Planted tree fallows and their influence on soil fertility and maize production in East Africa

Soil fertility depletion is a main constraint to food production in sub-Saharan Africa. This thesis concerns the potential of N2-fixing trees to increase nitrogen inputs to agroforestry systems and accordingly to improve crop production. The suitability of five tropical tree species (including two N2-fixing species, Leucaena leucocephala and Prosopis chilensis) for tree fallows in Tanzania were evaluated by comparing their leaf chemistry, their effects on soil properties and on maize growth. After five years fallow, the per cent total soil N was higher under Prosopis compared to under other tree species. Maize biomass production was higher on soils from Leucaena or Prosopis compared to grass fallow. Prosopis contributed 11% to the total soil C over a period of 8 years. Field experiments in Kenya were performed to test a low-level 15N-tracer technique to estimate biological nitrogen fixation in Sesbania sesban over an 18-months period, and to compare the effects of short-duration tree fallows on two subsequent maize harvests with natural fallow and continuous cropping. We estimated the N derived from atmosphere by Sesbania after 18 months to between 500 and 600 kg ha-1, depending on which plant parts were used for 15N data and on the choice of reference species. We consider the 15N dilution method to be appropriate for quantifying N2 fixation in improved fallows in studies of young trees with high N2-fixing ability. In an experiment examining the effects of tree fallows on subsequent maize crops approximately 70-90% of the N in Sesbania, and 50-70% in Calliandra calothyrsus, was derived from N2-fixation. The quantity of N added by N2-fixation, 280-360 kg N ha-1 for Sesbania and 120-170 kg N ha-1 for Calliandra, resulted in a positive N balance after two cropping seasons of 170-250 kg N ha-1 and 90-140 kg N ha-1 respectively. Both the content of inorganic N in the topsoil and the quantity of N mineralised during rainy seasons were higher after the Sesbania fallows than after the other treatments. The substantial accumulation of N in planted Sesbania demonstrated its potential to increase the sustainability of crop production on N-limited soils

Fuelwood demand and supply in Rwanda and the role of agroforestry

Fuelwood in Rwanda is assumed to come from forests and woodlands, thus contributing to large-scale deforestation. Available studies on fuelwood demand and supply support this assumption and indicate a continuously rising demand of fuelwood, notably from forest plantations. These assertions are insufficiently substantiated as existing forest stock may not be depleted by rapid increase in demand for food and energy resources resulting from population growth, but rather from the need for agricultural land. Evidence suggests that the demands for fuelwood, in addition to other sources of energy, is supplied from agroforestry systems which has not been quantified so far. This review analyses sources and use of fuelwood in Rwanda, indicating the importance of on-farms trees and woodlots in fuelwood supply. It is concluded that the effect of fuelwood consumption on land use is difficult to disentangle as many other factors including land clearing for agriculture, livestock farming, human settlements, illegal cutting of valuable timber species, the demand for charcoal in towns and past conflicts, contributed significantly to the high rate of deforestation in the country. If fuelwood demand is to be met on a sustainable basis, more fuelwood has to be produced on agricultural lands and in forest plantations through species site matching and proper management

Residual Biomass: A Comprehensive Review on the Importance, Uses and Potential in a Circular Bioeconomy Approach

ReviewThe paradigm shift towards sustainable growth is urgent, and biomass, which is the oldest energy source that humans have used since the discovery of fire, might play an important role. Biomass waste from forestry and agriculture is expected to fuel part of the increasing demand for biomass, and its valorization allows for more the efficient use of nutrients and resources. In this study, we carried out an extensive literature review on the valorization of residual agroforestry biomass since the 1970s to understand the leading research focuses on the subject over the last few decades, identify the most recent trends, and establish a possible solution path for the future of biomass. It was observed that most studies focused on biomass as being capable of replacing fossil energy sources. According to the literature, biomass has the most significant potential to meet requirements and ensure fuel supplies in the future. The developments of the last decades have significantly improved the conversion processes, leading to greener solutions, but there is still much to be studied and put into practice. Closing the loop into biomass waste recovery will be essential for a genuinely circular bioeconomyinfo:eu-repo/semantics/publishedVersio

Estudo da biomassa agroflorestal residual em Portugal: mercado, valorização e políticas

