MICROWAVE OVEN-DRYING OF SOIL SAMPLES FOR CHEMICAL-TESTING IN BRAZIL

In this experiment, we investigated the effect of microwave oven-dryin g on soil samples for chemical tests. Samples were irradiated until th ey achieved a constant weight and for one-half the time required. Two other treatments were applied, air-drying at room temperature and forc ed air oven-drying at 60 degrees C. Samples were analyzed for water pH , 0.01M CaCl2 pH, organic carbon (C), Mehlich 1 and resin available ph osphorus (P), exchangeable potassium (K) and calcium (Ca) plus magnesi um (Mg), and potential acidity [1N calcium acetate (pH 7.0) extractabl e hydrogen (H) plus aluminum (A1)]. The results showed that microwave- drying can induce erroneous interpretations of the ''fertility status' ' of the soil, thereby affecting fertilizer recommendations and lime r equirement determinations.