A modelling approach was chosen for analyzing the effects of competition between windbreaks and c... more A modelling approach was chosen for analyzing the effects of competition between windbreaks and crops for soil water and radiation in the Sahel. The model has a high spatial and temporal resolution to account for the heterogeneity in a windbreak-cropping system. The model was parameterised for millet (Pennisetum glaucum (L.) R. Br.), the tree species Bauhinia rufescens Lam. and soil
A model was developed to simulate the effects of competition for soil water and radiation between... more A model was developed to simulate the effects of competition for soil water and radiation between windbreaks and pearl millet crops in the Sahel. These effects on millet (Pennisetum glaucum (L.) R. Br.) growth were simultaneously simulated for each millet row parallel to the windbreak with small time steps for soil water processes, radiation availability and crop assimilation. The crop
ABSTRACT A model was developed to simulate the effects of competition for soil water and radiatio... more ABSTRACT A model was developed to simulate the effects of competition for soil water and radiation between windbreaks and pearl millet crops in the Sahel. These effects on millet (Pennisetum glaucum (L.) R. Br.) growth were simultaneously simulated for each millet row parallel to the windbreak with small time steps for soil water processes, radiation availability and crop assimilation. The crop routine of the model was based on an existing semi-deterministic model. The soil-water flow was simulated in two dimensions to account for horizontal gradients. Competition for water was expressed by distributing the available soil water between trees and millet in proportion to its uptake rates in a non-competitive situation. Competition for light was incorporated as light reduction through a two-dimensional (windbreak) barrier with time-increasing height and density. Tree parameters were introduced as fixed values or as time-dependent forcing functions. Crop, windbreak trees (Bauhinia rufescens Lam.), and soil data inputs were either field-determined or obtained from literature. Reasonable agreement between simulated and measured soil water content and dry matter production was obtained under the conditions in Niger. Global radiation intensities and soil water contents were simulated satisfactorily as a function of time and the distance from the windbreak. Hence, the model is appropriate to analyse competition for light and water between windbreaks and crops.
A modelling approach was chosen for analyzing the effects of competition between windbreaks and c... more A modelling approach was chosen for analyzing the effects of competition between windbreaks and crops for soil water and radiation in the Sahel. The model has a high spatial and temporal resolution to account for the heterogeneity in a windbreak-cropping system. The model was parameterised for millet (Pennisetum glaucum (L.) R. Br.), the tree species Bauhinia rufescens Lam. and soil characteristics and weather data of Sadore, Niger. Simulations were run for two wet years (1992 and 1993) and for a dry cropping season (1989). Simulations showed a strong yield reduction up to 2 m from the windbreak due to shading and/or water competition. For Sahelian sites with no access to groundwater, competition for water between trees and crops is likely to occur in the beginning of the rainy season. Water competition was surprisingly highest in the wet year 1992, intermediate in the dry year 1987 and lowest in the wet year 1993. Simulation results indicate that light and water competition depends on rainfall distribution and the period between the seasonal onset of tree and crop growth.
In the Sahelian zone, future food supply is insecure due to increasing land degradation. Wind ero... more In the Sahelian zone, future food supply is insecure due to increasing land degradation. Wind erosion contributes significantly to impoverishment of the sandy soils, which are often loose and sparsely covered by vegetation for most of the year. At the onset of the growing season (May - July), strong winds often precede rains and may cause damage to the young
Silvoarable agroforestry, the integration of trees and arable crops on the same area, has the pot... more Silvoarable agroforestry, the integration of trees and arable crops on the same area, has the potential to offer production, ecological, and societal benefits. However, the uptake of such systems in Europe has been limited by a combination of unsupportive policies and uncertainty concerning their productivity, profitability, and environmental impact. Faced with a lack of experimental data, the parameter-sparse Yield-SAFE model offers one method for generating plausible yield data and improving understanding of production in mixed tree-crop systems under European conditions. The applicability of the model was examined by: (i) selecting two contrasting sites in France and the UK with measured agricultural, silvoarable and/or forestry data, (ii) implementing the model in a software package, and (iii) inputting data and parameters on the climate, soils, management regime, and tree and crop types. Following calibration, Yield-SAFE provided credible descriptions of measured arable and tree (Populus spp.) yields in the monoculture and silvoarable systems at the two sites. An examination of the response of the model to changes in model parameters and environmental and management data showed that silvoarable crop yields were most sensitive to variations in tree parameters. Increased soil depths increased timber yields, and increasing stand density increased stand volume whilst decreasing individual tree volume. In all the simulations, the model predicted greater efficiency in use of land, i.e. greater land equivalent ratios, when trees and crops were combined rather than grown as sole crops. These results, supported by the sparse experimental data available, indicate that agroforestry provides a method of increasing food, timber and biomass production from limited land resources in Europe.
