Sistema agroflorestal multipropósito e o seu impacto na qualidade física do solo

Abstract

Agroforestry systems (AF) are consortia of arable crops with tree species, being a viable and effective alternative to ensure sustainability, providing improvements in the conservation aspects of natural resources, especially soil. The objective of this study was to evaluate the ability of an agroforestry system to improve soil physico-hidric quality in a short period of time in the southern region of Rio Grande do Sul. The study was conducted in the Cascata Experimental Station, belonging to Embrapa Clima Temperado, in Pelotas, RS. The AF was deployed in the second half of 2013, in an Ultisol, with sandy loam textural class, located in a soft undulating landscape. The AF area (0.25 hectares) was composed of perennial biomass-producing tree species of wood and fruit (lines), which are interspersed. Already in the central range between the lines were seedlings of a perennial sub-shrub and a perennial grass, complemented with annual species of green summer and winter manures. Soil collections were carried out in 2015, 2016 and 2017, in the area of AF (AF-row and AF-interrow) and in an adjacent area representative of the natural condition of the soil. Soil samples with preserved and not preserved structure were collected in the layers 0.00-0.10; 0.10-0.20 and 0.20-0.40m for the determination of soil quality attributes. The results were submitted to variance analysis and for variables with significant effect (F test, 5% probability) the Tukey mean comparison test was applied at a significance level of 5% probability (p <0.05). The results show that: i: although native forest soil has better physical and water quality, AF was efficient in terms of the performance of its indicators, highlighting the similarity between the carbon stocks of the AF area and native forest in the topsoil (0.0-0.2 m); ii: After four years of AF implementation, short-term changes in soil quality attributes were observed, with soil density, soil porosity and total organic carbon being the most sensitive to management performed in the line and between rows.