Applicability of the Mehlich-3 method for the site-specific soil nutrient management in Northern Mozambique

Mehlich 3 (M-3) is a multi-nutrient extractant which provides a rapid and cost-effective soil test for various soils. This study investigated the applicability of M-3 for cation and micronutrient determination under the specific soil fertilization and crop rotation given in northern Mozambique. Cations and micronutrients extracted with M-3 were compared with the classical methods; neutral ammonium acetate (NH4OAc) for calcium (Ca), potassium (K), magnesium (Mg), and sodium (Na); diethylene triamine penta-acetic acid (DTPA) for copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn); and Bray I for phosphorus (P). Results indicated that M-3 was useful for Ca, K, Mg, P and Zn determination. Various types of soil fertilization or crop rotations did not alter the accuracy and precision of cation determination using M-3 and NH4OAc. Addition of organic and chemical fertilizers was thought to adversely affect the quantity of M-3 and DTPA extractable micronutrients and their correlations. However, levels of M-3 micronutrients in soils were well above those considered to be critical levels as same as that of DTPA. This suggested that M-3 was an acceptable procedure for determining cations and micronutrients in the routine analysis and could be advantageous for soil nutrient management in the specific conditions given. Key words: Bray I, crop rotation, diethylene triamine penta-acetic acid (DTPA), Mehlich 3, Mozambique, Nacala, neutral ammonium acetate (NH4OAc)