Performances agronomiques des amendements a base de biochar en milieu paysan a l’ouest du Burkina Faso

Au Burkina Faso, la baisse de la fertilité des sols représente une contrainte importante pour la durabilité de l’agriculture. Dans cette étude, l’influence du compost, du biochar et du co-compost au biochar sur les propriétés chimiques du sol, le rendement du cotonnier et du maïs a été évaluée sur un lixisol endoplinthique en milieu paysan. Le dispositif était en blocs randomisés comportant trois traitements en quatre répétitions : T= compost + NPK + Urée, T2 = biochar pristine + NPK + urée, et T3=co-compost au biochar + NPK + urée. La dose d’apport des amendements était de 2,5t.ha-1.an-1 pendant deux ans, associée à la dose recommandée d’engrais minéraux (coton : NPK = 150 kg.ha-1 et urée = 50 kg.ha-1 ; maïs : NPK = 200 kg.ha-1 et urée = 100 kg.ha-1). L’adjonction du biochar pendant le compostage a augmenté les teneurs en azote total, magnésium total et phosphore total de l’amendement obtenu, respectivement de 48 %, 64 % et 68 % comparativement au compost. Même si les paramètres physico-chimiques du sol, deux ans après, n’ont pas été améliorés, une augmentation significative du rendement du coton graine de 14 % (biochar) et 19 % (co-compost au biochar) comparativement au compost a été observée la troisième année. Les amendements à base de biochar peuvent être suggérés aux producteurs pour l’amélioration du rendement des cultures à moyen terme.   English title: Agronomic Performance of Biochar-Based Amendments in Farmers’ environment in western Burkina Faso In Burkina Faso, declining soil fertility is a major constraint to agricultural productivity and sustainability. In the present study, compost, biochar and co-composted biochar were applied to endoplinthic lixisol, and the effects on soil physicochemical properties, cotton and maize yield over three  years (i.e., three cropping seasons) were investigated. The trial was a completely randomized block design included three treatments and four  repetitions: T1= compost + NPK + Urea, T2= pristine biochar + NPK + Urea and T3= co-composted biochar + NPK + Urea. The amendments rate were  2.5 t.ha-1 each year (2018 and 2019) combined with the recommended rate of mineral fertilizer (cotton: 150 kg.ha-1 NPK , 50 kg.ha-1 Urea; maize:  200 kg.ha-1 NPK, 100 kg.ha-1 Urea). The addition of biochar during the composting process increased the total nitrogen, total magnesium and total  phosphorus contents of co-composted biochar by 48%, 64% and 68% respectively compared to compost. Although the biochar-based amendments  did not improve the physico-chemical parameters of the soil, two years after their application, a significant increase in cotton yield by 14% (biochar)  and 19% (co-composted biochar) compared to compost in the third year was observed. Biochar-based amendments can be suggested to producers  for medium-term crop yield improvement

Effects of burning on soil macrofauna in a savanna-woodland under different experimental fuel load treatments

In West African savanna-woodland, the use of prescribed burning as a management tool has ecological implications for the soil biota. Yet, the effects of fire on soil inhabiting organisms are poorly understood. The aim of this study was to examine the responses of soil macro-invertebrates to early fires in a Sudanian savanna-woodland on a set of experimental plots subject to different fuel load treatments. The abundance of major macro-invertebrate taxa and functional groups, and taxon richness were quantified in soil cores collected from three different soil layers before and immediately after burning. The results indicated that, overall, there was substantial spatial and temporal variation in the composition of macro-invertebrate assemblages. The immediate effects of fire were to reduce total invertebrate numbers and numbers of many invertebrate groups dramatically. This is probably due to the fact that many of the surface-dwelling macrofauna perished as a result of less favorable microclimate due to fire, diminished resources, or migrate to safer environments. Fuel load treatment did not affect the community taxonomic richness or abundance of the soil-dwelling fauna. Furthermore, annual changes in community composition were more pronounced at the burnt site than in the control. This could be related to the inter-annual difference in precipitation pattern recorded during the two-year study period at our site. Since soil macrofauna population declines in fire-disturbed areas, increasing fire prevalence may jeopardize the long-term conservation of fire sensitive macrofauna groups. Special fire management attention is therefore recommended with due consideration to the type of burning and fuel properties to avoid the detrimental effects of intense fire affecting the resilience of savanna soil macrofauna species

