Length Of Fallow Period Research Articles

Satellite data reveals a recent increase in shifting cultivation and associated carbon emissions in Laos

Although shifting cultivation is the major land use type in Laos, the spatial-temporal patterns and the associated carbon emissions of shifting cultivation in Laos are largely unknown. This study provides a nationwide analysis of the spatial-temporal patterns of shifting cultivation and estimations of the associated carbon emissions in Laos over the last three decades. This study found that shifting cultivation has been expanding and intensifying in Laos, especially in the last 5 years. The newly cultivated land from 2016 to 2020 accounted for 4.5% (±1.2%) of the total land area of Laos. Furthermore, the length of fallow periods has been continuously declining, indicating that shifting cultivation is becoming increasingly intensive. Combining biomass derived from Global Ecosystem Dynamics Investigation and shifting cultivation maps and area estimates, we found that the net carbon emissions from shifting cultivation declined in 2001–2015 but increased in 2016–2020. The largest carbon source is conversion from intact forests to shifting cultivation, which contributed to 89% of the total emissions from 2001 to 2020. In addition, there were increased emissions from intensified use of fallow lands. This research provides useful information for policymakers in Laos to understand the changes in shifting cultivation and improve land use management. This study not only supports Reducing Emissions from Deforestation and Forest Degradation reporting for Laos but also provides a methodology for tracking carbon emissions and removals of shifting cultivation.

Tree species composition and diversity in abandoned Jhum lands of Mizoram, North East India

Shifting agriculture system (locally known as Jhum) is the main driver of deforestation and forest degradation in north eastern region. This system has been extensively practiced to sustain the livelihood in rural areas of Mizoram which possesses serious threats to forest ecosystem and soil fertility. The course of vegetation development in secondary forest in abandoned fallow is a major concern to understand the process of succession in different fallow length. This study was undertaken in Aizawl and Mamit districts, Mizoram with the objectives to determine the tree species diversity, richness and abundance in different fallow periods. Fallow ages of 2–5 years (F5), 6–10 years (F10), 11–20 years (F20) and 21–30 years (F30) were selected with a total number of 37 sites and two circular plots of 12.6 m were laid in each site to carry out extensive enumeration and analysis of tree species. A total number of 91 tree species and 38 families were recorded. The number of trees increased by 47% from F5 to F10 but the same was decreased by 35% from F10 to F30. Ecological indices indicate high diversity and species richness in F10 and F30 compared to F5 and F20. The basal area significantly increased with the length of fallow period. The average girth at breast height (GBH) in F5 was 30 cm but in F30, the GBH increased to 130 cm. The dominant species changed as fallow period increased e.g. F5 was dominated by Castanopsis tribuloides, F10—Rhus chinensis, F20—Macaranga denticulata and F30—Albizia chinensis. The changes in dominant species with respect to fallow ages in the present study could be due to large anthropogenic disturbance on the pioneer species as well as greater establishment ability of the climax species in relation to its environment, altitude and soil condition.

Modelling the effects of pasture renewal on the carbon balance of grazed pastures.

In New Zealand, pasture renewal is a routine management method for maintaining pasture productivity. However, knowledge of the renewal effects on soil organic carbon (SOC) stocks is still limited. Here we use a process-based model, CenW, to comprehensively assess the effects of pasture renewal on the carbon balance of a temperate pasture in the Waikato region of New Zealand. We investigated the effects of renewal frequency, length of fallow period, renewal timing, and the importance and quantification of age-related reductions in productivity. Our results suggest that SOC change depends on the combined effects of renewal on gross primary productivity (GPP), autotrophic and heterotrophic respiration, carbon removal by grazing and carbon allocation to roots. Pasture renewal reduces grazing removal proportionately more than GPP because newly established plants need to allocate more carbon to re-build their root system following renewal which limits foliage production. That lengthens the time before above-ground biomass has grown sufficiently to be grazed again. New plants have a lower ratio of autotrophic respiration to GPP, however, which partly compensates for the GPP loss during renewal. Our simulations suggested an average SOC loss of 0.16 tC ha-1 yr-1 if pastures were renewed every 25 years, but could gain an average of 0.3 tC ha-1 yr-1 if pastures were renewed every year. For maximizing pasture production, the optimal renewal frequency depends on the rate of pasture deterioration with more rapid deterioration rates favouring more frequent renewal. Additionally, the length of the fallow period, renewal timing, and associated environmental conditions are important factors that can affect SOC temporally, but the importance of those effects diminishes at the annual or longer time scales. A major uncertainty for a full understanding of the renewal effect on SOC lies in the rate of pasture deterioration with time since previous renewal.