Competition Parameter estimation Resource use Land use Land equivalent ratio Long-term yield pred... more Competition Parameter estimation Resource use Land use Land equivalent ratio Long-term yield prediction a b s t r a c t 1. Silvoarable agroforestry (SAF) is the cultivation of trees and arable crops on the same parcel of land. SAF may contribute to modern diversified land use objectives in Europe, such as enhanced biodiversity and productivity, reduced leaching of nitrogen, protection against flooding and erosion, and attractiveness of the landscape. Long-term yield predictions are needed to assess long-term economic profitability of SAF. 2. A model for growth, resource sharing and productivity in agroforestry systems was developed to act as a tool in forecasts of yield, economic optimization of farming enterprises and exploration of policy options for land use in Europe. The model is called Yield-SAFE; from "YIeld Estimator for Long term Design of Silvoarable AgroForestry in Europe". The model was developed with as few equations and parameters as possible to allow model parameterization under constrained availability of data from long-term experiments. 3. The model consists of seven state equations expressing the temporal dynamics of: (1) tree biomass; (2) tree leaf area; (3) number of shoots per tree; (4) crop biomass; (5) crop leaf area index; (6) heat sum; and (7) soil water content. The main outputs of the model are the growth dynamics and final yields of trees and crops. Daily inputs are temperature, radiation and precipitation. Planting densities, initial biomasses of tree and crop species,
Increased adoption of silvoarable agroforestry (SAF) systems in Europe, by integrating trees and ... more Increased adoption of silvoarable agroforestry (SAF) systems in Europe, by integrating trees and arable crops on the same land, could offer a range of environmental benefits compared with conventional agricultural systems. Soil erosion, nitrogen leaching, carbon sequestration and landscape biodiversity were chosen as indicators to assess a stratified random sample of 19 landscape test sites in the Mediterranean and Atlantic regions of Europe. At each site, the effect of introducing agroforestry was examined at plot-scale by simulating the growth of one of five tree species (hybrid walnut Juglans spp., wild cherry Prunus avium L., poplar Populus spp., holm oak Quercus ilex L. subsp. ilex and stone pine Pinus pinea L.) at two tree densities (50 and 113 trees ha -1 ) in combination with up to five crops (wheat Triticum spp., sunflower Helianthus annuus L., oilseed rape Brassica napus L., grain maize and silage maize Zea mays L.). At landscape-scale, the effect of introducing agroforestry on 10 or 50% of the agricultural area, on either the best or worst quality land, was examined. Across the 19 landscape test sites, SAF had a positive impact on the four indicators with the strongest effects when introduced on the best quality land. The computer simulations showed that SAF could significantly reduce erosion by up to 65% when combined with contouring practices at medium (> 0.5 and < 3 t ha -1 a -1 ) and high (> 3 t ha -1 a -1 ) erosion sites. Nitrogen leaching could be reduced by up to 28% in areas where leaching is currently estimated high (>100 kg N ha -1 a -1 ), but this was dependent on tree density. With agroforestry, predicted mean carbon sequestration through immobilization in trees, over a 60year period, ranged from 0.1 to 3.0 t C ha -1 a -1 (5 to 179 t C ha -1 ) depending on tree species and location. Landscape biodiversity was increased by introducing SAF by an average factor of 2.6. The implications of this potential for environmental benefits at European scale are discussed.
Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area ... more Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area of land, has been proposed in order to improve the environmental performance of agricultural systems in Europe. Based on existing models and algorithms we developed a method to predict the environmental effects of SAF at a farm-and landscape-scale. The method comprised of an assessment of soil erosion, nitrogen leaching, carbon sequestration and landscape diversity and allowed the comparison of the environmental performance of SAF with arable systems using these four indicators.
... AGRICULTURE 1. Get Manifesto and discussion on the SAFE Website2 (www.montpellier.inra. fr/sa... more ... AGRICULTURE 1. Get Manifesto and discussion on the SAFE Website2 (www.montpellier.inra. fr/safe/) 2. Copy correspondence to Gerry Lawson ([email protected]) 3. For UK discussion see the FWF website1 (www.agroforestry.ac.uk) World Agroforestry Congress ...
