A Semeadura Direta de espécies arbóreas consorciadas com milho e feijão é uma alternativa viável para a implantação de agroflorestas no Sul do Brasil?

Abstract

The vast majority of restoration projects in Brazil are conducted on private properties, typically to restore Permanent Preservation Areas (PPAs) and Legal Reserves. Consequently, it is necessary to explore different strategies for the reconstitution of Legal Reserve Areas, such as direct seeding and Agroforestry Systems, aiming to provide more attractive options for family farmers. The objective was to compare two forms of direct seeding in terms of species emergence, survival, establishment, and seedling growth over one year, as well as implementation costs. The experimental design used was a completely randomized block design, consisting of three blocks with two treatments each. The treatments consisted of conventional direct seeding and direct seeding with agroforestry practices (ground cover and annual agricultural crops at the edges of the beds). Each treatment had a total of 30 plots of 1 meter of direct seeding for 23 species, with 10 seeds per species deposited in each plot. Of the 13,800 seeds sown, 24% emerged, and 15.5% survived after one year of seeding. Seedling emergence in the seeding with agroforestry practices was higher than in the conventional seeding, with significant differences for some species. Survival curves indicated differences between the treatments, with conventional seeding performing better than agroforestry practices. However, there were no differences in the average number of individuals at the end of one year. The establishment percentages were 10% in conventional seeding and 9.67% in agroforestry practices. Cordia trichotoma was the only species that showed significant differences in plant height when comparing the treatments, with larger plants in the agroforestry practice treatment. Diameter showed a significant difference only for Enterolobium contortisiliquum, with a higher average also in the agroforestry practice treatment. The number of leaves in Syagrus romanzoffiana did not differ between the treatments. Direct seeding with agroforestry practices proved to be more cost-effective due to the production of agricultural crops that offset implementation costs. Both direct seeding models had lower implementation costs compared to planting seedlings in the entire area. Direct seeding with agroforestry practices is a viable method for restoring Legal Reserve areas in the region, in addition to being economically more attractive. However, the feasibility of the technique depends on the choice of species, as some did not perform well.