Effects of land use change on turnover and storage of soil organic matter in a tropical forest

Land-use change of tropical forests causes loss of soil organic matter and plant productivity. Effects of fallow or plantation vegetation on soil organic matter storage need to be clarified to optimize land-use that maximizes soil organic matter storage and plant productivity. We compared 30-year changes in soil carbon stocks and litter decomposition under different land-uses (primary dipterocarp forest, Macaranga forest, Imperata grassland, transition of Imperata grassland to Acacia plantation, transition of Imperata grassland to oil palm plantation) in Indonesia. The Imperata grassland maximizes soil carbon stocks for up to 10 years due to considerable root litter inputs, but additional organic matter storage is limited over the following 20 years, due to high grass litter decomposability in the less acidified soil. The conversion of Imperata grassland to oil palm plantation causes greatest loss of soil organic matter, whereas Acacia plantation on Imperata grassland or the Macaranga forest maximizes soil carbon stocks due to input of recalcitrant forest litters and reduced microbial activities in the acidified soils. Farmers could adopt short-term ( 10 years) fallow under Acacia plantation on Imperata grassland or Macaranga regeneration forest to maximize soil organic matter storage. The optimum and feasible land-use strategies should be selected based on the length of fallow period and the original acidity of soil.

Site selection and soil fertility management by the Outer Baduy People (Banten, Indonesia) in maintaining swidden cultivation productivity

Iskandar J, Iskandar BS, Partasasmita R. 2018. Site selection and soil fertility management by the Outer Baduy People (Banten, Indonesia) in maintaining swidden cultivation productivity. Biodiversitas 19: 1334-1346. The Outer Baduy people heavily depend on swidden cultivation for subsistence. They grow rice in the uplands every year based on their calendar. The cropping calendar and calendar of social events are often closely interlinked. There is also traditional wisdom for conservation of land and forest such as the zonation for land use system. The Outer Baduy swidden land productivity is mainly determined by the time period of forest fallow relative to that of the crops. The long-term success of the Outer Baduy swidden cultivation depends on how well the fallow period restores or maintain soil fertility. The aim of this research was to study the local knowledge of Outer Baduy of soil categories and soil fertility and the management of soil fertility in their traditional practice of swidden cultivation. The method used in this study was the qualitative one, applying observation and in-depth interviews to collect the primary data. In addition, soil analysis was conducted by the Laboratory of Soil, Faculty of Agriculture, Padjadjaran University, Sumedang, Indonesia. The results of this study showed that the soils are classified by the Outer Baduy based on color, water content, stoniness or rock parent material, and humus content. To maintain soil fertility in the swidden cultivation, the Outer Baduy people have developed some strategies, such as determining appropriate fallow time period, applying zero tillage, and planting legume crops in both the swidden fields and the fallow land. Traditionally, because the Outer Baduy are forbidden to use inorganic fertilizers, the length of fallow period and kind of vegetation succession have an important role in maintaining soil fertility.

