Eficiência de quatro extratores químicos na avaliação do manganês em solos do Estado do Ceará

Abstract

To study the eficiency of four methods of manganese extraction from the soil and correlation with manganese content in the plant, forty soil samples from different locations within the state of Ceará, Brazil, were tested in a greenhouse experiment in post with soybean (cultivar EMBRAPA-31, Mina). Extraction solutions were HCI 0,1N, Mehlich-1, DTPA and AB-DTPA. Treatments comprised samples without and with manganese addition (0 to 6 mg/kg ), applied two times. The statistical model was a completely randomized factoriaI40x2x3. The parametero analyzed were manganese content in the soil and plant, dry yield, manganese concentration in the plant tissues and manganese absorbed by the plant. Results shown that manganese extraction by HCI was higher than for the other extractors (4,97 to 156,97 mg/kg, with average of 42,73 mg/kg ). There was no significant response for dry matter production with different manganese rates. Manganese concentration in plant tissue was low, but significant differences were found for Mehlich-1 and DTPA. Available soil manganese and manganese extracted by the plants shown significant differences with r = 0,768 for DTPA and r = 0,607 for Mehlich-1. As a conclusion, we can say that soils studied are well suppleyed with manganese. The highest Mn contents were found for Cambisols and Red-yellow podzolic soils, and the lowest contents for Latosols and Quartzoses sandy soils. The best most promising extractor for manganese, among the four tested, was DTPA.