Effects of Spacing, Vetch Intercropping, Nitrogen Fertilization and Harvesting Height on Agronomic Performance and Nutritive Value of Elephant Grass in the Central Highlands of Ethiopia
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Date
2020-12
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Addis Ababa University
Abstract
The role of improved forage crops with proper management practices in enhancing the quantity and quality of fibrous feeds has been widely recognized. This study was conducted to evaluate agronomic performance and quality of elephant grass due to the effects of spacing, vetch intercropping, nitrogen fertilization and harvesting height in the central highlands of Ethiopia at Holetta and Debre Zeit. The experiments were laid out in a randomized complete block design. In experiment 1- vetch intercropping and elephant grass spacing: S1 (75 x 75 cm), S2 (100 x 50 cm), S3 (125 x 25 cm) and S4 (50 x 50 cm) were evaluated. Most measured traits revealed significant (P<0.05) differences between the treatments, locations and years. Vetch intercropping had more 70.0 and 8.5% dry matter yield (DMY) advantage over pure stand elephant grass at Holetta and Debre Zeit, respectively. When combined over years and locations, average annual DMY was 9.47, 12.16 and 12.01 t ha-1 for elephant grass planted in pure stand, intercropped with V. dasycarpa and V. villosa, respectively. In the combined analysis, forage DMY produced was 12.96, 11.02, 10.55 and 10.32 t/ ha when planted at spacings of S4, S3, S2 and S1, respectively. The crude protein (CP) content, in vitro dry matter digestibility (IVDMD) and in sacco dry matter degradability (DMD) were higher in vetch intercropping treatments than pure stand elephant grass over years and locations. Generally, vetch intercropping after three weeks of elephant grass planting at inter and intra row spacing of 50 cm substantially improved annual forage productivity. In experiment 2- harvesting heights of elephant grass: HH1 (50), HH2 (100) and HH3 (150 cm) and nitrogen fertilizer rates: N1 (0), N2 (50), N3 (100) and N4 (150 kg/ha) were studied. Elephant grass harvested at HH2 resulted in 58.8 and 42.4% yield advantage over HH1 at Holetta and Debre Zeit, respectively. In the combined analysis, fertilizer application rate of N3 had 0.6, 16.2 and 44.5% higher yield advantage when compared with N4, N2 and N1, respectively. The CP content, IVDMD and in sacco DMD were higher at HH1 and HH2 than HH3 with comparable and higher values recorded in N2, N3 and N4 than in N1 over locations. Generally, elephant grass harvested at HH2 (100 cm) with the rate of N3 (100 kg N/ha) annually in split applications better performed in DMY, CPY, CP content, IVDMD and in sacco DMD. In experiment 3- rates of nitrogen application: N1, N2, N3 and N4 and plant spacing: S1, S2, S3 and S4 were studied. The application of N3 at a plant spacing of S4 resulted in higher DMY advantages of 21.6 and 14.5% at Holetta and 60.0 and 32.2% at Debre Zeit than N1 and N2, respectively. When combined over locations, average annual DMY and CPY were 6.77, 7.84, 9.92, 10.69 t/ha and 0.51, 0.62, 0.83, 0.88 t/ha in application rates of N1, N2, N3 and N4, respectively. The DMY and CPY of elephant grass were comparable and significantly (P<0.05) higher in N3 and N4 than N1 and N2. In the combined analysis, forage DM produced in 7.08, 9.07, 8.51 and 10.57 t/ha when planted at spacings of S1, S2, S3 and S4, respectively. S4 had 24.2, 16.5 and 49.3% higher DMY advantage when compared with S3, S2 and S1, respectively. The CP content and IVDMD were higher in N3 and N4 than in N1 and N2 at Debre Zeit and over locations but the CPcontents were comparable and grater in N2, N3 and N4 than N1 at Holetta. Overall, in split applications of N3 (100 kg N/ha) annually at a spacing of S4 (50 cm) substantially improved the productivity of elephant grass. In view of its high potential and wider use as fodder, the different agronomic practices of this study should be evaluated under irrigation schemes and wider environments. Future research needs also to focus on management practice to minimize environmental stresses like frost and drought, and designing appropriate conservation practices is very essential.