A.D.S. FREITAS and N.P. STAMFORD

UFRPE - Department of Agronomy, Recife, Brazil

Abstract

A greenhouse experiment was carried out to evaluate the effects of applying organic materials and inoculation with Azospirillum sp. on dry matter production and nitrogen fixation of maize (Zea mays) grown in a Podzol Hydromorphic soil of the rainforest zone of Pernambuco, north-east Brazil. The treatments consisted of the addition of organic materials of different origin (cow manure, solid vinasse, vermicompost and fruit-horticultural compost) applied at levels of 0, 10 and 20 t/ha. Strain NFB 2, isolated from maize at the University Federal Rural of Pernambuco, and strain Sp 242, isolated from wheat at the Agrobiology Research Center - EMBRAPA, were applied individually to maize seedlings, and a control treatment without Azospirillum inoculation was included. Plants were cropped at 50 days after seedling transplant. Azospirillum inoculation as strain NFB 2 reduced total N accumulation, in the presence of applied organic material. Organic material addition increased the nitrogenase activity in the roots, and the fruit-horticultural compost (wider C:N ratio) showed the most pronounced effect on this parameter. The organic materials increased maize growth with the best responses at a rate of 20 t/ha.
Index terms: Diazotrophics, C:N ratio, organic matters, cow manure, vermicompost, vinasse.