Is conservation agriculture a climate-smart option for smallholders in sub-Saharan Africa?

Sub-Saharan Africa (SSA) faces the challenge of developing a climate-smart agriculture (CSA) that simultaneously ensures food security, mitigation and adaption to climate change (CC). Conservation agriculture (CA) is widely promoted in SSA and is considered as a way to meet these CSA objectives. The objective of the study was to assess whether CA in SSA contributes to the three pillars of CSA, seeking evidence from the peer-reviewed literature that compares the performances of CA and conventional tillage-based (CT) cropping systems. The positive yield responses to CA compared to CT are widely documented in SSA. The positive effects on soil fertility result in increased yield in the long term. Yield impacts in the shorter term are variable and depend to a great extent on the climatic context. CA responds better under low and/or erratic rainfall conditions, mainly due to the mulching effect on soil water conservation. This suggests the potential of CA as a cropping strategy to adapt to more variable rainfall in the future as predicted in many regions of SSA. However, an increase in yield does not necessarily translate into an increase in farm income. The economic impact of CA is highly dependent on the socioeconomic context. The potential of CA to mitigate CC remains unclear. Retention of crop residues as mulch may not always translate into soil carbon sequestration. Further studies on the impact of CA on soils' greenhouse gases emissions are needed. In conclusion, the ability of CA to contribute to CSA is very site- and farm-specific, and lies to a great extent in its capacity of retaining crop residues as mulch on the soil surface. (Texte intégral

Legumes in soil fertility management: The case of pigeonpea in smallholder farming systems of Zimbabwe

We investigated the current use of legumes in soil fertility management and the feasibility of promoting use of pigeonpea in smallholder farming systems of a Communal Area in Northeast of Zimbabwe. Participatory rural appraisal methods were used to establish farmer management strategies and perceptions on major constraints to crop productivity. Soil fertility parameters were evaluated through farmer participatory experiments. The study revealed limited cultivation of legumes for both human nutrition and soil fertility management. Legumes were generally regarded as women's crops, and therefore minor, because of men's domination over women in the household decision-making process. Balancing gender interests in terms of allocation of inputs and distribution of benefits at household level was identified as a major challenge to the implementation of legume technologies. Poor extension thrusts with respect to legume production, and poor agronomic practices were identified as major production constraints. Over-emphasis on maize in the current extension packages led to the relegation of legumes to the status of 'minor crops'. Participatory experiments suggested that pigeonpea can be successfully grown by farmers under poor soil fertility conditions. The crop yielded about 3 to 9 t ha-1 of shoot biomass in a single cropping season, and up to 23 t ha-1 after two seasons of growth. High amounts leaf litter released by the crop in one season (up to 3 t ha-1) are considered a potentially viable source of nutrients for subsequent crops, as confirmed by a 22% maize yield increase obtained from a field that was previous cultivated with pigeonpea. RÉSUMÉ Les investigations sur l' utilisation des légumineuses dans la gestion de fertilité du sol ainsi que les possibilités d' incorporer le pois cajan dans le système agricole de petits fermiers ont été fait dans un milieu rural au Nord-Est du Zimbabwe. La méthode "Participatory rural appraisal" a été utilisée pour déterminer les stratégies de gestion du sol et les perceptions qui contribuent à la réduction de la productivité de la récolte. Les paramètres de fertilité du sol ont été analysés en collaboration avec des agriculteurs. Cette étude a révelé qu' il y a une utilisation limitée de légumineuses dans l' alimentation des gens ainsi que dans la gestion de fertilité du sol. Les légumineuses sont géneralement considérées commes la récolte pour les femmes, sur ce, de peu d' importance, et à cause de la domination des hommes dans la prise de décision dans le foyer. L'exécution des téchnologies d' incorporer les légumineuses dans le système de production agricole s' est heurtée à un problème majeur de domination de l'homme, ses préférences dans la répartition et la distributions des intrants et les bénéfices. Un autre problème identifié, c'est une vulgarisation très limitée de la production de légumineuses et une difficile adaptation agronomique de variétés de légumineuses qui sont déjà dans le système. Le système de vulgarisation existant s'est concentré plus sur la production du maïs, ce qui a mené à considérer les lègumineuses commes les plantes de moins d' importance. Les expériences participatives ont suggeré que le pois cajan peut être produit par les fermiers dans des sols moins fertiles. La production a été estimée de 3 à 9 t ha-1 de biomasse dans une seule saison de production, et de 23 t ha-1 après deux saisons. Une quantité considérable de litière de feuilles venant de plantes dans une seule saison (jusqu'a 3 t ha-1) est considéree comme une source importante de nutriments pour les plantes consécutives, comme l' augmention de 22% de production de maïs l'a confirmé après une culture de pois cajan. (Af Crop Science and Production: 2001 9(4): 629-644

