Erosion Risk Potential Assessment Using GIS and RS for Soil and Water Resource Conservation Plan: The Case of Yisir Watershed, Northwestern Ethiopia
Habtamu Tadele Belay,
Demelash Ademe Malede,
Firaol Befekadu Geleta
Issue:
Volume 9, Issue 1, February 2020
Pages:
1-13
Received:
18 August 2019
Accepted:
21 February 2020
Published:
10 March 2020
Abstract: Soil erosion is more sensitive in the highlands of Ethiopia. The purpose of this study is evaluating erosion risk potential using RUSLE model with GIS and remote sensing to identify erosion potential areas for soil and water resources conservation plan and to prepare soil loss risk map. Collected data were processed and analyzed using Arc GIS10.2 version. Total average annual soil loss from the 2,120.33ha was estimated at 7161.06tons. The lower soil loss rate was 2.5t/ha/yr on plantation and natural forest, the maximum value was 100.62tons/ha/yr in steep slope cultivated land and average soil loss was 50.31 tons/ha/yr. About 6.35% of the area is under extremely very severe soil erosion rate. Level soil bund, graded soil, stone or stone faced soil bund, fanyajju, cutoff- drain in the above part of the catchment, waterway along the slope, trenches on grazing land, check dam SWC measures at Quala got, integrated physical with biological measures like tree Lucerne, Vetiver grass are the recommended SWC measures. This approach can be applied in other basin or watershed for assessment of erosion risk potential using GIS and RS, and this can be used as a preliminary watershed planning tool for decision makers in Ethiopia like Woreda Agriculture and Natural Resources management Office.
Abstract: Soil erosion is more sensitive in the highlands of Ethiopia. The purpose of this study is evaluating erosion risk potential using RUSLE model with GIS and remote sensing to identify erosion potential areas for soil and water resources conservation plan and to prepare soil loss risk map. Collected data were processed and analyzed using Arc GIS10.2 v...
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Effect of Schizochytrium sp., on the Growth, Fatty Acid Composition, Digestive Enzyme and Serum Biochemical Composition of Postlarval Litopenaeus vannamei
Guofang Zhong,
Jovin Hasjim,
Blandine Baert,
Ling Lu
Issue:
Volume 9, Issue 1, February 2020
Pages:
14-21
Received:
11 November 2019
Accepted:
28 November 2019
Published:
14 April 2020
Abstract: In this study, shrimp feed was substituted with a dried alga, Schizochytrium sp., at five levels (0, 10, 20, 40, and 60% of compound feed) to yield protein/energy (P/E) ratios of 22.72, 19.75, 16.71, 13.72 and 10.75 mg protein/KJ, respectively. The effects of this substitution on the specific growth rate (SGR), survival rate, fatty acid composition, digestive enzyme activities and biochemical composition of the sera in postlarval white shrimp (Litopenaeus vannamei) were evaluated. Four replicates, each consisting of 5,000 postlarval shrimp in a single cage, were performed at each substitution level. The postlarval shrimp were randomly distributed to 20 cages, and the duration of the trial was 50 d. The results showed that the best performance was obtained with a diet containing 40% dried Schizochytrium. The survival rate of the 40% trial group was 24% higher than that of the shrimp fed a control diet (p < 0.05). The final body weight gain and SGR peaked at a substitution level of 40% dried Schizochytrium (p < 0.05). The feed conversion ratios (FCRs) of the 20% and 40% trial groups were significantly lower than that of the control group (p < 0.05). The muscle protein and ash contents of the shrimp fed diets containing 20% and 40% dried algae were higher than those of the shrimp fed the control diet (p < 0.05). Although the level of dried Schizochytrium was associated with a decrease in the protease specific activity, an increase in the lipase activity was observed. The serum biochemical composition of the shrimp was significantly affected by the level of dried Schizochytrium in the diet (p < 0.05). In summary, when the feed content of dried Schizochytrium ranged from 20 to 40%, an optimal P/E ratio of 13.72-16.71 mg protein/KJ was achieved. Thus, such supplementation could increase the amount of highly unsaturated fatty acids (HUFAs) and decrease the required level of protein in the production of high-quality feed.
Abstract: In this study, shrimp feed was substituted with a dried alga, Schizochytrium sp., at five levels (0, 10, 20, 40, and 60% of compound feed) to yield protein/energy (P/E) ratios of 22.72, 19.75, 16.71, 13.72 and 10.75 mg protein/KJ, respectively. The effects of this substitution on the specific growth rate (SGR), survival rate, fatty acid composition...
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