Dados do Trabalho

Título

BIOMASS AND NUTRIENT UPTAKE OF LETTUCE (LACTUCA SATIVA) IN A VOLCANIC SOIL AMENDED WITH AN ORGANIC FERTILIZER DERIVED FROM PIURE (PYURA CHILENSIS) TUNICAE

Resumo

Thousands of tons of residues from the extraction of piure (Pyura chilensis), a tunicate marine filter-feeder, are generated annually on the coast of the Región de Los Lagos, Chile. The objective of this work was to evaluate the use of semi-discomposed tunicae residues as an organic fertilizer for greenhouse lettuce production in a volcanic soil (Andisol). During the winter-spring season, two consecutive harvests of plants were obtained under greenhouse conditions in a complete randomized block design with 3 replications (blocks). A plot of 1 x 0.5 m with 5 plants each was the experimental unit. The treatments consisted of the application of the organic fertilizer (OF, 2.05  kg/plot) or the chemical standard fertilization (CHF, 18,7 g/plot of a mixture of urea, triple superphosphate and KCl), both equivalent to 80 kg N/ha, 65 kg P2O5/ha, and 56 kg K2O/ha. The fertilization included 20 kg S/ha and 86 kg S/ha with the CHF and the OF, respectively. Treatments with 0.5X and 2X the OF rate and a control without fertilization were also included. No fertilizer application was considered after the first harvest. Aerial and root dry matter (DM) yield and nutrient concentration of plants were determined in both harvests. After the first one, soil fertility analyses were performed as well. In the first harvest, the greatest DM production and nutrient uptake was reached with the highest OF rate and the CHF, in comparison to the rest of the treatments. In the second harvest, the biomass production was higher with the OF in comparison to the CHF at equivalent NPK rates, while a similar trend was observed for the nutrient uptake, indicating that the organic residue kept a slow release of nutrients over time. Root and aerial DM were possitively correlated with soil P availability. In the soil, the application of the OF, at the 3 rates, clearly improved the availability of Ca and S, and the cation exchange capacity in comparison to the control and the CHF treatments (p<0,05).

Palavras-chave

ORGANIC AMENDMENTS; MARINE RESOURCES; VOLCANIC SOIL; GREENHOUSE.

Instituição financiadora

Proyect FIC 40018219-0 and Proyect REDES 21992.