Effects of Different Soil Management Practices Under Maize-Legume Production System on Rainfall-Runoff and Soil Loss Relationships in Bako, West Oromia, Ethiopia

Abstract

Soil erosion is one of the major factors responsible for soil degradation and becomes a threat to human survival. Sustainable soil management systems must be developed to reduce degradation and restore the productivity of the eroded land. Therefore; this study was carried out under natural rainfall conditions with the objective of investigating and evaluating the effects of different soil management practices on runoff, soil, nutrient losses at Bako, Ethiopia. Eighteen experimental runoff plots of 8 m length and 3 m width each were framed with corrugated iron sheets. The experimental design used was randomized complete block design (RCBD) with six treatments namely; sole maize conventional practices (SMCP), sole haricot bean conventional practices (SHCP), maize-haricot bean conventional practices (MHCP), maize-mulch conventional practices (MmCP), maize-haricot bean conservation agriculture (MHCA) and maize-mulch conservational agriculture (MmCA) that were replicated three times. Parameters observed included soil loss, runoff depth, and nutrient losses. The results revealed that there was a significant difference at (P<0.05) between the treatments regarding their effect on runoff depth, soil loss and sediment associated nutrient losses. The seasonal runoff depth ranged between 22.12 and 44.99 mm while the seasonal soil loss varied between 4.04 and 18.92 t/ha during the entire study period. The loss of nutrients and organic carbon (OC) were in the range of 82.719 to 368.747 kg/ ha for OC, for total N (TN) 7.550 to 33.538 kg/ ha, available P, 0.039 to 0.179 kg/ ha and 3.230 to 14.230 kg/ha for available K. The results showed that MHCP, SHCP, MmCP, MHCA and MmCA could control the runoff by the order of 50.83, 36.89, 24.13, 20.25 and 9.40% in comparison to SMCP. Treatments reduced the soil loss in the following order; MHCA > MHCP > SHCP > MmCA > MmCP which was 78.64, 75.21, 62.84, 49.47 and 47.99 % respectively. MHCA had higher reduction potential of nutrients for P, K, OC and TN which was 78.41, 77.30, 77.57 and 77.49 % respectively as compared to SMCP of farmer practices. The results indicated that practicing conservation agriculture can be used as better soil and water conservation tool to effectively check soil and nutrient losses under the existing slope and rainfall conditions in Bako area in Ethiopia.

Keywords: Soil erosion, Tillage practices, runoff, soil loss and nutrient loss