Paramu L. Mafongoya

The Potential Role of Neglected and Underutilised Crop Species as Future Crops under Water Scarce Conditions in Sub-Saharan Africa.

Modern agricultural systems that promote cultivation of a very limited number of crop species have relegated indigenous crops to the status of neglected and underutilised crop species (NUCS). The complex interactions of water scarcity associated with climate change and variability in sub-Saharan Africa (SSA), and population pressure require innovative strategies to address food insecurity and undernourishment. Current research efforts have identified NUCS as having potential to reduce food and nutrition insecurity, particularly for resource poor households in SSA. This is because of their adaptability to low input agricultural systems and nutritional composition. However, what is required to promote NUCS is scientific research including agronomy, breeding, post-harvest handling and value addition, and linking farmers to markets. Among the essential knowledge base is reliable information about water utilisation by NUCS with potential for commercialisation. This commentary identifies and characterises NUCS with agronomic potential in SSA, especially in the semi-arid areas taking into consideration inter alia: (i) what can grow under water-scarce conditions, (ii) water requirements, and (iii) water productivity. Several representative leafy vegetables, tuber crops, cereal crops and grain legumes were identified as fitting the NUCS category. Agro-biodiversity remains essential for sustainable agriculture.

Multispectral mapping of key grassland nutrients in KwaZulu-Natal, South Africa

Abstract RapidEye multispectral imagery is effective in vegetation assessment. This research intends to investigate the utility of using 5-m-resolution RapidEye-5 imagery combined with a machine learning algorithm to detect and map important forage fibre biochemicals such as neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin in an African tropical grassland. These fibre biochemicals are significant indicators of the palatability of forage digested by grazing ungulates. Analysis was conducted on 140 grass samples collected at plot level and then correlated and mapped using two competent tree ensemble modelling techniques. Results showed that the random forest (RF) method successfully mapped NDF, ADF and lignin with R2 values ranging between .67 and .74. In comparison, stochastic gradient boosting (SGB) was implemented as an alternative method, which produced very similar R2 values ranging between .65 and 0.72. Overall, the results showed that multispectral remote sensing can detect and map key forage fibre biochemicals in a grassland environment.

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.

Evaluation of agroforestry systems for maize (Zea mays) productivity in South Africa

Maize (Zea mays L.) is the staple food crop grown by most smallholder farmers in South Africa. Decline in soil fertility and expensive chemical fertilisers affect maize production by these farmers. Smallholder farmers cannot afford chemical fertilisers because these are expensive. Agroforestry systems offer cheap alternatives to expensive chemical fertilisers. A field experiment was established in the 2015/16 season at Wartburg. The objective of the study was to evaluate maize yields and productivity in agroforestry systems. The experiment had five treatments: sole (maize; pigeonpea; or Sesbania bispinosa); maize + Sesbania bispinosa; maize + pigeonpea laid out in a randomized complete block design replicated three times. The yield was in order: sole maize > maize + pigeonpea ≥ maize + pigeonpea. The land equivalent ratio (LER) was in the sequence maize + pigeonpea > sole pigeonpea > maize + S. bispinosa > sole S. bispinosa ≥ sole maize. Maize yield might be increased in the following season as a subsequent crop in the same field because of residual nutrients that would have been enhanced and set free for plant uptake during the previous season. Pigeonpea is recommended in agroforestry systems with maize because of its higher LER and combined production of grain for human and livestock consumption and firewood.

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.

Estimating LAI and mapping canopy storage capacity for hydrological applications in wattle infested ecosystems using Sentinel-2 MSI derived red edge bands

This study assessed the strength of Sentinel-2 multispectral instrument (MSI) derived Red Edge (RE) bands in estimating Leaf Area Index (LAI) and mapping canopy storage capacity (CSC) for hydrological applications in wattle infested ecosystems. To accomplish this objective, this study compared the estimation strength of models derived, using standard bands (all bands excluding the RE band) with those including RE bands, as well as different vegetation indices. Sparse Partial Least Squares (SPLSR) and Partial Least Squares Regression (PLSR) ensembles were used in this study. Results showed that the RE spectrum covered by the Sentinel-2 MSI satellite reduced the estimation error by a magnitude of 0.125 based on simple ratio (RE SR) vegetation indices from 0.157 m2· m−2 based on standard bands, and by 0.078 m2· m−2 based on red edge normalised difference vegetation (NDVI-RE). The optimal models for estimating LAI to map CSC were obtained based on the RE bands centered at 705 nm (Band 5), 740 nm (Band 6), 783 nm (Band 7) as well as 865 nm (Band 8a). A root mean square error of prediction (RMSEP) of 0.507 m2· m−2 a relative root mean square error of prediction (RRMSEP) of 11.3% and R2 of 0.91 for LAI and a RMSEP of 0.246 m2/m2 (RRMSEP = 7.9%) and R2 of 0.91 for CSC were obtained. Overall, the findings of this study underscore the relevance of the new copernicus satellite product in rapid monitoring of ecosystems that are invaded by alien invasive species.

