- Title
- Studies on soil acidity management strategies for sustainable agriculture
- Creator
- Swart, Nicolas
- Subject
- Soil acidity
- Subject
- Soil fertility
- Subject
- Sustainable agriculture
- Date Issued
- 2024-12
- Date
- 2024-12
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10948/69475
- Identifier
- vital:77260
- Description
- Soil acidity is a widespread problem which reduces plant growth and yield. There are calls for alternative crop and soil management strategies that can be used by farmers to deal with soil acidification in a sustainable manner. Current literature suggests that the benefits of sustainable soil management systems on soil acidity are highly variable, and within the context of conservation agriculture (CA), farmers need recommendations for techniques to improve liming efficiency. Such techniques include acid resistant cultivars and soil amendments such as biochar. However, dedicated scientific research is still needed to increase our understanding of the benefits of integrating various sustainable agriculture approaches on reducing the acidity on cropped lands. A series of experiments were thus conducted to test whether the integration of reduced lime dosages with organic amendments such as biochar, along with acid resistant wheat cultivars could improve nutrient availability and reduce the harms of acidity on plant roots. It was hypothesised that if lower than recommended doses of lime are applied in combination with biochar and acid resistant cultivars, there will be significant improvement of nutrient availability, soil acidity amelioration benefits and crop growth. The first experiment was a 60–day incubation trial to examine the interaction effects of reduced lime application rates and black wattle (Acacia mearnsii) biochar on the acidity and plant nutrient availability of a sandy clay loam, acidic podzolic soil. The changes in pH water (pHw) across treatments were monitored at 10-day intervals over the incubation period. Additionally, the initial and final status of each treatment in terms of essential macro-and micronutrients, pH(KCl), extractable aluminium (ext Al), exchangeable acidity (EA) and acid saturation (AS) were also measured. The second experiment examined the genotype × biochar × lime interaction effects on wheat plant root growth in the acid soil. Soil incubation results showed that the interaction effect of lime rate and biochar was not significant (p>0.05) for any of the tested soil nutrient availability and soil acidity parameters, except for pHw. However, lime rate effects were significant (p<0.05) on AS, EA, pH(KCl) and ext Al. As lime rate increased, the acidity decreased. Increasing the lime application rate significantly (p<0.05) enhanced the cation exchange capacity (CEC), calcium (Ca), magnesium (Mg) and phosphorous (P), but decreased potassium (K) and sulphur (S). The availability of micro-nutrients namely copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) also decreased as the lime rate increased. Biochar effects on EA, AS, pH(KCl) and ext Al were not significant (p>0.05). However, the biochar significantly reduced the availability of Ca and Mn but did not have a significant effecton all the other nutrients at the tested application rates. Unenriched biochar at 10 t ha-1 had an acidifying effect on the soil as it increased EA, when compared to enriched biochar. The significant (p <0.05) biochar × lime × time interaction effect on pHw showed that biochar applied without lime increased pHw, and the benefits were greatest at 10 t ha-1 biochar application rate. Similarly, lime applied without biochar also had a significant positive effect on pHw and the benefit increased at higher lime application rates. After 60 days of incubation, the lime applied at the highest rate of 5 t ha-1 without biochar (0 t ha-1 biochar) had the highest final pHw value. The 3-way interaction of lime, biochar and genotype was not significant (p>0.05). Koonap, the acid tolerant wheat variety outperformed the sensitive variety, Gariep under all treatments in the acid soil, as expected. There was, however, a significant (p<0.05) lime rate × biochar interaction. The highest application rates of lime (5 t ha-1) and biochar (10 t ha-1) were the best combination for root length for both the varieties. Overall, these results suggested a possible buffering effect of biochar at low lime application rates, thus limited benefits of combining reduced lime doses with biochar on reducing soil acidity or enhancing nutrient availability. The null hypothesis was thus rejected, and it was concluded that co-application of reduced lime rates and biochar will not significantly enhance benefits of liming. However, a positive interaction from co-application of biochar and lime on both pH and plant growth is possible at high application rates of both biochar and lime.
- Description
- Thesis (MSc) -- Faculty of Science, School of Natural Resource Science and Management, 2024
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (106 pages)
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
- Rights
- All Rights Reserved
- Rights
- Open Access
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NMU School of Natural Resource Management
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | SWART, N.pdf | 1 MB | Adobe Acrobat PDF | View Details Download |