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Manganese (Mn) mining produces a large amount of Mn-rich solid waste contributing to soil and groundwater pollution. Adding Mn-rich waste to soils could reduce mining pollution by allowing specialised plants to take up this mineral for growth, that is, phytoremediation. However, Mn interacts with other soil major and trace minerals. The interaction with phosphorus (P), a key element for plant nutrition and growth, has received less attention. In this study, we aimed to evaluate the effects of P sources (i.e. rock phosphate and monopotassium [KH2PO4]) and application rates on the P and Mn relationships in clay and sandy soils mixed with Mn-rich waste. Soils differing in texture were incubated for 60 days at room temperature (±20 °C), and changes in available P, Mn and soil pH were determined at 0, 30 and 60 days. The addition of Mn-rich solid waste significantly decreased available soil P in both soils with the greatest reduction of 62% and 52% from the sandy soil subjected to KH2PO4 and rock phosphate, respectively. In the clayey soil, the reduction was higher for the rock phosphate source implying more P was released from the rock phosphate in Mn-rich soils. This explanation was supported by the significant positive correlation between P and Mn for both soils when P is added in the form of rock phosphate. Our results suggest that Mn-rich waste is better in clay soils subjected to rock phosphate addition. Further research is needed to control Mn solid waste pollution levels in soils using specific crops with known phytoremediation properties. [ABSTRACT FROM AUTHOR]

Background: One of the main causes of land degradation in South Africa is bush thickening (BT) of mainly Senegalia or Vachellia species. Restoration methods are required to control BT, and to improve grass biomass production and soil conditions in South Africa. Objectives: The objectives of this study were to determine the effect of brush packing (BP) as a restoration method to increase grass biomass production, assess soil moisture after BP on different soil types, and document the perceptions of the local communities towards BP. Method: Methods included cutting the stems of woodies with a diameter of at least 10 cm at knee height by chainsaw and manual clipping after which an arborocide was applied to the stumps. A neutron probe was used to measure volumetric moisture content at two different soil depths. The grass biomass was analysed using ANOVA at a confidence level of 95%. Quantitative and qualitative approaches were used to gather information about the perceptions of local communities towards restoration in group discussions. Results: The short-term data showed that the implementation of BP as restoration method increased grass biomass production. The soil texture influenced the volumetric soil moisture. Higher soil moisture content was found in the deeper clayey soils. The local participants' interpretation towards the restoration project was positive. Conclusion: The project increased the grazing potential and contributed to job creation to improve the well-being of the people in the community. [ABSTRACT FROM AUTHOR]

Background: One of the main causes of land degradation in South Africa is bush thickening (BT) of mainly Senegalia or Vachellia species. Restoration methods are required to control BT, and to improve grass biomass production and soil conditions in South Africa. Objectives: The objectives of this study were to determine the effect of brush packing (BP) as a restoration method to increase grass biomass production, assess soil moisture after BP on different soil types, and document the perceptions of the local communities towards BP. Method: Methods included cutting the stems of woodies with a diameter of at least 10 cm at knee height by chainsaw and manual clipping after which an arborocide was applied to the stumps. A neutron probe was used to measure volumetric moisture content at two different soil depths. The grass biomass was analysed using ANOVA at a confidence level of 95%. Quantitative and qualitative approaches were used to gather information about the perceptions of local communities towards restoration in group discussions. Results: The short-term data showed that the implementation of BP as restoration method increased grass biomass production. The soil texture influenced the volumetric soil moisture. Higher soil moisture content was found in the deeper clayey soils. The local participants' interpretation towards the restoration project was positive. Conclusion: The project increased the grazing potential and contributed to job creation to improve the well-being of the people in the community. [ABSTRACT FROM AUTHOR]

