Use of reduced Bokashi doses is similar to NPK fertilization in iceberg lettuce production

The aim of the study was to compare horticultural variables of iceberg lettuce using two Bokashi compost doses, alone and in combination, with the bioactivator Penergetic (Penergetic International AG®) against standard mineral fertilization (NPK) in three crop cycles. Experiments were conducted in a plastic greenhouse at the Universidade Estadual de Londrina, Brazil (548 m a.s.l.). The treatments were: negative control (water, only); positive control (NPK, 4-14-8); Penergetic alone; Bokashi doses 5 g and 10 g/plant with or without a combination with Penergetic. Lettuce plants were grown in pots filled with soil. Commercial biomass (CM), head diameter (HD), plant height (PH) and chlorophyll index (CI) were evaluated. In the three cycles tested, the Bokashi 10 g/plant, Bokashi 10 g/plant + Penergetic, and NPK treatments surpassed the control. The studied variables (CM, HD, PH and CI) in the lower Bokashi dose treatment were also higher than controls but lower than higher Bokashi doses and NPK. Penergetic increases the CM in the lower Bokashi dose treatment just in the first production cycle, probably due to the poor organic matter content in the soil. The treatment Bokashi 10 g/plant improved significantly the lettuce horticultural variables vs. control treatments and was similar to chemical fertilization in two or three crop cycles.