Caractérisation des systèmes de production de Jatropha dans les exploitations agricoles de la zone Ouest du Burkina Faso

La production agricole est la principale source de développement socio-économique au Burkina Faso. Depuis les années 2000, la promotion du Biocarburant suscite un regain d’intérêt pour la plantation de Pourghère (Jatropha curcas L.). Dans 14 villages de la zone Ouest du Burkina Faso, une enquête semistructurée basée sur un questionnaire a été appliquée auprès de 210 producteurs de Jatropha. Les résultats des enquêtes indiquent que la production de Jatropha est récente. La superficie des plantations de Jatropha varie entre 7,5 et 30 ha par village. L’écartement le plus adopté pour la plantation de Jatropha est de 5 m entre les lignes et 2 m entre les plants (5 m × 2 m), soit une densité de 1071 plants/ha. Une proportion de 80,4% des producteurs enquêtés indique avoir 4 à 7 ans d’expérience dans la culture de Jatropha. Les rendements varient entre 300 et 700 kg/ha. Pour 78,5% des exploitants, leur engagement dans la culture de Jatropha a été motivé par les structures de promotion de Jatropha. Plus de 90% des producteurs pratiquent la technique de la pépinière-transplantation et 70% pratiquent la culture associée au Jatropha. Les enquêtes révèlent que 70% des producteurs associent les légumineuses au Jatropha et que 22% des producteurs pratiquent la fertilisation de Jatropha. L’application des traitements phytosanitaires au Jatropha peu pratiquée, ne concerne que 11% des producteurs.© 2015 International Formulae Group. All rights reserved.Mots clés: Biocarburant, pourghère (Jatropha curcas L.), enquêtes, exploitants, Burkina FasoEnglish Title:  Characterization of the systems of production of Jatropha in the agricultural exploitations of the West zone of Burkina FosoEnglish AbstractThe agricultural production is the main source of socioeconomic development of Burkina Faso. Since the years 2000, the promotion of biofuel causes a renewal of interest toward Jatropha curcas L. In 14 villages of the West zone of Burkina Faso, a semi-structured investigation based on a questionnaire has been applied on 210 farmers of Jatropha. The results of the investigations indicate that the production of Jatropha is recent. The surfaces of plantations of Jatropha vary between 7.5 and 30 ha per village. The more adopted spacing for the plantation of Jatropha is of 5 m between the lines and 2 m between the plantations (5 m × 2 m), thus a density of 1071 plants/ha. A proportion of 80.4% of producers investigated have 4 to 7 years of experience in the culture of Jatropha. The yields vary between 300 and 700 kg/ha. For 78.5% of farmers, their commitment in the production of Jatropha has been motivated by the structures of promotion of Jatropha. More than 90% of the producers practice the technique of the nursery-transplantation and 70% grow cereal associated with Jatropha. The investigations reveal that 70% of producers associate vegetables with Jatropha and that 22% of producers fertilize Jatropha fields. The rate of the application of pesticides in the field of Jatropha is little, it concerns only 11% of producers.© 2015 International Formulae Group. All rights reserved.Keywords: Biofuel, Jatropha curcas L., investigations, producers, Burkina Fas

Influence des haies de Jatropha sur le rendement d’une culture de sorgho (Sorghum vulgare) dans la zone Ouest du Burkina Faso: cas du terroir de Torokoro

