Induced toxicities of aluminum and manganese in sweet sorghum (Sorghum bicolor (L.) moench): I. Effects of the calcium silicate and carbonate in a laras red yellow podzolic soil

Abstract

Three sweet sorghum cultivars (Br500, Br602 and Ample-H-OK) were grown in a Red Yellow Podzolic Soil (Laras va riation) in the presence and absence of amendments of acidity, limestone and calcium silicate. The three cultivars showed differences in their response to the treatments. The best treatment for leaf production was not necessarily the one associated with higher stalk yelds. Limestone was a better means to correct acidity than silicate, as a rule. The cultivar Br602, however, showed a higher response to silicate, where as Br500 presented a better reaction to limestone. It was found that the plant response to the amendments was due to the reduction in aluminum saturation, and to increases in the effective cation exchange capacity, exchangeacle calcium and soil pH. Limestone caused a decrease in the contents of P, Ca, Mg and K in the dry matter, very likely by dilution effect. As expected, Al and Mn also decreased. On the other hand silicate application caused a raise in the contents of Ca, Mg, K, P and Al. Although visual symptoms of Mn toxicity were not observed, the c ontent of this element caused a decrease in dry matter yield. Soil aluminum affected dry matter production in the following decreasing order: Ample-H-OK, Br602, Br500 was the most influenced.