Biomass from the forestry and agricultural sectors contributes significantly to meeting the targets presented by the government for increasing bioenergy production and utilization. Characterization of agricultural and forest wastes are critical for exploiting and utilizing them for energy purposes. This research aims to give a broader view of this thematic, understand the market potential for residual agroforestry biomass, the stakeholders involved, how is it possible to valorize this type of waste, and which policies could be implemented to solve the logistics and other problems involved in these operations, as well as understanding its socio-economic impacts, particularly regarding the problem of wildfires. It is worth noting that although Portugal has a vast area of forest and agriculture, these areas are highly fragmented, which is a problem that would have to be overcome to maximize the potential for biomass waste recovery. These are the main issues involved that we will explore in order to find possible solutions. With the present work we were able to understand the potential of RAFB in the central region of Portugal as well as the points of view from different groups of stakeholders and how the business model though a web platform could work in practice.A biomassa do setor florestal e agrícola fornece uma importante contribuição para cumprir as metas nacionais para aumentar a produção e utilização de bioenergia. A caracterização de resíduos agrícolas e florestais é fundamental para a sua exploração e utilização para fins energéticos. Com esta investigação, pretende-se dar uma visão mais ampla desta temática, compreender o potencial de criação de mercado para a biomassa agroflorestal residual, os stakeholders envolvidos, de que forma é possível valorizar este tipo de resíduos, quais as políticas que podem ser implementadas para solucionar os diversos problemas relacionados com estas operações, bem como compreender os seus impactos socioeconómicos, particularmente no que concerne o problema dos fogos florestais. Vale a pena notar que embora Portugal tenha uma vasta área florestal e agrícola, estas áreas são altamente fragmentadas, o que é um problema que terá de ser superado para maximizar o potencial de valorização dos resíduos agroflorestais. Estas são as principais questões envolvidas que tentaremos explorar, a fim de encontrar possíveis soluções. Com este trabalho foi possível perceber o potencial da biomassa agroflorestal residual na região centro de Portugal bem como os pontos de vista de diferentes grupos de stakeholders e como um modelo de negócio suportado numa plataforma web poderia funcionar na prática.Mestrado em Economi

Land, trees, and women: evolution of land tenure institutions in Western Ghana and Sumatra

This research report examines three questions that are central to IFPRI research: How do property-rights institutions affect efficiency and equity? How are resources allocated within households? Why does this matter from a policy perspective? As part of a larger multicountry study on property rights to land and trees, this study focuses on the evolution from customary land tenure with communal ownership toward individualized rights, and how this shift affects women and men differently.This study's key contribution is its multilevel econometric analysis of efficiency and equity issues. Using a combination of community, village, and household surveys in Western Ghana and Sumatra, two areas with traditional matrilineal inheritance systems, the authors and their collaborators analyze the effectiveness of village-, household-, and parcel-level property-rights institutions and arrangements.Land tenure Ghana., Agroforestry Gender issues., Land tenure Sumatra., Land use, Rural Planning., Right of property Gender issues., Gender, Property rights, Natural resource management,

The importance of some Sahelian browse species as feed for goats

Browse species contribute substantially to the availability of feed for livestock in the Sahelian zone of Burkina Faso. This study aimed to identify the most appreciated and utilized browse species, to evaluate their potential for fodder production and nutritive value, and to test the possibility of using them in intensive animal production. In the first experiment the behaviour of cattle, sheep and goats was studied and a survey was undertaken in the study area to estimate the indigenous knowledge of browse species and their utilisation by ruminants. In the second experiment, Acacia senegal, Guiera senegalensis and Pterocarpus lucens, species that were found to be well utilized, were studied by estimating the phenological variation over time and the edible biomass production, total and directly accessible to sheep (0.87 m), goats (1.65 m) or cattle (1.47 m). Biomass production was also estimated using dendrometric parameters. The chemical composition of biomass (leaves and green pods) was determined in the third experiment, followed by measurement of the voluntary intake and apparent digestibility of the leaves and pods (except for G. senegalensis) using goats. Their effect (except for A. senegal leaves) on growth, carcass characteristics and parasite resistance was evaluated in the fourth experiment, feeding the browses ad libitum with a fixed amount of bran and hay and compared with a control diet containing cottonseed cake. The farmers classified the browse species according to their availability, their nutritive value, and several other usages. The feeding activities of all animal species decreased from rainy to dry season, with the decline in fodder availability, while resting and ruminating activities were increasing at the same time. Cattle browsed (leaves and litter) during the whole the study period for around 5% of the time spent on pasture. Sheep and goats made a shift in their feeding activities from grazing to browsing (28% and 52% of the time spent on pasture, respectively, for sheep and goats) when the herbaceous biomass decreased. A. senegal, G. senegalensis and P. lucens started the foliation phase as soon as the rains started, while A. senegal lost leaves earlier. The proportion of accessible biomass was higher for G. senegalensis, but P. lucens had higher total edible biomass. Goats browsing at higher height had more edible biomass at their disposal than cattle and sheep, although the chemical composition was similar for biomass accessible by all three animal species. The crown diameter predicted well the total edible biomass production of the three browse species. The crude protein (CP) content was 114, 157 and 217 g/kg dry matter (DM) and the neutral detergent fibre content 604, 534 and 412 g/kg DM for G. senegalensis, P. lucens and A. senegal, respectively. The highest intake was of the P. lucens leaves diet (864 g) and the lowest of the G. senegalensis diet (397 g). Pods from A. senegal were more consumed than pods of P. lucens. The leaves of A. senegal and P. lucens had similar digestibilities of CP, while A. senegal pods had higher digestibility of all nutrients than P. lucens pods. Goats fed A. senegal pods showed higher growth rate (56 g/day) and the goats on P. lucens pods had the lowest (24 g/day). The carcass weight, dressing percentage and weight of the primal cuts were higher for goats fed A. senegal pods, P. lucens leaves and the control diet. In conclusion, A. senegal pods and P. lucens leaves can be recommended as supplemental feed to poor quality roughages

