Abstract:
Poor soil fertility status due to erosion, intensive farming and leaching of nutrients are the
main contributers of food insecurity in Ethiopia. In this specific study, an attempt was made
to quantify nutrient balance of major elements at Kecha and Laguna micro watersheds in
2016 and 2017. Plant nutrient losses along with soil erosion was estimated through
measuring discharge and sediment loads coming from treated (Kecha) and untreated
(Laguna) catchment. Sediment samples from the gauging stations of both Kecha and Laguna
micro watersheds were collected three times daily, and at peak period during the rainy season
of the year 2016 and 2017. A total of 40 bulked sediment and water samples were collected
on a monthly basis. Input1
(inorganic) and Input2
(organic manure) were quantified through
interviews using semi-structured questionnaire. Plant samples were collected from 92 plots
of land for OUT1
(Grain) and OUT2
(Straw) and other input and output were calculated by a
transfer function. From the sediment, grain and straw samples of plants, NPK contents were
determined following standard laboratory procedures. The total sediment loss in Kecha and
Laguna micro watershed were analysed by Microsoft excel 2010 and ranged from 16.77 to
31.28 and 40.50 to 70.09 tons /ha in the year 2016 and 2017 respectively. Soil losses in the
year 2017 were much higher than that of the 2016. The nutrient losses were estimated to be
3.94-35.09 kg N/ha/year, 1.51-28.58 kg P/ha/year and 28.47-34.81 kg K/ha/year in Kecha
while, these values were 7.66 -46.85 kg N/ha/year, 3.89 -40.29 kg P/ha/year and 45.94-52.27
kg K/ha/year at Laguna. The nutrient balance was -89.37, -23.66 and -124.75 NPK kg/ha, and
-112.41, -20.62 and -130.26 NPK for Kecha and Laguna respectively. The main paths for
these negatives balance was residue removed and soil losses. The economic value of those
nutrient losses were 36,666.91 ETB and 46,142.38 ETB per year for Kecha and Laguna,
respectively. Generally, higher nutrient losses were observed in Laguna than Kecha
watershed, due to lack of soil water conservation practices, crop rotation and planting
leguminous plants. Therefore, efforts should be made to maintain crop residues in the farm
which can help to recycle nutrients and provide better soil physical conditions.
