different factors affecting shifting cultivation landscapes in Laos, further research should focus on spatially explicit analyses.
... The effect of government interventions on forest condition depends on policies and implementation practices. Ducourtieux et al. (2005) and Linquist et al. (2007) criticize the land allocation and village relocation policies of the Lao government, arguing that farmers do not have enough opportunities and resources to adopt alternative land uses and thus continue shifting cultivation, encroaching on forests as is the case in village 2. Raintree (2004) suggests that relocation leads to declining availability of NTFPs due to concentration of people in a few locations. In contrast, increase in forest cover and annual cropping area at the expense of shifting cultivation from 1993 to 2000 provides evidence for policy effectiveness (Thongmanivong and Fujita 2006). ...
Rural livelihoods in developing countries can be enhanced by improving access to natural resources, services, and markets. In remote rural areas of the humid or semihumid tropics, forests represent an important resource for livelihoods. In countries like Laos, where most primary forest has been converted to secondary forest, and where an intricate and interlinked mosaic of forest and farmland prevails, people depend on secondary forests as a prime source of goods and services. The linkages between local livelihoods and secondary forest resources are subject to changes caused by improving accessibility. This article studies how accessibility affects the condition of forests and local livelihoods by comparing three villages along a gradient of accessibility in Phonxay district, Luang Prabang province, northern Laos. The results of this research show that accessibility strengthens the influence of the government and of markets, and that local livelihoods improve with increasing accessibility, while forest condition deteriorates.
... In montane paddies, wetland rice is grown in wet season and it is rotated with rice or soybean, rice-bean, vegetables, etc. in dry season. Not all farmers have access to montane paddy lands (Linquist et al 2007), but where it is possible rice field productivity can be greatly enhanced. One component is increasing overall rice production by means of better varieties, fertilizers and pest control (Balasubramanian 2008). ...
... These policies are rooted in the policy-makers' general perception of shifting cultivation as a backward and underdeveloped form of land use (Mertz et al. 2009), representing a poverty trap (Bounthong et al. 2003) and mainly responsible for the continuing deforestation (Lawrence et al. 2010) and forest degradation (Fox 2000; Thongmanivong et al. 2009). However, various local case studies suggest that frequently, upland farmers have simply not had many alternatives to shifting cultivation and that these controversial policies have had little effect (Ducourtieux 2005; Roder 2001; Yokoyama 2004; Saito et al. 2006; Inoue et al. 2007; Leek 2007; Linquist et al. 2007; Yamamoto et al. 2009; Inoue et al. 2010; Hett et al. 2011; Alexander et al. 2010). Since the current and future role of shifting cultivation in the country's agricultural development remains highly contested , the availability of reliable and systematic evidence on the general characteristics and dynamics of this practice beyond that of anecdotal insights of case studies is crucial. ...
Despite the rapid agricultural transition which has occurred in the past decade, shifting cultivation remains a widespread agricultural practice in the northern uplands of Lao PDR. Little information is available on the basic socio-economic situation and respective possible patterns in shifting cultivation landscapes on regional level. Based on a recent approximation of the extend of shifting cultivation landscapes for two time periods and disaggregated village level Census data, this papers characterized these landscapes in terms of key socioeconomic parameters for entire northern Laos. Results showed that over 550,000 people lived in shifting cultivation regions. The poverty rate of this population was with 46.5% considerable higher than the national rural rate. The largest share of shifting cultivation landscapes are located in remote location and showed a high share of ethnic minority population, pointing to multi-dimensional marginality of these areas. We discuss that economic growth and increased market accessibility may not be sufficient to lift these landscapes out of poverty.
