Evaluación de una fuente de enmienda líquida en el rendimiento del arroz en un ultisol de la zona norte de Costa Rica

a field experiment was conducted, to evaluate the effect of applying a liquid lime amendment on rice yield and soil fertility, in an ultisol at los chiles, alajuela. the liquid amendment contains 40% of ca in form of caco3 and 6.9% of n as urea (cal 56？). the treatments were: control without lime; cal 56 8 l.ha-1; cal 56 10 l.ha-1; and cal 56 6 l.ha-1 + nitro ll 4 l.ha-1. nitro ll is a controlled-release liquid fertilizer that contains 33% of n. the products were applied in water with a back pump, using a volume of mixture of 200 l.ha-1, spraying on the ground 8 days after rice germination. plots 10x10 m were used, with an experimental design of randomized complete block with 4 treatments and 4 replicates. there were no significant differences in panicle size (cm), number of spikelets per panicle, total number of grains per panicle, number of grains filled, empty grains, and 1000-grain weight, although most of these variables showed higher values than the control with the application of the liquid amendment. there were significant differences (p<0.01) in rice grain yield. the dose of 8 l.ha-1 of cal 56 showed the best agronomic yield. the dose of 10 l.ha-1 of cal 56 increased slightly the content of ca and ecec in the soil.