Dans un contexte de désertification et avec la crise énergétique, un bon nombre d’acteurs de développement au Burkina Faso s’est intéressé au Jatropha curcas L. comme source d’énergie et de durabilité des productions. Afin d’évaluer l’influence de Jatropha sur les propriétés chimiques du sol et la productivité du sorgho associée, des essais ont été suivis pendant trois ans dans le terroir de Torokoro en zone Sud soudanienne de pluviométrie d’environ 1200 mm. Les plants de Jatropha, âgés de 6 ans, sont plantés aux écartements de 5 m entre les lignes et 2 m entre les plants. Le dispositif expérimental comporte trois blocs composés chacun de deux parcelles de 400 m2 correspondants aux 2 traitements: une par celle avec l’association sorgho-Jatropha et une parcelle en culture pure de sorgho (témoin). Les prélèvements de sol ont été effectués sous houppier, à 1 m et2m de la haie. Les résultats indiquent que Jatropha améliore la teneur du sol en carbone de 10% et de 8% en matière organique par rapport au témoin. Jatropha est aussi source de phosphore et de potassium et influence positivement la productivité du sorgho. Jatropha améliore donc les propriétés chimiques du sol et la productivité du sorgho.© 2015 International Formulae Group. All rights reserved.Mots clés: Jatropha curcas L., sol, Sorgho, Rendements, propriétés chimiques, Burkina FasoEnglish Title: Influence of Jatropha hedges on the yield of a sorghum crop (Sorghum vulgare) in the western region of Burkina Faso: case of Torokoro localityEnglish AbstractIn a context of desertification and with the energy crisis, a number of development actors in Burkina Faso became interested in Jatropha curcas L. as a source of energy and sustainability of production. To assess the influence of Jatropha on soil chemical properties and on the productivity of associated sorghum, experiments were followed for three years in the village of Torokoro in south sudanian region, with a rainfall of about 1200 mm. Jatropha plants, aged 6, are planted at 5 m between rows and 2 m between plants. The experiment consisted of three blocks each consisting of two plots of 400 m2 corresponding to two treatments: a plot with sorghum and Jatropha in association and a plot with sorghum only (control). Soil samples were taken under crown, at 1m and 2 m from the hedge. The results indicate that Jatropha improves the carbon content in the soil of 10%, and the organic matter content of 8% compared to the control. Jatropha is also a source of phosphorus and potassium and positively influences the productivity of sorghum. Therefore, Jatropha improves the chemical properties of soil and productivity of sorghum.© 2015 International Formulae Group. All rights reserved.Keywords: Jatropha curcas L., soil, Sorghum, yields, chemical properties, Burkina Fas

Impact of Jatropha plantation on soil chemical and biological properties in the South Sudanian region in Burkina Faso

In Burkina Faso, about 100,000 ha of Jatropha were planted during the past 10 years. Despite this enthusiasm, few results exist on the impact of the plant on soil properties. This study contributes to better knowledge of Jatropha farming and was carried out in 2013 with Jatropha farmers in Torokoro and Tin villages in the south Sudanian zone of Burkina Faso (rainfall 900-1200 mm). Data collection plots of 400 m2 repeated 3 times were installed in 3 farmers’ fields in each village. Soil samples were collected at 3 distances (D0= under the crown, D1= 1m and D2= 2m) from the Jatropha trees lines and in a fallow as a control sample for each field. The results showed significant differences between distances for soil pH. Soil nutrients increase with distance from the crown (from 9.33% to 12.20%) for available phosphorus in Torokoro-6 years and decrease from 22.45% to 23.71% in Torokoro-2 years). Soil respiration and microbial biomass decreases also with distance. The density of spores of mycorrhizal fungi is higher for the control soils (14.64%) and it decreases from crown to 2m (from 2.22% to 9.53% in Tin-2 years). The study showed the contribution of Jatropha trees on soil fertility improvement.© 2015 International Formulae Group. All rights reserved.Keywords: Jatropha, soil biology, microbial biomass, carbon, nitrogen, Burkina Fas

Who are these youths? Language in the service of policy

In the 1990s policy relating to children and young people who offend developed as a result of the interplay of political imperatives and populist demands. The ‘responsibilisation’ of young offenders and the ‘no excuses’ culture of youth justice have been ‘marketed’ through a discourse which evidences linguistic changes. This article focuses on one particular area of policy change, that relating to the prosecutorial decision, to show how particular images of children were both reflected and constructed through a changing selection of words to describe the non-adult suspect and offender. In such minutiae of discourse can be found not only the signifiers of public attitudinal and policy change but also the means by which undesirable policy developments can be challenged