... Rice cultivation in local households' food security and livelihood systems is popular in an area located at the centre of genetic diversity of cultivated rice in montane mainland Southeast Asia (MMSEA; Pandey and van Minh, 1998; Canh et al., 2003; Douangsavanh et al., 2006; Pandey et al., 2006; Pfeiffer et al., 2006; Schiller et al., 2006; Heerink et al., 2007; Linquist et al., 2007). Internationally, the relationship between agrobiodiversity and socioeconomic development has become a focus of interest, such as the impact of land conversion on agrobiodiversity (Zimmerer, 2004) as land use transformation has taken place in most MMSEA areas (Rerkasem and Rerkasem, 1995; Rasul and and crop variety diversity (Rerkasem et al., 2002; Perreault, 2005). ...
Production of rice (Oryza sativa) under a shifting cultivation system (swidden rice) and paddy fields (wet rice) is an important livelihood strategy in Xishuangbanna, Yunnan, China where households are facing conversion from subsistence systems to commercial plantation-dominated systems represented by smallholder rubber plantations. However, there are few studies of the effects on rice production and varieties diversity, as well as livelihood effects at a household level during this conversion. This paper presents a household level analysis of agrobiodiversity loss and food security, as well as livelihood vulnerability during agroecosystems' conversion in Xishuangbanna. First, a quantitative assessment was made of the statistical data for rice and rubber production during the past 50 years in Xishuangbanna and at a village level from 1985 to 2005 for three villages from the valley floor and upland hills, respectively. Second, at a household level, 60 per cent of households from the three villages were investigated with a questionnaire from 1998 to 2005. The process of transformation has led to significant changes in the household's income and its proportion. Meanwhile, households have suffered livelihood vulnerability from excessive rubber plantations. The centrality of rice in Southeast Asian agricultural and social systems, contrasted with the significant erosion of rice-based agroecosystem of local households, calls for increased attention to the livelihood vulnerability during this conversion. Correspondingly, practical strategies to resolve livelihood vulnerability are proposed, such as construction of paddy and effective irrigation systems for food security, agroforestry systems in rubber plantation, instead of monoculture, and diversification of sources of household income. Copyright © 2010 John Wiley & Sons, Ltd.
... (Birch-Thomsen et al., 2010); 99.(Linquist et al., 2007); 100.(Dressler, 2006); 101.(Rist et al., 2010); 102.(Abdullah and Hezri, 2008); 103.(Mwavu and Witkowski, 2008); 104.(Dalle and de Blois, 2006); 105.(Brown, 2006); 106.(Xu, 2006); 107.(Dendi et al., 2005); 108.(Gafur et al., 2000); 109.(McMorrow and Talip, 2001); 110.(Turkelboom et al., 2008); 111.(Valentin et al., 2008). I: increase; D: decrease; NC: no change; PA: protected areas; U: urbanization; Agr: agroforestry systems; Mf: manged fallows; De.l: degraded land; Veg.: vegetables or flowers; Mon: monoculture tree crops; MixF: mixed fruit trees; AnCr: annual crops; PdR.: paddy rice; Gp: grass pasture; C.: charcoal extraction; ID: illicit drugs. ...
... Rapid population growth and government policies aimed at protecting forests no longer permit traditional slash-and-burn management with long fallows and have resulted in increased cropping intensity. The result is that fallow periods of only 2 or 3 yr, which is in line with the current government land allocation policies, are common (Linquist et al., 2007). These short fallows are not sustainable using traditional management practices (Saito et al., 2006b) and the development of stable alternatives for these areas is necessary. ...
Shortened fallows have reduced the productivity of traditional upland rice (Oryza sativa L.)-based slash-and-burn systems in northern Laos. New cultivars and management methods are needed for food security in the region. To assess their potential for increasing upland rice productivity, this study compared two improved and three traditional upland rice cultivars in three fertilizer treatments: no fertilizer, nitrogen (90 kg N/ha), and N plus phosphate (50 kg P/ha), in six trials over 2 yr. The two improved cultivars had consistently higher grain yields than the traditional cultivars across all fertilizer treatments (3.9 vs. 2.1 t/ha). The improved cultivars had greater total biomass and harvest index, more panicles, and were shorter than the traditional cultivars. They were also more responsive to N without applied P than traditional cultivars. Two of three traditional cultivars gave a response that was similar to the improved cultivars when both N and P were applied. In addition, on-farm trials were conducted at 13 locations to compare the productivity of the improved cultivars with fertilizer (N-P-K 60-26-50 kg/ha) to farmers' practice consisting of traditional cultivars without fertilizer. In these trials, the improved cultivars with fertilizer achieved much higher grain yields than farmers' practice (3.0 vs. 1.8 t/ha). Improved cultivars and moderate inorganic fertilizer application offer a new approach to increasing the productivity of upland rice in Laos.
