FERTILIZATION OF MILLET CV SOUNA-III IN SENEGAL - DRY-MATTER PRODUCTION AND NUTRIENT-UPTAKE

In a fertilizer and manure experiment, millet was grown under four tre atments (no fertilizer or manure, farmyard manure, chemical fertilizer , and both). Grain yield and total aboveground biomass production of t he unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutr ient availability, as amount of rainfall and its distribution were fav ourable. Results show only small differences in distribution of dry ma tter among the various plant organs between the best and the non-ferti lized treatments. Nutrient supply from natural sources, defined as cro p content of N, P, and K at maturity without fertilizer application, a mounted to 104, 16 and 103 kg ha-1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of po tassium, as the combined content of these three elements is linearly r elated to total aboveground biomass production. Minimum removal of nit rogen and phosphorus per ton grain dry matter amounts to 29 and 4 kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural bio mass and for maintenance of electro-neutrality is discussed.