Improving Gene Delivery: Synergy between Alkyl Chain Length and Lipoic Acid for PDMAEMA Hydrophobic Copolymers

In the field of gene delivery, hydrophobic cationic copolymers hold great promise. They exhibit improved performance by effectively protecting genetic material from serum interactions while facilitating interactions with cellular membranes. However, managing cytotoxicity remains a significant challenge, prompting an investigation into suitable hydrophobic components. A particularly encouraging approach involves integrating nutrient components, like lipoic acid, which is known for its antioxidant properties and diverse cellular benefits such as cellular metabolism and growth. In this study, a copolymer library comprising 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and lipoic acid methacrylate (LAMA), combined with either n ‐butyl methacrylate ( n BMA), ethyl methacrylate (EMA), or methyl methacrylate (MMA), is synthesized. This enables to probe the impact of lipoic acid incorporation while simultaneously exploring the influence of pendant acyclic alkyl chain length. The inclusion of lipoic acid results in a notable boost in transfection efficiency while maintaining low cytotoxicity. Interestingly, higher levels of transfection efficiency are achieved in the presence of n BMA, EMA, or MMA. However, a positive correlation between pendant acyclic alkyl chain length and cytotoxicity is observed. Consequently, P(DMAEMA‐ co ‐LAMA‐ co ‐MMA), emerges as a promising candidate. This is attributed to the optimal combination of low cytotoxic MMA and transfection‐boosting LAMA, highlighting the crucial synergy between LAMA and MMA

The use of woodland products to cope with climate variability in communal areas in Zimbabwe

Common lands provide smallholder farmers in Africa with firewood, timber, and feed for livestock, and they are used to complement human diets through the collection of edible nontimber forest products (NTFPs). Farmers have developed coping mechanisms, which they deploy at times of climatic shocks. We aimed to analyze the importance of NTFPs in times of drought and to identify options that could increase the capacity to adapt to climate change. We used participatory techniques, livelihood analysis, observations, and measurements to quantify the use of NTFPs. Communities recognized NTFPs as a mechanism to cope with crop failure. We estimated that indigenous fruits contributed to approximately 20% of the energy intake of wealthier farmers and to approximately 40% of the energy intake of poor farmers in years of inadequate rainfall. Farmers needed to invest a considerable share of their time to collect wild fruits from deforested areas. They recognized that the effectiveness of NTFPs as an adaptation option had become threatened by severe deforestation and by illegal harvesting of fruits by urban traders. Farmers indicated the need to plan future land use to (1) intensify crop production, (2) cultivate trees for firewood, (3) keep orchards of indigenous fruit trees, and (4) improve the quality of grazing lands. Farmers were willing to cultivate trees and to organize communal conservation of indigenous fruits trees. Through participatory exercises, farmers elaborated maps, which were used during land use discussions. The process led to prioritization of pressing land use problems and identification of the support needed: fast-growing trees for firewood, inputs for crop production, knowledge on the cultivation of indigenous fruit trees, and clear regulations and compliance with rules for extraction of NTFPs. Important issues that remain to be addressed are best practices for regeneration and conservation, access rules and implementation, and the understanding and management of competing claims on the common lands. Well-managed communal resources can provide a strong tool to maintain and increase the rural communities’ ability to cope with an increasingly variable climate

Optimizing Biocompatibility and Gene Delivery with DMAEA and DMAEAm: A Niacin-Derived Copolymer Approach