Background: Obesity (Ob) linked to Breast Cancer (BC) has reached epidemic proportions worldwide (WW) including Indonesia, Brazil, Bangladesh and also developed countries. To assess the prevalence and asso iated risk factors of cebtral Ob and BC WW, are commonly linked with geography (wet and warm climate), race, immigrant, but not SES. Problem: Low and middle-SES are associated with lower outcone affect late diagnosis, late hospitalization and treatment, but not with p53 mutation caused by AFB1 exposure. Objectives: Low and middle-SES and neighborhood are linked to AFB1 exposure as the cause of Ob/BC prevalence. Method: PRISMA design of Systematic Review using Science Direct and EBSCO data based with keywords Ob/BC AND SES. A Bayesian network of Ob (BMI, WC, WHR) and SES (neighborhood) are used. Mainly high AFB1 high guideline AFB1 exposures are recorded. Result: One flowchart detected 152 references and one table or 30 references which included 153,099 subjects at least supported SES/AFB1-associated Ob/BC prevalence or almost related. Conclusion: Low and middle-SES represent AFB1 exposure as the cause of Ob/BC beyond geography, race, ethnic. Keywords: Aflatoxin B1, Waist Circumference, Obesity, Breast cancer, sociieconomic status (SES), Neighborhood.
Soil erosion supplies large quantities of sediments to rivers of Southeastern Asia. It reduces soil fertility of agro-ecosystems located on hillslopes, and it degrades, downstream, water resource quality and leads to the siltation of reservoirs. An increase in the surface area covered with commercial perennial monocultures such as teak plantations is currently observed at the expanse of traditional slash-and-burn cultivation systems in steep montane environments of these regions. The impacts of land-use change on the hydrological response and sediment yields have been investigated in a representative catchment of Laos monitored for 13 years. After the gradual conversion of rice-based shifting cultivation to teak plantation-based systems, overland flow contribution to stream flow increased from 16 to 31% and sediment yield raised from 98 to 609 Mg km −2. This result is explained by the higher kinetic energy of raindrops falling from the canopy, the virtual absence of understorey vegetation cover to dissipate drop energy and the formation of an impermeable surface crust accelerating the formation and concentration of overland flow. The 25-to-50% lower 137 Cs activities measured in soils collected under mature teak plantations compared to soils under other land uses illustrate the severity of soil erosion processes occurring in teak plantations.
Information related to environmental conditions such as soil characteristics is essential for the development of an effective lowland rice production strategy in the mountainous region of northern Laos. In this study, we investigate soils of lowland rice fields located at various topographical positions in an intermountain basin in order to evaluate the soil characteristics with special reference to mineralogical properties, charge characteristics, and P status of the soils. Five rice field sites were selected, including those located in the lower part of the basin (LP), upper part of the basin (UP), floodplain (FP), and fallow land at a hill slope (MF). The clay mineral composition was dominated by kaolin minerals and quartz in UP and MF and by kaolin minerals in LP. A higher proportion of illite and predominance of quartz was found in FP. All the soils showed point of zero salt effect (PZSE) values of less than 4.0, irrespective of horizon and site, which are 2.0-3.0 units lower than pH_w. The σ_p values ranged from 3.88 to 9.76 cmol_c kg^<-1> at the A horizon. The Feo/Fed and Alo/Ald ratios ranged mostly from 0.2 to 0.4 and 0.2 to 1.0, respectively. On the basis of these results, the soils in the study area were considered to be at a stage prior to a strongly weathered phase. The total P and Bray-P contents of the soils ranged from 139-503mg kg^<-1> and 1-63mg kg^<-1>, respectively. The Bray-P contents were in the order FP>UP>LP>MF. The total P contents and most of the inorganic P fractions extracted by sequential P analysis were highest at the A horizon in FR. The amount of inorganic P fractions in the surface soils of UP were higher than those of MF and LP. Therefore, it was suggested that eroded soil materials, including nutrients such as P from MF, were translocated to UP; however, they were prevented from reaching LP owing to its topographical position. The soils in FP seemed to be affected by the different soil materials transported by occasional flooding. These results indicated that it is necessary to establish lowland rice field management technologies by taking into account the difference in topography and its influence on soil fertility.
