The need to reduce the use of traditional fertilizers and
prevent soil degradation demands the search for new
ways of fertilization. The combined application of waste
materials (generated by the paper industry) and seaweed
may be an alternative source of fertilization. The objective
of this study was to evaluate the effect of pellets made of
waste materials ash and sludge, produced by the paper
industry with the addition of seaweed (
Ulva lactuca L.) on
the production of lettuce (
Lactuca sativa
L.) as an indicator
plant and N mineralization in the soil. Two trials were
conducted on an Entisol soil. The first trial evaluated the
productive response of lettuce to the combined application
of pellet+seaweed. Lettuce plants were grown in pots under
greenhouse conditions for 3-mo. Three types of pellets, with
and without seaweed added, were applied in doses of 10,
20, and 30 t ha
-1. N mineralization was measured by 12 wk
incubation, evaluating the three types of pellets with and
without the addition of seaweed. The results showed that all
the combined pellet+seaweed treatments had higher aerial
biomass production (p ≤ 0.05) and increased chlorophyll
content. The aerial biomass production reached 4.16 g
pot
-1 and was 7-fold higher than pellet treatments without
seaweed, while chlorophyll content was 17% higher (p ≤
0.05). In terms of N mineralization, the maximum release
was recorded in the Pellet 3+seaweed treatment, reaching 55
mg kg
-1. All the treatments with seaweed (p ≤ 0.05) better
higher N mineralization values compared to the treatments
without seaweed. Similarly, increased values for potentially
mineralizable N and mineralization rate constant were
observed in the treatments that included pellets+seaweed and
seaweed alone compared to those consisting of pellets alone.
The pellets+seaweed amendments resulted in an increase in
soil N mineralization and production parameters of lettuce.
