Nitrogen and Phosphorus Uptake and Partitioning in Finger Millet as Influenced by Phosphorus Fertilization

Abstract

Finger millet (Eleusine coracana) production in Eastern Africa remains low due to a variety of factors including soil nutrient depletion. As intensive row-crop production evolves, improvements in managing soil nutrient quantity and availability of less renewable nutrients like P becomes increasingly important. The yields in Kenya are typical of low input systems ranging below 1.0 t ha-1 against a potential of 5.0 t ha-1 in a season. In an attempt to overcome this constraint, On-station experiments were conducted at the Alupe research station during the long and short rain seasons of 2015 to investigate the influence of phosphate fertilizer rates (0, 12.5, 25 and 37.5 kg ha-1 P2O5) on nutrient uptake and partitioning in finger millet. Partitioning of N and P was significantly influenced (P<.05) by phosphate rates and variety. Most phosphorus and nitrogen content was partitioned to the grains (>30%) while the least to the roots (<19%). Variety U-15 had the greatest partitioning of nitrogen to the grains while the local variety, Ikhulule had the least. Application of phosphorus led to increase in the nitrogen and phosphorus uptake in finger millet with the most in the grains with a maximum of 106.5 kg ha-1 on the 37.5 kg ha-1 P2O5 rate during the short rains while the roots had the lowest uptake with 16.9 kg ha-1 and 22.1 kg ha-1 in the long and short rains seasons respectively on the control. This study on nutrient use provides an opportunity to further improve P fertilization to specific rates in relation to crops needs as farmers will be assured of greater yields, profitable and sustainable production. Limited use of P fertilizer restricts the uptake of phosphorus and nitrogen as well as the balance in partitioning and recommends application of 25 kg ha-1 P2O5 with improved varieties.