Rational management of tobacco (Nicotiana tabacum L.) crop residues to obtain organic compost

Abstract

Crop residues may be used to produce organic composts for agricultural use. The aim of this study was to evaluate the effect of two inoculums on the decomposition speed of tobacco residues (stems). The experiment was carried out in a completely randomized design, with three treatments and six replications. The residue used in the study was passed through a forage chopper and mixed to the inoculums in a concrete truck mixer. The treatments evaluated were: TF + EB + RB - tobacco residue, bovine manure and bovine rumen; TF + EB + MP - tobacco residue, bovine manure and Microsept-Dust and TF + EB - tobacco residue and bovine manure. The temperature and humidity of the piles were monitored weekly. The piles were initially turned up side down every seven days, and then every fourteen days till closing 60 days. Samples for chemical analysis of the composted material were collected at 30, 60 and 90 days after the beginning of the composting process. The temperature of the piles stayed around 57 to 60 ºC in the period between the 20 to 40 days after the beginning of the composting process. The mix containing cattle rumen (RB) presented the lowest temperature after forty days. At the end of the composting the mix containing Microsept-Dust (MP) presented the lowest humidity. The C/N relation of the composts obtained was around 10/1 and 11/1. The three treatments presented pH values close to the neutrality in the mature stage. A period of sixty days seems to be sufficient to obtain a mature and stable biocompost of tobacco waste using manure independent of the addition of inoculums.