Field researchers and agricultural extension workers often encounter field-to-field variations in soil properties and rice yields that make it difficult for them to transfer appropriate agricultural technology and suitable management practices to local farmers. To address this constraint, we examined grain yield and shoot biomass of rice (Oryza sativa L.) and the general fertility status of topsoils (0-10cm) collected from 80 paddy fields with different topographical positions in an intermountain basin in northern Laos. The soils of studied rice fields showed fewer nutrients such as exchangeable bases, CEC, and T-C and T-N contents than the soils of lowland rice fields in Thailand. While higher levels of exchangeable K and available P and Si were found in rice fields at the upper part of the basin and the floodplains located in river catchments, the rice fields located in the lower part of the basin had lower soil nutrients probably due to less flooding and inflow of soil nutrients from the surrounding hill slopes. The yield of high yielding varieties (HYVs) was strongly correlated to CEC, exchangeable Ca, Mg, and K, and available P and Si. On the other hand, indigenous varieties (IVs) did not show a proportional relationship with those elements. Higher yields of HYVs were found in rice fields where soil fertility was relatively high. However, the yields of HYVs were not significantly higher than the yields of IVs under low fertility conditions, indicating that it would be invaluable to supply chemical fertilizer to grow HYVs in such infertile rice fields. In contrast, planting IVs in such conditions could be a better choice for local residents to obtain stable rice production without costly agricultural materials.
An evaluation of opportunity to improve productivity of highland paddy with green manure was conducted as a participatory research in collaboration with farmers of Tee Cha village, Sop Moei sub-district, Mae Hong Son province in northern Thailand. Four species of legumes (Lablab purpureus, Vigna umbellata, Canavalia ensiformis and Mimosa invisa inermis) were grown before the farmer-managed rice crop (cv. RD21) in farmer's highland paddy field. The biomass and nutrient contents of the legumes and rice yield and yield component were evaluated. Rice yield in the farmer's field was increased for 16-44% after green manuring, depending on the legume species, with V. umbellata having the highest effect on rice yield, followed by C. ensiformis. Farmers evaluation of the green manure legumes agreed with measurement of nitrogen content of the legumes and subsequent rice yield. The experiment and participatory results suggest that there is an opportunity to improve rice yield in highland paddy with green manuring.
This meta-analysis of land-cover transformations of the past 10–15 years in tropical forest-agriculture fronties world-wide shows that swidden agriculture decreases in landscapes with access to local, national and international markets that encourage cattle production and cash cropping, including biofuels. Conservation policies and practices also accelerate changes in swidden by restricting forest clearing andencouraging commercial agriculture. However, swidden remains important in many frontier areas where farmers have unequal or insecure access to investment and market opportunities, or where multifunctionality of land uses has been preserved as a strategy to adapt to current ecological, economic and political circumstances. In some areas swidden remains important simply because intensification is not aviable choice, for example when population densities and/or food market demands are low. The transformation of swidden landscapes into more intensive land uses has generally increased householdincomes, but has also led to negative effects on the social and human capital of local communities to varying
degrees.From an environmental perspective, the transition from swidden to other land uses oftencontributes to permanent deforestation, loss of biodiversity, increased weed pressure, declines in soil fertility, and accelerated soil erosion. Our prognosis is that, despite the global trend towards land use intensification, in
many areas swidden will remain part of rural landscapes as the safety component of diversified systems, particularly in response to risks and uncertainties associated with more intensive land use systems.