Impact of secondary forest fallow period on soil microbial biomass carbon and enzyme activity dynamics under shifting cultivation in North Eastern Hill region, India

Length of the secondary forest fallow period has often played an important role in affecting the soil fertility status for first year cultivation of crops in shifting cultivation system. However, information regarding the soils after the first year cultivation is limited. The objective of the study was to assess the effect of different shifting cultivation fallow period on the dynamics of soil health status during the first and second year. Results suggest that increase in the fallow period significantly (p<0.05) decreased the bulk density (BD), while increasing the soil organic carbon (SOC), soil nutrients, MBC and enzyme activities. While the SOC decreases between 6.1 and 31.3% due to cultivation compared to the soil condition before burning during the first year, MBC decreases between 33.61 and 60.9%. The SOC was recovered at the end of second year, while the MBC increases sharply during the second year. Enzyme activities in general decreased after burning and increased gradually during the second year. PCA results indicated that length of fallow period >10year maintains one cluster where fallow period including 10 and below maintains another cluster during the first and second year. Results therefore suggest that MBC, MBC:SOC and soil enzyme activities played as an indicator of soil health and maintaining secondary forest fallow period >10years was better in conserving soil health for first and second year under shifting cultivation.

The Effect of Fallow Period Length on the Abundance and Diversity of Usable Plant Assemblages in Shifting Cultivation System (Swidden Agriculture) in Northern Laos

ABSTRACT Shifting cultivation, or swiddening, involves alternating cycles of cropping and fallow periods. Rather than being abandoned, the fallow swidden fields provide a source of important plant products for remote, forest-dwelling human communities. In northern Laos, the traditional length of fallow periods used to range between five and 11 years, depending on the availability of land and quality of the soil. Fallow periods are currently being shortened because of population pressures and government policies. To determine the potential impacts of shorter fallow periods, 128 swidden fallows of various ages (up to 20 years), located at altitudes between 400 and 800 m a.s.l. in northern Laos were sampled for usable plants. The impact of fallow length on plant abundance and species diversity was analysed. The number of usable plant species was found to increase with the fallow age until it was 11–12 years old, and then decline, while the abundance of usable plants increased beyond that period. We conclude ...

Land use evolution and management under recurrent conflict conditions: Umbundu agroforestry system in the Angolan Highlands

The article analyzes the effects of long term armed conflicts on the characteristics and evolution of traditional land uses. The main focus is on the Umbundu agroforestry system, an endogenous and dynamic traditional African land use in the Angolan Central Highlands, an area that has experienced numerous conflicts during the last 200 years. The study used field research and a literature review to analyze the historical evolution of the system and its recovery after the conflicts. The results provided a characterization of the system's main traits and stakeholders through time. The main focus of the system was maintaining a continuous supply of food crops under changing ownership and security, constrained by soil fertility, and the availability of water and fertilizers. Land use conflicts moulded the system, allowing it to be rich during low and medium intensity conflicts, though constraining it when conflicts escalated to a military civil war. The evolution of the land use system was examined using the frame of multi-functionality. Additional focus is made on its current and future challenges to become a sustainable and profitable agrarian land use system. The study has implications for land use management (e.g. regarding the length of fallow period) as well as conflict management.

Effects of Different Types of Litters and Fertilizer Application on Growth and Productivity of Maize (Zea mays L. var. Across 86 Pool 16) in Senegal

Achieving food security in its totality continues to be a challenge not only for developing nations, but also for the developed world. In the 1996 Rome Declaration on World Food Security, food security is defined as: food that is available at all times, to which all persons have means of access; that is nutritionally adequate in terms of quantity, quality, and variety; and is acceptable within a given culture (Madeley, 2002). Therefore, food insecurity is not simply a failure of agriculture to produce sufficient food at the national level, but instead a failure of livelihoods to guarantee access to sufficient food at the household level. Thus, availability, access, and affordability are all elements of food security. Food security is affected by a complexity of factors. The root cause in developing countries, Africa in general and Sub–Saharan Africa in particular, is the inability of people to gain access to food due to poverty (IAC, 2004). The major challenge for Africa in terms of food security is its underdeveloped agricultural sector that is characterized by over–reliance on primary agriculture, low soil fertility, minimal use of external farm inputs, environmental degradation, significant food crop loss both pre– and post–harvest, minimal value addition and product differentiation, and inadequate food storage and preservation that results in significant commodity price fluctuation. In Senegal, as in all other West–African countries, the food situation is far from being satisfactory, and more than 32% of households live under the poverty line (Daps, 1990). Ninety five percent of the food in Sub–Saharan Africa is grown under rain fed agriculture (IAC, 2004). Hence, food production is vulnerable to adverse weather conditions. Since the 70’s, agriculture in the Sahelian area has been characterized by erratic rainfalls (Davis–Carter, 1989). There is an overall decline in farm input investment including fertilizers, seeds, and the adoption of technology. The soils continue to degrade leading to the reduction of farm productivity. Other factors that negatively affect agriculture in Africa include the decline in the use and length of fallow periods, the expansion of agricultural production into marginal and fragile areas, the removal of vegetation through over grazing, the rapid population growth leading to land pressure, the limited access to agriculture– related technical assistance, and the lack of knowledge Effects of Different Types of Litters and Fertilizer Application on Growth and Productivity of Maize (Zea mays L. var. Across 86 Pool 16) in Senegal

