An integrated approach for the delineation of arable land and its cropping suitability under variable soil and climatic conditions in the Nkonkobe municipality, Eastern Cape, South Africa
- Authors: Manyevere, Alen
- Date: 2014
- Subjects: Soils -- Classification -- South Africa -- Eastern Cape , Soil degradation -- South Africa -- Eastern Cape , Ethnoscience -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11965 , http://hdl.handle.net/10353/d1019856 , Soils -- Classification -- South Africa -- Eastern Cape , Soil degradation -- South Africa -- Eastern Cape , Ethnoscience -- South Africa -- Eastern Cape
- Description: Arable crop production in Nkonkobe Municipality is low due to abandonment of potentially productive land and low productivity of the cultivated land. Little attention has been given to farmers perspectives with regards to crop production and land abandonment. Understanding the relationships of indigenous knowledge systems, where local approaches to soil classification, appraisal, use and management and land evaluation, and scientific approaches could be important for the effective use of available soil resources while avoiding those resources that are vulnerable to degradation. In addition, the interactions between soil factors and climate could be useful in understanding the erodibility of soils. The intergration of scientific research and indigenous knowledge systems could help in the identification and delineation of high potential land and on crop suitability evaluation. The objectives of the study were: (i) to determine farmers‟ perspectives with regards to land utilisation and abandonment, constraints on crop production and crop preferences, (ii) to integrate and compare indigenous knowledge systems with scientific approaches of soil classification and potential, (iii) to determine the effect of climate and soil factors on erodibilities of soils in the Municipality (iv) to delineate arable land and evaluate its suitability for maize, potato, sorghum and cowpea under rainfed agriculture. Using semi-structured and open-ended interviews, information on limitations to crop production, cropping preferences, indigenous soil classifications, cropping potential ratings and erosion was captured. Descriptive and correlation statistics were used to analyse farmers‟ responses. The information was later used for a pilot participatory mapping and the determination of the agricultural potential of the soils in three selected villages of the Municipality. Field boundaries of soil texture, colour, depth, and slope position were captured using global positioning systems (GPS). The relationship between the degree of erosion and soil and slope factors was analysed by step-wise regression. Crop suitability for rainfed agriculture was done using the FAO guidelines for Land evaluation for rainfed agriculture. The spatially referenced crop suitability classes were produced by applying the Law of Limiting Combinationusing GIS Boolean Logic. The major biophysical factors, affecting crop production and land utilisation were soil degradation and low and erratic rainfall, while other factors included lack of farming equipment and security concerns. Maize, spinach and cabbage were the main crops grown, with maize sorghum and wheat the most abandoned crops. While it was difficult to accurately correlate indigenous classification with international scientific classification, the importance of colour, texture and soil depth for both classification and soil potential, suggests that some form of correlation is possible which enabled communication and other extension information to be conveyed. The shallow and stony soil (urhete) correlated well with the Leptosols in World Reference Base (WRB) or Mispah and shallow Glenrosa soils in the South African system. The red structured clays (umhlaba obomvu) matched the Nitisols in WRB or Shortlands in the South African system. The non-swelling black clayey soils (umhlaba omnyama) matched soils with melanic A horizons in both the WRB and South African soil classification systems. The dongwe and santi soils developed in alluvial sediments belonged to the Dundee, Oakleaf or Augrabies soils in the South African classification system and fluvisols or Cambisols in the WRB system. There was good agreement between farmers assessment of the cropping potential and scientific approaches but scientifically high potential red soils were rated lowly by the farmers due to difficulties in management caused by shortages of farm machinery, especially under dryland farming. Overall, the soil factors affecting erosion were influenced largely by climate, while parent material was also important. Climate had a dominant influence on soil factors most notably fine sand and very fine sand fractions and exchangeable sodium percentage being more important on soil forms occurring in arid and semi-arid climate and less in the sub-humid and humid areas, where clay mineralogy, particularly kaolinite and sesquioxide dominated. Dolerite derived soils were the most stable and should be given the highest priority for cropping development while mudstone and shale derived soils had a lower cropping potential. While slope gradient and length had some effect on soil erosion in arid and semi arid environments its influence was generally overshadowed by soil factors especially in humid zones. Cow pea and sorghum were the most adapted crops in the region while potato and maize were marginally suitable under rainfed agriculture. The study revealed that most adapted crops were not necessarily the most preferred crops by the farmers. A small percentage of the land was delineated as arable and therefore optimisation of this available land should be prioritized.
