The effects of earthworms on soil structure and the resulting physical properties in natural or c... more The effects of earthworms on soil structure and the resulting physical properties in natural or cultivated systems were studied in different sites of the Macrofauna project. Four main results were obtained from these experiments: 1. In kaolinitic soils (Lamto, Manaus, Yurimaguas), irrespective of clay content, andogeic earthworms play a major role in soil structure formation and maintenance, while in smectitic soils (Martinique), the effects of earthworms on soil structure formation and maintenance are not as clear. In the Vertisols of Martinique, the effect of roots and organic materials seem predominant in soil structure development and earthworms play a secondary role. 2. Endogeic earthworm species have different effects on soil properties. Large earthworms such as Pontoscolex corethrurus or Millsonia anomala egest large and compact casts. They increase the proportion of large aggregates in soil and the bulk density ; they are called 'compacting species'. Conversely, smal...
2 Abstract The relationships between the structural variations of a fenisol and the plant parasit... more 2 Abstract The relationships between the structural variations of a fenisol and the plant parasitic nematode communities of sugarcane were studied along three transects. These transects, about 20 m long, started in horizon A and ended in a levelled area where horizon C began. Results were analysed with the Co-inertia analysis method, which allowed us to study simultaneously the soil and nematode data. Progressive variations of the content of some physico-chemical soil elements (organic matter, phosphorus, pH) appear linked to those of the abundance of some nematode species (Heniicricoloideszenioides and Prarylenclzus). This analysis also shows relations that do not vary according to a gradient along the transects. For instance, the abundance of Helicotylenclius can be correlated with the existence of high calcium grades.
The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means o... more The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means of improving soil fertility and increasing crop yield in eastern and southern Africa, including western Kenya. However, this improved fallow practice may also increase the nematode population in the soil. An experiment was conducted to monitor the effects of plant-parasitic nematodes on crops
ABSTRACT The soil organic carbon plays an important role in climate change regulation through car... more ABSTRACT The soil organic carbon plays an important role in climate change regulation through carbon emissions and sequestration due to land use changes, notably tropical deforestation. Monitoring soil carbon emissions from shifting-cultivation requires to evaluate the amount of carbon stored at plot scale with a sufficient level of accuracy to be able to detect changes. The objective of this work was to map soil carbon stocks (30 cm and 100 cm depths) for different land use at regional scale using high resolution satellite dataset. The Andohahela National Parc and its surroundings (South-Est Madagascar) - a region with the largest deforestation rate in the country - was selected as a pilot area for the development of the methodology. A three steps approach was set up: (i) carbon inventory using mid infra-red spectroscopy and stock calculation, (ii) spatial data processing and (iii) modeling and mapping. Soil spectroscopy was successfully used for measuring organic carbon in this region. The results show that Random Forest was the inference model that produced the best estimates on calibration and validation datasets. By using a simple and robust method, we estimated uncertainty levels of of 35% and 43% for 30-cm and 100-cm carbon maps respectively. The approach developed in this study was based on open data and open source software that can be easily replicated to other regions and for other time periods using updated satellite images.
... properties and nematodes indicate that, apart from the direct influence of the host plant, th... more ... properties and nematodes indicate that, apart from the direct influence of the host plant, the ... Author Keywords: Bio-indicator; Diversity; Improved fallows; Nematodes; Soil status. ... because of population pressure, gains in crop production after these short-duration weed fallows may ...
Soil carbon (C) mineralization rate is a key indicator of soil functional capacity but it is time... more Soil carbon (C) mineralization rate is a key indicator of soil functional capacity but it is time consuming to measure using conventional laboratory incubation methods. Recent studies have demonstrated the ability of visible-near infrared spectroscopy (NIRS) for rapid non-destructive determination of soil organic carbon (SOC) and nitrogen (N) concentration.