Gene therapy is pivotal in nanomedicine, offering a versatile approach to disease treatment. This study aims to achieve an optimal balance between biocompatibility and efficacy, which is a common challenge in the field. A copolymer library is synthesized, incorporating niacin-derived monomers 2-acrylamidoethyl nicotinate (AAEN) or 2-(acryloyloxy)ethyl nicotinate (AEN) with N,N -(dimethylamino)ethyl acrylamide (DMAEAm) or hydrolysis-labile N,N -(dimethylamino)ethyl acrylate (DMAEA). Evaluation of the polymers’ cytotoxicity profiles reveals that an increase in AAEN or DMAEA molar ratios correlates with improved biocompatibility. Remarkably, an increase in AAEN in both DMAEA and DMAEAm copolymers demonstrated enhanced transfection efficiencies of plasmid DNA in HEK293T cells. Additionally, the top-performing polymers demonstrate promising gene expression in challenging-to-transfect cells (THP-1 and Jurkat cells) and show no significant effect on modulating immune response induction in ex vivo treated murine monocytes. Overall, the best performing candidates exhibit an optimal balance between biocompatibility and efficacy, showcasing potential advancements in gene therapy

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

CLIMATE CHANGE AND VARIABILITY: SMALLHOLDER FARMING COMMUNITIES IN ZIMBABWE PORTRAY A VARIED UNDERSTANDING

Increasing awareness of risks associated with climate change and variability among smallholder farmers is critical in building their capacity to develop the necessary adaptive measures. Using farmer participatory research approaches and formal questionnaire surveys, interaction has been made with >800 farmers in two distinct smallholder farming systems of Makoni and Wedza Districts in eastern Zimbabwe to determine the current level of understanding of climate change and variability, current responses to perceived changes, as well as identify sources of agro-meteorological information. The results indicated that farmers portrayed a varied understanding both within and across the study sites. While poor rainfall distribution was seen as the major indicator for climate change by over two-thirds of the respondents in both sites, more farmers in Makoni attributed delay in onset of rains, high incidences of flush floods and unpredictable \u2018wind movements\u2019 yielding cyclones to climate change. In Wedza, it was recurrent droughts, winter and summer temperature extremes, and increased pest and disease incidences for both crops and livestock that indicated climate change. Perceived changes were linked more to natural and human forces (Makoni), unknown forces as well as breakdown in cultural norms and beliefs and rise of Christianity (Wedza). Disparities between the two sites could be attributed to the inherent differences of the communities in terms to their social settings. The national extension, Agritex, was ranked first by 50-60% of the farmers as major source of weather information. Electronic media (radio and television) ranked second with 47% of farmers in Makoni and 35% in Wedza. Concerns were raised over inadequacies of such information, apparent lack of reliability, timing and frequency of dissemination that directly influenced the utilisation of the information. Common coping strategies included early planting which was the more prevalent in Makoni, while combinations of cereals and legumes were a preferred solution in Wedza. We concluded that farmers\u2019 interaction with various information sources and knowledge sharing platforms needs to be enhanced in order to deepen their understanding as well as increase their capacity to respond to pressures of climate variability and change.L\u2019am\ue9lioration des connaissances des petits fermiers sur les risques lies au changement du climat et sa variabilit\ue9 est un fait important pour l\u2019\ue9dification de leur capacit\ue9 de d\ue9velopper des mesures n\ue9cessaires d\u2019adaptation. En utilisant des m\ue9thodes de recherche participative et un questionnaire d\u2019enqu\ueate formelle, l\u2019interaction a \ue9t\ue9 faite avec plus de 800 fermiers de deux syst\ue8mes d\u2019exploitation distincts de districts de Makoni et Wedza \ue0 l\u2019Est du Zimbabwe, afin de d\ue9terminer le niveau actuel de compr\ue9hension du changement du climat et sa variabilit\ue9, les m\ue9canismes d\u2019adaptation aux changements per\ue7us, ainsi qu\u2019identifier les sources d\u2019information agro m\ue9t\ue9orologique. Les r\ue9sultats ont indiqu\ue9 que les fermiers avaient un niveau vari\ue9 de compr\ue9hension dans les deux sites d\u2019\ue9tude.Alors qu\u2019une faible distribution des pr\ue9cipitations \ue9tait consid\ue9r\ue9e comme \ue9tant l\u2019indicateur majeur du changement du climat par plus de 2/3 des r\ue9pondants dans les deux sites, la plupart des fermiers de Makoni ont affirm\ue9 que le retard dans l\u2019apparition des pluies, incidence \ue9lev\ue9e des inondations et mouvement du vent impr\ue9dictible r\ue9sultant du cyclone par le changement du climat. En Wedza, le changement du climat \ue9tait manifest\ue9 \ue0 travers les s\ue9cheresses r\ue9currentes, des temp\ue9ratures extr\ueames pendant l\u2019hiver et l\u2019\ue9t\ue9 ainsi que l\u2019accroissement d\u2019incidences de pestes et maladies affectant des cultures et le b\ue9tail. Les changements per\ue7us \ue9taient plus li\ue9s aux forces naturelles et humaines (Makoni), des forces inconnues aussi bien que la non-observance des normes culturales et les croyances et le d\ue9veloppement de la chr\ue9tient\ue9 (Wedza). Les disparit\ue9s entre les deux sites pourraient \ueatre attribu\ue9es aux diff\ue9rences inh\ue9rentes des deux communaut\ue9s en termes de leurs environnements sociaux. La vulgarisation nationale, Agritex, \ue9tait rang\ue9e la premi\ue8re par 50-60% des fermiers comme source majeur de l\u2019information sur le climat suivi du media \ue9lectronique (radio et t\ue9l\ue9vision) avec 47% des fermiers dans Makoni et 35% dans Wedza. Les probl\ue8mes \ue9voqu\ue9s \ue9taient li\ue9s au manque de consistance de l\u2019information, manque apparent de fiabilit\ue9, le temps et la fr\ue9quence de diss\ue9mination qui directement influencent l\u2019utilisation de l\u2019information. Les strat\ue9gies communes d\u2019adaptation consistaient en la plantation \ue0 temps sp\ue9cialement dans Makoni, pendant que les combinaisons des c\ue9r\ue9ales et des l\ue9gumes \ue9taient une solution pr\ue9f\ue9r\ue9e en Wedza. En conclusion, l\u2019interaction des fermiers avec des sources vari\ue9es d\u2019information et les plateformes de partage de connaissance ont besoin d\u2019\ueatre d\ue9velopp\ue9e afin d\u2019am\ue9liorer leur niveau de compr\ue9hension aussi bien renforcer leur capacit\ue9 \ue0 r\ue9pondre aux pressions du changement du climat et sa variabilit\ue9

