Silicon Fertilization of Rice on Everglades Histosols

Rice (Oryza sativaL.), one of the world's most widely grown grain crops, is seldom grown on Histosols, in part because of many problems related to plant nutrition. Studies were conducted on Terra Ceia muck (Typic Medisaprists) in the Everglades to determine the effect of calcium silicate slag on ‘Lebonnet’ rice production. Grain yields were increased in excess of 30% in each of 3 yr by preplant application of slag at 10 Mg ha−1or more. Rice in plots receiving slag had greater height, greater number of panicles per square meter, heavier grains, and less disease. Although the slag contained a number of plant nutrients, Si appeared to be the factor most responsible for the observed results. A positive linear relationship was observed in all years between straw Si and grain yield. First crop straw averaged 1.3, 5.0, and 5.9 dag Si kg−1in plots receiving 0, 10, and 20 Mg slag ha−1, respectively. A first crop straw Si concentration <3.0 dag Si kg−1was associated with reduced rice yield. Perhaps Si application should be considered in other regions when difficulties are encountered with rice production on Histosols.