Obert Jiri

The effect of managing improved fallows of Mucuna pruriens on maize production and soil carbon and nitrogen dynamics in sub-humid Zimbabwe

Mucuna pruriens has emerged as a successful forage or green manure legume for use in the smallholder animal-livestock systems of Zimbabwe. The efficiency of N recovery from mucuna residues in subsequent maize crops can be low and the loss of nitrate nitrogen from the soil profile prior to maize N demand is proposed as a reason for this. An experiment was established in the 1999–2000 wet season at seven on-farm sites in a communal farming district of Zimbabwe (average rainfall 650–900 mm) on acidic (pH < 5), and inherently infertile soils with texture ranging from sandy/sandy loam (n = 5) to clay (n = 2). Improved fallows of mucuna grown for 19 weeks produced between 4.7 and 8.5 t/ha dry matter (DM) at the sandy/sandy loam sites and between 9.5 and 11.2 t/ha DM at the clay sites. This biomass was then either cut and removed as hay, or ploughed in as a green manure. Weedy fallow treatments, which represent typical farmer practice, produced 3.3–6.3 t/ha DM. A maize crop was then grown on these same sites in the following 2000–2001 wet season and the dynamics of soil N and C and maize production were investigated. Where mucuna was green manured, a positive linear response (r2 = 0.72) in maize yield to increasing mucuna biomass (containing 101–348 kg N/ha) was found. On the sandy sites, and where no P fertiliser was applied to the previous mucuna phase, a maize grain yield of 2.3 t/ha was achieved following the mucuna green-manure system; this was 64% higher than the maize yield following the weedy fallow and 100% higher than the maize yield following the mucuna ‘removed’ hay system. Apparent nitrogen recoveries in the range of 25 to 53% indicate that there are large quantities of nitrogen not utilised by the subsequent maize phase. The loss of 73 kg/ha of nitrate N from the soil profile (0–120 cm) early in the wet season and prior to maize N demand is proposed as a reason for low N recovery. No change in labile C (measured with 333 mM KMnO4) was detected through the soil profile at this time and it is suggested that labile C movement occurred between the sampling times.

Building climate change resilience through adaptation in smallholder farming systems in semi-arid Zimbabwe

Purpose This study aimed to determine factors that increase resilience and cause smallholder farmers to adapt better to climate change and vulnerability. Design/methodology/approach In this study, the authors used the vulnerability to resilience model and binary logit model to analyse the factors influencing household decisions to adapt. Findings Households with increased access to climate information through extension services were likely to have better adaptation abilities. It was also shown that younger farmers were likely to adapt to climate change given their flexibility to adopt new techniques and their access and use of modern information and technology. Larger households were found to have higher probability of adapting as most adaptation strategies are labour intensive. Household’s possession of livestock and access to credit significantly enhanced adaptation. However, households with higher farm income have lesser incentives to adapt to because their current farming practices might already be optimum. Research limitations/implications Given that most of the smallholder farmers are vulnerable, such as women-headed households and the elderly, who are labour constrained, there is need for research and development of labour saving technologies to increase resilience to climate change and vulnerability. Originality/value These findings underscore the importance of enabling farmer access to information and better technologies which enable them to increase adaptive capacity and resilience.

Smallholder Farmer's Perceived Effects of Climate Change on Crop Production and Household Livelihoods in Rural Limpopo Province, South Africa

Abstract This study investigated the perceived effects of climate change on crop production and household livelihoods of smallholder farmers in Mopani and Vhembe district, South Africa. Data was collected through a questionnaire administered to 150 smallholder farmers. The questionnaires were complemented by 8 focus group discussions and secondary data. Multinomial logit regression model was used to analyse the factors influencing smallholder farmers’ choice of climate change adaptation strategies. The study findings revealed that subsistence farmers perceived prolonged droughts (56.4%) as the main shock stressing crop production. Droughts often lead to low crop yield and high crop failure (73.3%). In response to the prevailing climatic conditions different gender adopted different strategies, 41% of female farmers adapted by changing planting dates, while male farmers employed crop variety and diversification (35%) and mixed cropping (15%). The smallholder farmers were vulnerable with limited adaptive capacity to withstand climate change due to compromised social, human, physical, natural and financial assets. The results showed that smallholder farmers tend to adapt better when they have access to extension officers (P<0.01). Therefore, it is important for the government to strengthen the relationship between smallholder farmers and extension officers for better climate change adaptation.