Chapter Solid Biomass from Forest Trees to Energy: A Review

Among the different terrestrial ecosystems, forests are the most important biomass carbon producers and the ones that store the most standing biomass carbon. Consequently, they are also the major source of biomass for energy. Forest biomass has been used as a fuel from early times, and from the late twentieth century onward, there has been a renewed interest in its use to produce heat and electricity. The interest in forest biomass as an energy source relates to some of its features, such as relative abundance and uniformity worldwide and neutrality of CO2 emissions. Nonetheless, its use is not free of risks, mostly related with the sustainability of the forest systems and their productions. This study reviews the state of the art of the forest sources of biomass for energy, their assessment, their properties as a fuel, as well as the conversion technologies used in the most common energy applications

Solid Biomass from Forest Trees to Energy: A Review

Among the different terrestrial ecosystems, forests are the most important biomass carbon producers and the ones that store the most standing biomass carbon. Consequently, they are also the major source of biomass for energy. Forest biomass has been used as a fuel from early times, and from the late twentieth century onward, there has been a renewed interest in its use to produce heat and electricity. The interest in forest biomass as an energy source relates to some of its features, such as relative abundance and uniformity worldwide and neutrality of CO2 emissions. Nonetheless, its use is not free of risks, mostly related with the sustainability of the forest systems and their productions. This study reviews the state of the art of the forest sources of biomass for energy, their assessment, their properties as a fuel, as well as the conversion technologies used in the most common energy applications

The Economic Case for Landscape Restoration in Latin America

Degraded lands—lands that have lost some degree of their natural productivity through human activity—account for over 20 percent of forest and agricultural lands in Latin America and the Caribbean. Some 300 million hectares of the region's forests are considered degraded, and about 350 million hectares are now classified as deforested. The agriculture and forestry sectors are growing and exerting great pressure on natural areas. With the region expected to play an increasingly important role in global food security, this pressure will continue to ratchet up. In addition, land degradation is a major driver in greenhouse gas emissions in the region. Forest and landscape restoration can offer a solution to these increasing pressures

Compost and fertilizer mineralization effects on soil and harvest in parkland agroforestry systems in the south-Sudanese zone of Burkina Faso

Decomposition of, and the subsequent nutrient release from tree leaf litter as well as external inputs of nutrients are important in the traditional agroforestry parklands of West Africa. The management of nutrient resources is essential to optimize crop performance and soil fertility. To explore temporal and spatial nutrient release in such management options has been the overall objective of this study. Specifically, this thesis investigated: (i) decomposition patterns and nutrient release from litters of Faidherbia albida and Vitellaria paradoxa; (ii) limitation of microbial respiration, as a result of low nitrogen (N) and phosphorus (P) in the F. albida and V. paradoxa parklands; and (iii) the effects of applications of combined compost and urea on maize yield in the F. albida and V. paradoxa parklands. The litter of F. albida lost more mass and nutrients than litter of V. paradoxa. However, the decomposition rate of V. paradoxa increased in the presence of F. albida litter or following the application of inorganic fertilizers. Soil microbial respiration was mainly limited by P-fixation, but N was also limiting. Two microbial growth peaks were observed when excess carbon and P were present, suggesting that either two pools of N are sequentially available to microbes or that two microbial communities do exist. Respiration tests also indicated that P and N availability to microorganisms were higher under the canopy than outside it. Maize yield was similar with the addition of urea, compost, or a combination of compost and urea, if applied at an equivalent N-content. However, in the driest year, the combination of compost and urea had the greatest effect in the increase of maize yield as compared with control treatments. The maize yield under the canopies of F. albida was up to 2.3 times the yield outside the canopies, while under the canopies of V. paradoxa it was 0.6 to 0.8 times the yield outside the canopies. The yield under the canopy was relatively better in dry year. Compost-N and inorganic fertilizer-N recoveries in maize shoot biomass were low, indicating that a large proportion of maize shoot-N is derived from the soil. Also, under the canopy of F. albida, the proportion of N derived from fertilizer in maize shoot was lower compared with that outside the canopy, implying that the soil N-pool was more readily available to plants under trees. In conclusion, there is a potential to improve the decomposition rate of V. paradoxa litter by inorganic fertilizer application or by mixing it with F. albida litter. Thus, the litter of V. paradoxa can be a useful to improve soil quality, rather than being burnt as is nowadays practiced by the farmers. Application of combined compost and inorganic fertilizer offers a management option that is cheaper than only inorganic fertilizers and more manageable than only compost applications