Enhancing phosphorus availability in some phosphate fixing soils of the Transkei region, South Africa using goat manure
- Authors: Gichangi, Elias Maina
- Date: 2007
- Subjects: Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11960 , http://hdl.handle.net/10353/80 , Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Description: Low availability of soil phosphorus (P) caused by strong sorption of P is a major constraint to agricultural production in most South African soils, particularly those from the high rainfall areas. The aim of this study was therefore to investigate whether combined addition of goat manure with inorganic P fertilizers could enhance P availability in some P fixing soils of the Transkei region, South Africa. The study addressed the following specific objectives (i) to assess P sorption capacities and requirements of selected soils and their relationship with selected soil properties and single point sorption test, (ii) to assess the effects of goat manure and lime addition on P sorption properties of selected P fixing soils (iii) to assess the temporal changes in concentration of inorganic and microbial biomass P fractions following application of inorganic fertilizer P with goat manure in a laboratory incubation experiment, and, (iv) to assess the effects of goat manure application with inorganic phosphate on inorganic and microbial biomass P fractions, P uptake and dry matter yield of maize. Sorption maxima (Smax) of seven soils examined ranged from 192.3 to 909.1 (mg P kg-1) and were highly and positively correlated with sorption affinity constant (r = 0.93, p = 0.01) and organic C (r = 0.71, p = 0.01). The amount of P required for maintaining a soil solution concentration of 0.2 mg P l-1 ranged from 2.1 to 123.5 mg P kg-1 soil. Soils collected from Qweqwe (a Cambisol), Qunu (an Acrisol), Ncihane (a Luvisol) and Bethania (a Ferralsol) had lower external P requirement values and were classified as lower sorbers, whereas soils from Ntlonyana (a Planosol), Chevy Chase (a Ferralsol) and Flagstaff (a Ferralsol) were classified as moderate sorbers. The results suggested that P availability could be compromised in 43 percent iii of the soils studied and that measures to mitigate the adverse effects of P sorption were needed to ensure that P is not a limiting factor to crop production, where such soils are found. Goat manure addition at varying rates (5, 10 and 20 tha-1 dry weight basis) to two of the moderately P fixing soils from Chevy Chase and Flagstaff, reduced P sorption maxima (Smax) compared to the control treatment. Phosphate sorption decreased with increasing amounts of goat manure in both soils but the extent of reduction was greater on Chevy Chase soil than on Flagstaff soil. The relative liming effects of the different rates of goat manure followed the order 20 t GM ha-1 > 10 t GM ha-1 > 5 t GM ha-1. In a separate experiment, addition of inorganic P at varying rates (0, 90, 180, and 360 kg P ha-1) to Flagstaff soil increased labile P fractions (resin P, biomass P and NaHCO3-Pi) and the increases were greater when goat manure was co-applied. The control treatments contained only 17.2 and 27.5 mg P kg-1 of resin extractable P in the un-amended and manure amended treatments, respectively which increased to 118.2 and 122.7 mg P kg-1 on day 28 of incubation. Biomass P concentration was increased from 16.8 to 43.9 mg P kg-1 in P alone treatments but the fraction was greatly enhanced with manure addition, increasing it from 32.6 to 97.7 mg P kg-1. NaOH-Pi was the largest extractable Pi fraction and ranged from 144.3 to 250.6 mg P kg-1 and 107.5 to 213.2 mg P kg-1 in the unamended and manure amended treatments, respectively. Dry matter yield and P uptake by maize grown in the glasshouse were highly and significantly (p = 0.05) correlated with the different P fractions in the soil. The correlations followed the order resin P (r = 0.85) > NaOH-Pi (r = 0.85) > NaHCO3-Pi (r = 0.84) >> biomass P (r = 0.56) for dry matter yield at 6 weeks after planting. At 12 weeks after planting, goat manure had iv highly significant effects on resin P and biomass P but had no effect on NaHCO3-Pi and NaOH–Pi. The combination of biomass P, resin P and NaHCO3-Pi explained 75.8 percent of the variation in dry matter yield of which 63.0 percent of the variation was explained by biomass P alone. The greatest increase in biomass P occurred when added P was co-applied with 5 or 10 tha-1 goat manure. The predictive equation for maize dry matter yield (DM) was: DM (g) = 1.897 biomass P + 0.645 resin P (r = 0.73). Resin P was the fraction that was most depleted due to plant uptake and decreased by 56 to 68 percent between the 6th week and the 12th week of sampling indicating that it played a greater role in supplying plant available P. The results therefore suggested that the use of goat manure may allow resource poor farmers to use lower levels of commercial phosphate fertilizers because of its effect to reduce soil P sorption. In addition, higher increases in biomass P due to manure addition observed at lower rates of added P indicated that goat manure has potential for enhancing bioavailability and fertilizer use efficiency of small inorganic P applications.
