Enhancing finger millet productivity through nitrogen fertilizer management in Buyende District

Abstract

Finger millet (Eleusine coracana (L.) Gaertn) is the third most important dry land cereal grown in arid and semi-arid regions of the world. Also, the crop is one of the major food security crops for billions of the world’s poorest people. It is a major source of calcium and iron for millions of the poor in arid and semi-arid regions of Sub-Saharan Africa. In Uganda, production of the crop is mainly constrained by poor soil fertility and weed infestation, yet fertilizer use is still limited to approximately 1 % of the total farm households. Therefore, it is imperative that efforts are made to leverage the benefits of fertilizer use to develop strategic methods for management of weed proliferations. The objective of this study, therefore, was determination of finger millet response to N (rate, placement and time of application) for increased finger millet yield, while maintaining minimum weed infestation. A screen house experiment was conducted in Makerere University Agricultural Research Institute Kabanyolo (MUARIK) preceding the field experiment that was conducted in Buyende district, eastern Uganda. Treatments included four N rates i.e.; 0 (control), 20, 40 and 60 kg ha-1 in form of urea for both experiments. Nitrogen placement distances included; 5, 10 and 15 cm from the crop rows, and timing of application of the second N split dose at mid tillering (T1) or at flowering (T2). Seremi 2 variety was used as the test crop in a completely randomized block design and factorial arrangement. Data on finger millet were collected on plant height, leaf area, number of tillers, and number of fingers, finger length, and total above ground biomass and grain yield. Weed data were collected on species richness, weed biomass and weed density, and were analyzed using Gen-Stat Edition 14. Significant means were separated using the Least Significance Difference (LSD) at 5 % level of significance. xi Results from screen experiment were significantly affected by single effects of N rate and placement distance well as field results showed a significant (p<0.05) interaction between N rate, placement distances and timing on number of tillers and finger length. Also, there was interaction between N rate and placement distance on leaf area, head weight, grain yield and Agronomic Nitrogen use efficiency (ANUE). The maximum grain yield was 1160 attained 60 kg N ha-1 as compared to 2776 kg ha-1 achieved with application of 60 kg N ha-1 placed at 15 cm from the crop rows. This discrepancy in finger millet grain yield could be attributed to the differences in environmental conditions under screen house and field experiments. The most effective timing of the second N dose of application was obtained at mid tillering with 60 kg N ha-1 application. This implied that this crop benefited more from application of the second N split dose during the vegetative stage, and not over the reproductive stage. Thus, application of N at reproductive stage is rather too late for the accumulation of the vegetative resources required for increased grain yield. On the other hand, combinations of N rate, placement and timing had no significant effect on weed growth in finger millet. However, minimum weed growth was attained with application of 20 kg N ha-1, and at distance of 5 cm from crop rows for both experiments. Surprisingly, a strong and positive relationship was observed between weed density and finger millet grain yield. This relationship suggested that there was no substantial interspecific competition between finger millet and the weeds to affect grain yield. Therefore, N rates ≥60 kg ha-1 should be placed at 15 cm and ≤40 kg N ha-1 at 5 cm from crop rows. The second N split dose should be applied at mid tillering for increased finger millet productivity in eastern Uganda. Further research is required to integrate the phenomenon of the critical period of weed competition in weed and N management practices for optimal finger xii millet yields. In addition, investigation on the N management strategies, including N sources on different finger millet varieties and other cereals, under different agro ecologies and social economic frameworks are required