O objetivo do trabalho foi avaliar a composição química e variáveis fermentativas de diferentes híbridos de milho e sua interferência na estabilidade aeróbia da silagem. Os híbridos utilizados foram o Maximus VIP3, Defender VIP e Feroz VIP, sendo híbridos simples, triplo e duplo, respectivamente. A composição química e a estabilidade aeróbia foi avaliada 60 dias após a vedação dos silos. Amostras de um quilo foram colocadas em recipientes de polipropileno revestido com saco plástico e transferidos para câmara climática à temperatura de 25 ± 2 °C, e as temperaturas das silagens foram medidas três vezes ao dia durante sete dias. Na composição química, apenas a fração A dos hidratos de carbono não fibrosos apresentou diferença entre os tratamentos. O híbrido Maximus VIP3 foi superior em relação aos demais para produção de ácido acético, e não diferiu do híbrido Defender VIP na concentração de ácido lático. Tempo significativamente mais longo foi necessário para que a temperatura da silagem de Maximus VIP3 aumentasse em 2°C (125,3 horas), enquanto as outras silagens não diferiram entre si (53,3 e 45,3 horas para Defender VIP e Feroz VIP). O híbrido Maximus VIP3 apresentou alta concentração de açucares e maior estabilidade aeróbia, sendo recomendado para produção de silagem pelas suas características.

The objective of this study was to evaluate the chemical composition and the fermentative variables of different maize hybrids and their interference in the aerobic stability of silage. The hybrids used were the Maximus VIP3, Defender VIP and Feroz VIP, being simple, triple and double hybrids, respectively. The chemical composition and the aerobic stability were evaluated 60 days after the silos were sealed. One kilo of sample from each replicate was placed in polypropylene containers lined with plastic bags and transferred to a climatic chamber at 25 ± 2°C, and the silage temperatures were measured three times a day for seven days. In the chemical composition, only the fraction A of the non-fibrous carbohydrates presented a difference between the treatments. The Maximus VIP3 hybrid was superior in relation to the others for acetic acid production and did not differ from the Defender VIP hybrid in lactic acid concentration. A longer time was required for the Maximus VIP3 silage temperature to increase by 2°C (125.3 hours), while the other silages did not differ significantly (53.3 and 45.3 hours for Defender VIP and Feroz VIP). The hybrid Maximus VIP3 is recommended for silage production due to its characteristics, including a high concentration of sugars and a greater aerobic stability.

Dichromate oxidation and dry combustion analysis were evaluated as reference methods to determine organic carbon in Brazilian soils using near infrared spectroscopy (NIRS) as an alternative. The main objective of this study was to evaluate which of the reference methods could provide a calibration model with higher predictive ability. A total of 161 soil samples obtained from horizons in full profiles (Parque Estadual da Mata Seca, Minas Gerais State, Brazil) were used. Models were mean centered and built from partial least squares. The dichromate oxidation method presented a lower accuracy when compared to dry combustion analysis as reference for NIRS. Figures of merit such as sensitivity, analytical sensitivity, detection and quantification limits, adjust and linearity presented results very similar. A paired t-test was applied to the figures of merit results and with 95% confidence did not show significant differences between the two methods used as reference for NIRS. The non-parametric Mann Whitney test showed that the samples provided with the partial least squares (PLS) model when the reference method was the dichromate oxidation or dry combustion analysis come from the same population, indicating that the reference methods employed for multivariate calibration from NIRS provide the same results practically.