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Argentijnse ‘bioprof’ Pablo Tittonell verlaat Wageningen Universiteit. Hij inspireerde drie jaar lang studenten, medewerkers en boeren.

Argentijnse ‘bioprof’ Pablo Tittonell verlaat Wageningen Universiteit. Hij inspireerde drie jaar lang studenten, medewerkers en boeren.

Argentijnse ‘bioprof’ Pablo Tittonell verlaat Wageningen Universiteit. Hij inspireerde drie jaar lang studenten, medewerkers en boeren.

This paper focuses on an integrated approach which addresses the problems on managing the excess inputs of heavy metals viz., Cd, Pb, Cu and Zn in Dutch agroecosystems under different farming systems.

This book addresses methodological issues of production ecology. A central issue is the combination of the agricultural model with reliable data in relation to scale. A model is developed with data from a single point, whereas decisions are to be made for areas of land. Such an approach requires the use of a skilful treatment of available data and information. The book is divided into four parts. Advanced information science yields the best possible models in an efficient way. Geographical Information Systems combine various layers of spatial information. Statistics upscale local information towards regions and test its reliability. Modern trends in automated modeling are identified. The book is illustrated with various practical studies, ranging from the individual model to the whole European Community.

Design and management of irrigation infrastructure in farmer managed irrigation systems (FMISs) are strongly influenced by social and agro-ecological conditions of an area. This thesis analyzes the elements of social and agro-ecological conditions in FMISs in the mid-hills of Nepal and examines their relationships with irrigation infrastructure, especially water division structures. Of the various types of water division structures, this thesis concentrates mainly on the proportioning weir, which is a fixed control type of structure.This thesis suggests that in an irrigation system, hydraulic, agro-ecological and socio-cultural conditions determine the choice of water division structures, which in turn shape the irrigation management functions and local organization's primary objective. As the current approach to irrigation development and management considers farmers as the major actor in both turnover of agency-built irrigation system and rehabilitation of FMISs, understanding of these conditions shaping irrigation infrastructure is vital for further developing them in close partnership with local community. Failure to recognize these conditions, while further developing them, can erode the existing management practices and the current and potential contribution of irrigation to local livelihoods.

This book addresses methodological issues of production ecology. A central issue is the combination of the agricultural model with reliable data in relation to scale. A model is developed with data from a single point, whereas decisions are to be made for areas of land. Such an approach requires the use of a skilful treatment of available data and information. The book is divided into four parts. Advanced information science yields the best possible models in an efficient way. Geographical Information Systems combine various layers of spatial information. Statistics upscale local information towards regions and test its reliability. Modern trends in automated modeling are identified. The book is illustrated with various practical studies, ranging from the individual model to the whole European Community.

This book addresses methodological issues of production ecology. A central issue is the combination of the agricultural model with reliable data in relation to scale. A model is developed with data from a single point, whereas decisions are to be made for areas of land. Such an approach requires the use of a skilful treatment of available data and information. The book is divided into four parts. Advanced information science yields the best possible models in an efficient way. Geographical Information Systems combine various layers of spatial information. Statistics upscale local information towards regions and test its reliability. Modern trends in automated modeling are identified. The book is illustrated with various practical studies, ranging from the individual model to the whole European Community.

Design and management of irrigation infrastructure in farmer managed irrigation systems (FMISs) are strongly influenced by social and agro-ecological conditions of an area. This thesis analyzes the elements of social and agro-ecological conditions in FMISs in the mid-hills of Nepal and examines their relationships with irrigation infrastructure, especially water division structures. Of the various types of water division structures, this thesis concentrates mainly on the proportioning weir, which is a fixed control type of structure.This thesis suggests that in an irrigation system, hydraulic, agro-ecological and socio-cultural conditions determine the choice of water division structures, which in turn shape the irrigation management functions and local organization's primary objective. As the current approach to irrigation development and management considers farmers as the major actor in both turnover of agency-built irrigation system and rehabilitation of FMISs, understanding of these conditions shaping irrigation infrastructure is vital for further developing them in close partnership with local community. Failure to recognize these conditions, while further developing them, can erode the existing management practices and the current and potential contribution of irrigation to local livelihoods.

In this volume of the SARP research proceedings two 'Application Programs' are introduced. Five papers are presented on agro-ecological zonation and characterization, dealing with rainfall mapping, GIS and soil data base investigation. Nine papers are presented on crop rotation optimization, having crop rotation of rice-peanut and barley-rice as subjects

This volume of the SARP Research Proceedings presents a framework for the use of crop growth models in agro-ecological characterization and zonation of rice

This volume of the SARP Research Proceedings presents a framework for the use of crop growth models in agro-ecological characterization and zonation of rice

In this volume of the SARP research proceedings two 'Application Programs' are introduced. Five papers are presented on agro-ecological zonation and characterization, dealing with rainfall mapping, GIS and soil data base investigation. Nine papers are presented on crop rotation optimization, having crop rotation of rice-peanut and barley-rice as subjects

In this volume of the SARP research proceedings two 'Application Programs' are introduced. Five papers are presented on agro-ecological zonation and characterization, dealing with rainfall mapping, GIS and soil data base investigation. Nine papers are presented on crop rotation optimization, having crop rotation of rice-peanut and barley-rice as subjects