Poor soil fertility is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. I... more Poor soil fertility is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. Improved fallows can help to raise agricultural productivity in these systems of low financial capital, however, experimental testing of their potential application domain and design is costly and time consuming. Models can evaluate alternative systems relatively quickly and at relatively low cost, but must first be validated
Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood p... more Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood production in Madagascar. Nevertheless, little is known about their biomass production and partitioning and their potential in terms of carbon sequestration. If above-ground biomass (AGB) can be estimated based on established allometric relations, below-ground (BGB) estimates are much less common. The aim of this work was to
The effects of earthworms on soil structure and the resulting physical properties in natural or c... more The effects of earthworms on soil structure and the resulting physical properties in natural or cultivated systems were studied in different sites of the Macrofauna project. Four main results were obtained from these experiments: 1. In kaolinitic soils (Lamto, Manaus, Yurimaguas), irrespective of clay content, andogeic earthworms play a major role in soil structure formation and maintenance, while in smectitic soils (Martinique), the effects of earthworms on soil structure formation and maintenance are not as clear. In the Vertisols of Martinique, the effect of roots and organic materials seem predominant in soil structure development and earthworms play a secondary role. 2. Endogeic earthworm species have different effects on soil properties. Large earthworms such as Pontoscolex corethrurus or Millsonia anomala egest large and compact casts. They increase the proportion of large aggregates in soil and the bulk density ; they are called 'compacting species'. Conversely, smal...
2 Abstract The relationships between the structural variations of a fenisol and the plant parasit... more 2 Abstract The relationships between the structural variations of a fenisol and the plant parasitic nematode communities of sugarcane were studied along three transects. These transects, about 20 m long, started in horizon A and ended in a levelled area where horizon C began. Results were analysed with the Co-inertia analysis method, which allowed us to study simultaneously the soil and nematode data. Progressive variations of the content of some physico-chemical soil elements (organic matter, phosphorus, pH) appear linked to those of the abundance of some nematode species (Heniicricoloideszenioides and Prarylenclzus). This analysis also shows relations that do not vary according to a gradient along the transects. For instance, the abundance of Helicotylenclius can be correlated with the existence of high calcium grades.
The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means o... more The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means of improving soil fertility and increasing crop yield in eastern and southern Africa, including western Kenya. However, this improved fallow practice may also increase the nematode population in the soil. An experiment was conducted to monitor the effects of plant-parasitic nematodes on crops
ABSTRACT The soil organic carbon plays an important role in climate change regulation through car... more ABSTRACT The soil organic carbon plays an important role in climate change regulation through carbon emissions and sequestration due to land use changes, notably tropical deforestation. Monitoring soil carbon emissions from shifting-cultivation requires to evaluate the amount of carbon stored at plot scale with a sufficient level of accuracy to be able to detect changes. The objective of this work was to map soil carbon stocks (30 cm and 100 cm depths) for different land use at regional scale using high resolution satellite dataset. The Andohahela National Parc and its surroundings (South-Est Madagascar) - a region with the largest deforestation rate in the country - was selected as a pilot area for the development of the methodology. A three steps approach was set up: (i) carbon inventory using mid infra-red spectroscopy and stock calculation, (ii) spatial data processing and (iii) modeling and mapping. Soil spectroscopy was successfully used for measuring organic carbon in this region. The results show that Random Forest was the inference model that produced the best estimates on calibration and validation datasets. By using a simple and robust method, we estimated uncertainty levels of of 35% and 43% for 30-cm and 100-cm carbon maps respectively. The approach developed in this study was based on open data and open source software that can be easily replicated to other regions and for other time periods using updated satellite images.
... properties and nematodes indicate that, apart from the direct influence of the host plant, th... more ... properties and nematodes indicate that, apart from the direct influence of the host plant, the ... Author Keywords: Bio-indicator; Diversity; Improved fallows; Nematodes; Soil status. ... because of population pressure, gains in crop production after these short-duration weed fallows may ...
Soil carbon (C) mineralization rate is a key indicator of soil functional capacity but it is time... more Soil carbon (C) mineralization rate is a key indicator of soil functional capacity but it is time consuming to measure using conventional laboratory incubation methods. Recent studies have demonstrated the ability of visible-near infrared spectroscopy (NIRS) for rapid non-destructive determination of soil organic carbon (SOC) and nitrogen (N) concentration.
Poor soil fertility is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. I... more Poor soil fertility is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. Improved fallows can help to raise agricultural productivity in these systems of low financial capital, however, experimental testing of their potential application domain and design is costly and time consuming. Models can evaluate alternative systems relatively quickly and at relatively low cost, but must first be validated
Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood p... more Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood production in Madagascar. Nevertheless, little is known about their biomass production and partitioning and their potential in terms of carbon sequestration. If above-ground biomass (AGB) can be estimated based on established allometric relations, below-ground (BGB) estimates are much less common. The aim of this work was to
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Papers by Alain Albrecht