Factors Influencing the Integration of Non-Timber Forest Products Into Field Crop Cultivation: A Case Study From Eastern Nepal

This article examines the feasibility of integrating five non-timber forest product (NTFP) species into field crop cultivation in eastern Nepal. Cost-benefit analyses including Net Present Value (NPV) and Benefit-Cost Ratio (BCR) show that all the NTFP species are more profitable than field crops. This profitability relationship holds true even under a sensitivity analysis assuming a 20% reduction in yield and/or fall in prices. However, despite the profitability, farmers do not readily integrate these species into their farmlands on a large scale. A regression analysis of constraining factors explored in a household survey revealed that domestication of NTFP species is significantly influenced by factors such as knowledge and skill required for domestication, frequency of visits to a forest, length of fallow period, size of upland terraces, cattle and goat herd size, accessibility of a forest, permit system, trading system, and market uncertainty. Overall, the unfavorable institutional environment has been the major factor constraining the integration of NTFP species into farmland. Policy recommendations include transferring management to local people such as changing the open-access status of national forests; providing NTFP collection permits to local residents; amending inappropriate policies; promoting group marketing; and taking an adaptive, collaborative approach to community forestry.

Intensity Of Agricultural Labour Use By Gender In Rural Households Of Imo State

This study was designed to analyze the intensity of agricultural labour use by gender and its determinants in rural households of Imo State. Data were collected with structured questionnaire from 60 male and 60 female headed households, and analysed using means, frequency distribution, percentages and ordinary least squares multiple regression model. The amount of labour use per hectare was estimated at about 186.5 mandays and 203. 7 mandays for male and female farmers respectively. Determinants of labour use intensity by gender were labour requirements for land preparation, labour required for planting, labour required for weeding, labour required for harvesting type of tools used, timing of farm operations, length of fallow period, difference in income between farm and non-farm products, state of infrastructure and labour according to type of crop mixture. There is need to develop labour saving technologies to achieve increased food crops outputs and farm income in Imo State. Keywords: intensity, agricultural labour, gender, rural households JOAFSS Vol. 4 (1) 2006: pp. 51-59

Evaluation of short-term fallowing as a strategy for the management of recurring organic enrichment under salmon cages

Rotation of cages within fish farm leases and the subsequent fallowing of areas of seabed is commonly used to allow recovery of infaunal communities following periods of organic enrichment. To investigate the effect of different background environmental conditions on recovery response, two Atlantic salmon ( Salmo salar) fish farm sites in southeast Tasmania were sampled over two commercial fallowing cycles. Despite similar stocking levels and feed input there were significant differences in the way in which sediment at each farm responded to the cessation of fish stocking. Sediments at both farms showed some improvement in the community structure over a three month fallow period, but the community structure only recovered to that present before stocking not to that at the reference sites. The similarity of the impact sites to the reference sites increased from ca. 25% to 31% at one site and 11% to 27% at the other after fallowing. Rate and extent of recovery were affected by farm location, initial impact of the sediments, and length of fallow period. Initial recovery was faster at the more sheltered site than at the more exposed site, possibly reflecting differences in environmental resilience with the more sheltered location better able to assimilate organic inputs. Accordingly general fallowing management protocols may need to be adapted to reflect differences between sites. The findings of this study suggest that the recovery response of benthic communities can be predicted once baseline conditions are understood.

