Soil productivity has been declining in the central highlands of Kenya due to intensive cropping. To obtain information on potential points which could be managed to better conserve nutrients within the farming system, the flux of nitrogen and phosphorus was monitored in four randomly selected farms in Embu District during the 1990/91 short rainy season and in three farms during the same season in 1991/92. Grain yields, stover production, stover removal, and fertiliser and manure use were measured. Maize yields on average were nearly 4 t/ha in the 1990/91 and 5 t/ha in 1991/92. Measured stover produciton averaged 2.9 t/ha and 4.9 t/ha in the 1990/91 and 1991/92 seasons, respectively. Averaged across all farms and years, 72 percent of all stover was fed to animals. Nitrogen and phosphorus removal by grain averaged 50.7 kg/ha and 17.5 kg/ha, respectively, and by stover 4.9 kg/ha and 1.9 kg/ha, respectively. All four farms received chemical fertiliser in 1990/91 but only one received fertiliser in 1991/92. Fertiliser supplied more than 50 percent of the phosphorus. Manure was applied in five of the seven farm-years and supplied most of the nitrogen in the system. Inputs of nutrients by manure far exceeded their removal by stover. Due to the importance of manure in maintaining the productivity of the soil, sustaining the production of fodder and developing improved manure-handling techniques are suggested as key elements in sustaining maize productivity in this area.