Influence of harvesting height and fertilizer rate on morphological characteristics and yield performance of desho grass (Pennisetum glaucifolium) under supplementary irrigation in southern Ethiopia
Abstract
The study was conducted to evaluate the effect of using different fertilizer rates and harvesting heights on morphological characteristics, biomass yield and economic feasibility of desho grass (Pennisetum Glaucifolium) under supplementary irrigation in Southern Ethiopia. The experiment was conducted in a randomized complete block design in a factorial arrangement with three replications. The factors of the treatments were four NPS fertilizer rates (0, 50, 100 and 150 kg/ha) and four harvesting heights (25, 50, 75 and 100 cm). Data on morphological characteristics and forage yield at each harvesting height were collected and analyzed using the general linear model procedures of SAS version (9.4) and the Duncan multiple range test was used for mean comparison. The tiller number was higher (P<0.05) when harvested at 100 cm height compared to those harvested at 75,50 and 25 cm height of harvesting after planting and 150 kgNPS/ha applied during the combined analysis. The tiller number found at the second harvest was higher (P<0.05) than at the first harvest. The number of leaves per plant was significantly increased with increasing NPS fertilizer rate (P<0.001), increment of harvesting height (P<0.001) and harvesting cycle (P<0.001). The leaf number per plant counted at 25 cm height was lower (P<0.05) than the other heights of harvest with no significant differences between 75 and 100 cm heights of harvesting at combined analysis. The leaf number was higher (P<0.05) at the application of 150kgNPS/ha than the others at the combined analysis. The leaf number found at the second harvest was higher (P<0.05) than at the first harvest. Leaf length was significantly increased with an increase of NPS fertilizer rate and increment of cutting height (P<0.05) but not affected by the harvesting cycle (P>0.05). At the combined analysis result, the leaf length at 100cm height was longer (P<0.05) than those harvested at 75, 50 and 25 cm heights of harvesting. The leaf length was higher (P<0.05) at the application of 150kgNPS/ha than the others while there was no significant difference between 50 and 100 kgNPS/ha. Days to forage harvest was higher (P<0.05) than those harvested at 75, 50 and 25 cm height when harvested at 100 cm height while lower by application of 150 and 100 kgNPS/ha when compared with unfertilized and 50kgNPS/ha during combined analysis. The leaf stem ratio was higher (P<0.05) when harvested at 25 cm than three harvesting heights while intermediate result was found at 50 and 75 cm during the combined analysis result. A higher (P<0.05) leaf stem ratio was found by application of 150kgNPS/ha when compared with 100 and 50 kgNPS/ha or no fertilizer. Dry matter yield was increased with increasing NPS fertilizer rate and increased with increment of harvesting height (P<0.05). The leaf percentage found at 25cm was higher (P<0.05) than those later three heights of harvesting while the higher leaf percentage was found by application of 150 kgNPS/ha when compared with 100 and 50 kgNPS/ha or no fertilizer. The stem percentage found at 100 cm was higher (P<0.05) than at 75, 50 and 25 cm heights of harvesting. The lower stem percentage was at the application of 150 kgNPS/ha than 100, 50 kgNPS/ha, or no fertilizer. The partial budget analysis result revealed that the net benefit-cost ratio found at the application of 150 kgNPS/ha at 75 cm height was higher than other combinations while the least benefit-cost ratio was at 25 cm height with no fertilizer. Based on the findings of this research, it can be concluded that utilization of 150 kg/ha NPS fertilizer rate combined with 75 cm height of harvesting could be used in the cultivation of desho grass to achieve higher at the most agronomic performance, biomass yield and Cost-benefit ratio (6.04). Further investigation is needed using different organic and inorganic fertilizers in different agroecological zones across years under rain-fed and irrigation conditions.