Effects of BT Maize (MON810) crop and its residues on selected soil biological properties and N and P release in a sandy loam soil from Alice, Eastern Cape, South Africa
- Authors: Landzela, Besule
- Date: 2013
- Subjects: Bacillus (Bacteria) , Bacillus thuringiensis , Corn -- Planting , Biomass , Plant proteins , Enzymes , Soil fertility , Crop residue management
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11870 , http://hdl.handle.net/10353/d1007542 , Bacillus (Bacteria) , Bacillus thuringiensis , Corn -- Planting , Biomass , Plant proteins , Enzymes , Soil fertility , Crop residue management
- Description: There are apprehensions that genetic modification of maize with Bacillus thuringiensis (Bt) may have negative effects on soil biodiversity, ecosystem processes and functions. This study aimed at determining the effect of Bt maize crop, Bt maize residues and its genetic modification on microbial biomass carbon (MBC), selected enzyme activities, vesicular arbuscular mycorrhizal (VAM) fungi and N and P release patterns. The study was conducted under field, glasshouse and laboratory conditions. In 2010/2011 season, four maize cultivars; DKC 61-25B (Bt), DKC 61-24 (non-Bt), PAN 6Q-321B (Bt) and PAN6777 (non-Bt) were planted. Determination of MBC, enzyme activities and fungal spore count was done at 42, 70, and 105 days after planting (DAP). A loam soil amended with Bt or non-Bt maize leaf residues from a study of 2009/2010 season was incubated to investigate effects of Bt maize residues on MBC and soil enzyme activities. Leaf residues of Bt and non-Bt maize cultivars (DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777) were used and soil without residues was used as a control. Samples were collected at 7, 28 and 56 days of incubation (DOI). An incubation study was also carried out in the laboratory to determine the effect of Bt maize residues (i.e. leaf, stem and root) and its genetic modification on N and P release patterns. Residues of DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777and soil without residues as a control were incubated in the laboratory. After destructive sampling at 0, 7, 14, 28, and 56 DOI, N in the form of NH4-N and NO3-N and P mineralisation were determined. Amendment of soil with residues enhanced MBC (p < 0.05) at all the sampling dates. For example MBC increased from 95 in the control to 146.3 mg/kg in the DKC 61-25B treatment at the end of the glasshouse trial. In the field DKC 61-25B had 9.1 mg/kg greater MBC than DKC 61-24, while PAN 6Q-321B had 23.9 mg/kg more MBC than PAN6777 at the end of the trial. However, no differences (p < 0.05) were observed in enzyme activities under field and glasshouse conditions except for dehydrogenase that had greater activity where DKC 61-25B and PAN 6777 were grown. There were no differences between the type of residues (Bt and non-Bt) on enzyme activities tested. However, differences were observed among the sampling dates. No effects of Bt maize crop on fungal spore count were observed. Similarly no differences were observed in leaf, stem and root tissues composition between Bt and non-Bt maize cultivars. Net N and P mineralisation from Bt maize cultivars did not differ from that of non-Bt maize cultivars. However, differences were observed among the cultivars. The results of this study suggested that Bt maize with Bt MON810 event can be grown in the central region of the Eastern Cape (EC), South Africa without affecting MBC, soil enzyme activities, VAM, and release of N and P nutrients from its residues.
- Full Text:
- Date Issued: 2013
- Authors: Landzela, Besule
- Date: 2013
- Subjects: Bacillus (Bacteria) , Bacillus thuringiensis , Corn -- Planting , Biomass , Plant proteins , Enzymes , Soil fertility , Crop residue management
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11870 , http://hdl.handle.net/10353/d1007542 , Bacillus (Bacteria) , Bacillus thuringiensis , Corn -- Planting , Biomass , Plant proteins , Enzymes , Soil fertility , Crop residue management
- Description: There are apprehensions that genetic modification of maize with Bacillus thuringiensis (Bt) may have negative effects on soil biodiversity, ecosystem processes and functions. This study aimed at determining the effect of Bt maize crop, Bt maize residues and its genetic modification on microbial biomass carbon (MBC), selected enzyme activities, vesicular arbuscular mycorrhizal (VAM) fungi and N and P release patterns. The study was conducted under field, glasshouse and laboratory conditions. In 2010/2011 season, four maize cultivars; DKC 61-25B (Bt), DKC 61-24 (non-Bt), PAN 6Q-321B (Bt) and PAN6777 (non-Bt) were planted. Determination of MBC, enzyme activities and fungal spore count was done at 42, 70, and 105 days after planting (DAP). A loam soil amended with Bt or non-Bt maize leaf residues from a study of 2009/2010 season was incubated to investigate effects of Bt maize residues on MBC and soil enzyme activities. Leaf residues of Bt and non-Bt maize cultivars (DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777) were used and soil without residues was used as a control. Samples were collected at 7, 28 and 56 days of incubation (DOI). An incubation study was also carried out in the laboratory to determine the effect of Bt maize residues (i.e. leaf, stem and root) and its genetic modification on N and P release patterns. Residues of DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777and soil without residues as a control were incubated in the laboratory. After destructive sampling at 0, 7, 14, 28, and 56 DOI, N in the form of NH4-N and NO3-N and P mineralisation were determined. Amendment of soil with residues enhanced MBC (p < 0.05) at all the sampling dates. For example MBC increased from 95 in the control to 146.3 mg/kg in the DKC 61-25B treatment at the end of the glasshouse trial. In the field DKC 61-25B had 9.1 mg/kg greater MBC than DKC 61-24, while PAN 6Q-321B had 23.9 mg/kg more MBC than PAN6777 at the end of the trial. However, no differences (p < 0.05) were observed in enzyme activities under field and glasshouse conditions except for dehydrogenase that had greater activity where DKC 61-25B and PAN 6777 were grown. There were no differences between the type of residues (Bt and non-Bt) on enzyme activities tested. However, differences were observed among the sampling dates. No effects of Bt maize crop on fungal spore count were observed. Similarly no differences were observed in leaf, stem and root tissues composition between Bt and non-Bt maize cultivars. Net N and P mineralisation from Bt maize cultivars did not differ from that of non-Bt maize cultivars. However, differences were observed among the cultivars. The results of this study suggested that Bt maize with Bt MON810 event can be grown in the central region of the Eastern Cape (EC), South Africa without affecting MBC, soil enzyme activities, VAM, and release of N and P nutrients from its residues.
