Fanyaaju stabilization and productivity of Pennisetum Pedicellatum in response to planting position and spacing at Hawassa Lake watershed, Southern Ethiopia

The efficiency of physical soil conservation structures could be improved through properly managed biological conservation strategies. Even though the physical soil and water conservation structures were implemented in many parts of Ethiopia; the structures were not stabilized well. The experiment was carried out in Hawassa Lake watershed by considering two planting positions (burm and embankment) and four spacings (5, 10, 15, and 20 cm) with four replications from 2018 to 2020 in RCBD design with a factorial combination of treatments. Results showed that desho grass planted on the embankment of fanyaaju with 20 cm space provided soil aggregate stability values of 31.65, 20.53,15.70, 11.74, and 18.70% at sieve sizes of >2 mm, 1–2 mm, 0.5–1 mm, 0.25–0.5 mm, and <0.25 mm, respectively. These values were significantly higher than others. The lower soil aggregate stability was recorded on desho grass planted at the end of the burm with 5 cm planting space. Desho grass planted on embankments with 15 cm and 20 cm also registered higher soil moisture values of 29.32 and 23.9%, respectively. The highest grass biomass yield of 1755.1 g was recorded on the embankment + PS of 15 cm. Thus, the desho plants maintained on the fanyaaju embankment with 20 cm space showed prolific root and stem growth and stabilized the physical structure. The marginal rate of return produced on 20 cm + Emb was 62.92%, showing economic viability over other treatments. Therefore, the study strongly recommends planting desho grass on the embankment of fanyaaju with 20 cm planting space as the best option for bund stabilization and productivity.