Short-term trials often fail to show good response to K application. In addition, such trials are often conveniently placed close to easy access roads in fertile valleys where K fertility is not an issue. It is on higher land that K is in short supply and where crops respond well to its use. Linked to the lack of awareness is the lack of advice. In many countries of sub-Saharan Africa, government advisory services are in disarray and, even if extension officers are aware of the appropriate use of fertilizers, their limited funding prevents them from promoting them properly.
Lack of awareness leads to lack of demand and lack of the second 'A' - Availability .
Input suppliers target commercial growers and do not waste their marketing resources targeting farmers who cannot afford to buy the product. Not only is this what farmers themselves want but governments and donors recognize that foreign private sector investment is crucial to achieving the growth rates needed to reduce poverty, ensure greater food security and protect the natural resource base. The logistical problems associated with purchasing fertilizer, when there are no suppliers in the immediate neighbourhood, and the only means of travel available to smallholder farmers is by foot or by bicycle, highlights another of the 'A's - Accessibility . They need a local supplier who, in turn, needs to be confident that the purchased stock will be sold. Here, perhaps, is the pivotal point at which accessibility, availability and affordability come together.