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Marc Janssens

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Solomon Gebreyowhans Gebreabezgi

Haramaya university

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Mekelle university

Haramaya university

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Mekelle university

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Papers by Marc Janssens

Biomass Estimation Techniques for Enclosures in a Semi-Arid Area: A Case Study in Northern Ethiopia. Deutscher Tropentag

For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particula... more For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particular in the northern regional state Tigray, the area under study. In order to change this situation, the local government started to establish enclosures. In these sites, grazing is no longer permitted so that forest can naturally regenerate. In order to develop sustainable yield planning for forest rehabilitation areas in Tigray, one needs to know the effect of closing areas on biomass accumulation. In an enclosure, aboveground dry weight of herbaceous and woody species was estimated at 1,84 ton/ha. A combination of destructive and non-destructive methods was tested. The non-destructive study was rejected because of a non-accurate wood density estimation, and low correlation coefficients for the weight predicting models. Best fit-least square regression models were developed using diameter at 30 cm height as the independent variables and dry weight as the dependent variable. Coefficients of determination for the selected total biomass models of the destructive study ranged from 0,67 up to 0,99, whereas they ranged from 0,20 to 0,90 for the woody species in the non-destructive study. Equations for foliage biomass generally had lower coefficients of determination than the equations for either stem or total biomass of the woody species. Non woody biomass was measured in different enclosures in order to estimate the biomass production in function of the management technique. 98% of the total herbaceous biomass of the sampled grass plots belonged to Hypperrhenia hirta, while in the grazing land nearby it was only 11%. The correlation coefficient between grass biomass and basal area of the woody vegetation was -0,11. Based on this study this enclosure is not adopted for fuelwood collection.

Fruticultura orgánica en el trópico: Situación y ejemplos de Mesoamérica

La situación en la fruticultura orgánica de Mesoamérica no es fácil a cualificar y cuantificar. I... more La situación en la fruticultura orgánica de Mesoamérica no es fácil a cualificar y cuantificar. Indudablemente existenáreas certificadas sin embargo faltan datos exactos. En otra manera muchos campesinos cultivan frutas y vegetales sin el uso de fertilizantes inorgánicos y sin aplicaciones de pesticidazas por falta de insumos propios. Este estudio esta basado en ejemplos y practicas conocidas y trata a reflejar filosofías practicas del campesinado y las fortalezas y debilidades correspondientes. De lo masénfasis se ha dedicado al chayote en Costa Rica y México, a la pitahaya en Nicaragua, a la papaya en el Estado Tabasco y al mango, rambutan y caña de azúcar en el estado Chiapas, México, y a las huertas familiares en Cuba. Resultados de una encuesta entre consumidores reflejan el interés para consumir productos orgánicos, establecer la interacción agricultores-consumidores como parte del proceso de desarrollo agroecológico y fortalecer la educación de los consumidores y productores en los aspectos agroecológicos y de salud.

Maria Mercedes Martinez-Salgado, Rodrigo Ortega Blu, Marc J.J. Janssens: Spatial Variability of Nitrogen Mineralisation in Wine Grape Fields in Chile. www.tropentag.de/2009/proceedings/node67.html

Nitrogen is the most important element determining yield and quality of wine grape. Actual manage... more Nitrogen is the most important element determining yield and quality of wine grape. Actual management has tended to minimise the use of mineral N on vineyards, relying more on the soil N being mineralised each season. The balance between vineyard N demand and N supply is critical, not only from the production stand point but also from the environmental one; however few studies have been performed to estimate the amounts of N mineralised and the variability of the mineralisation in vineyard fields, in Chile. Two fields of different soil texture, of approximately 2-ha each, were studied during the growing season (November through April). Intact soil cores (0-20cm), containing ionic resins in the bottom, were incubated in situ, for 4 or 5 periods lasting 35 days each. Sampling points were systematically distributed over the fields with the help o a GPS receiver and a Geographic Information System, with an intensity $>$ 10 samples ha$^{-1}$. After each incubation period soil and resi...

