CHAPTER 2 LITERATURE REVIEW
2.7. SUMMARY
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financial stress to all farmers. Therefore, the use of HEDMs will be helpful, as they are potentially cheap and LaDePa will be potentially beneficial due to its organic nature and soil conservation and amelioration qualities.
The Food and Agriculture Organisation (FAO) has encouraged climate-smart agriculture (CSA) as a way to mitigate the effects of climatic changes on agriculture (Kaczan et al., 2013).
These are ways (such as conservation agriculture) that can be implemented by farmers to ensure food security, sustainability and reduction of greenhouse gas emissions (e.g. ammonia and nitrous oxide) from farmland fertiliser application under current climatic conditions. Fertiliser application practices, such as foliar application, soluble fertiliser granules application, deep placement and fertigation (fertiliser dissolved in water that is used for irrigating crops), help in the reduction of greenhouse gas emissions (Lipper et al., 2014). Coupled with these practices, proper application HEDMs, such as struvite and LaDePa, will be effective in reducing greenhouse gas emissions since they are slow-release fertilisers, thereby avoiding global warming. Building on this background, the use of HEDMs could benefit farmers and all players within the value chain and also SSA region at large.
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waterless toilets that provide the user with necessary comfort, safety, light and privacy. These toilets were installed mainly in the peri-urban areas surrounding the city of Durban with some installed in selected areas of the city.
Dry sanitation is a cheap alternative compared with the use of waterborne systems. It can save municipalities costs and also provide the needed sanitation to the customer. Also, waste disposal with a waterborne system can result in environmental problems due to the presence of nitrogen and phosphorus in the final effluent which is disposed in the rivers and/or landfills leading to unnecessary environmental costs. Groundwater contamination and eutrophication are the most common problems associated with disposal of wastewater, which are difficult and costly to correct. Even though waste management and containment in dry systems is effective, disposing these wastes is a challenge as they have to undergo treatment first.
A new way a waste disposal was then introduced which saw the conversion of wastes into useable agricultural inputs, HEDMs. Faecal sludge collected from the VIP latrines was developed into an organic fertiliser named Latrine Dehydrated and Pasteurised (LaDePa) pellets, an organic fertiliser and source of nitrogen (3%), phosphorus (1.5%) and potassium (1.5%), which can also be used as a soil ameliorating product. The urine collected from the UDDTs was developed into two products namely, Nitrified Urine Concentrate (NUC), a rich inorganic nitrogen source (21%) and struvite, a rich inorganic phosphorus source (12.6%) which also contains nitrogen (5.6%).
Subsistence farming practises with low rates of adoption of agricultural implements is evident across the SSA. The rate of fertiliser use across SSA is very low, which results in low yields and food insecurity, considering that most families in this region rely on farming for a living.
The rate of fertiliser use, however, among the commercial farmers in this region, is high.
HEDMs could be used to replace or supplement the existing commercial fertilisers. These HEDMs are potentially cheaper agricultural inputs that could reduce farming production costs, which could possibly make the smallholder farmers food-secure.
The world is about to face a phosphorus crisis due to the continuously diminishing phosphorus rock deposits. Phosphorus is a basic plant nutrient source required for crop establishment. Most of the produced phosphorus from phosphate rocks in form of ores is used for agricultural purposes, with only a low amount being used for other industrial purposes. It is predicted that the remaining phosphorus rock deposits may last only a hundred years from now. In this light,
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an alternative phosphorus source has to be established in order to avoid future food crisis.
Struvite, a urine based phosphorus source, can be used as an agricultural fertiliser as it is highly concentrated and comparable to the existing commercial phosphorus fertilisers. This may help in alleviating the phosphorus threat that the world is currently facing.
South Africa is one of the biggest fertiliser producers in SSA. It, however, imports raw fertiliser products from different countries across the globe to process them into finished products for local use with the remainder being exported, mostly to other southern African countries. There is a net fertiliser trade deficit as the amount that is exported is less than the amount that is imported into the country. South Africa is, however, a price taker in the global fertiliser trade, as it consumes less than 1% of the total global fertilisers used. The government has removed fertiliser import barriers in an effort to reduce fertiliser prices, hence fertiliser prices are only affected by international markets, especially the Rand/USD exchange rate.
The farm gate fertiliser prices are higher than prices of imported fertiliser due to shipment, handling, packing and transportation costs. However, most subsistence farmers cannot afford the fertilisers because of low income. Creation of HEDMs does not only bring business opportunities, job creation or an effective sanitation provision, but will also lead to reduced fertiliser imports and increased fertiliser exports, thereby enlarging the stake of agribusinesses in the total GDP of South Africa.
Due to the rising concerns about global warming, climate-smart agriculture is now preferable to reduce the level of greenhouse gas emissions into the atmosphere. Chemical fertiliser application can lead to the release of nitrous oxide and ammonia from farmlands, which causes global warming. Conservation agriculture and organic farming may help in reducing these emissions. Organic farming is also gaining popularity due to environmental conservation practises it is associated with, such that certain consumers are prepared to spend an extra amount for organic foods. LaDePa, an organic HEDM can be used in organic farming and can potentially bring the same yields and quality products as those developed from commercial organic fertilisers. Building on this, HEDMs should thoroughly be tested in order to prove their competitiveness on the market and in production of crops as they show great potential as plant nutrient sources.
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