Abayneh E (2005). Characteristics, genesis and classification of reddish soils from Sidamo Ethiopia. Ph.D thesis, Universiti of Putra Malaysia. pp. 25-52.

Ahn PM (1993). Tropical soils and fertilizer use. Longman Group UK Limited, Longman House, Burnt Mill, Harlow. pp. 112-117.

Allison (1965). Methods of soil analysis. Agronomy Journal. pp. 1372-1378.

Berhanu D (1980). The physical criteria and their rating proposed for land evaluation in the highland region of Ethiopia. Land Use Planning and Regulatory Department, Ministry of Agriculture, Addis Ababa, Ethiopia.

Bouyoucos J (1962). Hydrometer method improved for making particle size analysis of soil. Agron. J. 54:464-465.
Crossref

Cottenie A (1980). Soil and plant testing as a basis of fertilizer recommendations. FAO soil bulletin 38/2. Food and Agriculture Organization of the United Nations, Rome.

FAO (2006). Plant nutrition for food security: A guide for integrated nutrient management. FAO, Fertilizer and Plant Nutrition Bulletin 16, Rome.

FAO (2008). Guideline for soil description. 4th edition. Food and Agricultural Organization of the United Nation, Rome, Italy.

FAO (2008). A guide to laboratory establishment for plant nutrient analysis. FAO fertilizer and plant nutrition bulletin no. 19. Food and Agricultural Organization of the United Nations. Rome, Italy.

Foth HD (1990).Fundmentals of soil: Routledge fundamentals of physical geography series, London. pp. 35-40.

Fisseha I (1992). Macro and micronutrients distribution in Ethiopian Vertisols landscapes. Ph.D. Dissertation submitted to Institute fur Bondenkunde und Standortslehre, University of Hohenheim, Germany. P. 201.

Havlin JL, Beaton JD, Tisdale SL, Nelson WL (1999). Soil fertility and fertilizers. Prentice Hall, New Jersely. pp. 345-355.

Hazelton P, Murphy B (2007). Interpreting soil test results: What do all the numbers mean? 2nd Edition. CSIRO Publishing. P. 152.

Landon JR (1991).Booker tropical soil manual. A handbook for soil survey and agricultural land evaluation in the tropics and sub tropics.John Wiley and Sons, New York. pp. 94-95.

Murphy HF (1968). A report on fertility status and other data on some soils of Ethiopia.

Olsen SR, CV Cole, FS Watanabe, LA Dean (1954). Estimation of available phosphorus in soils by extraction with sodium carbonate. USDA Circular 939:1-19.

Rayment G, Higginson F (1992). Australian Laboratory Handbook of Soil and Water Chemical Methods.Inkata Press, Melbourne. Australian Soil and Land Survey Handbook, 3 Reeuwijk L (2002). Procedures for Soil Analysis. 6th edition.– Technical Paper/International Soil Reference and Information Centre, Wageningen, The Netherlands.

Soil Taxonomy (2010). Key to Soil Taxonomy. Eleventh Edition. United States Department of Agriculture, Natural Resources Conservation Service.

Tan KH (1996). Soil smapling, preparation, and analysis. Marcel Dekker, Inc. New York, USA. pp. 68-78.

Tekalign T (1991). Soil, plant, water, fertilizer, animal manure and compost analysis. Working Document No. 13. International Livestock Research Center for Africa, Addis Ababa.

Wakene N, Heluf G (2003). Forms of phosphorus and status of available micronutrients under different land-use systems of Alfisols in Bako area of Ethiopia. J. Ethiopian Nat. Res. 5:17-37.

WRB (2006). World Reference Base for Soil Resources. A framework for international classification, correlation and communication Food and Agricultural Organization of the United Nation, Rome, Italy.