Long-term effects of improved legume fallows on soil invertebrate macrofauna and maize yield in eastern Zambia

Though improved fallows have been widely promoted as low-input technologies suitable for soil fertility replenishment in smallholder agriculture in southern Africa, their interaction with soil invertebrates has not been studied. In the present study we compared the population of soil macrofauna in maize grown in gliricidia (Gliricidia sepium), leucaena (Leucaena leucocephala), Leucaena diversifolia, sesbania (Sesbania sesban) and acacia (Acacia anguistissima) and continuously cropped monoculture maize. The objectives of the study were to determine (1) the effect of the type and length of fallows on soil macrofauna communities and functional groups, and (2) the long-term effect of legume fallows on maize yield. The number of invertebrate orders per sampling unit was significantly influenced by the type of fallow but not by the length of fallow period. Maize grown in legume fallows had more numbers of invertebrate orders than monoculture maize. Among the soil invertebrate macrofauna, centipede and millipede populations were significantly influenced by fallow type. The density of earthworms varied with both the type and length of fallow practice. Earthworm populations under maize grown in gliricidia fallows were significantly higher than those under fully fertilized monoculture maize. The population densities of other invertebrate orders and functional groups did not significantly differ between maize grown continuously in monoculture and in legume fallows. The highest maize grain yield (3.0–6.0 t ha−1) was recorded in fully fertilized monoculture. Maize grown in gliricidia and leucaena fallows consistently gave 2.0–4.0 t ha−1 throughout the study period, while maize grown without fertilizer yielded less than 2 t ha−1. These legumes produced 0.4–2.9 t ha−1 of re-sprout biomass annually, which released nutrients contributing to higher maize yields over a long period of time. It is concluded that these legume fallows can improve maize yields in addition to their positive impact on the diversity and functions of soil invertebrates.

Long-term effects of fallow systems and lengths on crop production and soil fertility maintenance in West Africa

In the development of short fallow systems as alternatives to shifting cultivation in West Africa, a long-term trial was established at the International Institute of Tropical Agriculture (IITA) on an Alfisol in the forest-savanna transitional zone of southwestern Nigeria, comparing three fallow systems; natural regrowth fallow, cover crop fallow and alley cropping on soil productivity and crop yield sustainability. The natural fallow system consisted of natural regrowth of mainly Chromolaena odorata shrub as fallow vegetation. The cover crop fallow system consisted of Pueraria phaseoloides, a herbaceous legume as fallow vegetation. The alley cropping system consisted of woody hedgerows of Leucaena leucocephala as fallow vegetation. The fallow lengths were 0 (continuous cropping), 1, 2 and 3 years after 1 year of maize/cassava intercropping. Biomass produced from natural fallow and cover crop fallow was burnt during the land preparation. Fertilizer was not applied throughout the study. Without fertilizer application, maize yield declined from above 3.0 t ha−1 to below 0.5 t ha−1 during 12 years of cultivation (1989–2000) on a land cleared from a 23-year old secondary forest. Temporal change in cassava tuber yield was erratic. Mean maize grain yields from 1993–2000 except for 1999 were higher in cover crop fallow system (1.89 t ha−1) than in natural fallow system (1.73 t ha−1), while natural fallow system outperformed alley cropping system (1.46 t ha−1). During the above 7 years, mean cassava tuber yield in cover crop system (7.7 t ha−1) did not differ from natural fallow system (8.2 t ha−1), and both systems showed higher cassava tuber than the alley cropping system (5.7 t ha−1). The positive effect of fallowing on crop yields was observed for both crops in the three systems, however, insignificant effects were seen when fallow length exceeded 1 year for cover crop and alley cropping, and 2 years for natural fallow. Soil pH, organic carbon, available P and exchangeable Ca, Mg and K decreased considerably after 12 years of cultivation, even in a 3-year fallow subplot. After 12 years, soil organic carbon (SOC) within 0–5 cm depth in alley cropping (13.9 g kg−1) and natural fallow (13.7 g kg−1) was higher than in cover crop fallow (11.6 g kg−1). Whereas significant increase in SOC with either natural fallow or alley cropping was observed only after 2 or 3 years of fallow, the SOC in the 1-year fallow alley cropping subplot was higher than that in continuous cropping natural fallow subplot. It can be concluded from our study that in transforming shifting cultivation to a permanent cropping, fallow with natural vegetation (natural fallow), herbaceous legumes (cover crop fallow) and woody legumes (alley cropping) can contribute to the maintenance of crop production and soil fertility, however, length of fallow period does not need to exceed 2 years. When the fallow length is reduced to 1 year, a better alternative to natural regrowth fallow would be the cover crop for higher maize yield and alley cropping for higher soil organic matter. For fallow length of 2 years, West African farmers would be better off with the natural fallow system.

