Incorporation of rock phosphate (RP) into cow-dung paper-waste mixtures at rates of 2% P and abov... more Incorporation of rock phosphate (RP) into cow-dung paper-waste mixtures at rates of 2% P and above was earlier shown to accelerate the bioconversion and humification of the waste/waste mixtures but the optimum rate of RP incorporation was not established. This study sought to establish an optimal RP application rate for efficient vermidegradation of cow-dung paper-waste mixtures. A range of RP incorporation rates (0, 0.5, 1.0, 1.5, 2, and 4% P as RP) were mixed with cow-dung paper-waste mixtures with an optimized C: N ratio of 30 and allowed to vermidegrade following introduction of Eisenia fetida earthworms at a stocking density of 12. 5 g worms kg-1. The bioconversion of the waste mixtures was monitored by measuring C: N ratios, polymerization index (PI), and humification index (HI). An application rate of 1% P as RP resulted in the fastest bioconversion and maturation of cow-dung paper-waste mixtures. The final vermicompost had a C: N ratio of 7, PI of 14.4, and HI of 27.1%. A P-fractionation study revealed that the extractability of P increased linearly with the rate of RP application with the water soluble P fraction making the largest (1002.4mg P kg-1) contribution to the mineralized P. An RP incorporation rate of 1% P is therefore recommended for efficient vermidegradation of cow dung paper-waste mixtures but 2 higher rates of RP incorporation should be considered where greater P enrichment in final vermicomposts is desired.
The ability of cyanobacteria to fix N 2 and produce exopolysacharides varies widely among differe... more The ability of cyanobacteria to fix N 2 and produce exopolysacharides varies widely among different strains. The objective of this study was to identify and isolate cyanobacteria strains with ability to fix N 2 and produce exopolysaccharides with a view to evaluate them for their biofertilization and conditioning potential of degraded soils in arid and semi arid areas of the Eastern Cape Province, South Africa. Cyanobacteria were isolated from four sites by culture and plating techniques using growth media BG11 for all strains and BG110 for atmospheric N2=fixing strains. The number s of strains isolated were 2, 28, 35, and 32 for Guquka, Hertzog, Fort Cox College, and Qunu soils, respectively. Only three of the 97 strains had bioconditioning and biofertilization potential emphasizing the importance of screening in order to identify cyanobacteria strains suitable for improving the physical and chemical fertility of soils. Other isolated cyanobacteria strains produced no exopolysaccha...
Innovations as Key to the Green Revolution in …, 2011
The introduction of urine diversion toilets in South Africa has created opportunities for the rec... more The introduction of urine diversion toilets in South Africa has created opportunities for the recycling of human urine in agriculture. One of such possibilities is the use of human urine as a source of nitrogen during the composting of organic wastes. This study evaluated the ...
Ecological sanitation is a system that, unlike the traditional waterborne sewerage and pit toilet... more Ecological sanitation is a system that, unlike the traditional waterborne sewerage and pit toilet systems, regards human excreta as a resource to be recycled rather than as a waste. There is, however, little or no information on the fertiliser value of human excreta in South Africa. This study, therefore, evaluated the effectiveness of human manure as a source of nutrients using cabbage as a test crop at Ntselamanzi location, Alice, South Africa as part of a project intended to generate knowledge and good practice in ecological sanitation. Treatments were arranged in a randomised complete block design with 4 replications and consisted of a control, 100 kg N•ha-1 as goat manure, and 4 non-zero rates of human manure and NPK fertiliser applied to supply the equivalent of 50, 100, 200, and 400 kg N•ha-1. Human manure resulted in higher cabbage yields than goat manure but was out-yielded by inorganic fertiliser. The greater effectiveness of human manure when compared with goat manure was attributed to the fact that it was a better source of K and P for plants as it maintained higher levels of these nutrients in soil than goat manure. For greater agronomic effectiveness, the human manure should be co-applied with some inorganic N fertiliser as it proved to be a poor source of nitrogen. The human manure increased soil pH and therefore has potential for improving crop growth in acidic soils through its liming effects as well. The dry human manure was evaluated as comparable to Type B sludge in South Africa with respect to microbial content and could therefore be used to fertilise some crops/plants provided stipulated restrictions to minimise human exposure are adhered to.
Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects... more Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects of conservation agriculture (CA) principles on earthworms under the semi-arid climate of the central Eastern Cape (EC) of South Africa (SA) are limited. Therefore, this study investigated the effects of tillage, crop rotations, and residue management on earthworms’ abundance and species richness. The study design followed a split-split plot with three replicates. The main plot was allocated to tillage treatment, which had conventional tillage (CT) and no-tillage (no-till) as factors. Crop rotation treatment was allocated to a subplot, and had maize (Zea mays)–fallow–maize (MFM), maize–fallow–soybean (Glycine max) (MFS), maize–wheat (Triticum aestivum)–maize (MWM), and maize–wheat–soybean (MWS). Residue management was in the sub-subplot with residue retention and residue removal. The study was carried out over four cropping seasons: summer 2015–2016, winter 2016, spring 2016, and summer ...
Vermicomposting using Eisenia fetida has been shown to improve phosphorus mineralization from roc... more Vermicomposting using Eisenia fetida has been shown to improve phosphorus mineralization from rock phosphate (RP). There is, however, a lack of information on the potential of integrating microbial inoculants like phosphate-solubilizing bacteria (PSB) during vermicomposting as a way of improving vermidegradation, and the release of nutrients from igneous RP-amended composts. This study evaluated the potential of using Eisenia fetida and Pseudomonas fluorescence in enhancing the vermidegradation, and nutrient release in igneous RP- amended cow and pig manure-based vermicomposts at a C/N ratio of 30. Compost maturity, nutrient and phytotoxicity parameters were measured to determine vermicompost quality. Final vermicompost results showed that the pig manure treatments achieved greater maturity as indicated by lower C/N of 10.3, high humification index (HI) of 7.6%, and humification ratio (HR) of 12.89% in the treatment with E. fetida and P. fluorescence. The inclusion of E. fetida alon...
In organic soil fertility management, rock phosphate (RP) is gaining momentum as an acceptable ph... more In organic soil fertility management, rock phosphate (RP) is gaining momentum as an acceptable phosphorus source, though much of this P is not bioavailable for plant uptake, particularly in igneous RP. This study evaluated the nutrient solubilization, biodegradation and heavy metal concentration when cow dung - waste paper mixture amended with increasing rates of igneous RP was vermicomposted with . The cow dung was optimized to a C/N ratio of 30 using waste paper and amended with RP to provide 0%; 2%; 4% and 8% of elemental phosphorus on a dry w/w basis. Incorporation of RP at 2% and 8% P enhanced compost biodegradation resulting in a 12% and 22% significantly ( < 0.001) lower final C/N ratio, respectively, compared to the control; together with higher humification parameters. Amending the cow dung - waste paper mixture with 2%, 4% and 8% P as rock phosphate, resulted in a 39%; 50% and 65% more resin extractable P, respectively, relative to the control. Similarly, the bicarbonat...
Due to rapid expansion in the poultry industry, production of poultry manure has also consequentl... more Due to rapid expansion in the poultry industry, production of poultry manure has also consequently increased, resulting in unplanned disposal of this manure to the soil in some cases, with possible negative environmental consequences. In this study, 10 separate poultry manure samples were collected from different sites located in the central Eastern Cape, South Africa and characterized for chemical and phytotoxic properties. The poultry manures had an average neutral pH (range 6.94 - 7.97) whilst the electrical conductivity was highly variable from 2.45 dS/m to 12.3 dS/m between the 10 sites. The high conductivity values recorded in some of the manures indicate that caution may need to be practiced when directly applying these manure to the soil, to avoid buildup of soluble salts. All samples showed a very high concentration of total P (1963.1 mg/kg - 2644.1 mg/kg) with the plant available fraction ranging from 21.3% - 37.7% of the total P. All the heavy metals measured (Cr, Cu, Ni,...