Long-term impact of no-till conservation agriculture on abundance and order diversity of soil macrofauna in continuous maize monocropping system

ABSTRACT Unsuitable soil management in agriculture is known to results in the deterioration of soil health and the decline of biodiversity. The experiment tested whether no-tillage with mulch (NT), could boost biological activity of soil macrofauna population in continuous maize monocropping system compared with rotational tillage with mulch (RT) and conventional tillage (CT). Soil macrofauna was sampled at the end of the 2014/2015 growing season using 25 × 25 × 25 cm steel monoliths. The mean density of individual orders was higher (p < 0.001) under NT (46%) and RT (38%) compared with CT (16%). However, the Shannon-Weaver index revealed that the diversity and evenness of orders were similar for all treatments. Macrofauna patterns revealed that NT and RT contained higher (p < 0.001) population of Isoptera and Diplopoda. Isoptera was 51% and 17% higher in NT than CT and RT, while in Diplopoda, NT was 39% and 2% higher than CT and RT, respectively. It was concluded that NT and RT systems favoured the development of macrofauna communities in the studied maize continuous monoculture cropping system but did not favour order diversity of macrofauna. This suggests the importance of crop rotation for the development of the more diverse macrofaunal population.

Characterisation of pigeon pea (Cajanus cajan) landraces grown in two climatic zones in KwaZulu-Natal province, South Africa

Pigeon pea is an important legume in arid and semi-arid areas of the Sub-Saharan Africa. Knowledge of adaptation characteristics of genotypes would significantly enhance its production in diverse environments of the region. Field experiments were conducted at two sites, namely Makhathini and Newlands Research Stations, both in KwaZulu-Natal province, South Africa, to assess the variation in agronomic characteristics among six local landraces obtained from smallholder farmers. The six landraces were categorised based on seed coat colour according to farmers’ perception. Significant differences were observed among landraces with respect to plant height and time to 50% flowering, indicating phenotypic variability. The Light Brown-seeded landrace planted at Newlands flowered earlier (106 d after planting). The Dark Brown-seeded landrace flowered within 150 d at Makhathini and reached physiological maturity in 185 d, earlier than other landraces. The results of principal component analysis suggested that yield of the Light Brown-seeded landrace was associated with two important agronomic parameters, namely harvest index (HI) and pod mass. The Light Brown-seeded and Cream with Brown-seeded landraces were associated with desirable yield traits including grain yield, HI and pod mass and can, therefore, be recommended as suitable parental lines in crop improvement programmes to improve pigeon pea grain yield.

A Synthesis of Smallholder Farmers’ Adaptation to Climate Change in Southern Africa: Averting Adaptation Vacuum

Smallholder agricultural ecosystems are threatened by climate change. Based on available evidence, of all the climate change outcomes, southern Africa is one of the regions worst affected by climate change. Adaptation to climate change involves changes in agricultural management practices in response to changes in climate conditions. It often involves a combination of various individual responses at the farm-level and assumes that farmers have access to alternative practices and technologies. This review examines farmer adaptation strategies to climate change in southern Africa based on a cross-section database of three countries (South Africa, Zambia and Zimbabwe). We review the state of knowledge of agricultural vulnerability and responses to predicted climate change and consider adaptation options. The review describes farmer perceptions to changes in long-term temperature and precipitation as well as various farm-level adaptation measures and barriers to adaptation at the farm household level. It also reviews smallholder farmer constraints to autonomous adaptation and implications on adaptation policies. More research is needed on local level assessment methods and standard indicators of change in response to effects from climate change, while regional monitoring networks are needed to observe these responses to enable educated adaptation. Adaptation measures can offset anticipated agricultural losses, reduce vulnerability and improve resilience to climate change.