Most fertilisers applied to Namibian crop fields are imported, yet Namibia has vast resources that could be used to improve soil fertility. Organic fertilisers such as animal manure and compost could be sourced from farms, or grown on the crop fields, such as green manures and fertiliser trees, or harvested from nature, such as kelp and guano, or sourced from abattoirs or other agricultural processing facilities, such as blood, bone, horn, feather, fish and seed meals. Inorganic fertilisers are usually sourced from quarries or mines on land, while others can be extracted from seawater or salt. Some locally-sourced fertiliser materials could be applied directly to the soil, perhaps after simple processing such as crushing or milling, or after more complex processing such as through chemical reactions. Rock salt and brine solution have been analysed to assess their suitability for extraction of nutrients from which to manufacture chemical fertilisers as byproducts of purifying the salt for industrial uses. It is important that harvesting of rock salt and brine from pans north of Cape Cross be done without disrupting the natural regeneration through underground connection to the sea, to ensure sustainability of these valuable resources. Labelling of fertilisers should include a breakdown of the major elements contained, so that farmers who test their soils could determine appropriate application rates to balance minerals that will produce crops of good quality. Keywords: by-products, fertiliser, inorganic fertiliser, manure, organic fertiliser, productivity, soil fertility.