In savannas, partitioning of below‐ground resources by depth could facilitate tree–grass coexistence and shape vegetation responses to changing rainfall patterns. However, most studies assessing tree versus grass root‐niche partitioning have focused on one or two sites, limiting generalization about how rainfall and soil conditions influence the degree of rooting overlap across environmental gradients.We used two complementary stable isotope techniques to quantify variation (a) in water uptake depths and (b) in fine‐root biomass distributions among dominant trees and grasses at eight semi‐arid savanna sites in Kruger National Park, South Africa. Sites were located on contrasting soil textures (clayey basaltic soils vs. sandy granitic soils) and paired along a gradient of mean annual rainfall.Soil texture predicted variation in mean water uptake depths and fine‐root allocation. While grasses maintained roots close to the surface and consistently used shallow water, trees on sandy soils distributed roots more evenly across soil depths and used deeper soil water, resulting in greater divergence between tree and grass rooting on sandy soils. Mean annual rainfall predicted some variation among sites in tree water uptake depth, but had a weaker influence on fine‐root allocation.Synthesis. Savanna trees overlapped more with shallow‐rooted grasses on clayey soils and were more distinct in their use of deeper soil layers on sandy soils, consistent with expected differences in infiltration and percolation. These differences, which could allow trees to escape grass competition more effectively on sandy soils, may explain observed differences in tree densities and rates of woody encroachment with soil texture. Differences in the degree of root‐niche separation could also drive heterogeneous responses of savanna vegetation to predicted shifts in the frequency and intensity of rainfall. [ABSTRACT FROM AUTHOR]

Moringa oleifera Lam , often grows well under cultivation in the tropics and sub-tropics. It does well in sandy to clayey soils and tolerates low rainfall. The plant is well-known for its nutritional and medicinal properties, hence it is fast gaining popularity in South Africa and the rest of the world. The objective of this study was to predict the suitable areas for cultivating M. oleifera in South Africa using climate and edaphic variables that significantly affect its growth and development. We used an Analytical Hierarchical Process (AHP) and Geographic Information System (GIS) weight function to assign suitability weights to criteria and sub-criteria that affect the plant's growth and a predictive cultivation suitability map. Area under the curve (AUC) was used to evaluate the model's performance. The Analytical Hierarchical Process indicated that the most influential variable determining M. oleifera cultivation were, minimum temperature, soil texture, annual rainfall, mean temperature and soil pH, respectively. Further, the results showed that approximately 16.5% (200,837 km2) of South Africa land area has optimal growth conditions, 17.8% (216,758 km2) suitable conditions, 46% (560,794 km2) less suitable conditions and 19% (240,699 km2) not suitable conditions for cultivating M. oleifera. The area under the curve (AUC) metric of our suitability model suggested that the map is 81% accurate for predicting the spatial suitability of cultivating M. oleifera in South Africa. The results also confirm that the use of AHP model with GIS weight function is useful for explicit identification of sites for M. oleifera cultivation for maximum production output. The results of this study can be useful information for the land-use policy makers and farmers for informed decision regarding the cultivation of M. oleifera in South Africa. • Moringa oleifera is fast gaining popularity in South Africa. • We predicted the spatial suitability of cultivating Moringa. • Minimum temperature mostly influences Moringa growth. • Soil pH has the least influence on Moringa growth. • 16.5% of South Africa area has optimal conditions for cultivating Moringa. [ABSTRACT FROM AUTHOR]

