Atributos químicos do solo em sistema agroflorestal no Sudoeste do Paraná

Abstract

The search for agricultural production systems that have a lower environmental impact, are more economically viable and ecologically sustainable is necessary, given that there is currently an expansion of production systems based on monocultures, with indiscriminate use of pesticides and soluble mineral fertilizers, which leads to the degradation of biomes and their soils. For this reason, agroforestry systems (SAF'S) have become an important alternative for producing food in line with environmental preservation, as they understand varied agroecosystems and seek to act in a similar way to the dynamics of natural ecological succession. The aim of this study was to chemically characterize the soil after 5 years of implementing an agroforestry system and to compare this data with that of a secondary forest (M) and a pasture system (P). The experiment was carried out at UTFPR, Campus Dois Vizinhos, with a predominantly Cfa (humid subtropical) climate and soil classified as a Red Nitosol Dystrophic Latosolic. The agroforestry was set up in September 2013 on 1,800 m² which until 2010 was cultivated with vegetables and from 2010 to 2013 was occupied with forage plants (ramie - Boehmeria nivea - and purple star grass - Cynodon nlemfluensis). For comparison purposes, the soil of an area that had been grazed for 5 years and cultivated with Aruanã grass (Panicum maximum) and a mixed Ombrophilous Forest in a secondary stage of regeneration was evaluated. Soil sampling was carried out in October 2018, with eight replicates in each treatment, totaling 24 samples. The soil's chemical attributes varied between treatments. The revolving of the soil when the agroforestry was planted, plus the history of fertilization during the period when the soil was cultivated with vegetables, explains the high P content (164.9 mg kg-1) in the 0-20 cm layer. This also explains the pH values obtained, which in the SAF were in the 5.5 range, while in the forest and pasture the values were below 5.5. It can be concluded that five years of implementing the agroforestry system were not enough to significantly alter the availability of nutrients in the soil and raise the MOS content to the levels of the soil under natural forest. Thus, it is necessary to continue monitoring the chemical attributes of the soil under these use systems over time to identify possible changes over time.