South Africa (SA) is food secure on a national level, however citizens in rural and marginalised areas face household food insecurity due to lack of access to this food. South Africa has low fertility soils and scarce water resources. Climate change reports of unpredictable weather conditions will further exacerbate these challenges. The majority of the agricultural production methods in SA are industrialised and rely heavily on external inputs. Alternative agricultural production methods which are environmentally less taxing, are affordable and yield nutritious food, need to be investigated and adopted. A long-term trial investigating the differences in yields between conventional and organic farming systems was established at the NMMU George Saasveld campus. A baseline study preceded the cropping seasons to establish pre-treatment soil conditions before the two farming systems were be implemented. The trial was a randomized complete block design split into organic, conventional and control plots. In the first cropping season (summer) three crops cabbage (Brassica oleracea var. capitata), sweet potato (Ipomea batatas) and cowpea (vigna ungucuilata) were planted under the different treatments. Soil fertility changes after application of chemical and organic fertilizer were measured. Soil pH and phosphorus increased whilst potassium and soil carbon decreased from baseline levels. The organic plots were found to have higher soil pH, potassium and carbon, whilst P was higher in the conventional plots. The organic cabbages had a yield 12% lower than conventional cabbages, organic cowpeas were 51% lower than conventional cowpeas. Baboons damaged sweet potato plots before maturity. Broccoli (Brassica oleracea var. italica), radish (Raphanus sativa) and green pea (Pisum sativum) were planted in the second cropping season (winter). Organic broccoli yields were 51% lower than conventional broccoli, organic green peas were 18 % lower than conventional green peas. The organic radish yields were 36% lower than conventional yields and this was statically significant. The yield differences were statically significant between control and conventional cabbages (25%) and broccolis (68%). The results indicate that there is on average an initial 25% yield difference between organic and conventional farming systems. Similar studies have shown that the yield gap can be reduced within three to four years. This study presents preliminary results of trials that are to continue for ten years, during which time the yield differences may vary.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:26946 |
| Date | January 2016 |
| Creators | Mashele, N'wa-Jama |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | xiii, 121 leaves, pdf |
| Rights | Nelson Mandela Metropolitan University |
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