Socioeconomic development with regard to the availability of resources in Benin, West Africa

by Marc Janssens and U. Singer

The socio-economic part within the IMPETUS-Project analyses interdependencies between resource av... more The socio-economic part within the IMPETUS-Project analyses interdependencies between resource availability and socio-economic development in Benin. The results of various research activities of natural and social sciences are integrated in a modelling system, in order to calculate development scenarios of resource utilisation and food security in Benin for the next two decades. Missing data concerning water usage and economic parameters

Caffeine and theobromine composition of mate (Ilex paraguariensis) leaves in five plantations of Misiones, Argentina

Plant Foods for Human Nutrition, 2003

Marked differences regarding both caffeine and theobromine contents of mate leaves (Ilex paraguar... more Marked differences regarding both caffeine and theobromine contents of mate leaves (Ilex paraguariensis) were found among 230 mass selected candidate trees distributed across 5 plantations in the region of Misiones, Argentina. In the vast majority of the analyzed samples, the caffeine concentrations ranged within the established limits for mate leaves, however theobromine contents (average content 0.96%) generally surpassed literature figures so far published . By means of a simple cluster analysis using "group average" as the clustering algorithm, the samples were divided into eight different groups according to the contents of both purine alkaloids. Based upon this division it will be possible to pick appropriate genotypes for breeding ideotypes which meet more precisely the different specific consumer expectations.

Inheritance studies of caffeine and theobromine content of Mate (Ilex paraguariensis) in Misiones, Argentina

In order to start a genetic improvement program for quality in the Mate crop (Ilex paraguariensis... more In order to start a genetic improvement program for quality in the Mate crop (Ilex paraguariensis), it was attempted to estimate the actual genetic parameters of caffeine, theobromine and related quality traits, using available progeny tests in Misiones, Argentina. Using cluster analysis, eight groups of similar characteristics could be identified, and individual within full-sib family selection for quality was performed. Additive effects were strong for caffeine but weak for theobromine. Co-heritability between caffeine and theobromine was positive, suggesting that additive genetic correlations and dominance correlations are concurring. The strong influence of paternal progenitors regarding caffeine needs more research.

Soil use and management strategy for raising food and cash output in Rwanda

Rwanda is a poor country and land is scarce, with only 0.65 ha of suitable farmland per household... more Rwanda is a poor country and land is scarce, with only 0.65 ha of suitable farmland per household. Literature search for identifying constraints and solutions to productive and sustainable agriculture and livestock production was carried out. The country is facing with increasing soil fertility depletion and erosion due to steep landscape, continuous cultivation and high but not well distributed rainfall. Crops adequately allocated to the 0.65 ha farmland may produce enough food for energy and protein, but not cooking oil; animal production for meeting fat requirements is already at the limit. Forest resources are insufficient to produce necessary poles, timber, fuel and other forest-related products; alternatives must be found. Strategies to raise agricultural production include soil and water conservation, fertility improvement, irrigation and drainage, high-yielding plant varieties, improved animal management, pest control and reduction of postharvest losses. Labour shortage at critical periods of agricultural operations can be reduced through appropriate mechanisation. Such improvements that are high demanding in investments may substantially raise crop and livestock production, allowing Rwanda to develop agro-industries and the commercial sector. Alternatively, preference may be given to investments in high-value exports that can pay for imports of food, fuel and other necessities.