- Full Text:
- Date Issued: 2013
The economics of Bt maize/yieldgard production: case of smallholder farmers in the Eastern Cape Province
- Mandikiana, Brian Washington
- Authors: Mandikiana, Brian Washington
- Date: 2011
- Subjects: Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11167 , http://hdl.handle.net/10353/326 , Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Description: Maize is the staple food for most South Africans. This implies that any damage to the maize crop will affect food security of many South Africans. Although Eastern Cape Province is not a traditionally maize producing area, smallholder farmers in the province produce it mostly for subsistence purposes and some sell the surplus on the local market or use it to secure other good through barter trading. In South Africa, insect-resistant Bt maize/yieldgard has been used commercially for approximately 10 years now. Available impact studies on Bt maize reveal that, this technology is beneficial not only to farmers but consumers of maize products as well. Welfare gains as well as positive effects for human health are realised by both groups. Due to the costs and effectiveness associated with traditional and conventional maize stem borer control methods, Bt technology has the potential to be part of the solution. This thesis has attempted to investigate the economic viability of planting Bt maize seeds under smallholder farming conditions and identify factors as well as perceptions relating to attributes of Bt maize and to analyze the relationships between those perceptions and choices regarding use of Bt technology. Data was collected from 90 households who were selected using purposive sampling through the use of the snowball method. To collect data, a questionnaire was administered through face-to-face interviews. Gross margin analysis revealed that Bt maize is a more profitable option as compared to conventional maize seeds. Furthermore, econometric analyses, through use of the binomial regression model revealed that perceptions could be used to distinguish between users and non-users of Bt maize seed in the Eastern Cape Province. Results of inferential analysis indicate that the statistically significant variables at 5% level are gene erosion, quality and nutrition of products and food labels for Bt maize products perceptions. On the other hand, low expenses, seed market availability and farmers’ knowledge perceptions were significant at 10%. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of Bt maize adoption. In view of the research findings, several policy proposals are suggested to support policy formulation. Key words: Bacillus thuringiensis (Bt) maize, yieldgard, smallholder farmers, perceptions, Flagstaff, gross margin analysis, binomial logistic regression model, Eastern Cape Province.
- Full Text:
- Date Issued: 2011
- Authors: Mandikiana, Brian Washington
- Date: 2011
- Subjects: Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11167 , http://hdl.handle.net/10353/326 , Corn -- Planting , Corn -- South Africa -- Eastern Cape , Corn -- South Africa -- Economic conditions , Farms, Small -- South Africa -- Eastern Cape , Bacillus thuringiensis , Bacillus (Bacteria) , Food security -- South Africa -- Eastern Cape , Food supply -- South Africa -- Eastern Cape
- Description: Maize is the staple food for most South Africans. This implies that any damage to the maize crop will affect food security of many South Africans. Although Eastern Cape Province is not a traditionally maize producing area, smallholder farmers in the province produce it mostly for subsistence purposes and some sell the surplus on the local market or use it to secure other good through barter trading. In South Africa, insect-resistant Bt maize/yieldgard has been used commercially for approximately 10 years now. Available impact studies on Bt maize reveal that, this technology is beneficial not only to farmers but consumers of maize products as well. Welfare gains as well as positive effects for human health are realised by both groups. Due to the costs and effectiveness associated with traditional and conventional maize stem borer control methods, Bt technology has the potential to be part of the solution. This thesis has attempted to investigate the economic viability of planting Bt maize seeds under smallholder farming conditions and identify factors as well as perceptions relating to attributes of Bt maize and to analyze the relationships between those perceptions and choices regarding use of Bt technology. Data was collected from 90 households who were selected using purposive sampling through the use of the snowball method. To collect data, a questionnaire was administered through face-to-face interviews. Gross margin analysis revealed that Bt maize is a more profitable option as compared to conventional maize seeds. Furthermore, econometric analyses, through use of the binomial regression model revealed that perceptions could be used to distinguish between users and non-users of Bt maize seed in the Eastern Cape Province. Results of inferential analysis indicate that the statistically significant variables at 5% level are gene erosion, quality and nutrition of products and food labels for Bt maize products perceptions. On the other hand, low expenses, seed market availability and farmers’ knowledge perceptions were significant at 10%. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of Bt maize adoption. In view of the research findings, several policy proposals are suggested to support policy formulation. Key words: Bacillus thuringiensis (Bt) maize, yieldgard, smallholder farmers, perceptions, Flagstaff, gross margin analysis, binomial logistic regression model, Eastern Cape Province.
- Full Text:
- Date Issued: 2011
- «
- ‹
- 1
- ›
- »