Using Moringa oleifera Extracts to Control Blackrot (Xanthomonas campestris) in Field Grown Rape (Brassica napus)

The leaf, bark and seed extracts of Moringa oleifera were evaluated for their efficacy under field conditions in suppressing Xanthomonas campestris pv. campestris in rape (Brassica napus. L.). Xanthomonas campestris pv. campestris is an important bacterial pathogen of agricultural importance causing devastating black rot disease of Brassicas. Three extracts concentrations of 60, 100 and 140% were sprayed as foliar applications weekly and the antibacterial activity was evaluated by recording number of totally defoliated plants. The three extracts showed significant effect against the test pathogen (p > 0.05). The antibacterial activity of seed extract demonstrated higher activity against the Xanthomonas campestris pv. campestris as evidenced by lower mean leaf defoliation of 1.59 cm followed by bark (2.58 cm) and lastly leaf extracts (2.96 cm) (p < 0.05). There were no significant differences based on the concentration levels used. Observations revealed that 100% and 140% levels were not significantly different from each other on enhancing growth of the stem diameter. Moringa seed at 60% concentration level can be used to enhance growth of rape. The conclusion is that Moringa seed extracts can be effectively implemented to suppress Xanthomonas campestris pv. campestris pathogen in field grown rape in an integrated disease control program.

Contextual vulnerability of rainfed crop-based farming communities in semi-arid Zimbabwe: A case of Chiredzi District

Purpose The purpose of this paper is to assess smallholder farmers’ vulnerability to climate change and variability based on the socioeconomic and biophysical characteristics of Chiredzi District, a region that is susceptible to the adverse effects of climate change and variability. Design/methodology/approach Vulnerability was assessed using the Vulnerability to Resilience and the Climate Vulnerability and Capacity frameworks. Findings The major indicators and drivers of vulnerability were identified as droughts, flash floods, poor soil fertility and out-migration leaving female- and child-headed households. From sensitivity analysis, it was shown that different areas within the district considered different biophysical and socioeconomic indicators to climate change and variability. They also considered different vulnerability indicators to influence the decisions for adaptation to climate change and variability. Originality/value The results of this study indicate that the area and cropping systems are greatly exposed and are sensitive to climatic change stimuli, as shown by the decline in main cereal grain yield. These results also showed that there is a need to define and map local area vulnerability as a basis to recommend coping and adaptation measures to counter climate change hazards.

Influence of smallholder farmers’ perceptions on adaptation strategies to climate change and policy implications in Zimbabwe

Abstract Smallholder agricultural production is largely affected by climate change and variability. Despite the negative effects brought by climate variability, smallholder farmers are still able to derive livelihoods. An understanding of factors that influence farmers’ responses and adaptation to climate variability can improve decision making for governments and development partners. This study investigated farmers’ perceptions and adaptation strategies to climate change and how these influence adaptation policies at local level. A survey was conducted with 100 households randomly selected from Chiredzi district. Data collected was used to derive farmer perceptions to climate change as well as the influence of their perceptions and subsequent adaptation methods to ensuing local agricultural adaptation measures and policies. The results indicated that smallholder farmers perceived general reduction in long-term annual rainfall and rising local average temperatures. Adverse trends in rainfall and average temperature perceived by farmers were consistent with empirical data. These perceptions and other socio-economic factors helped to shape smallholder farmer agricultural adaptation strategies. Policy implications are that the government and development partners should seek ways to assist autonomous adaptations by farmers through investments in planned adaptation initiatives.

Integration of indigenous and scientific knowledge in climate adaptation in KwaZulu- Natal, South Africa

Abstract Indigenous knowledge has for generations assisted rural subsistence farming communities adapt to climate change and make daily decisions regarding agriculture. This study was conducted in the rural community of Swayimane, uMshwathi Municipality, KwaZulu-Natal, South Africa. The main objective of the research was to determine the indigenous indicators used by rural farmers, identify the means through which seasonal climate information is disseminated and assess the strengths and weaknesses of indigenous and scientific knowledge. The other objective of the research was to evaluate the integration of indigenous and scientific weather forecasting. The research used 100 questionnaires which were administered to the subsistence farmers of the community. Focus group discussions and key informant interviews were conducted with small groups of individuals. Results showed that majority of the indigenous indicators related to rainfall and seasonal predictions. Also, seasonal scientific climate information was mainly disseminated via television and radio. Local farmers highlighted that indigenous knowledge was essential in predicting seasonal changes and rainfall and scientific knowledge was not trusted. Indigenous knowledge is transmitted by oral tradition, from generation to generation and mainly among the elderly, and, thinly, to the younger generation. Scientific information was thought to be too technical and difficult to comprehend. It can be concluded that subsistence farmers were open to the integration of scientific and indigenous weather forecasting. They highlighted that it would improve decision making concerning their agricultural activities.