Saponin Content and Quality-Related Traits of Mass-Selected Yerba Maté ( Ilex paraguariensis A. St.-Hil.) Trees

Journal of Herbs, Spices & Medicinal Plants, 2006

Since 1998, new maté trees were identified in five plantations in Misiones, Argentina, through ma... more Since 1998, new maté trees were identified in five plantations in Misiones, Argentina, through mass selection. Emphasis was put on capturing genes related to caffeine, theobromine, saponin, twig color, anthocyanin, waxiness, leaf chlorophyll, and leaf thickness, characteristics that influence maté leaf quality in the drinking vessel or in the bombilla. Subsequently, saponin content of maté leaves was positively correlated with

Culture and fruit quality of rambutan ( Nephelium lappaceum L.) in the Soconusco region, Chiapas, Mexico

by Alfred Pohlan and Marc Janssens

Fruits, 2004

Culture and fruit quality of rambutan (Nephelium lappaceum L.) in the Soconusco region, Chiapas, ... more

Biomass estimation techniques for enclosures in a semi-arid area: a case study in Northern Ethiopia

For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particula... more For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particular in the northern regional state Tigray, the area under study. In order to change this situation, the local government started to establish enclosures. In these sites, grazing is no longer permitted so that forest can naturally regenerate. In order to develop sustainable yield planning for forest rehabilitation areas in Tigray, one needs to know the effect of closing areas on biomass accumulation. In an enclosure, aboveground dry weight of herbaceous and woody species was estimated at 1,84 ton/ha. A combination of destructive and non-destructive methods was tested. The non-destructive study was rejected because of a non-accurate wood density estimation, and low correlation coefficients for the weight predicting models. Best fit-least square regression models were developed using diameter at 30 cm height as the independent variables and dry weight as the dependent variable. Coefficients of determination for the selected total biomass models of the destructive study ranged from 0,67 up to 0,99, whereas they ranged from 0,20 to 0,90 for the woody species in the non-destructive study. Equations for foliage biomass generally had lower coefficients of determination than the equations for either stem or total biomass of the woody species. Non woody biomass was measured in different enclosures in order to estimate the biomass production in function of the management technique. 98% of the total herbaceous biomass of the sampled grass plots belonged to Hypperrhenia hirta, while in the grazing land nearby it was only 11%. The correlation coefficient between grass biomass and basal area of the woody vegetation was -0,11. Based on this study this enclosure is not adopted for fuelwood collection.

Transformation of Coffee Plantations through Tropical Timber Production in the Region of Soconusco, Chiapas, Mexico

MARROQUÍN AGREDA, F., POHLAN J., JANSSENS M. J. J., BORGMAN, J.: Effects of Production Systems with Maize (Zea Mays L.) Fertility and Biological Diversity in Soconusco, Chiapas. Deutscher Tropentag, October 11 - 13, 2005 in Stuttgart, "The Global Food & Product Chain – Dynamics, Innovations, Conf...

Vanderlinden, E., Pohlan, J., Janssens, M.J.J. 2004. Culture and fruit quality of Rambutan (Nephelium lappaceum L.) in the Soconusco, Chiapas, Mexico. Fruits:59 (5)

Fruits

Hermann A. Jürgen Pohlan, Marc J. J. Janssens, (2010), GROWTH AND PRODUCTION OF COFFEE, in Soils, Plant Growth and Crop Production, [Ed. Willy H. Verheye], in Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford, UK, [http://www.eolss....

Bridging the gap between integrated and organic agriculture to ensure food security

by Marc Janssens and Marc Janssens

c) INTTAS, Loma Plata 1045 – Chaco, C.d.c. 883 Asuncion, Paraguay. E-mail: [email protected] d)... more c) INTTAS, Loma Plata 1045 – Chaco, C.d.c. 883 Asuncion, Paraguay. E-mail: [email protected] d) ECOSUR, El Colegio de la Frontera Sur, Antiguo Aeropuerto km 2.5; Apdo. Postal 36, Summary Many tropical farming systems are evolving by expanding the cropped area and encroaching on the environment. Most of them are of organic nature and labour unproductive. The developing world is importing countless quantities of cereals, meat and other food, mostly from non-organic farming systems outside the tropics. In fact, the digestive tracts are largely colonised. There are cases where non-subsidised imports can be cheaper than locally produced commodities. Reversing this trend will imply farmer training and a healthy synergism between intensive and organic cultivation techniques. Zero-tillage, enabled by herbicides like glyphosate has gained recognition as a second green revolution step. Seed coating, encompassing whatever fungicides and micro-fertilisers, combined with appropriate seedbed pr...

