Abstract
Two field experiments in 1988 and 1989 were conducted at the Fortuna Substation to evaluate levels and methods of potassium fertilization on tomato cv Duke. Applications of K2O ranging from 0 to 336 kg/ha, either banded (by hand) or through drip irrigation system (fertigation) showed no significant (P = 0.5) mean difference between treatments in tomato yield. The average tomato yield for the 1988 experiment varied from 46,689 kg/ha for the 0-K2O/ha treatment to 45,605 kg/ha for 336 kg of K2O/ha banded, and 48,617 kg/ha for 3 3 6 kg of K2O/ha in combined fertigation and banded application. In the 1989 experiment, the corresponding figures were 46,779, 47,962 and 44,060 kg/ha, respectively. The highest average tomato production in the combined 1988 and 1989 experiments was obtained with 196 kg of K2O/ha in combined fertigation and banded application, and with 252 kg of K2O/ha banded, yielding 48,095 and 48,018 kg/ha, respectively, whereas the 0-K2O treatment produced 46,707 kg/ha. The lack of significant response to K2O application seems to be the result of a high inherent available K content of the San Antón soil prevailing on the experimental site, a finding confirmed by laboratory analysis as 367 p/m.