Atributos físicos de um Planossolo Háplico sob sistema de integração lavoura-pecuária-floresta para agricultura familiar no Agreste paraibano

• Autor(a) principal: Nóbrega, Camila Costa da
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/29801
• topic: Funções de Pedotransferência; Manejo conservacionista; Solos frágeis; Semiárido; Sistemas integrados de produção agropecuária; CNPQ::CIENCIAS AGRARIAS

In the Northeastern semi-arid, anthropic intervention combined with the particularities of the climate, such as low precipitation and high temperatures, causes serious problems of areas degradation. The adoption of conservationist actions in agricultural environments, like the integrated systems in the Agrosilvopastoral modality – ILPF, is a good strategy for providing ecosystem services and is possible to be adopted in small, medium and large rural properties. The objectives of the present study were: I) To evaluate the physical attributes of a Planossolo Háplico and to select indicators of soil physical quality under a crop-livestock-forest integration system for family farming in the Agreste of Paraíba; II) Assess the total organic carbon stock and both aggregate and structural stability; III) Generate and validate Pedotransfer Functions (PTFs) to predict retained moisture at specific potentials of the soil water retention curve. The research was conducted in an area located at the Experimental Station of the Paraiba Company of Research, Rural Extension and Land Regularization - EMPAER, in the city of Alagoinha, PB. The experimental design utilized was that of randomized blocks with 5 treatments and 4 repetitions. The treatments were 1) Gliricídia + Brachiaria decumbens (GC+BD); 2) Sabiá + Brachiaria decumbens (SB+BD); 3) Ipê roxo + Brachiaria decumbens (IP+BD); 4) Milho + Brachiaria decumbens (ML+BD); 5) Brachiaria decumbens (BD). Soil samples with disturbed and undisturbed structure were collected in the layers of 0,00-0,10; 0,10-0,20 and 0,20-0,30 m. On the first chapter, soil physical attributes were evaluated and the S index was determined. On the second chapter, soil aggregation and carbon variables were determined. On the third chapter, water retention in the soil was determined for matrix potentials between 0 and -1,500 kPa. Pedotransfer functions (PTFs) were also generated and validated for each point of the retention curve and existing PTFs from literature were applied. According to the results obtained in the first study, it was possible to observe differences between the systems, for different physical attributes of the soil, and the ones that best explained the variability of treatments, through the analysis of main components, were the macroporosity and soil density. Soil density showed a strong correlation with the other attributes, being considered essential to evaluate the physical quality of a soil. According to the S index, all treatments showed good structural quality, despite having low water content in the 0.00-0.10 m layer, suggesting excessive soil aeration. In the second study, it was found that the values of aggregate and structural stability were higher in the 0.00-0.10 m layer for all treatments, due to higher levels of organic carbon and exchangeable cations in this layer. It was also verified that the BD treatment provided an improvement in stability of soil aggregates, compared to the other treatments for all the three evaluated layers. It was observed that, in the 0.20-0.30 m layer, the carbon recovery by the integration systems was superior to the carbon deposition in the native forest used as reference, indicating that ILPF is contributing to soil improvement. In the third chapter it was possible to observe an increase in the available water content in all treatments as depth increased. The points of the soil water retention curve were estimated with reasonable precision (R² ≈ 0.88) from the generated PTFs, being possible to use these functions in simulation models of soil water retention, in order to obtain results with greater speed and ease, considering the studied Planossolo Háplico, the geographic region, the climate, hydrology and land use. In addition, the results demonstrated that the tested PTFs from literature showed low predictive efficiency. At last, the integration, after the three years period, has not yet promoted a significant improvement in the physical attributes of the Planossolo under study, however, a longer evaluation time is essential for morex significant changes to be observed.