«JM Thamaga-Chitja March 2008 Submitted in fulfilment of the requirements for degree: Doctor of Philosophy (Food Security), African Centre for Food ...»
5. Table 6.3 shows a comparison of the amount of nutrient (kg) removed by crops to produce one ton of harvest when using a commercial inorganic fertiliser (Hygrotech, 2005). The number of wheelbarrow loads of manure required to provide the equivalent nutrients removed is indicated (van Averbeke & Yogananth, 2003). The strength (nutrient concentration of manure vs. fertilizer) of the commercial fertiliser versus manure is also indicated in Table 6.3.
It is evident from Table 6.3 that the strength of commercial fertiliser is incomparable to manure due to the concentrated form of commercial fertiliser. The current rate of manure application by the Mbumbulu farmers (EFO) is 8998.716 kg/ha or 120 wheelbarrow loads per hectare per annum. One needs comparatively less commercial fertiliser to produce one ton of a crop (Table 6.3). For example, 3.34kg of N is required to produce one ton of cabbage compared to 334 wheelbarrow loads of manure per hectare. As per the decision support tool, indicating the output for all three areas (Appendix C), cabbage production would be limited by inadequate N. It can be unequivocally stated that organic production based on manure as the source of
Evidently, it is not possible for the farmers to have an adequate load of manure given their current livestock level because the mean wheelbarrow loads indicated in table
6.4 are lower than those indicated by the model for crops in appendix D, E and F. The concentration of nutrients in manure depends on several factors. The most important factors that affect the concentration of nutrients in manure are the levels of moisture and its soil content (van Averbeke & Yogananth, 2003). Uncomposted manure kept in an animal enclosure (pen), known as a kraal in rural South Africa, constitutes significant soil (van Averbeke & Yogananth, 2003). It is common practice for manure to be left to accumulate in the animal enclosure where it mixes with soil as animals walk on it. The higher the soil content, the lower the nutrient concentration.
All calculations of wheelbarrows of manure in this study were based on a soil content of 60% in manure as shown in the extensive study of manure by van Averbeke and Yoganath (2003). Table 6.5 presents the results of the manure analysis.
As shown in table 6.5, the manure sample contained low proportions of N, P and K nutrients. In comparison, most commercial fertilisers contain between 20% and 30% of N, P and K nutrients per 100kg of fertiliser (van Averbeke and Yogananth, 2003).
Mkhabela’s (2006) study in the KwaZulu-Natal midlands indicated that: N = (2%), P = (1.5%) and K = (2%), are low, as they are in this study, although the potassium results vary noticeably between the study areas. Nevertheless, it is questionable (especially in Mbumbulu (EFO)) whether farmers can continue to use kraal manure as the sole source of soil nutrition for reasons that include soil fertility imbalances, weed problems, pollution hazards and produce quality.
The number of wheelbarrow loads of manure required to meet crop needs, as shown in Table 6.3 is excessively high. Excessive manure application is prohibited in certified organic farming and may lead to an oversupply of nutrients in the soil, which may lead to imbalances in the soil and contamination by pathogens (BDOCA, 2006;
Kuepper, 2003). Nutrient imbalances in the soil may lead to difficulties in absorption of some minerals, especially micronutrients (Titshall, 2006). Soil samples were collected from the three farmer areas and analysed to assess the state of fertility. As noted previously, the study was concerned only with three nutrients: nitrogen (N), phosphorous (P) and potassium (K). However, the soil results presented in Table 6.6 bear reference only to phosphorous and potassium (K) because nitrogen is unstable in soil due to rapid soil environmental changes that affect the availability of this mineral.
Furthermore, nitrogen also has high leaching tendencies.
The soil analysis presented in Chapter three (Table 3.5) indicates a general deficiency of P in the three study areas. Plants that require large amounts of P will not perform well in such soils without corrective soil nutrition strategies. On the other hand, with the exception of Mbumbulu, all areas have high levels of K. The following three examples are used to evaluate whether areas would be able nutritionally to support
As indicated in Table 6.6, the Mbumbulu soil samples do not currently meet the nutrient requirements of the three examples of crops used, because the reserve nutrient values are lower than crop requirements. This situation is likely to affect yields.
Due to the fact that farmers in Mbumbulu (EFO) were certified organic producers, the demonstration in Table 6.7 presents an important case. Evidently crops such as cabbage would be of limited yield due to the deficit in crop nutrient requirement (NPK). On the other hand, nutrient requirements for salad vegetables, such as tomatoes, onion and garlic, are met except for K in the case of tomatoes. Information presented in Table 6.7 is critical for farmers because it provides a clear picture of which crops would be uneconomical to plant due to possible poor yield because of deficit in nutrient requirements.
It is important to state that corrective soil nutrition plans must take into account the current availability of minerals and soil type. For example, in clay soils, most soil P is not available to plants, even when it is indicated as high in the soil test. Therefore, budgeting for P is more difficult in such soils. Furthermore, the absorption of nutrients by plants is affected by the availability of other minerals in the soil. The mode of application of manure is also an important factor to consider because the method of manure application has a direct relationship to nutrient availability (Magdoff & van Es, 2000). These findings show that farmers need to understand or have access to an extension officer who is able to interpret such soil test results and assist them in designing appropriate soil nutrition improvement plans that take into account their current practices. These plans may include crop rotation and the use of compost.
