Caracterização de composto orgânico de misturas de resíduos de origem animal, vegetal e mineral submetidas a doses de inoculantes

Abstract

The compost is an effective method to reuse biodegradable residue, the process is mediated by microorganisms, whereby different organic materials are transformed in stable compost and nutritional quality to agricultural applications. However, the use of organic fertilizer in large scale agriculture is limited because of its action and long time liberation as well as nutrients concentrations to plant development. To increase the nutrients content available in the compost, the supplementation or enrichment with nutrients and addition of microorganisms has been proposed. The objective of this study was evaluating the physicochemical quality of chicken bed organic compost, with two mix proportion, inoculant doses and changes in composting times. The experiment was carried out in the experimental area of Hydraulics and Irrigation Laboratory of the Goiano Federal Institute - Rio Verde Campus. The experimental design used was Completely Randomized Design (CRD), analyzed in factorial scheme 2 x 4 x 5 with three repetitions. The treatments consisted of 2 mixtures to the compost formation denominated M1 (50% of plant biomass, 25% rock dust, and 20% of chicken bed) and M2 (53% of plant biomass, 27% of chicken bed 20% of rock dust), four inoculant doses (50, 100, 150 and 200% recommended dose of 150 g.m-3), and five composting times (15, 30, 45, 60 and 75 days). To the compost preparation was used the chicken bed (CB), plant biomass (PB) and to the enrichment, was used the rock dust (RD). After mixing and inoculation, the volume of 150L of the compost, was been conditioning in a compost reactor. The experiment was conducted for seventy five days and there were evaluated the physical parameters like temperature (daily), humidity (weekly) and density (fortnightly) The chemical parameters evaluated were total Nitrogen (total N), total Phosphorus (total P), Potassium (K), Calcium (Ca), Magnesium (Mg) (fortnightly). During the composting, the temperature followed the typical standard mentioned in the literature, However, the M1 (Tmax. 52 °C) was slightly smaller than M2 (Tmax. 55°C), indicating inhibitory effects of microbial activity to the mixture used in the M1 due to reduction of organic material. The estimated humidity presented intervals between 45 and 58%, representing optimal conditions for biological activity. The minimum density (dry basis) for the composting time of fifteen days to M1 and M2 was 0.42 and 0.31 g.cm-3, already at the end of the last compost, at the time of seventy five days was 0.67 and 0.55 g.cm-3, respectively. In general, the mix 2 (M2) presented higher increment for N and P above 27.00 and 30.00%, to the K there was an increase above 27% for the composting times of 60 and 75 days. In M1, the maximum of N( 4.7g.kg-1), maximum P (1.32 g.kg-1), maximum K (8.51 g.kg-1), maximum Ca (3.15 cmolc dm·³), maximum Mg (4.36 cmolc dm·³) were obtained in the inoculants doses of 86.00; 84.00; 100.00; 90.00 and 90,00%, respectively, this doses has increased by about 33.75% of N, 5.54% of P, 31.07% of Ca and 24.28% of Mg. In M2, the maximum N (9.95 g.kg-1), maximum P (1.32 g.kg-1), maximum K (8.82 g.kg-1), maximum Ca (2.94 cmolc dm·³), maximum Mg (4.36 cmolc dm·³) were obtained in inoculants doses of 150.00; 100.00; 150.00; 162.00 and 80.00%, respectively, this doses has increased by about 13.63% of N, 12.17% of K, 16.30% of Ca and 34.22% of Mg in relation of recommended dose. Is recommended the use of second mixture (53% of plant biomass, 27% of chicken bed 20% of rock dust) mainly in with the inoculant dose of 150% (225 g.m-3).