Young people, crime and school exclusion: a case of some surprises

During the 1990s the number of young people being permanently excluded from schools in England and Wales increased dramatically from 2,910 (1990/91) to a peak of 12,700 (1996/97). Coinciding with this rise was a resurgence of the debate centring on lawless and delinquent youth. With the publication of Young People and Crime (Graham and Bowling 1995) and Misspent Youth (Audit Commission 1996) the 'common sense assumption' that exclusion from school inexorably promoted crime received wide support, with the school excludee portrayed as another latter day 'folk devil'. This article explores the link between school exclusion and juvenile crime, and offers some key findings from a research study undertaken with 56 young people who had experience of being excluded from school. Self-report interview questions reveal that whilst 40 of the young people had offended, 90% (36) reported that the onset of their offending commenced prior to their first exclusion. Moreover, 50 (89.2% of the total number of young people in the sample), stated that they were no more likely to offend subsequent to being excluded and 31 (55.4%) stated that they were less likely to offend during their exclusion period. Often, this was because on being excluded, they were 'grounded' by their parents

Excavating youth justice reform: historical mapping and speculative prospects

This article analytically excavates youth justice reform (in England and Wales) by situating it in historical context, critically reviewing the competing rationales that underpin it and exploring the overarching social, economic, and political conditions within which it is framed. It advances an argument that the foundations of a recognisably modern youth justice system had been laid by the opening decade of the 20th Century and that youth justice reform in the post‐Second World War period has broadly been structured over four key phases. The core contention is that historical mapping facilitates an understanding of the unreconciled rationales and incoherent nature of youth justice reform to date, while also providing a speculative sense of future prospects

Effectiveness of an HIV Prevention Program for Women Visiting Their Incarcerated Partners: The HOME Project

Having an incarcerated partner presents a unique HIV risk for women, particularly low-income women of color. We developed a population-specific risk reduction intervention for women visiting men in prison that was peer educator-based and included individual and community-level intervention components. Women who were assessed prior to the intervention period had a positive association between the number of unprotected penetrative intercourse (UPI) episodes prior to their partners’ incarceration and the number of UPI episodes following partners’ release from prison. However, this association was negated among women assessed during the intervention. Intervention participants also were more likely to be tested for HIV, to have partners who got tested, and to talk with their partners about significantly more HIV-related topics. Conducting intervention and evaluation activities with women visiting incarcerated men is feasible and is a useful model for reaching more at-risk women

Nitrogen and Carbon Isotopic Dynamics of Subarctic Soils and Plants in Southern Yukon Territory and its Implications for Paleoecological and Paleodietary Studies

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C3 plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ15N and organic carbon δ13C than plants from the same sites with a positive shift occurring with depth in two soil profiles analyzed. All plants analyzed have an average whole plant δ13C of −27.5 ± 1.2 ‰ and foliar δ13C of ±28.0 ± 1.3 ‰, and average whole plant δ15N of −0.3 ± 2.2 ‰ and foliar δ15N of ±0.6 ± 2.7 ‰. Plants analyzed here showed relatively smaller variability in δ13C than δ15N. Their average δ13C after suitable corrections for the Suess effect should be suitable as baseline for interpreting diets of Late Pleistocene herbivores that lived in eastern Beringia. Water availability, nitrogen availability, spacial differences and intra-plant variability are important controls on δ15N of herbaceous plants in the study area. The wider range of δ15N, the more numerous factors that affect nitrogen isotopic composition and their likely differences in the past, however, limit use of the modern N isotopic baseline for vegetation in paleodietary models for such ecosystems. That said, the positive correlation between foliar δ15N and N content shown for the modern plants could support use of plant δ15N as an index for plant N content and therefore forage quality. The modern N isotopic baseline cannot be applied directly to the past, but it is prerequisite to future efforts to detect shifts in N cycling and forage quality since the Late Pleistocene through comparison with fossil plants from the same region