Three questions were posed and discussed with a view to answering the first subproblem of this study, i.e. what crops can be grown organically by the participating farmers? Mbumbulu met the agronomic requirements of 95% of the crops on the model list. Centocow met the agronomic requirements of 90% of the crops on the model list. Muden met only 80% of the agronomic requirements of the crops on the model list. The popular amadumbe was rejected as a suitable crop for all areas (although by only a small margin for Mbumbulu) due to its very high minimum water requirement. Peach was deemed unsuitable to grow satisfactorily in Muden and Centocow due to its deficit in minimum water requirement and a short rainy season that may not sustain the full crop cycle.
91 Muden deemed unsuitable for both lemon and mint crops due to an inadequate rainy season for grape’s crop cycle and due to low water requirements. The systematic evidence provided by the comparison of commercial fertiliser and pen manure, in relation to crop nutrient needs, showed that all three groups do not meet organic nutrient requirements because of the poor concentration of nutrients in pen manure. In all three areas, the farmers do not have adequate livestock to produce the required number of wheelbarrow loads of manure. Organic production would be difficult to sustain based on the current manure availability. The poor nutrient condition of their soils (Table 3.2) in relation to current crop nutrient requirements is an unsustainable and unbalanced condition which can only contribute to accentuate soil deterioration.
Evidently, the current farming practices of all three groups do not meet organic nutrient requirements and are not sustainable. The continued ‘harvesting’ of alreadydepleted soils without proper soil enrichment will have a detrimental effect for all three groups.
The following section provides an account on the farmers’ experience of the tool, including testing of the model, group discussions, opinion, impressions and usefulness of the tool.
6.4 Threats to commercialisation of organic farming Agriculture makes a small but important contribution to household food security in the poor former homelands of South Africa by functioning as a buffer against hunger and poverty. Despite the fact that there are indications that organic farming may offer smallholder farmers opportunities to realise commercial goals that may not be possible through conventional agriculture, this study has shown that smallholder farmers are faced with a lack of resources to realise commercial goals. The purpose of this section is to crystallise constraints that threaten the commercial production of identified crops.
Exclusive organic farming is based on total elimination of synthetics inputs in production and processing of agricultural products. The definition of production risks for this study is based on the risk related to the elimination of agrochemicals in
Table 6.8 is a summary of presents elements that present a threat to the commercialisation of organic farming.
Evidence presented in section 3.1 and Table
3.1 indicates that all the groups studied are essentially practicing rain-fed agriculture due to a lack of irrigation or effective irrigation. Shortage of water is detrimental to productivity and improved yields. All three farmer groups are unable to solve their irrigation or lack thereof on their own. External assistance in the form of providing irrigation infrastructure is essential.
Lack of effective irrigation is a threat to organic production and or expansion thereof for participating farmers. Lwayo et al (2006) discovered that EFO farmers have not
Poor knowledge of organic farming and disease control among all three groups is a major threat for organic agriculture, especially for EFO who are certified organic producers and are prohibited from using agrochemicals. As most crop disease is prevalent when there is water, participating farmers are likely to experience most diseases during the most productive period, threatening yields and livelihoods.
Mean annual rainfall data was used to determine the availability of water during the summer months for the three areas. A special rainfall distribution model, as explained in Chapter five, section 5.2.3, was used to determine the monthly rainfall. The probability of disease onset was based on water availability and warm summer temperatures. The availability of moisture (rainfall) was used as a basis for setting the disease risk profile and is presented in Table 5.2. The disease risk profile is delivered in three ranges, as low, medium and high risk of development. Appendix D, E and F present model outputs for the three areas where the annual disease risk is detailed. A summary of the disease risk output derived from Appendix D, E and F, which relates to periods of high moisture (summer months), is presented in Table 6.9.
It is evident from Table 6.9 that periods of high moisture (November to March) are related to high risk of disease occurrence. Mbumbulu is the most risky area for disease onset. Mbumbulu has higher humidity levels compared to the other areas due to the proximity to the coast and a high rainfall (Camp, 1999). Muden can be associated with medium risk for disease onset.
94 According to Table 6.9, October is associated with the onset of the period of increased risk of disease, but these months are also those that the farmers look forward to because of their rainfall. During October to March, farmers are faced with disease management decisions. As stated earlier, agrochemicals are forbidden in certified organic farming. Organic farmers require adequate knowledge of natural disease control. The lack of knowledge of natural disease control was reported as one of the production constraints for all groups. This is a serious problem that will continue to hamper success for the Mbumbulu (EFO) certified farmers and may deter the Muden and Centocow farmers from practising certified organic agriculture.
Lack of extension services, as stated by the Centocow group and EFO, is a threat to information needs of farmers. Stefano (2005) reiterates that access to agricultural information is problematic to rural farmers. Furthermore, extension officers are mostly trained in conventional farming techniques and would find it challenging to support organic farmers.