A modelling approach was chosen for analyzing the effects of competition between windbreaks and c... more A modelling approach was chosen for analyzing the effects of competition between windbreaks and crops for soil water and radiation in the Sahel. The model has a high spatial and temporal resolution to account for the heterogeneity in a windbreak-cropping system. The model was parameterised for millet (Pennisetum glaucum (L.) R. Br.), the tree species Bauhinia rufescens Lam. and soil
A model was developed to simulate the effects of competition for soil water and radiation between... more A model was developed to simulate the effects of competition for soil water and radiation between windbreaks and pearl millet crops in the Sahel. These effects on millet (Pennisetum glaucum (L.) R. Br.) growth were simultaneously simulated for each millet row parallel to the windbreak with small time steps for soil water processes, radiation availability and crop assimilation. The crop
ABSTRACT A model was developed to simulate the effects of competition for soil water and radiatio... more ABSTRACT A model was developed to simulate the effects of competition for soil water and radiation between windbreaks and pearl millet crops in the Sahel. These effects on millet (Pennisetum glaucum (L.) R. Br.) growth were simultaneously simulated for each millet row parallel to the windbreak with small time steps for soil water processes, radiation availability and crop assimilation. The crop routine of the model was based on an existing semi-deterministic model. The soil-water flow was simulated in two dimensions to account for horizontal gradients. Competition for water was expressed by distributing the available soil water between trees and millet in proportion to its uptake rates in a non-competitive situation. Competition for light was incorporated as light reduction through a two-dimensional (windbreak) barrier with time-increasing height and density. Tree parameters were introduced as fixed values or as time-dependent forcing functions. Crop, windbreak trees (Bauhinia rufescens Lam.), and soil data inputs were either field-determined or obtained from literature. Reasonable agreement between simulated and measured soil water content and dry matter production was obtained under the conditions in Niger. Global radiation intensities and soil water contents were simulated satisfactorily as a function of time and the distance from the windbreak. Hence, the model is appropriate to analyse competition for light and water between windbreaks and crops.
A modelling approach was chosen for analyzing the effects of competition between windbreaks and c... more A modelling approach was chosen for analyzing the effects of competition between windbreaks and crops for soil water and radiation in the Sahel. The model has a high spatial and temporal resolution to account for the heterogeneity in a windbreak-cropping system. The model was parameterised for millet (Pennisetum glaucum (L.) R. Br.), the tree species Bauhinia rufescens Lam. and soil characteristics and weather data of Sadore, Niger. Simulations were run for two wet years (1992 and 1993) and for a dry cropping season (1989). Simulations showed a strong yield reduction up to 2 m from the windbreak due to shading and/or water competition. For Sahelian sites with no access to groundwater, competition for water between trees and crops is likely to occur in the beginning of the rainy season. Water competition was surprisingly highest in the wet year 1992, intermediate in the dry year 1987 and lowest in the wet year 1993. Simulation results indicate that light and water competition depends on rainfall distribution and the period between the seasonal onset of tree and crop growth.
In the Sahelian zone, future food supply is insecure due to increasing land degradation. Wind ero... more In the Sahelian zone, future food supply is insecure due to increasing land degradation. Wind erosion contributes significantly to impoverishment of the sandy soils, which are often loose and sparsely covered by vegetation for most of the year. At the onset of the growing season (May - July), strong winds often precede rains and may cause damage to the young
Silvoarable agroforestry, the integration of trees and arable crops on the same area, has the pot... more Silvoarable agroforestry, the integration of trees and arable crops on the same area, has the potential to offer production, ecological, and societal benefits. However, the uptake of such systems in Europe has been limited by a combination of unsupportive policies and uncertainty concerning their productivity, profitability, and environmental impact. Faced with a lack of experimental data, the parameter-sparse Yield-SAFE model offers one method for generating plausible yield data and improving understanding of production in mixed tree-crop systems under European conditions. The applicability of the model was examined by: (i) selecting two contrasting sites in France and the UK with measured agricultural, silvoarable and/or forestry data, (ii) implementing the model in a software package, and (iii) inputting data and parameters on the climate, soils, management regime, and tree and crop types. Following calibration, Yield-SAFE provided credible descriptions of measured arable and tree (Populus spp.) yields in the monoculture and silvoarable systems at the two sites. An examination of the response of the model to changes in model parameters and environmental and management data showed that silvoarable crop yields were most sensitive to variations in tree parameters. Increased soil depths increased timber yields, and increasing stand density increased stand volume whilst decreasing individual tree volume. In all the simulations, the model predicted greater efficiency in use of land, i.e. greater land equivalent ratios, when trees and crops were combined rather than grown as sole crops. These results, supported by the sparse experimental data available, indicate that agroforestry provides a method of increasing food, timber and biomass production from limited land resources in Europe.
