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This paper presents the results of a study using participatory mapping to collectively understand deforestation dynamics in Murehwa, a communal area approximately 90 km northeast of Harare, Zimbabwe’s capital city. The study engaged smallholder farmers in a deliberative process through participatory mapping exercises in 15 villages. For each exercise, participants collaboratively drew two maps of their village, one for 1990 and another for 2021. They depict village boundaries, land uses and the magnitude of change between the two dates. Participatory mapping served as a platform for collective thinking, with the resulting maps used to facilitate discussions. They involved comparing land use between the two maps and identifying the drivers of the observed changes. Thematic approach was used to analyse the discussions in order to come up with collectively identified drivers of land use changes. The findings show that deforestation and resulting land use changes are primarily rooted in economic depression, selling of wood, tobacco farming, veld fires, unauthorised wood exploitation, illegal selling of land, increase in gardening, agricultural expansion and population growth. These results lay a foundational step towards the co-construction of a governance framework for practising agriculture in forest-adjacent areas. Moreover, the paper shares methodological reflections and experiences intended to promote initiatives where the construction of a shared understanding facilitates sustainable land-use practices that foster natural resource conservation.

Mulching in smallholder conservation agriculture (CA) systems is constrained by lack of adequate crop residues. A three-year study assessed the effects of reduced tillage systems combined with different plant residue mulch and nitrogen (N) fertiliser on nitrogen uptake using the normalised difference vegetation index (NDVI), maize growth and yield, and agronomic efficiency. A split plot design with three or four replicates was used. Maize, Hyparrheniagrass, leaf litter, sunnhemp and Tephrosiaresidue mulch in CA and a conventional control were the main treatments. The N subtreatments were 0, 60 and 120 kg N ha−1. The main treatments had a similar effect on NDVI, and N increased NDVI across the treatments. The conventional practice had taller plants compared with CA. The conventional and CA treatments had a similar effect on maize yields. The different plant residues in CA had a similar effect on yields. Nitrogen increased yield, and 60 and 120 kg N ha−1had a similar effect. The 60 kg N ha−1subtreatment had a higher agronomic N efficiency than 120 kg N ha−1. The study demonstrated that CA with different plant residues and the conventional practice give similar yields in the short term.

AbstractFlue-cured tobacco consumes large quantities of wood, therefore, use of alternative energy sources to preferred indigenous miombowood and energy-efficient barns may reduce tobacco-related deforestation of miombowoodlands. The objective of this study was to identify smallholder farmers’ perceptions and constraints on use of alternative energy sources to miombowood and energy-efficient barns for tobacco curing, and identify factors affecting type of barn owned in Zimbabwe’s tobacco growing belt. Multistage sampling of tobacco growers from districts lists, was used to select 200 smallholder farmers. In addition, twelve key informants were interviewed. Semi-structured questionnaires were administered to the respondents. Multinomial regression was used to analyse factors affecting type of barn owned and all the other variables were analysed using descriptive statistics. Eucalyptusspecies were perceived to have low calorific value, coal was associated with health problems and Bamboo (Oxytenanthera abyssinica) was deemed unsuitable for tobacco curing. Unavailability of electricity was cited as a constraint to the use of coal. Farmers with tertiary education and females were more likely to own more energy-efficient barns, relative to conventional barns. Setting up of electricity-powered tobacco processing centres, and demonstrations on energy-efficient barns and alternative energy sources in communities are recommended.

In this report, we describe the design of an efficient and robust sulfurization step in the production process of phosphorothioate (PS) oligonucleotides by solid-phase synthesis. Average stepwise sulfurization efficiencies >99.9% were obtained with “aged” solutions of phenylacetyl disulfide (PADS) in the solvent system acetonitrile/3-picoline (0.2 M, 1:1, v/v). Preparation of the reagent at least 1 day prior to use yields PS-oligonucleotides with low-level phosphate (PO) diester content. The use of freshly prepared PADS solutions gave oligonucleotide products with increased PO-diester content (stepwise sulfurization efficiency 99.5−99.7%). Short aging periods combined with short sulfurization contact times lead to formation of oligonucleotide 4,4‘-dimethoxytrityl-C-phosphonate derivatives. Investigation of reagent stability and sulfurization efficiency revealed significant changes in solution composition over time caused by dissociation of the PADS molecule. The “in situ” formation of a reactive intermediate, presumably a polysulfide, appears to be crucial for optimal synthesis results.