Processo De Conversão Das Plantações De Café De Chiapas (México) Através De Sistemas Agroflorestais Em Plantações Florestais, e Suas Implicações Ecológicas

by Marc Janssens and Oliver Jende

The Soconusco is considered the heart of coffee production in Mexico and belongs to the Mesoameri... more The Soconusco is considered the heart of coffee production in Mexico and belongs to the Mesoamerican coffee belt. The coffee agro- ecosystems are undergoing a thorough transformation process, although insufficiently documented as yet. In this study, different aspects of a gradual conversion process from coffee to timber production were evaluated, with the aim to understand, how the agro-ecosystem coffee changes in horizontal and vertical structure, in

Conversion process and reforestation practices of coffee plantations in Chiapas, Mexico

by Marc Janssens and Oliver Jende

Contact Address: Effects of Production Systems with Maize (Zea mays L.) on Soil Fertility and Biological Diversity in the Soconusco, Chiapas, Mexico

The abuse of chemical products in the production systems in the Central American tropical region ... more The abuse of chemical products in the production systems in the Central American tropical region has caused a series of drastic effects on the natural resources leading to the lowering of yields at medium and long terms. It also destroys sustainable production and depends highly on external inputs such as fertilizers and pesticides. The objectives of the research were to analyze the bases for the implementation of sustainable agriculture practices in Chiapas agricultural systems with maize. The investigation was carried out during cropping cycle 2002–2003 in the region of the Soconusco, Chiapas, Mexico. Four treatments with experimental areas of one hectare each were selected: (i) production system with maize (roza-tumba-quema = slash and burn) with 2 years cropping; (ii) production system with 6 years monoculture maize; (iii) production system with 12 years monoculture maize; (iv) area with tropical rain forest. In each experimental unit the physical and chemical soil properties, t...

Harvest maturity, harvesting and field handling of rambutan

Stewart Postharvest Review, 2008

Purpose of the review: This review provides a better understanding of rambutan fruit growth, matu... more Purpose of the review: This review provides a better understanding of rambutan fruit growth, maturity and quality indices for harvesting, nutritional content and composition of major rambutan cultivars. The importance of harvesting methods, plant protection in the field and careful postharvest handling techniques are illustrated in relation to retaining fruit quality after harvest. Findings: Improved clonal material has been exchanged among Australia and South-East Asian countries. In other continents, there is still a need for improvement as illustrated by the case of rambutan production in Mexico. Commercial grading during the packing operation also needs further attention in some of the newer rambutan producing countries. Directions for future research: Clonal adaptation to the growing environment requires intensive field trials in the newer producing countries outside South-East Asia and Australia. Postharvest technology, which encompasses all operations involving packing, storage and transportation, remains of paramount importance due to the delicate nature of the rambutan fruit.

Alternativas para la transformación de areas productoras de coca en la región del Chapare Bolivia

Journal of Food Agriculture and Environment

The Chapare region of Bolivia is classified as “humid sub-tropic”. About 92% of the 35,000 famili... more The Chapare region of Bolivia is classified as “humid sub-tropic”. About 92% of the 35,000 families of inhabitants are involved in farming. Until now, 93% of the coca (Erythroxylum coca Lam.) cultivation has been eradicated leading to serious social, economic and ecological problems. The most important agricultural crops grown in the Chapare region are citrus and banana, which occupy 20.8 and 18.8% of the total area under cultivation, respectively. Both crops are intended for the market and therefore play an important role in the economy of the region. Cassava (7.3%) and rice (7.2%) are cultivated for personal consumption. The average area of land possessed by a family amounts to 10.4 ha, but due to lack of capital and high labour costs, only 2.6 ha/family are cultivated. The remaining land (74%) is under forest and fallow. Generally, poor quality seeds are used. The intensive use of agrochemicals is common in the area. Clearing vegetation by burning (chaqueo) is a common activity t...