- Full Text:
- Date Issued: 2007
- Authors: Gichangi, Elias Maina
- Date: 2007
- Subjects: Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11960 , http://hdl.handle.net/10353/80 , Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Description: Low availability of soil phosphorus (P) caused by strong sorption of P is a major constraint to agricultural production in most South African soils, particularly those from the high rainfall areas. The aim of this study was therefore to investigate whether combined addition of goat manure with inorganic P fertilizers could enhance P availability in some P fixing soils of the Transkei region, South Africa. The study addressed the following specific objectives (i) to assess P sorption capacities and requirements of selected soils and their relationship with selected soil properties and single point sorption test, (ii) to assess the effects of goat manure and lime addition on P sorption properties of selected P fixing soils (iii) to assess the temporal changes in concentration of inorganic and microbial biomass P fractions following application of inorganic fertilizer P with goat manure in a laboratory incubation experiment, and, (iv) to assess the effects of goat manure application with inorganic phosphate on inorganic and microbial biomass P fractions, P uptake and dry matter yield of maize. Sorption maxima (Smax) of seven soils examined ranged from 192.3 to 909.1 (mg P kg-1) and were highly and positively correlated with sorption affinity constant (r = 0.93, p = 0.01) and organic C (r = 0.71, p = 0.01). The amount of P required for maintaining a soil solution concentration of 0.2 mg P l-1 ranged from 2.1 to 123.5 mg P kg-1 soil. Soils collected from Qweqwe (a Cambisol), Qunu (an Acrisol), Ncihane (a Luvisol) and Bethania (a Ferralsol) had lower external P requirement values and were classified as lower sorbers, whereas soils from Ntlonyana (a Planosol), Chevy Chase (a Ferralsol) and Flagstaff (a Ferralsol) were classified as moderate sorbers. The results suggested that P availability could be compromised in 43 percent iii of the soils studied and that measures to mitigate the adverse effects of P sorption were needed to ensure that P is not a limiting factor to crop production, where such soils are found. Goat manure addition at varying rates (5, 10 and 20 tha-1 dry weight basis) to two of the moderately P fixing soils from Chevy Chase and Flagstaff, reduced P sorption maxima (Smax) compared to the control treatment. Phosphate sorption decreased with increasing amounts of goat manure in both soils but the extent of reduction was greater on Chevy Chase soil than on Flagstaff soil. The relative liming effects of the different rates of goat manure followed the order 20 t GM ha-1 > 10 t GM ha-1 > 5 t GM ha-1. In a separate experiment, addition of inorganic P at varying rates (0, 90, 180, and 360 kg P ha-1) to Flagstaff soil increased labile P fractions (resin P, biomass P and NaHCO3-Pi) and the increases were greater when goat manure was co-applied. The control treatments contained only 17.2 and 27.5 mg P kg-1 of resin extractable P in the un-amended and manure amended treatments, respectively which increased to 118.2 and 122.7 mg P kg-1 on day 28 of incubation. Biomass P concentration was increased from 16.8 to 43.9 mg P kg-1 in P alone treatments but the fraction was greatly enhanced with manure addition, increasing it from 32.6 to 97.7 mg P kg-1. NaOH-Pi was the largest extractable Pi fraction and ranged from 144.3 to 250.6 mg P kg-1 and 107.5 to 213.2 mg P kg-1 in the unamended and manure amended treatments, respectively. Dry matter yield and P uptake by maize grown in the glasshouse were highly and significantly (p = 0.05) correlated with the different P fractions in the soil. The correlations followed the order