Performance of leafy vegetables with gliricidia and elephant grass mulch

Abstract

The dependence on external inputs, combined with their limited availability and regulatory restrictions in organic systems, represents a major challenge to the sustainability of vegetable production. This study aimed to determine the effects of the use of mulch formed from gliricidia straw and elephant grass on the agronomic performance and on the transfer of N from mulch to vegetables grown in the succession lettuce-Indian spinach, in an organic system. The design was randomized blocks, with four replications. The treatments were: mulch with 100 % of gliricidia, 75 % of gliricidia + 25 % of elephant grass, 50 % of gliricidia + 50 % of elephant grass, 25 % of gliricidia + 75 % of elephant grass, 100 % of elephant grass, and no mulch. Agronomic traits and transfer of N from straw to vegetables were evaluated. The biomass yield in the vegetables was higher in the treatments with 75 % or more of gliricidia. The transfer of N from straws with higher proportions of gliricidia to lettuce varied between 45 and 50 %. For the Indian spinach, mulching with gliricidia promoted nitrogen transfer ranging from 26 to 38 %. Mulching with gliricidia also resulted in higher rates of nitrogen transfer to the vegetables. There was no difference in the efficiency of N recovery from straw for the vegetables between the mulches made of gliricidia or elephant grass.

KEYWORDS: Lactuca sativa, Basella alba, Gliricidia sepium, Pennisetum purpureum, organic agriculture.