The mountainous mainland Southeast Asia region, that covers adjoining parts of Cambodia, Lao PDR, Myanmar, Thailand, Vietnam and China, contains the region's largest remaining tropical forest. The people living in the forested mountains, who belong to a diversity of ethnic minority groups, possess a wealth of local knowledge and skills in forest management. With rapid decrease in forest area, implementation of forest conservation policies, improved access to market and replacement of shifting cultivation with permanent cropping, land use and management in the region has been rapidly changing. Some indigenous knowledge and technology in forest management will inevitably continue to be lost in the process, but not all. This paper shows how local forest management systems have been adapted to deal with the change, with specific focus on deployment and adaptation of indigenous knowledge and skills. First background on the region and its traditional land use systems will be provided. A review will then be made of the cropping system changes that have been taking place and their driving forces and how local farmers have adapted indigenous knowledge and skill in forest management to meet current needs and conditions. Cases drawn from studies in the region will illustrate how deployment of indigenous technology not only helps the farmers to improve their productivity but can also provide services in forest regeneration and biodiversity conservation. To do this farmers, including those who were former migratory opium growers, make use of the knowledge of their own environment and locally available genetic resources and the community's organizational and management skills. It will also be shown that farmers’ knowledge and skills are not static, but continually revised and integrating modern inputs as well as transfer of new ideas and innovations.
Traditional tropical japonica genotypes (Oryza sativa) are typically grown without fertilizer for subsistence in slash-and-burn systems by resource-poor farmers in northern Laos. Recent short fallows have reduced soil fertility and rice productivity in these systems. Genotypes adapted to a range of soil fertility conditions are needed for their food security. Rainfed experiments were conducted to identify genotypes with high yield and to examine the nature of genotype by environment (G × E) interaction for grain yield. Two improved indica genotypes and seven traditional genotypes including indica and tropical japonica groups were grown without fertilizer in ten environments over the course of 2 years. The effects of G, E and G × E interaction were significant for grain yield, yield components, plant height and days to flowering. Two improved indica genotypes (B6144F-MR-6-0-0 and IR 55423-01) and a traditional indica genotype Chao Mat out-yielded the other genotypes across the environments (2.1 t ha−1 vs. 1.6 t ha−1). Pattern analysis showed that 40.2% of the G × E sum of squares was captured by a two genotype group by two environment group summary. One environment group had higher contents of soil organic carbon and extractable P and K, and mean grain yield than another environment group. The performance of one genotype group including consisting of improved and traditional indica genotypes was more stable across two environment groups than that of another group consisting of tropical japonica genotypes, which performed well only in the high soil fertility environment group. The low grain yield of tropical japonica genotypes in the low soil fertility environment group was the result of low sink size and grain-filling percentage. In conclusion, two improved genotypes are identified for high yield in both low and high soil fertility conditions and soil organic carbon appears to be a major factor contributing the G × E interaction for grain yield as well as overall productivity.
A study of air photographs and satellite imagery of a Hani village (Mengsong) in southwestern Yunnan between 1965 and 1993 showed that swidden cultivation did not lead to permanent conversion of forest land to agriculture but rather a conversion of a fairly homogeneous secondary closed-canopy forest into a highly heterogeneous land cover of different stages of forest succession. An analysis showed a direct correlation between government policies on producing food from hilly lands and the destruction of forest cover. This analysis also showed that since the Household Responsibility System was introduced in late 1979, allowing farmers the right to decide where, what, and how much to plant, farmers have decreased the amount of land farmed and intensified their farming methods.
This paper investigates changes in land cover, land-tenure policies, and market pressures in Baka village, Yunnan Province, China. Before 1950 local farmers engaged in many forms of collective behavior including common property management, religious rites, and other activities led by clan leaders. Between 1950 and 1978 peoples' communes governed the management of most lands. All farming activities were organized, and the amount of land to be farmed was determined according to instructions from upper administration levels. The implementation of the Household Responsibility System after 1979 gave individual households greater incentives to produce cash crops. These changes caused a demise in the planting of traditional crops, increased differentiation between rich and poor, and a gradual decline in collective forms of land management.
