Impacts of the subsidy programme on maize yields and production are critical for programme benefits, and hence estimating these impacts is critical for economic cost benefit evaluation of the programme. Increases in production result from the yield response to incremental fertiliser use as a result of the programme, and lead to changes in average maize yields. These, together with any changes in crop areas, lead to changes in total maize supply from smallholder production. This in turn affects smallholder maize consumption, the balance between overall maize supply and demand in the country, and maize prices. This report presents information on these elements in the maize system in attempting to develop a consistent understanding of programme production and other impacts. We begin from an examination of historical changes in maize prices and supply to provide a context for examination of changes in maize yields and production, which in turn informs estimation of the yield response to and incremental production from the subsidy programme.