Competition Parameter estimation Resource use Land use Land equivalent ratio Long-term yield pred... more Competition Parameter estimation Resource use Land use Land equivalent ratio Long-term yield prediction a b s t r a c t 1. Silvoarable agroforestry (SAF) is the cultivation of trees and arable crops on the same parcel of land. SAF may contribute to modern diversified land use objectives in Europe, such as enhanced biodiversity and productivity, reduced leaching of nitrogen, protection against flooding and erosion, and attractiveness of the landscape. Long-term yield predictions are needed to assess long-term economic profitability of SAF. 2. A model for growth, resource sharing and productivity in agroforestry systems was developed to act as a tool in forecasts of yield, economic optimization of farming enterprises and exploration of policy options for land use in Europe. The model is called Yield-SAFE; from "YIeld Estimator for Long term Design of Silvoarable AgroForestry in Europe". The model was developed with as few equations and parameters as possible to allow model parameterization under constrained availability of data from long-term experiments. 3. The model consists of seven state equations expressing the temporal dynamics of: (1) tree biomass; (2) tree leaf area; (3) number of shoots per tree; (4) crop biomass; (5) crop leaf area index; (6) heat sum; and (7) soil water content. The main outputs of the model are the growth dynamics and final yields of trees and crops. Daily inputs are temperature, radiation and precipitation. Planting densities, initial biomasses of tree and crop species,
Increased adoption of silvoarable agroforestry (SAF) systems in Europe, by integrating trees and ... more Increased adoption of silvoarable agroforestry (SAF) systems in Europe, by integrating trees and arable crops on the same land, could offer a range of environmental benefits compared with conventional agricultural systems. Soil erosion, nitrogen leaching, carbon sequestration and landscape biodiversity were chosen as indicators to assess a stratified random sample of 19 landscape test sites in the Mediterranean and Atlantic regions of Europe. At each site, the effect of introducing agroforestry was examined at plot-scale by simulating the growth of one of five tree species (hybrid walnut Juglans spp., wild cherry Prunus avium L., poplar Populus spp., holm oak Quercus ilex L. subsp. ilex and stone pine Pinus pinea L.) at two tree densities (50 and 113 trees ha -1 ) in combination with up to five crops (wheat Triticum spp., sunflower Helianthus annuus L., oilseed rape Brassica napus L., grain maize and silage maize Zea mays L.). At landscape-scale, the effect of introducing agroforestry on 10 or 50% of the agricultural area, on either the best or worst quality land, was examined. Across the 19 landscape test sites, SAF had a positive impact on the four indicators with the strongest effects when introduced on the best quality land. The computer simulations showed that SAF could significantly reduce erosion by up to 65% when combined with contouring practices at medium (> 0.5 and < 3 t ha -1 a -1 ) and high (> 3 t ha -1 a -1 ) erosion sites. Nitrogen leaching could be reduced by up to 28% in areas where leaching is currently estimated high (>100 kg N ha -1 a -1 ), but this was dependent on tree density. With agroforestry, predicted mean carbon sequestration through immobilization in trees, over a 60year period, ranged from 0.1 to 3.0 t C ha -1 a -1 (5 to 179 t C ha -1 ) depending on tree species and location. Landscape biodiversity was increased by introducing SAF by an average factor of 2.6. The implications of this potential for environmental benefits at European scale are discussed.
Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area ... more Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area of land, has been proposed in order to improve the environmental performance of agricultural systems in Europe. Based on existing models and algorithms we developed a method to predict the environmental effects of SAF at a farm-and landscape-scale. The method comprised of an assessment of soil erosion, nitrogen leaching, carbon sequestration and landscape diversity and allowed the comparison of the environmental performance of SAF with arable systems using these four indicators.
... AGRICULTURE 1. Get Manifesto and discussion on the SAFE Website2 (www.montpellier.inra. fr/sa... more ... AGRICULTURE 1. Get Manifesto and discussion on the SAFE Website2 (www.montpellier.inra. fr/safe/) 2. Copy correspondence to Gerry Lawson ([email protected]) 3. For UK discussion see the FWF website1 (www.agroforestry.ac.uk) World Agroforestry Congress ...
Uploads
Papers by M. Mayus