Residual Effect of Lime and Micronutrients on an Oxisol under Crop Rotation.

Sônia Sena ALFAIA Takashi MURAOKA About the authors

An experiment was conducted during three years on a Central Amazonian Oxisol under a rotation of soybean (1985), rice (1986), cowpea (1987) and cowpea (1988) to evaluate the residual effect of lime and its interaction with micronutrients. The treatments were 0,2, 3 and 5 t/ha of lime, and 2, 3 and 5 t/ha of lime plus micronutrients (5 kg/ha Cu; 7,5 kg/ha Mn; 0,5 kg/ha Mo; 4,5 kg/ha Zn; 2,0 kg/ ha B). During the first two years, the lime application did not affected the soybean (260 to 732 kg/ha) and rice (557 to 919 kg/ha) grain yields, but significant increases in yield were obtained with lime and micronutrients (soja: 1986 to 2357 kg/ha; rice: 1471 to 2133 kg/ha). In the third year, cowpea crop presented a small response to micronutrients, while the last cowpea crop did not present response to the treatments and grain yield was smaller than in the third year. Soil analyses in the first and second crop showed all nutrient concentrations above critical levels, except Cu and Mn whose concentrations were low in the soil. Yields of soybean and rice presented a high positive correlation with Cu and Mn concentration in the soil. It is possible that the lime reduced Cu and Mn availability in the first and second years in the treatments without micronutrients.

lime; micronutrients; crop rotation; Oxisol

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