Environmental science and pollution research international, 2018
Vermicomposting is a bio-oxidative process that involves the action of mainly epigeic earthworm s... more Vermicomposting is a bio-oxidative process that involves the action of mainly epigeic earthworm species and different micro-organisms to accelerate the biodegradation and stabilization of organic materials. There has been a growing realization that the process of vermicomposting can be used to greatly improve the fertilizer value of different organic materials, thus, creating an opportunity for their enhanced use as organic fertilizers in agriculture. The link between earthworms and micro-organisms creates a window of opportunity to optimize the vermi-degradation process for effective waste biodegradation, stabilization, and nutrient mineralization. In this review, we look at up-to-date research work that has been done on vermicomposting with the intention of highlighting research gaps on how further research can optimize vermi-degradation. Though several researchers have studied the vermicomposting process, critical parameters that drive this earthworm-microbe-driven process which ...
ABSTRACT INTRODUCTION During coal combustion at electricity power stations, 70% of the solid resi... more ABSTRACT INTRODUCTION During coal combustion at electricity power stations, 70% of the solid residue is fly ash with South Africa generating more than 26 million tons of fly ash annually, posing serious disposal challenges, as only 5% is utilized in the construction industry. However, limited research is available on potential effects and uses of South African fly ashes in agriculture and land reclamation. MATERIALS AND METHODS Total elemental concentration was determined using ICP-OES and Skalar CFA following microwave digestion. Plant available elements were extracted using DTPA-TEA and Ammonium nitrate, whilst plant available P was extracted using Olsen method. Elemental release was estimated using an incubation experiment at 0%, 5%, 10% and 20% fly ash incorporation rate to soil. RESULTS AND DISCUSSION For all fly ash samples, total P content ranged from 553.3 to 1514 mg P/kg and Olsen extractable P from 130 to 345.5 mg P kg-1. Matla fly ash had a higher total and extractable P of 1028 mg kg-1 and 256.15 mg kg-1 with the available P being 24.9% of total P. Application of fly ash at 10% incorporation rate raised extractable P content of the soil from a P deficient level to levels above the more than 25 mg kg -1 critical for most crops (Johnson et al. 2013). With a few exceptions, the heavy metal content of the fly ash samples followed the order Fe&gt; Cr&gt;Pb&gt; Ni&gt; Cu&gt; Zn. The DPTA extractable levels for the elements were low and less than 2mg kg-1 except for Fe which had levels ranging from 4.8 to 136 mg Fe kg-1. Except for Cr, all heavy metals (Cu, Pb, Fe, Ni) showed significantly (P = 0.05) low extractability at all fly ash incorporation rates compared to the soil alone control, suggesting possible precipitation of the elements.The results obtained showed that, excluding Pb, all fly ash samples studied, when incorporated into soil at 10% or less, the heavy metal load was below the maximum permissible levels recommended in South Africa. CONCLUSION These results suggest that the South African fly ashes studied can be an important source of essential elements like P with minimum risk to soil contamination from heavy metal release.
A glasshouse experiment was conducted to evaluate the external P requirement of two soils (Flagst... more A glasshouse experiment was conducted to evaluate the external P requirement of two soils (Flagstaff and Qunu) from the Transkei region of South Africa with varying sorption properties using oat (Avena sativa L.) as a test crop. Eight levels of P application estimated from the Langmuir equations that gave a range of P concentrations in the soil solution were evaluated. The rates were 0
Communications in Soil Science and Plant Analysis, 2000
Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phos... more Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phosphate rock (PPR) from southwest Tanzania, its mixture with triple superphosphate (TSP), and a compacted mixture of Panda PR and TSP (PPR+TSP) for wheat, rape, maize, and soybean on two United States soils (Hiwassee and Windthorst). The mixture of Panda PR and TSP was prepared by mixing ground
Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. H... more Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers' fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption.
Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. H... more Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers' fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption.
