Forage productivity and nutritive value during pasture renovation in integrated systems

Integrated crop-livestock-forestry systems are strategies to diversify production in the same area, aiming at higher sustainability. Corn is one of the most used crops in integrated systems due to its multiple uses on the farm. The objective of this study was to evaluate the effect of light restriction on morphological and productive characteristics of the forage components (corn for silage and pastures) in integrated livestock production systems. The experiment was carried out on Embrapa’s integrated systems in São Carlos, SP, Brazil, during two growing seasons. In the integrated crop-livestock (iCL) system corn was sown simultaneously with Piatã-grass. In the integrated crop-livestock- forestry (iCLF) system, besides corn and Piatã-grass, Eucalyptus urograndis trees were planted in single 15 × 2 m rows. Corn productivity and pasture yield and nutritive value were evaluated in iCL and iCLF systems. In iCLF, evaluations were made in four positions relative to the tree lines: 1.5, 3.75, 7.5, and 11.25 m. Photosynthetically active radiation (PAR) transmission by trees was also measured in the same positions. Results of the corn crop indicated that the position relative to the tree lines affected (P < 0.001) all morphological characteristics and production parameters. Production was not affected by position relative to the tree lines in the first year but was lower in the position closer to the trees in the second year. As an average of all positions evaluated in iCLF, corn DM production in the first agricultural year was 43.3% inferior compared to the second year (5266.1 vs. 9816.7 kg DM ha⁻¹). In iCL, the average corn DM production for the two years was 10082 kg DM ha⁻¹. For the corn, the relationship between PAR transmission and the relative yield (production in each position in iCLF divided by the production in iCL) was influenced by drought in the 2013/2014 growing season. Considering the results for the renovated pastures, position relative to the tree lines affected pasture height (P < 0.0001), specific leaf area (P < 0.0012), digestibility (P < 0.0085) and crude protein (P < 0.0001).