This thesis provides a framework for integrated nutrient management in agricultural land use systems, with particular reference to its impact on productivity, fertilizer use efficiency, and sustainability in well-delimited tracts of land (agro-ecological units), characterized by a specific set of soil and climatic properties. Most of the research was conducted in Kenya, but methodology and results can be applied to any tropical region.Quantitative assessments are made of the nitrogen, phosphorus and potassium balance in the root zone of the arable land in sub-Saharan Africa. Land use systems are characterized by nutrient inputs (mineral fertilizer, manure, atmospheric deposition, biological nitrogen fixation, sedimentation) and nutrient outputs (removal of harvested crop parts and residues, leaching, denitrification, erosion), and the balance between the two. It is shown that outputs exceed inputs all over the continent. As scale-inherent simplifications were inevitable, a more detailed study is presented for the Kisii District in Kenya, with similar results. The alarming figures call for agronomic and policy interventions in the soil nutrient balance. A scaleneutral decision- support model of this nature is described, in which scenarios for improved nutrient management are worked out.Mineral fertilizers are, with the present abolishment of subsidies in many African countries, increasingly expensive, and it is evident that they must be used efficiently. With this in mind, a network of 70 researcher-managed, but farm-based factorial fertilizer trials was established in rainfed agricultural Kenya. The trial sites were chosen such that they represent wider ranges of similar environments. As such, the results form a basis for fertilizer recommendations that are not just crop-specific, but also specific for agro- ecological units. The site selection procedure is demonstrated, based on a profound scrutiny of soil and climate maps in Kenya, and followed by results of four years study on the response of maize to fertilizers and manure in three agro-ecological units.The above approach leads to recommendations which apply to a district scale, but do not account for spatial variability between and within individual farmers' fields. Field-level heterogeneity, however, affected some trials as it was beyond the researcher's control. Two examples are dealt with in detail, i.e. (i) bypass flow and associated nitrogen leaching in a cracking clay soil, and (ii) the spotty emergence of the parasitic weed Striga hermonthica.As the establishment and maintenance of a trial network is costly and timeconsuming, computer models are increasingly used as an alternative. The QUantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model describes relations between (i) soil chemical parameters, (ii) potential supply of N, P and K from soils and fertilizers, (iii) actual uptake of N, P and K by maize, and (iv) maize grain yield. Characteristic features of the model are the inclusion of all macronutrients, acknowledging interactions between them, and the low input requirements enabling agronomists in tropical environments to test the model. The four steps of QUEFTS are calibrated with input data from fertilizer trials in different agro- ecological units. A complete run of the modified version shows a high correlation between measured and calculated yield, but although new relations are found, the basic structure and theoretical concepts of the original QUEFTS still stand.

This thesis provides a framework for integrated nutrient management in agricultural land use systems, with particular reference to its impact on productivity, fertilizer use efficiency, and sustainability in well-delimited tracts of land (agro-ecological units), characterized by a specific set of soil and climatic properties. Most of the research was conducted in Kenya, but methodology and results can be applied to any tropical region.Quantitative assessments are made of the nitrogen, phosphorus and potassium balance in the root zone of the arable land in sub-Saharan Africa. Land use systems are characterized by nutrient inputs (mineral fertilizer, manure, atmospheric deposition, biological nitrogen fixation, sedimentation) and nutrient outputs (removal of harvested crop parts and residues, leaching, denitrification, erosion), and the balance between the two. It is shown that outputs exceed inputs all over the continent. As scale-inherent simplifications were inevitable, a more detailed study is presented for the Kisii District in Kenya, with similar results. The alarming figures call for agronomic and policy interventions in the soil nutrient balance. A scaleneutral decision- support model of this nature is described, in which scenarios for improved nutrient management are worked out.Mineral fertilizers are, with the present abolishment of subsidies in many African countries, increasingly expensive, and it is evident that they must be used efficiently. With this in mind, a network of 70 researcher-managed, but farm-based factorial fertilizer trials was established in rainfed agricultural Kenya. The trial sites were chosen such that they represent wider ranges of similar environments. As such, the results form a basis for fertilizer recommendations that are not just crop-specific, but also specific for agro- ecological units. The site selection procedure is demonstrated, based on a profound scrutiny of soil and climate maps in Kenya, and followed by results of four years study on the response of maize to fertilizers and manure in three agro-ecological units.The above approach leads to recommendations which apply to a district scale, but do not account for spatial variability between and within individual farmers' fields. Field-level heterogeneity, however, affected some trials as it was beyond the researcher's control. Two examples are dealt with in detail, i.e. (i) bypass flow and associated nitrogen leaching in a cracking clay soil, and (ii) the spotty emergence of the parasitic weed Striga hermonthica.As the establishment and maintenance of a trial network is costly and timeconsuming, computer models are increasingly used as an alternative. The QUantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model describes relations between (i) soil chemical parameters, (ii) potential supply of N, P and K from soils and fertilizers, (iii) actual uptake of N, P and K by maize, and (iv) maize grain yield. Characteristic features of the model are the inclusion of all macronutrients, acknowledging interactions between them, and the low input requirements enabling agronomists in tropical environments to test the model. The four steps of QUEFTS are calibrated with input data from fertilizer trials in different agro- ecological units. A complete run of the modified version shows a high correlation between measured and calculated yield, but although new relations are found, the basic structure and theoretical concepts of the original QUEFTS still stand.