Transformation, adaptation and development: relating concepts to practice

In recent years there has been a growing number of academic reviews discussing the theme of transformation and its association with adaptation to climate change. On the one hand this has stimulated exchange of ideas and perspectives on the parameters of transformation, but it has also given rise to confusion in terms of identifying what constitutes a non-incremental form of adaptation on the ground. What this article aims to do instead is help researchers and practitioners relate different interpretations of transformation to practice by proposing a typological framework for categorising forms of change that focuses on mechanisms and objectives. It then discusses how these categorisations link to the broader conceptions and critiques noted above, with the idea that this will enable those who seek to analyse or plan adaptation to better analyse what types of action are potentially constitutive of transformation. In doing so, it should equally assist in the identification and specification of critical questions that need to be asked of such activity in relation to issues of sustainability and equity. As the term transformation gains ground in discussions of climate change adaptation, it is necessary to take a step back, review quite what commentators mean when they use the word, and consider the implications on people, especially the most vulnerable and marginalised, of “doing” or promoting transformation in its different forms

Vitamin B3 Containing Polymers for Nanodelivery

Abstract Polymeric nanoparticles (NPs) with an integrated dual delivery system enable the controlled release of bioactive molecules and drugs, providing therapeutic advantages. Key design targets include high biocompatibility, cellular uptake, and encapsulating efficiency. In this study, a polymer library derived from niacin, also known as vitamin B3 is synthesized. The library comprises poly(2‐(acryloyloxy)ethyl nicotinate) (PAEN), poly(2‐acrylamidoethyl nicotinate) (PAAEN), and poly( N ‐(2‐acrylamidoethyl)nicotinamide) (PAAENA), with varying hydrophilicity in the backbone and pendant group linker. All polymers are formulated, and those with increased hydrophobicity yield NPs with homogeneous spherical distribution and diameters below 150 nm, as confirmed by scanning electron microscopy and dynamic light scattering. Encapsulation studies utilizing a model drug, neutral lipid orange (NLO), reveal the influence of polymer backbone on encapsulation efficiency. Specifically, efficiencies of 46% and 96% are observed with acrylate and acrylamide backbones, respectively. Biological investigations showed that P(AEN) and P(AAEN) NPs are non‐toxic up to 300 µg mL −1 , exhibit superior cellular uptake, and boost cell metabolic activity. The latter is attributed to the cellular release of niacin, a precursor to nicotinamide adenine dinucleotide (NAD), a central coenzyme in metabolism. The results underline the potential of nutrient‐derived polymers as pro‐nutrient and drug‐delivery materials