Incorporation of rock phosphate (RP) into cow-dung paper-waste mixtures at rates of 2% P and abov... more Incorporation of rock phosphate (RP) into cow-dung paper-waste mixtures at rates of 2% P and above was earlier shown to accelerate the bioconversion and humification of the waste/waste mixtures but the optimum rate of RP incorporation was not established. This study sought to establish an optimal RP application rate for efficient vermidegradation of cow-dung paper-waste mixtures. A range of RP incorporation rates (0, 0.5, 1.0, 1.5, 2, and 4% P as RP) were mixed with cow-dung paper-waste mixtures with an optimized C: N ratio of 30 and allowed to vermidegrade following introduction of Eisenia fetida earthworms at a stocking density of 12. 5 g worms kg-1. The bioconversion of the waste mixtures was monitored by measuring C: N ratios, polymerization index (PI), and humification index (HI). An application rate of 1% P as RP resulted in the fastest bioconversion and maturation of cow-dung paper-waste mixtures. The final vermicompost had a C: N ratio of 7, PI of 14.4, and HI of 27.1%. A P-fractionation study revealed that the extractability of P increased linearly with the rate of RP application with the water soluble P fraction making the largest (1002.4mg P kg-1) contribution to the mineralized P. An RP incorporation rate of 1% P is therefore recommended for efficient vermidegradation of cow dung paper-waste mixtures but 2 higher rates of RP incorporation should be considered where greater P enrichment in final vermicomposts is desired.
The ability of cyanobacteria to fix N 2 and produce exopolysacharides varies widely among differe... more The ability of cyanobacteria to fix N 2 and produce exopolysacharides varies widely among different strains. The objective of this study was to identify and isolate cyanobacteria strains with ability to fix N 2 and produce exopolysaccharides with a view to evaluate them for their biofertilization and conditioning potential of degraded soils in arid and semi arid areas of the Eastern Cape Province, South Africa. Cyanobacteria were isolated from four sites by culture and plating techniques using growth media BG11 for all strains and BG110 for atmospheric N2=fixing strains. The number s of strains isolated were 2, 28, 35, and 32 for Guquka, Hertzog, Fort Cox College, and Qunu soils, respectively. Only three of the 97 strains had bioconditioning and biofertilization potential emphasizing the importance of screening in order to identify cyanobacteria strains suitable for improving the physical and chemical fertility of soils. Other isolated cyanobacteria strains produced no exopolysaccha...
Innovations as Key to the Green Revolution in …, 2011
The introduction of urine diversion toilets in South Africa has created opportunities for the rec... more The introduction of urine diversion toilets in South Africa has created opportunities for the recycling of human urine in agriculture. One of such possibilities is the use of human urine as a source of nitrogen during the composting of organic wastes. This study evaluated the ...
Ecological sanitation is a system that, unlike the traditional waterborne sewerage and pit toilet... more Ecological sanitation is a system that, unlike the traditional waterborne sewerage and pit toilet systems, regards human excreta as a resource to be recycled rather than as a waste. There is, however, little or no information on the fertiliser value of human excreta in South Africa. This study, therefore, evaluated the effectiveness of human manure as a source of nutrients using cabbage as a test crop at Ntselamanzi location, Alice, South Africa as part of a project intended to generate knowledge and good practice in ecological sanitation. Treatments were arranged in a randomised complete block design with 4 replications and consisted of a control, 100 kg N•ha-1 as goat manure, and 4 non-zero rates of human manure and NPK fertiliser applied to supply the equivalent of 50, 100, 200, and 400 kg N•ha-1. Human manure resulted in higher cabbage yields than goat manure but was out-yielded by inorganic fertiliser. The greater effectiveness of human manure when compared with goat manure was attributed to the fact that it was a better source of K and P for plants as it maintained higher levels of these nutrients in soil than goat manure. For greater agronomic effectiveness, the human manure should be co-applied with some inorganic N fertiliser as it proved to be a poor source of nitrogen. The human manure increased soil pH and therefore has potential for improving crop growth in acidic soils through its liming effects as well. The dry human manure was evaluated as comparable to Type B sludge in South Africa with respect to microbial content and could therefore be used to fertilise some crops/plants provided stipulated restrictions to minimise human exposure are adhered to.
Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects... more Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects of conservation agriculture (CA) principles on earthworms under the semi-arid climate of the central Eastern Cape (EC) of South Africa (SA) are limited. Therefore, this study investigated the effects of tillage, crop rotations, and residue management on earthworms’ abundance and species richness. The study design followed a split-split plot with three replicates. The main plot was allocated to tillage treatment, which had conventional tillage (CT) and no-tillage (no-till) as factors. Crop rotation treatment was allocated to a subplot, and had maize (Zea mays)–fallow–maize (MFM), maize–fallow–soybean (Glycine max) (MFS), maize–wheat (Triticum aestivum)–maize (MWM), and maize–wheat–soybean (MWS). Residue management was in the sub-subplot with residue retention and residue removal. The study was carried out over four cropping seasons: summer 2015–2016, winter 2016, spring 2016, and summer ...
Vermicomposting using Eisenia fetida has been shown to improve phosphorus mineralization from roc... more Vermicomposting using Eisenia fetida has been shown to improve phosphorus mineralization from rock phosphate (RP). There is, however, a lack of information on the potential of integrating microbial inoculants like phosphate-solubilizing bacteria (PSB) during vermicomposting as a way of improving vermidegradation, and the release of nutrients from igneous RP-amended composts. This study evaluated the potential of using Eisenia fetida and Pseudomonas fluorescence in enhancing the vermidegradation, and nutrient release in igneous RP- amended cow and pig manure-based vermicomposts at a C/N ratio of 30. Compost maturity, nutrient and phytotoxicity parameters were measured to determine vermicompost quality. Final vermicompost results showed that the pig manure treatments achieved greater maturity as indicated by lower C/N of 10.3, high humification index (HI) of 7.6%, and humification ratio (HR) of 12.89% in the treatment with E. fetida and P. fluorescence. The inclusion of E. fetida alon...
In organic soil fertility management, rock phosphate (RP) is gaining momentum as an acceptable ph... more In organic soil fertility management, rock phosphate (RP) is gaining momentum as an acceptable phosphorus source, though much of this P is not bioavailable for plant uptake, particularly in igneous RP. This study evaluated the nutrient solubilization, biodegradation and heavy metal concentration when cow dung - waste paper mixture amended with increasing rates of igneous RP was vermicomposted with . The cow dung was optimized to a C/N ratio of 30 using waste paper and amended with RP to provide 0%; 2%; 4% and 8% of elemental phosphorus on a dry w/w basis. Incorporation of RP at 2% and 8% P enhanced compost biodegradation resulting in a 12% and 22% significantly ( < 0.001) lower final C/N ratio, respectively, compared to the control; together with higher humification parameters. Amending the cow dung - waste paper mixture with 2%, 4% and 8% P as rock phosphate, resulted in a 39%; 50% and 65% more resin extractable P, respectively, relative to the control. Similarly, the bicarbonat...
Due to rapid expansion in the poultry industry, production of poultry manure has also consequentl... more Due to rapid expansion in the poultry industry, production of poultry manure has also consequently increased, resulting in unplanned disposal of this manure to the soil in some cases, with possible negative environmental consequences. In this study, 10 separate poultry manure samples were collected from different sites located in the central Eastern Cape, South Africa and characterized for chemical and phytotoxic properties. The poultry manures had an average neutral pH (range 6.94 - 7.97) whilst the electrical conductivity was highly variable from 2.45 dS/m to 12.3 dS/m between the 10 sites. The high conductivity values recorded in some of the manures indicate that caution may need to be practiced when directly applying these manure to the soil, to avoid buildup of soluble salts. All samples showed a very high concentration of total P (1963.1 mg/kg - 2644.1 mg/kg) with the plant available fraction ranging from 21.3% - 37.7% of the total P. All the heavy metals measured (Cr, Cu, Ni,...