Biomass Estimation Techniques for Enclosures in a Semi-Arid Area: A Case Study in Northern Ethiopia. Deutscher Tropentag

For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particula... more For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particular in the northern regional state Tigray, the area under study. In order to change this situation, the local government started to establish enclosures. In these sites, grazing is no longer permitted so that forest can naturally regenerate. In order to develop sustainable yield planning for forest rehabilitation areas in Tigray, one needs to know the effect of closing areas on biomass accumulation. In an enclosure, aboveground dry weight of herbaceous and woody species was estimated at 1,84 ton/ha. A combination of destructive and non-destructive methods was tested. The non-destructive study was rejected because of a non-accurate wood density estimation, and low correlation coefficients for the weight predicting models. Best fit-least square regression models were developed using diameter at 30 cm height as the independent variables and dry weight as the dependent variable. Coefficients of determination for the selected total biomass models of the destructive study ranged from 0,67 up to 0,99, whereas they ranged from 0,20 to 0,90 for the woody species in the non-destructive study. Equations for foliage biomass generally had lower coefficients of determination than the equations for either stem or total biomass of the woody species. Non woody biomass was measured in different enclosures in order to estimate the biomass production in function of the management technique. 98% of the total herbaceous biomass of the sampled grass plots belonged to Hypperrhenia hirta, while in the grazing land nearby it was only 11%. The correlation coefficient between grass biomass and basal area of the woody vegetation was -0,11. Based on this study this enclosure is not adopted for fuelwood collection.

Fruticultura orgánica en el trópico: Situación y ejemplos de Mesoamérica

La situación en la fruticultura orgánica de Mesoamérica no es fácil a cualificar y cuantificar. I... more La situación en la fruticultura orgánica de Mesoamérica no es fácil a cualificar y cuantificar. Indudablemente existenáreas certificadas sin embargo faltan datos exactos. En otra manera muchos campesinos cultivan frutas y vegetales sin el uso de fertilizantes inorgánicos y sin aplicaciones de pesticidazas por falta de insumos propios. Este estudio esta basado en ejemplos y practicas conocidas y trata a reflejar filosofías practicas del campesinado y las fortalezas y debilidades correspondientes. De lo masénfasis se ha dedicado al chayote en Costa Rica y México, a la pitahaya en Nicaragua, a la papaya en el Estado Tabasco y al mango, rambutan y caña de azúcar en el estado Chiapas, México, y a las huertas familiares en Cuba. Resultados de una encuesta entre consumidores reflejan el interés para consumir productos orgánicos, establecer la interacción agricultores-consumidores como parte del proceso de desarrollo agroecológico y fortalecer la educación de los consumidores y productores en los aspectos agroecológicos y de salud.

Maria Mercedes Martinez-Salgado, Rodrigo Ortega Blu, Marc J.J. Janssens: Spatial Variability of Nitrogen Mineralisation in Wine Grape Fields in Chile. www.tropentag.de/2009/proceedings/node67.html

Nitrogen is the most important element determining yield and quality of wine grape. Actual manage... more Nitrogen is the most important element determining yield and quality of wine grape. Actual management has tended to minimise the use of mineral N on vineyards, relying more on the soil N being mineralised each season. The balance between vineyard N demand and N supply is critical, not only from the production stand point but also from the environmental one; however few studies have been performed to estimate the amounts of N mineralised and the variability of the mineralisation in vineyard fields, in Chile. Two fields of different soil texture, of approximately 2-ha each, were studied during the growing season (November through April). Intact soil cores (0-20cm), containing ionic resins in the bottom, were incubated in situ, for 4 or 5 periods lasting 35 days each. Sampling points were systematically distributed over the fields with the help o a GPS receiver and a Geographic Information System, with an intensity $>$ 10 samples ha$^{-1}$. After each incubation period soil and resi...