Factors Affecting Infestations of the Stalk BorerBusseola fusca(Lepitoptera: Noctuidae) on Maize in the Forest Zone of Cameroon with Special Reference to Scelionid Egg Parasitoids

The effect of vegetation, intercropping, and Telenomus spp. egg parasitism during the vegetative stage of maize on Busseola fusca (Fuller) (Lepitoptera: Noctuidae) infestations and maize yields at harvest were studied during two consecutive cropping seasons, in the humid forest zone of Cameroon. Six locations grouped into three blocks, representing gradients in human population densities of 15–88 inhabitants/km2 were chosen. The fields were located at 20–90 min walking distance from the next road. Differences between blocks in the measured variables were mostly not significant indicating that the population density gradient was not strong enough to affect length of fallow period and thereby vegetation, the population dynamics of pests and natural enemies, and maize yields in forest fields. Numbers of egg batches per plant but also egg parasitism by and sex ratio of Telenomus spp. were significantly higher during the second than the first season (66.9 versus 19.9% and 0.67 versus 0.21, respectively). As a result, the number of borers per plant was only 0.22 versus 0.73 during the first season. Similarly, total mortality of immature B. fusca was 60.5% during the first and 93.2% during the second season. The seasonal differences in unexplained mortality was probably because rainfall caused drowning of migrating first instars. High mean parasitoid mortality at the beginning of the first season was probably caused by high superparasitism promoted by low host density conditions. Across seasons, abundance of grasses in the surroundings of a field was negatively related to egg batch density. Likewise, numbers of B. fusca decreased with increasing density of the nonhost cassava in the field, indicating increasing mortality of migrating larvae. Egg numbers per plant was negatively and egg parasitism or parasitoid sex ratio was positively related to yield.

Who is Interested in Commercial Agriculture?: Subsistence Agriculture and Salaried Work in the City Among Yucatec Maya from the State of Yucatán

Francisco Gurri is Titular A research faculty and Coordinatorof El Colegio de la Fontera Sur (ECOSUR) in Campeche,Mexico. Emilio Moran is James H. Rudy Professor of An-thropology and Director of the Anthropological Center forTraining and Research on Global Environmental Changeat Indiana University.Slash-and-burn agriculture and the patchy distributionof water resources in the state of Yucatan have always beenlimiting factors for the number of individuals that couldmake a living on the land surrounding a village or town(Duch 1992; Illsey 1984; Levy and Hernandez 1992). In thepast, population pressure (Redfield 1950; Redfield and VillaRojas 1934; Teran and Rasmussen 1994), or the excessive con-centration of land or water holes in the hands of a few(Goldkind 1965,1966) would eventually lead to the break upof the community, usually along patrilineal lines. Individualslacking sufficient land and water would migrate out of thearea in search of new, unclaimed cenotes (karst water holes)with sufficient land for cultivation.Local population control mechanisms were bolstered byagrarian laws, that, while guaranteeing land to communitymembers in the form of ejidos, also required ejido membersto be active participants of the community (Murguia 1979; ReCruz 1996; Redfield and Villa Rojas 1934). Teran andRasmussen (1994) and Murguia (1979) claim that these lawsled to the over exploitation of the areas where ejidos hadbeen granted. Support for these scholars' claims comes fromthe length of fallow periods in the maize area before andafter the agrarian reform. Fallow periods for forest regenera-tion time after slash-and-burn agriculture in the Maya maizeregion of the state decreased from 50 years at the beginningof the 20

