Abstract

The effect of liquid fertilizers with Si, Ca or Mg on the growth of sorghum (Sorghum bicolor) was evaluated in an Ultisol under greenhouse conditions. Four liquid fertilizers (two potassium silicates, calcium carbonate and magnesium oxide) were applied into the soil in liquids at doses of 2 and 4 ml.pot^-1, plus a control, in a randomized unrestricted design with 9 treatments and 4 replicates. Growth variables, assessed 45 days after sowing, were dry weight of root and aerial parts. Analysis of soil and plant at the end of the test was performed. The application of Ca and Mg significantly increased growth and nutrient uptake of sorghum. Liquid calcium carbonate promoted the highest values of dry biomass and absorption of N, P, Ca, S, Cu, Zn, Mn and B. Si sources had no significant effects on biomass, except for K silicate with Ca and Mg at the dose of 4 ml.pot^-1, which also produced a significant increase in K absorption. Calcium carbonate and magnesium oxide significantly increased soil pH and decreased exchangeable acidity and Al, and also increased Ca or Mg content in the soil.

Keywords:  Silicon; calcium; magnesium; fertilizer; sorghum