Socioeconomic development with regard to the availability of resources in Benin, West Africa

by Marc Janssens and U. Singer

The socio-economic part within the IMPETUS-Project analyses interdependencies between resource av... more The socio-economic part within the IMPETUS-Project analyses interdependencies between resource availability and socio-economic development in Benin. The results of various research activities of natural and social sciences are integrated in a modelling system, in order to calculate development scenarios of resource utilisation and food security in Benin for the next two decades. Missing data concerning water usage and economic parameters

Caffeine and theobromine composition of mate (Ilex paraguariensis) leaves in five plantations of Misiones, Argentina

Plant Foods for Human Nutrition, 2003

Marked differences regarding both caffeine and theobromine contents of mate leaves (Ilex paraguar... more Marked differences regarding both caffeine and theobromine contents of mate leaves (Ilex paraguariensis) were found among 230 mass selected candidate trees distributed across 5 plantations in the region of Misiones, Argentina. In the vast majority of the analyzed samples, the caffeine concentrations ranged within the established limits for mate leaves, however theobromine contents (average content 0.96%) generally surpassed literature figures so far published . By means of a simple cluster analysis using "group average" as the clustering algorithm, the samples were divided into eight different groups according to the contents of both purine alkaloids. Based upon this division it will be possible to pick appropriate genotypes for breeding ideotypes which meet more precisely the different specific consumer expectations.

Inheritance studies of caffeine and theobromine content of Mate (Ilex paraguariensis) in Misiones, Argentina

In order to start a genetic improvement program for quality in the Mate crop (Ilex paraguariensis... more In order to start a genetic improvement program for quality in the Mate crop (Ilex paraguariensis), it was attempted to estimate the actual genetic parameters of caffeine, theobromine and related quality traits, using available progeny tests in Misiones, Argentina. Using cluster analysis, eight groups of similar characteristics could be identified, and individual within full-sib family selection for quality was performed. Additive effects were strong for caffeine but weak for theobromine. Co-heritability between caffeine and theobromine was positive, suggesting that additive genetic correlations and dominance correlations are concurring. The strong influence of paternal progenitors regarding caffeine needs more research.

Soil use and management strategy for raising food and cash output in Rwanda

Rwanda is a poor country and land is scarce, with only 0.65 ha of suitable farmland per household... more Rwanda is a poor country and land is scarce, with only 0.65 ha of suitable farmland per household. Literature search for identifying constraints and solutions to productive and sustainable agriculture and livestock production was carried out. The country is facing with increasing soil fertility depletion and erosion due to steep landscape, continuous cultivation and high but not well distributed rainfall. Crops adequately allocated to the 0.65 ha farmland may produce enough food for energy and protein, but not cooking oil; animal production for meeting fat requirements is already at the limit. Forest resources are insufficient to produce necessary poles, timber, fuel and other forest-related products; alternatives must be found. Strategies to raise agricultural production include soil and water conservation, fertility improvement, irrigation and drainage, high-yielding plant varieties, improved animal management, pest control and reduction of postharvest losses. Labour shortage at critical periods of agricultural operations can be reduced through appropriate mechanisation. Such improvements that are high demanding in investments may substantially raise crop and livestock production, allowing Rwanda to develop agro-industries and the commercial sector. Alternatively, preference may be given to investments in high-value exports that can pay for imports of food, fuel and other necessities.

Saponin Content and Quality-Related Traits of Mass-Selected Yerba Maté ( Ilex paraguariensis A. St.-Hil.) Trees

Journal of Herbs, Spices & Medicinal Plants, 2006

Since 1998, new maté trees were identified in five plantations in Misiones, Argentina, through ma... more Since 1998, new maté trees were identified in five plantations in Misiones, Argentina, through mass selection. Emphasis was put on capturing genes related to caffeine, theobromine, saponin, twig color, anthocyanin, waxiness, leaf chlorophyll, and leaf thickness, characteristics that influence maté leaf quality in the drinking vessel or in the bombilla. Subsequently, saponin content of maté leaves was positively correlated with