"The forests of Southeast Asia contain biologically diverse communities of vegetation and wildlife. These lands also support millions of tribal people who produce food and fiber for local and regional consumption. Today, traditional uses of forestland are being transformed by national market forces and changing national policies of landownership and land use. While tropical forest loss is recognized as a regional and global problem, little is known about the link between resource use at the local level and its effects on forest fragmentation and loss at the landscape scale. This study analyzed human-induced loss and fragmentation of tropical forests in three upland watersheds in northern Thailand between 1954 and 1992. During this 38-year period, forest cover declined, agricultural cover increased, population and population density grew, and agriculture changed from subsistence to cash crops. These changes resulted in forest fragmentation and loss, with implications for biological and cultural diversity, sustainable resource use, and the economic conditions of the region. By linking the outcome of individual land use decisions and measures of landscape fragmentation and change, we illustrate the hierarchy of temporal and spatial events that, in summation, result in global biome changes."
Landscapes in the mountainous north of Lao People's Democratic Republic (hereafter Lao PDR or Laos) are undergoing rapid transformation as road access is being improved and the area is integrated into the regional economies of Southeast Asia, particularly China. Rural livelihoods in the upland areas, long based on subsistence agricultural production, are changing as more households engage in the market economy. This study assesses land use changes from 1993 to 2000, as well as agricultural production in 4 northern provinces of Laos: Luang Prabang, Oudomxay, Bokeo, and Luang Namtha. The spatial data available for this region are limited, but several trends are apparent from 1993: the area of traditional upland agriculture and swidden farming (ie shifting agriculture) has decreased, while permanent intensive agriculture has increased. There is some evidence that forest cover has increased since 1997, probably as a result of the succession of abandoned swidden areas to secondary forest, but the quality and extent of this forest cover remains unclear. Agricultural sector analysis in the 4 northern provinces supported the land use data, showing a rise in commercial agricultural production of cash crops (including sugar cane, paddy rice, and maize) at the expense of subsistence agricultural production. All these changes reflect the government's policy of reducing shifting cultivation practices in the upland areas and promoting cash crop production. The new exposure to external market forces has begun to bring about changes in Laotian rural communities, with the development of village collectives to manage resources and negotiate with outside traders. However, it is also envisaged that this commercialization will increase the demand for privatization of agricultural land; this will require a renegotiation of current government land allocation policies.
Slash-and-burn farmers in the hills of Laos urgently need techniques that can sustain rice yields and reduce weed pressure
under short fallow periods. For this, the potential of pigeon pea (Cajanus cajan (L.) Huth) as a fallow crop was evaluated
in variety, establishment, and cropping systems studies conducted at Houay Khot station (19° N) from 1992 to 1995. Introduced
perennial varieties were not superior to local material for the parameters evaluated. Some semi-perennial varieties produced
grain yields up to 2.2 t ha-1 but were inferior in weed suppression and survival 12 months after planting. All varieties lost much of their weed competitiveness
after the first picking of pods. In studies without weeding, < 10% initially established plants were present 15 months after
planting. Compared with pigeon pea, Gliricidia sepium and Leucaena leucocephala performed better in biomass production, weed
suppression, persistence, and self-regeneration after cultivation of rice. In a rotation study, rice yield was 1.3, 1.5, 2.3,
1.6, 1.8, 1.8, and 2.2 t ha-1 (LSD 5% = 0.5 t) for continuous rice, rice-pigeon pea intercropping, rice after pigeon pea, rice after cowpea, rice after
Stylosanthes hamata, rice after maize, and rice after fallow, respectively. Compared with continuous rice, intercropping or
rotation with pigeon pea reduced nematode (Meloidogyne graminicola) infestation of rice and weed biomass in the rice crop.