Brazilian Amazonian caboclo agriculture: effect of fallow period on maize yield

Traditional Amazonian farmers ( caboclos) along the Xingu River near Altamira, Pará, Brazil, practice shifting cultivation using fallow periods (periods during which cultivated areas are temporarily abandoned and invaded by secondary forest) which they consider necessary to restore soil nutrients and control weeds and insect pests. At the end of the growing season, maize production was measured in the farmers' fields in randomly selected 9-m 2 quadrats. Yield was significantly higher in agricultural plots derived from secondary forest ( n = 11) than from old growth (‘virgin’) forest ( n = 11). Yield on plots derived from mature secondary forest (11–30 yr old; n = 4) was also significantly higher than that on plots derived from young secondary forest (3–10 yr old; n = 7) and ‘virgin’ forest. A significant positive relationship was encountered between length of fallow period and maize yield over the range of fallow ages studied (3–30 yr).

Human-Environmental Influences and Interactions in Shifting Agriculture When Farmers Form Expectations Rationally

This paper contains a study of the response of shifting agriculture to several social and environmental changes in circumstances in which farmers form in a relatively sophisticated manner their expectations of the future values of key economic variables. Farmers are ‘given’ a model of expectations formation in which the expected future value of variables interact in the same manner as in the current period. With this structure of expectations, the responses of the length of fallow period (the inverse of the percentage of available land cultivated in the initial period), the total area of land under cultivation and lying fallow in the initial period of a rotational cycle, and the initial-period wage rate and spatial structure of land rent to changes in several social and environmental parameters are examined. Several salient characteristics commonly attributed to shifting, or rotational, agriculture are replicated. Higher crop prices and increased population shorten fallow periods. Those same changes also increase the total area of land under shifting agriculture. Higher interest rates also shorten fallow periods. Fallows are longer at locations farther from central markets. Less commonly recognized is that social feedbacks operate to reduce pressure on more fragile land, although this does not imply that, other things being equal, fragile tropical land will not be ‘overused’ in an ecological sense.

Economics of Non-Timber Forest Production Promotion and Marketing: A case study from Malekhukhola Watershed of Dhading District, Nepal

This article examines the prospects of promoting NTFPs in the mountains of Nepal. Despite being profitable, the farmers do not readily accept cultivating NTFP species on their farmlands on a large scale. The analyses revealed that domestication of MAP species is significantly influenced by various factors such as, knowledge and skill required for domestication, frequency of visits to forest, the length of fallow period, size of upland terraces, cattle and goat herd size, accessibility to forest, inappropriate permit system, difficult trading system and market uncertainty. The inappropriate NTFP permit system, difficult trading system and free access to forest have negatively influenced domestication of MAP species. Overall, lack of a favorable institutional environment has been the major factor constraining the integration of NTFP species into farmland on a large scale by farmers. Policy recommendations include handing over the use and management responsibility to local people, to that prevent open access status of national forests, providing NTFP collection permits to local residents, lobbying for amending inappropriate policies, rules and regulations, promoting group marketing and adaptive collaborative forest management approach to community forestry. Key Words: NTFP collection, Marketing, Domestication, Factors affecting MAP domestication DOI: 10.3126/init.v2i1.2537 The Initiation Vol.2(1) 2008 pp145-156

Wheat crop surveys in southern NSW. 3. The incidence of take-all

Heavy take-all (Ophiobolus graminis Sacc.) infection was observed in 24 per cent of the 463 wheat crops surveyed in southern New South Wales in 1963. Simple tests of independence showed that the occurrence of heavy take-all infection was positively associated with weed density and cropping intensity. Clover ley history, nature of the previous crop, length of fallow period, sowing time, and weed type did not appear to be significantly associated with the occurrence of take-all. When the possibility of interactions was considered, heavy take-all was found most commonly in the early sown, heavily weed infested second crops after wheat or barley. Sixty per cent of these crops were heavily infected. The results of this survey suggest that a number of hypotheses developed under controlled experimental conditions do not hold widely in the field