Culture and fruit quality of rambutan ( Nephelium lappaceum L.) in the Soconusco region, Chiapas, Mexico

by Alfred Pohlan and Marc Janssens

Fruits, 2004

Culture and fruit quality of rambutan (Nephelium lappaceum L.) in the Soconusco region, Chiapas, ... more

Biomass estimation techniques for enclosures in a semi-arid area: a case study in Northern Ethiopia

For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particula... more For centuries, land degradation triggered by deforestation has occurred in Ethiopia, in particular in the northern regional state Tigray, the area under study. In order to change this situation, the local government started to establish enclosures. In these sites, grazing is no longer permitted so that forest can naturally regenerate. In order to develop sustainable yield planning for forest rehabilitation areas in Tigray, one needs to know the effect of closing areas on biomass accumulation. In an enclosure, aboveground dry weight of herbaceous and woody species was estimated at 1,84 ton/ha. A combination of destructive and non-destructive methods was tested. The non-destructive study was rejected because of a non-accurate wood density estimation, and low correlation coefficients for the weight predicting models. Best fit-least square regression models were developed using diameter at 30 cm height as the independent variables and dry weight as the dependent variable. Coefficients of determination for the selected total biomass models of the destructive study ranged from 0,67 up to 0,99, whereas they ranged from 0,20 to 0,90 for the woody species in the non-destructive study. Equations for foliage biomass generally had lower coefficients of determination than the equations for either stem or total biomass of the woody species. Non woody biomass was measured in different enclosures in order to estimate the biomass production in function of the management technique. 98% of the total herbaceous biomass of the sampled grass plots belonged to Hypperrhenia hirta, while in the grazing land nearby it was only 11%. The correlation coefficient between grass biomass and basal area of the woody vegetation was -0,11. Based on this study this enclosure is not adopted for fuelwood collection.

Transformation of Coffee Plantations through Tropical Timber Production in the Region of Soconusco, Chiapas, Mexico

MARROQUÍN AGREDA, F., POHLAN J., JANSSENS M. J. J., BORGMAN, J.: Effects of Production Systems with Maize (Zea Mays L.) Fertility and Biological Diversity in Soconusco, Chiapas. Deutscher Tropentag, October 11 - 13, 2005 in Stuttgart, "The Global Food & Product Chain – Dynamics, Innovations, Conf...

Vanderlinden, E., Pohlan, J., Janssens, M.J.J. 2004. Culture and fruit quality of Rambutan (Nephelium lappaceum L.) in the Soconusco, Chiapas, Mexico. Fruits:59 (5)

Fruits

Hermann A. Jürgen Pohlan, Marc J. J. Janssens, (2010), GROWTH AND PRODUCTION OF COFFEE, in Soils, Plant Growth and Crop Production, [Ed. Willy H. Verheye], in Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford, UK, [http://www.eolss....

Bridging the gap between integrated and organic agriculture to ensure food security

by Marc Janssens and Marc Janssens

c) INTTAS, Loma Plata 1045 – Chaco, C.d.c. 883 Asuncion, Paraguay. E-mail: [email protected] d)... more c) INTTAS, Loma Plata 1045 – Chaco, C.d.c. 883 Asuncion, Paraguay. E-mail: [email protected] d) ECOSUR, El Colegio de la Frontera Sur, Antiguo Aeropuerto km 2.5; Apdo. Postal 36, Summary Many tropical farming systems are evolving by expanding the cropped area and encroaching on the environment. Most of them are of organic nature and labour unproductive. The developing world is importing countless quantities of cereals, meat and other food, mostly from non-organic farming systems outside the tropics. In fact, the digestive tracts are largely colonised. There are cases where non-subsidised imports can be cheaper than locally produced commodities. Reversing this trend will imply farmer training and a healthy synergism between intensive and organic cultivation techniques. Zero-tillage, enabled by herbicides like glyphosate has gained recognition as a second green revolution step. Seed coating, encompassing whatever fungicides and micro-fertilisers, combined with appropriate seedbed pr...