Environmental science and pollution research international, 2018
Vermicomposting is a bio-oxidative process that involves the action of mainly epigeic earthworm s... more Vermicomposting is a bio-oxidative process that involves the action of mainly epigeic earthworm species and different micro-organisms to accelerate the biodegradation and stabilization of organic materials. There has been a growing realization that the process of vermicomposting can be used to greatly improve the fertilizer value of different organic materials, thus, creating an opportunity for their enhanced use as organic fertilizers in agriculture. The link between earthworms and micro-organisms creates a window of opportunity to optimize the vermi-degradation process for effective waste biodegradation, stabilization, and nutrient mineralization. In this review, we look at up-to-date research work that has been done on vermicomposting with the intention of highlighting research gaps on how further research can optimize vermi-degradation. Though several researchers have studied the vermicomposting process, critical parameters that drive this earthworm-microbe-driven process which ...
ABSTRACT INTRODUCTION During coal combustion at electricity power stations, 70% of the solid resi... more ABSTRACT INTRODUCTION During coal combustion at electricity power stations, 70% of the solid residue is fly ash with South Africa generating more than 26 million tons of fly ash annually, posing serious disposal challenges, as only 5% is utilized in the construction industry. However, limited research is available on potential effects and uses of South African fly ashes in agriculture and land reclamation. MATERIALS AND METHODS Total elemental concentration was determined using ICP-OES and Skalar CFA following microwave digestion. Plant available elements were extracted using DTPA-TEA and Ammonium nitrate, whilst plant available P was extracted using Olsen method. Elemental release was estimated using an incubation experiment at 0%, 5%, 10% and 20% fly ash incorporation rate to soil. RESULTS AND DISCUSSION For all fly ash samples, total P content ranged from 553.3 to 1514 mg P/kg and Olsen extractable P from 130 to 345.5 mg P kg-1. Matla fly ash had a higher total and extractable P of 1028 mg kg-1 and 256.15 mg kg-1 with the available P being 24.9% of total P. Application of fly ash at 10% incorporation rate raised extractable P content of the soil from a P deficient level to levels above the more than 25 mg kg -1 critical for most crops (Johnson et al. 2013). With a few exceptions, the heavy metal content of the fly ash samples followed the order Fe&gt; Cr&gt;Pb&gt; Ni&gt; Cu&gt; Zn. The DPTA extractable levels for the elements were low and less than 2mg kg-1 except for Fe which had levels ranging from 4.8 to 136 mg Fe kg-1. Except for Cr, all heavy metals (Cu, Pb, Fe, Ni) showed significantly (P = 0.05) low extractability at all fly ash incorporation rates compared to the soil alone control, suggesting possible precipitation of the elements.The results obtained showed that, excluding Pb, all fly ash samples studied, when incorporated into soil at 10% or less, the heavy metal load was below the maximum permissible levels recommended in South Africa. CONCLUSION These results suggest that the South African fly ashes studied can be an important source of essential elements like P with minimum risk to soil contamination from heavy metal release.
A glasshouse experiment was conducted to evaluate the external P requirement of two soils (Flagst... more A glasshouse experiment was conducted to evaluate the external P requirement of two soils (Flagstaff and Qunu) from the Transkei region of South Africa with varying sorption properties using oat (Avena sativa L.) as a test crop. Eight levels of P application estimated from the Langmuir equations that gave a range of P concentrations in the soil solution were evaluated. The rates were 0
Communications in Soil Science and Plant Analysis, 2000
Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phos... more Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phosphate rock (PPR) from southwest Tanzania, its mixture with triple superphosphate (TSP), and a compacted mixture of Panda PR and TSP (PPR+TSP) for wheat, rape, maize, and soybean on two United States soils (Hiwassee and Windthorst). The mixture of Panda PR and TSP was prepared by mixing ground
Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. H... more Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers' fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption.
Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. H... more Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers' fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption.
Uploads
Papers by Pearson Mnkeni