resin P (r = 0.85) > NaOH-Pi (r = 0.85) > NaHCO3-Pi (r = 0.84) >> biomass P (r = 0.56) for dry matter yield at 6 weeks after planting. At 12 weeks after planting, goat manure had iv highly significant effects on resin P and biomass P but had no effect on NaHCO3-Pi and NaOH–Pi. The combination of biomass P, resin P and NaHCO3-Pi explained 75.8 percent of the variation in dry matter yield of which 63.0 percent of the variation was explained by biomass P alone. The greatest increase in biomass P occurred when added P was co-applied with 5 or 10 tha-1 goat manure. The predictive equation for maize dry matter yield (DM) was: DM (g) = 1.897 biomass P + 0.645 resin P (r = 0.73). Resin P was the fraction that was most depleted due to plant uptake and decreased by 56 to 68 percent between the 6th week and the 12th week of sampling indicating that it played a greater role in supplying plant available P. The results therefore suggested that the use of goat manure may allow resource poor farmers to use lower levels of commercial phosphate fertilizers because of its effect to reduce soil P sorption. In addition, higher increases in biomass P due to manure addition observed at lower rates of added P indicated that goat manure has potential for enhancing bioavailability and fertilizer use efficiency of small inorganic P applications.
- Full Text:
- Date Issued: 2007
Growth performance, carcass characteristics and meat quality of Nguni, Bonsmara and Angus steers raised on natural pasture
- Authors: Muchenje, Voster
- Date: 2007
- Subjects: Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11580 , http://hdl.handle.net/10353/199 , Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Description: The objective of the current study was to compare tick loads, growth, carcass characteristics and meat quality of Nguni, Bonsmara and Angus steers raised on natural pasture. A total of 30, 7-month old steers each of Bonsmara and Angus, and 40 Nguni steers were kept at the University of Fort Hare Farm till slaughter at 18 months. Monthly weights of the steers were recorded. Carcasses were electrically stimulated. The m. longissimus thoracis et lumborum was sampled for the measurement of meat colour, pH, drip loss, sarcomere length (SL), water holding capacity (WHC), cooking losses, myofibrillar fragmentation length (MFL), Warner Bratzler shear force (WBSF), fatty acid profiles and sensory characteristics of the steers. Urine samples were collected at the slaughter line for the determination of stress hormone concentrations. The Nguni had the lowest tick load (P < 0.05) while the Angus had the highest tick load (P < 0.05). Tick load did not affect the growth rate and carcass characteristics of the steers. Bonsmara and Angus steers had higher (P < 0.05) carcass weight and dressing percentage than the Nguni steers. Meat quality characteristics were similar (P > 0.05) among all the breeds, except that Nguni meat was darker (L*) (P < 0.05) than meat from the other two breeds. The Bonsmara had the highest (P > 0.05) concentrations while the Nguni had the lowest (P > 0.05) concentrations of stress hormones. There were significant (P < 0.05) correlations between WB values of meat aged for two and 21 days in Nguni and Bonsmara, but not in Angus. The correlations among stress responsiveness hormones and meat quality were breed-dependent. Except monounsaturated fatty acids (MUFA) and the n-6/n-3 ratio, fatty acid profiles among the breeds were similar (P > 0.05). Cholesterol levels among the breeds were similar (P > 0.05). The Nguni had the best (P < 0.05) sensory characteristics, such as flavour and tenderness. It can be concluded that while the Nguni is a small framed breed, its meat quality is similar to that of Bonsmara and Angus and has the best meat taste when raised on natural pasture.