Processo De Conversão Das Plantações De Café De Chiapas (México) Através De Sistemas Agroflorestais Em Plantações Florestais, e Suas Implicações Ecológicas

by Marc Janssens and Oliver Jende

The Soconusco is considered the heart of coffee production in Mexico and belongs to the Mesoameri... more The Soconusco is considered the heart of coffee production in Mexico and belongs to the Mesoamerican coffee belt. The coffee agro- ecosystems are undergoing a thorough transformation process, although insufficiently documented as yet. In this study, different aspects of a gradual conversion process from coffee to timber production were evaluated, with the aim to understand, how the agro-ecosystem coffee changes in horizontal and vertical structure, in

Conversion process and reforestation practices of coffee plantations in Chiapas, Mexico

by Marc Janssens and Oliver Jende

Contact Address: Effects of Production Systems with Maize (Zea mays L.) on Soil Fertility and Biological Diversity in the Soconusco, Chiapas, Mexico

The abuse of chemical products in the production systems in the Central American tropical region ... more The abuse of chemical products in the production systems in the Central American tropical region has caused a series of drastic effects on the natural resources leading to the lowering of yields at medium and long terms. It also destroys sustainable production and depends highly on external inputs such as fertilizers and pesticides. The objectives of the research were to analyze the bases for the implementation of sustainable agriculture practices in Chiapas agricultural systems with maize. The investigation was carried out during cropping cycle 2002–2003 in the region of the Soconusco, Chiapas, Mexico. Four treatments with experimental areas of one hectare each were selected: (i) production system with maize (roza-tumba-quema = slash and burn) with 2 years cropping; (ii) production system with 6 years monoculture maize; (iii) production system with 12 years monoculture maize; (iv) area with tropical rain forest. In each experimental unit the physical and chemical soil properties, t...

Harvest maturity, harvesting and field handling of rambutan

Stewart Postharvest Review, 2008

Purpose of the review: This review provides a better understanding of rambutan fruit growth, matu... more Purpose of the review: This review provides a better understanding of rambutan fruit growth, maturity and quality indices for harvesting, nutritional content and composition of major rambutan cultivars. The importance of harvesting methods, plant protection in the field and careful postharvest handling techniques are illustrated in relation to retaining fruit quality after harvest. Findings: Improved clonal material has been exchanged among Australia and South-East Asian countries. In other continents, there is still a need for improvement as illustrated by the case of rambutan production in Mexico. Commercial grading during the packing operation also needs further attention in some of the newer rambutan producing countries. Directions for future research: Clonal adaptation to the growing environment requires intensive field trials in the newer producing countries outside South-East Asia and Australia. Postharvest technology, which encompasses all operations involving packing, storage and transportation, remains of paramount importance due to the delicate nature of the rambutan fruit.

Alternativas para la transformación de areas productoras de coca en la región del Chapare Bolivia

Journal of Food Agriculture and Environment

The Chapare region of Bolivia is classified as “humid sub-tropic”. About 92% of the 35,000 famili... more The Chapare region of Bolivia is classified as “humid sub-tropic”. About 92% of the 35,000 families of inhabitants are involved in farming. Until now, 93% of the coca (Erythroxylum coca Lam.) cultivation has been eradicated leading to serious social, economic and ecological problems. The most important agricultural crops grown in the Chapare region are citrus and banana, which occupy 20.8 and 18.8% of the total area under cultivation, respectively. Both crops are intended for the market and therefore play an important role in the economy of the region. Cassava (7.3%) and rice (7.2%) are cultivated for personal consumption. The average area of land possessed by a family amounts to 10.4 ha, but due to lack of capital and high labour costs, only 2.6 ha/family are cultivated. The remaining land (74%) is under forest and fallow. Generally, poor quality seeds are used. The intensive use of agrochemicals is common in the area. Clearing vegetation by burning (chaqueo) is a common activity t...