Aim: High‐resolution spatial soil data are crucial to species distribution modelling for fundamental research and conservation planning. Recent globally modelled soil layers (e.g. SoilGrids) have transformed distribution modelling, but may fail to represent regional soil characteristics accurately. We hypothesize that in the Cape biodiversity hotspot of South Africa, the use of global soil layers has led to underestimation of the importance of edaphic factors as determinants of species' and vegetation distributions. We present a series of new, regionally modelled layers to address this deficiency. Location: Greater Cape Floristic Region (GCFR, South Africa). Methods: We georeferenced edaphic characteristics from literature and other sources and used boosted regression trees (BRT) to associate edaphic characteristics with spatially explicit topographic, climatic, soil texture and biotic variables. Multinomial BRTs were used to predict mapped vegetation types from the collated edaphic and other data. Results: BRTs reliably predicted pH (92% of variance), Na (87%), K (85%), electrical conductivity (81%) and P (73%), but were less accurate for total N (55%) and total C (61%), for which data were sparser. Soil clay and pH values differed markedly in range and in spatial variation from those in SoilGrids. Using our new edaphic layers, we were able to accurately predict spatial distributions of vegetation types within the GCFR (multi‐class AUC = 0.96). The multinomial BRT predicted vegetation less well when based on SoilGrids data alone (AUC = 0.84). Main conclusions: The more faithful representation of soil properties in our model is attributable both to its use of ca. 10‐fold more samples, and to its regional focus. Our model of edaphic characteristics captures important edaphic variability that is vital for understanding plant and consequently faunal distributions, with wide‐ranging conservation implications. Ongoing development of global syntheses of soil data requires more samples, especially in areas with high spatial heterogeneity and extreme edaphic conditions. [ABSTRACT FROM AUTHOR]

Grapevine leafroll is the most damaging grapevine virus disease in South Africa, and the primary vector of Grapevine leafroll-associated virus 3 (GLRaV-3) is vine mealybug, Planococcus ficus (Signoret). Preventing re-infection of newly planted, virus-free grapevines is critical to control and prevent the spread of leafroll disease. Results from a previous survey raised concern that mealybugs surviving on leafroll-infected root remnants in the soil could transmit the virus to newly planted grapevines. This study aimed to determine if P. ficus commonly occurs on grapevine roots in the Western Cape Province of South Africa, if and for how long it can survive on remnant roots in soil, and if it can transmit GLRaV-3 to healthy grapevines after surviving on remnant roots. Surveys to determine the occurrence of mealybugs on grapevine roots were conducted at different times of the growing season in vineyards near Robertson, McGregor, Montagu, Somerset West and Malmesbury over three seasons. A field trial was conducted on a sand-clay-loam soil with 23% clay and a sandy-loam soil with 10% clay over 12 months to determine survival of different life stages of vine mealybug confined on root sections from leafroll-infected Pinotage/R110 grapevines. Results indicate that P. ficus does not readily occur on grapevine roots in the Western Cape, and that it does not survive well on root remnants of grapevines for any length of time. Implications for planting virus-free grapevines in soil where leafroll-infected vines were removed, are discussed. [ABSTRACT FROM AUTHOR]

This study extended the association between hookworm transmission in KwaZulu-Natal and the sandy coastal plain by investigating the parasite's occurrence in isolated areas of sandy soils further inland. A school-based prevalence survey was carried out in selected inland sandy areas and in surrounding areas dominated by clay soils within a narrow altitudinal range of between 500 and 700 m to reduce the effect of altitude on climate-related factors (rainfall and temperature). Sandy areas situated on the coastal plain were included in the analysis for comparative purposes. Soil samples (0–50 mm depth) were collected from each locality to assess their nematode loadings and to analyse selected physical and chemical properties. Significant differences were found between the moderate prevalence of hookworm infection among children living in inland areas with sandy soils (17.3%) and the low prevalence in surrounding non-sandy areas (5.3%, P < 0.001), and between infection among children living in all inland areas (9.3%) and the high prevalence on the coastal plain (62.5%, P < 0.001). Amounts of fine and medium sand were highest in both the coastal plain soils and in inland sandy areas and these fractions showed a significant positive correlation with hookworm prevalence and nematode loadings. Clay, coarse sand and organic matter contents were highest in surrounding non-sandy soils and showed a significant negative correlation with the nematode variables. No statistically significant correlations were found with soil pH at study localities. We conclude that properties of inland sandy soils, particularly particle size distribution, correlate well with hookworm prevalence and nematode loadings and therefore provide a more suitable habitat for nematodes than surrounding non-sandy areas. These results suggest that particle size distribution of sand fractions, organic matter and clay content in the soil influence the survival of hookworm larvae and hence the parasite's transmission. [ABSTRACT FROM AUTHOR]