FarmLime: Low-cost lime for small-scale farming

Mitchell, C.J. ORCID: 2005 FarmLime: Low-cost lime for small-scale farming. Nottingham, UK, British Geological Survey, 138pp. (CR/03/066N) (Unpublished)

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FarmLime (Low-cost lime for small-scale farming) is a multidisciplinary research project that aims to increase the food security of small-scale farmers by improving their access to agricultural lime which neutralises soil acidity and adds nutrients. This project focused on farming districts in northern Zambia that have highly acidic soils with poor crop yields. The aim was to locate suitable carbonate rocks in these farming districts and produce agricultural lime using a low cost method, eliminating the high transportation costs that farmers currently incur if they use lime. Perceptions The commonly held view is that small-scale farmers do not use agricultural lime because they don’t appreciate its benefits, it is expensive and difficult to obtain. A socio-economic survey carried out in Solwezi and Mkushi confirmed some of these views but indicated that farmers knew the benefits of using lime and that uptake of agricultural lime could be encouraged. The main constraints on the use of lime were the absence of soil testing and a lack of cash in the rural economy. Lime Resources Carbonate rocks occur throughout Zambia including those farming districts with highly acidic soils. A technical evaluation programme found that the dolomite from Solwezi and Mkushi is suitable for the production of agricultural lime. It has a Neutralising Value (NV) of 103–104% and a magnesium oxide (MgO) content of 19–21%. Dolomite suitable for agricultural lime(minimum 80% NV and 6% MgO) occurs in seven of the nine Zambian provinces. Lime Production A low cost production method would be an ideal way to provide agricultural lime for small-scale farmers. Current production methods and the best means of extracting and milling dolomite on a small scale were investigated. Large-scale operations use open cast quarrying, crushing and milling of dolomite to produce agricultural lime. This could be replicated on a small-scale using manual extraction and crushing, and hammer milling. The costs of producing agricultural lime from the Mkushi dolomite by large-scale operations are estimated to be US$31 per tonne. Thiscost could be reduced to about US$20 per tonne by quarrying a softer dolomite and incorporating a manual jaw crusher for the crushing stage. Following this research, entrepreneurs in Solwezi started small-scale production of agricultural lime. Crop Trials The most effective means of showing the benefits of using agricultural lime was thought to be through demonstration crop trials. Therefore, maize and groundnut trials were set up in Chalata and Kasansama camps in Mkushi. These sites had highly acidic soils (pH 4.6 to 5) and low crop yields (e.g. 1.5 tonnes of maize per hectare). The limed plots produced up to 6.7 tonnes of maize and up to 320 kg of groundnuts per hectare. These trials have convinced neighbouring farmers to use locally produced lime (from HiQwalime at US$1 per 50 kg bag). Economics The main economic justification for the use of agricultural lime is that money could be raised through the sale of surplus crops. Where the price of maize is high and the cost of agricultural lime is low the economic benefits are very high. However, where the opposite is true the economic benefits are marginal although still in favour of using lime. However, despite these positive economic benefits uptake of lime will still depend on the availability of cash in the rural economy.

Item Type: Publication - Report
Programmes: BGS Programmes > Economic Minerals
Funders/Sponsors: Great Britain. Department for International Development
Additional Information. Not used in RCUK Gateway to Research.: This item has been internally reviewed but not externally peer-reviewed
NORA Subject Terms: Earth Sciences
Date made live: 14 Jan 2010 12:27 +0 (UTC)

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