- Full Text:
- Date Issued: 2007
- Authors: Muchenje, Voster
- Date: 2007
- Subjects: Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11580 , http://hdl.handle.net/10353/199 , Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Description: The objective of the current study was to compare tick loads, growth, carcass characteristics and meat quality of Nguni, Bonsmara and Angus steers raised on natural pasture. A total of 30, 7-month old steers each of Bonsmara and Angus, and 40 Nguni steers were kept at the University of Fort Hare Farm till slaughter at 18 months. Monthly weights of the steers were recorded. Carcasses were electrically stimulated. The m. longissimus thoracis et lumborum was sampled for the measurement of meat colour, pH, drip loss, sarcomere length (SL), water holding capacity (WHC), cooking losses, myofibrillar fragmentation length (MFL), Warner Bratzler shear force (WBSF), fatty acid profiles and sensory characteristics of the steers. Urine samples were collected at the slaughter line for the determination of stress hormone concentrations. The Nguni had the lowest tick load (P < 0.05) while the Angus had the highest tick load (P < 0.05). Tick load did not affect the growth rate and carcass characteristics of the steers. Bonsmara and Angus steers had higher (P < 0.05) carcass weight and dressing percentage than the Nguni steers. Meat quality characteristics were similar (P > 0.05) among all the breeds, except that Nguni meat was darker (L*) (P < 0.05) than meat from the other two breeds. The Bonsmara had the highest (P > 0.05) concentrations while the Nguni had the lowest (P > 0.05) concentrations of stress hormones. There were significant (P < 0.05) correlations between WB values of meat aged for two and 21 days in Nguni and Bonsmara, but not in Angus. The correlations among stress responsiveness hormones and meat quality were breed-dependent. Except monounsaturated fatty acids (MUFA) and the n-6/n-3 ratio, fatty acid profiles among the breeds were similar (P > 0.05). Cholesterol levels among the breeds were similar (P > 0.05). The Nguni had the best (P < 0.05) sensory characteristics, such as flavour and tenderness. It can be concluded that while the Nguni is a small framed breed, its meat quality is similar to that of Bonsmara and Angus and has the best meat taste when raised on natural pasture.
- Full Text:
- Date Issued: 2007
Narratives of South African heteroseual relationships: understanding masculine and feminine togetherness
- Authors: Tracey, Tiffany
- Date: 2007
- Subjects: Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Language: English
- Type: Thesis , Doctoral , D Soc Sc (Psych)
- Identifier: vital:11601 , http://hdl.handle.net/10353/176 , Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Description: Heterosexuality often appears as a monolithic way of being that has been disciplinarily defined as right and natural for all sexual subjects (Foucault, 1979). However, it may also be viewed as a social construction, subject to alteration and variation according to social and historical context. In the following research, the stories of ten couples and from the South African soap opera Isidingo reveal the ways that heteronorms shape togetherness between men and women. In the research a queer stance is used to interrogate the ways that togetherness appears as natural and normal, such that the contingency of such togetherness is revealed. The queer stance was used to unsettle the unquestioned assumption of heteronormativity by interrogating the construction from a political position not included by the norm (Stein & Plummer, 1994). Within the general queer stance the concept of performance has been used to account for the ways in which subjects are able to unsettle normative constraints: Butler’s (1993) conception of repetition, Holzman’s (1991) account of the revolutionary developmental potential of performance, Billig’s (1991) understanding of the rhetorical constructions of everyday philosophers. Further Bakhtin’s (1994) dialogic ontology suggests that utterances, performances and/or narratives Using these theoretical underpinnings, the narratives show how stories of togetherness collude with heteronorms while at the same time existing alongside alternative forms of togetherness. Possibly because norms are broad, overarching constructions, they do not define the entirety of the couples’ tales. Rather moments of resistance and alteration are interwoven with normative themes. This unpredictable ambivalence appears in the couples narratives as the assertion that all relationships are the same, and that all relationships are unique. Couples position themselves within a social network, and this network instructs the couple on heteronormative ways of being together. They also witness normative