- Full Text:
- Date Issued: 2014
Optimization of the vermidegradation of cow dung – waste paper mixtures
- Authors: Unuofin, Frank Oshioname
- Date: 2014
- Subjects: Biodegradation , Vermicomposting , Waste paper , Earthworm culture , Phosphatic fertilizers
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11966 , http://hdl.handle.net/10353/d1021276 , Biodegradation , Vermicomposting , Waste paper , Earthworm culture , Phosphatic fertilizers
- Description: Vermicomposting is an eco-friendly waste management strategy. Its successful performance necessitate that key functioning parameters like earthworm stocking density, nutrient enrichment be established for each target waste/waste mixture. One main target waste mixture in South Africa, and in the University of Fort Hare in particular is waste paper mixed with cow dung and rock phosphate (RP) for phosphorus (P) enrichment. This study was carried out to address the following specific objectives, to determine (i) the effect of Eisenia fetida stocking density on the bioconversion of cow dung waste paper mixtures enriched with rock phosphate, (ii) an optimum application rate of low grade South African Rock Phosphate and time required for efficient vermicomposting of cow dung-waste paper mixtures, and (iii) to determine if the phosphorus in RP is responsible for improved biodegradation during the vermicomposting of cow dung-waste paper mixtures. Results of this study revealed that bioconversion of cow dung waste paper mixtures enriched with RP was highly dependent on E. fetida stocking density and time. The stocking density of 12.5 g-worms kg-1 feedstock of the mixtures resulted in highest earthworm growth rate and humification of the waste mixture as reflected by a C: N ratio of < 12, polymerization index (PI) or humic acid/fulvic acid ratio of > 1.9, and a humification index of >13 for the cow dung waste paper mixtures. A germination test carried out also revealed that the resultant vermicompost had no inhibitory effect on the germination of tomato, carrot, and radish. Extractable P increased with stocking density up to 22.5 g-worm kg-1 feedstock, suggesting that for maximum P release from RP enriched wastes, a high stocking density should be considered. Informed by an earlier study which demonstrated that RP improved vermidegration, a follow up study was done to determine the optimum amount of rock phosphate necessary for efficient vermidegradation of cow dung waste paper mixtures while ensuring a phosphorus rich vermicompost. The results showed that addition of RP at rates ≤ 1% P as RP efficiently enhanced the bioconversion of cow dung waste paper mixtures as reflected by low C: N ratio, high polymerization index (PI), HI and HR used as maturity indicators for matured compost. Final vermicompost products obtained at minimum amounts of RP application rates resulted highly humified vermicompost with finer morphological structure, with no inhibitory effect on the germination of tomato, carrot, and radish similar to the ones obtained at higher RP rates. The findings suggest that 1%P as RP application rate is optimum for efficient vermidegradation of cow dung waste paper mixtures. Since P or Ca happen to be the most prevalent elements in most rock phosphate used for compost enrichment, a study was carried out to determine if P or Ca in RP is predominantly responsible for the improved biodegradation of cow-dung waste paper mixture observed during vermicomposting. Phosphorus sources in form of triple superphosphate (TSP), phosphoric acid (PHA) and Ca in form of calcium chloride (CaCl2) salt were compared with rock phosphate. The results from the study indicated that TSP, a water soluble P source, resulted in greater and faster degradation of the waste mixtures than RP while the Ca source had the least effect. With TSP incorporation the compost maturity C: N ratio of 12 was reached within 28 days while RP, PHA and CaCl2 needed 42, 56 and more than 56 days, respectively. The results indicated that P was largely responsible for the enhanced bioconversion of the waste mixtures. This appeared linked to the effect of P to stimulate microbial growth as reflected by higher microbial biomass carbon levels where water soluble P sources were applied. The C: N ratios of the final vermicomposts at day 56 were 10, 11.5, 13, 14, and 23 for TSP, RP,PHA, Control (No P added) and CaCl2 treatments, respectively. Although TSP gave superior superior performance, RP may still be the preferred additive in the vermicomposting of cow dung waste paper mixtures as it is cheaper and produces mature compost in a shorter period of 8 weeks. Generally, the results of this study have shown that the vemidegradation of cow dung waste paper mixtures can be optimized through adoption of an E. fetida stocking density of 12.5g- worm kg-1 and an RP incorporation rate of 1% P as RP. However, higher rates of RPincorporation may be adopted where final vermicomposts with higher P fertilizer value are desired. Phosphorus appears to be the RP constituent responsible for its ability to enhance the vermidegradation of cow dung waste paper mixtures. Future studies should explore the effectiveness of other P-bearing minerals for their effectiveness in enhancing vemidegradation.
- Full Text:
- Date Issued: 2014