In spite of the beneficial effects, rotation or intercropping systems with pigeon pea will only be viable if economic benefits
from harvested grain or from using plant parts as livestock feed can be obtained. Because of high mortality and weed invasion
pigeon pea is not suitable for fallow improvement if fallow duration is more than one year.
Decline in soil fertility accelerated by shorter fallow periods was expected to be a major constraint in slash-and-burn rice production systems in northern Laos. In this paper we describe relationships between fallow period, soil fertility parameters, weeds and rice yield. Soil infertility is not perceived a major yield constraint by the farmers. Of the various soil parameters observed only soil organic matter showed consistent association with rice yield (r=0.42, ppAgeratum conyzoides and Lygodium flexuosum. Soil loss during the cropping period ranged from 300–29.300 kg ha–1. For the same period organic matter, total N, available P and available K content in the top 0–3 cm decreased by 11,12,17, and 17%, respectively, and loss of total N for the soil depth of 0–25 cm was estimated at 400 kg ha–1. Soil physical properties, moisture stress and available N are the most likely detriments to rice yields. Further attempts to relate soil properties to rice yield should include repeated measurements during the cropping season and observations on soil physical properties.
About 25% of Laos' four million people practise shifting cultivation (mainly of rice) on a third of the country's cropped area. Official policy is to eliminate shifting cultivation by the year 2000. Diagnostic surveys of shifting cultivation were conducted in Luang Prabang and Oudomsay Provinces in northern Laos to understand the practice from a farmer's perspective, to observe fields, and to identify and give priority to problems and research to address problems. Weeds, low and possibly declining soil fertility, intensification of the cropping cycle, rats (plus birds, wild pigs), and insects lowered rice yields or reduced system sustainability. The forest ecosystem has been degraded by logging, burning, and rice monocropping; and potentials for environmental rehabilitation through natural succession are minimal. Farmers cannot adopt high labor and cash cost innovations; and improved fallow is needed as an intermediate step prior to crop diversification, adoption of agroforestry technologies, and sedentary agriculture.
In northern Laos, upland rice is grown as a subsistence crop under rainfed conditions with no fertilizer inputs. It has traditionally
been grown under slash-and-burn systems with long fallows, which restore soil fertility and reduce insect and weed pressure.
However, increasing population density and government policies aimed at reducing the area under slash-and-burn have reduced
fallows to as little as two or three years between rice crops. In this paper the impact of intensifying upland rice cultivation
and rainfall on upland rice productivity was evaluated using yield and rainfall data from Luang Prabang province from 1992
to 2004. In addition, an experiment was conducted in 2004 to evaluate the effect of upland rice cropping intensification on
soil nitrogen (N) and phosphate (P) availability and root pests (Tetraneura nigriabdominalis-root aphids and Meloidogyne graminicola Golden & Birchfield-nematodes). Rice yields were associated with total rainfall from June through August, corresponding to
mid-tillering through flowering growth stages of upland rice. Increased cropping intensity resulted in a significant reduction
of upland rice yields with higher rice yields being associated with longer fallows. Furthermore, when rice was annually cropped
in the same field without fallows, rice yields rapidly declined. A study conducted in 2004 indicated that increasing cropping
intensity reduced the soil N and P availability and increased root aphid infection of rice. The long-term productivity of
upland rice can not be sustained with increased cropping intensity using the current management practices. Therefore, improved
crop and resource management technologies are necessary for sustainable production.
Production of upland rice under shifting cultivation system is an important economic activity in the mountainous areas of northern Vietnam. A comparative study of two districts with differential market access and population pressure was conducted to highlight the effect of these variables on upland rice systems in northern Vietnam. Farmers in the district with a greater population pressure have a shorter cropping and a shorter fallowing cycle than in the district with lower population pressure. Farmers reported a high incidence of food shortage in both districts. Income from livestock and wages are important for food purchases, especially in the district with a better access to market. Even in these upland districts, access to lowland fields is a critical determinant of food security.
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