performances in a way that is similar to the observation of disciplines, suggested by Foucault (1979). Although couples often go with their social network’s observations, the manner in which couples position themselves within this network assists them in arguing for alternatives to heteronorms. Spatial expressions also at times serve to fix togetherness. Homes are structured in line with social constructions of heteronorms. However, couples can and do mould their understandings of their homes, such space is reveal as an intersection between social and individual concerns. Narratives of work again reveal that heteronorms structure but can also be ignored within heterosexual relationships. Couples tell of receiving particular benefits from normative performances, and it is likely that these dividends make it difficult to opt for an altered version of togetherness. At the same time, the gender dualism of a heteronormative division of labour inserts oppression into togetherness, and this may lead couples to seek an unusual way of being together. In these ways, heterosexuality can be read as a multiple and contingent performance, rather than an immovable, unchangeable imperative.
- Full Text:
- Date Issued: 2007
- Authors: Tracey, Tiffany
- Date: 2007
- Subjects: Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Language: English
- Type: Thesis , Doctoral , D Soc Sc (Psych)
- Identifier: vital:11601 , http://hdl.handle.net/10353/176 , Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Description: Heterosexuality often appears as a monolithic way of being that has been disciplinarily defined as right and natural for all sexual subjects (Foucault, 1979). However, it may also be viewed as a social construction, subject to alteration and variation according to social and historical context. In the following research, the stories of ten couples and from the South African soap opera Isidingo reveal the ways that heteronorms shape togetherness between men and women. In the research a queer stance is used to interrogate the ways that togetherness appears as natural and normal, such that the contingency of such togetherness is revealed. The queer stance was used to unsettle the unquestioned assumption of heteronormativity by interrogating the construction from a political position not included by the norm (Stein & Plummer, 1994). Within the general queer stance the concept of performance has been used to account for the ways in which subjects are able to unsettle normative constraints: Butler’s (1993) conception of repetition, Holzman’s (1991) account of the revolutionary developmental potential of performance, Billig’s (1991) understanding of the rhetorical constructions of everyday philosophers. Further Bakhtin’s (1994) dialogic ontology suggests that utterances, performances and/or narratives Using these theoretical underpinnings, the narratives show how stories of togetherness collude with heteronorms while at the same time existing alongside alternative forms of togetherness. Possibly because norms are broad, overarching constructions, they do not define the entirety of the couples’ tales. Rather moments of resistance and alteration are interwoven with normative themes. This unpredictable ambivalence appears in the couples narratives as the assertion that all relationships are the same, and that all relationships are unique. Couples position themselves within a social network, and this network instructs the couple on heteronormative ways of being together. They also witness normative performances in a way that is similar to the observation of disciplines, suggested by Foucault (1979). Although couples often go with their social network’s observations, the manner in which couples position themselves within this network assists them in arguing for alternatives to heteronorms. Spatial expressions also at times serve to fix togetherness. Homes are structured in line with social constructions of heteronorms. However, couples can and do mould their understandings of their homes, such space is reveal as an intersection between social and individual concerns. Narratives of work again reveal that heteronorms structure but can also be ignored within heterosexual relationships. Couples tell of receiving particular benefits from normative performances, and it is likely that these dividends make it difficult to opt for an altered version of togetherness. At the same time, the gender dualism of a heteronormative division of labour inserts oppression into togetherness, and this may lead couples to seek an unusual way of being together. In these ways, heterosexuality can be read as a multiple and contingent performance, rather than an immovable, unchangeable imperative.
- Full Text:
- Date Issued: 2007
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