Influência das águas do estuário do Rio Pará na fertilidade do solo das ilhas de várzea em Belém, Pará

Abstract

ResumoO Rio Pará é um imenso estuário formado por diversos rios e baías, compondo um grande contingente de água doce para o oceano. Nesse ambiente, encontram-se muitas ilhas, sendo 39 pertencentes à cidade de Belém. São ilhas com pouca porcentagem de área de terra irme, com presença de áreas cultivadas por agricultores familiares. O trabalho teve como objetivo avaliar o efeito da movimentação da água do estuário do Rio Pará na fertilidade do solo das ilhas de Belém, Pará. A amostragem foi realizada em 23 ilhas em ecossistema de várzea com área superior a 10 ha, incluindo as três maiores que possuem signiicativa área de terra irme (Mosqueiro, Caratateua e Cotijuba) e três ilhas pertencentes ao município de Ananindeua, situadas ao sul de Mosqueiro (Mutum, Santa Rosa e João Pilatos). As amostras foram coletadas em ambiente ribeirinho, contornando as ilhas, procurando contemplar as áreas exploradas pela população. O estudo indica que existe variabilidade na fertilidade do solo no ambiente insular de Belém, com diferença signiicativa entre os arquipélagos avaliados, para os teores de Cálcio (Ca +2 ), Magnésio (Mg +2 ), Potássio (K + ) e Alumínio (Al +3 ), além da Soma de Bases (SB) e Capacidade de Troca Catiônica (CTC). Não se observou diferença signiicativa para os valores de Fósforo disponível (P). Observou-se também um gradiente decrescente na direção sul-norte para o K + e o pH. Abstract Inluence of water of the Rio Pará estuary on soil fertility of várzea islands in Belém, Pará. The ParáRiver is an immense estuary formed by numerous rivers and bays, composing a large body of fresh water that lows into the ocean. In this environment, there are many islands, of which 39 belong to the city of Belém. These Revista Biotemas, 31 (4), dezembro de 2018 16 S. Brazão e Silva et al.islands have a small percentage of terra irma, including areas cultivated by family farmers. The objective of this study was to evaluate the effect of the water movement of the Pará River estuary on soil fertility of islands of Belém, Pará. Sampling was carried out on 23 islands in a várzea ecosystem with an area greater than 10 ha, including three signiicantly large islands (Mosqueiro, Caratateua and Cotijuba) and three islands (Mutum, Santa Rosa and João Pilatos) that belong to the municipality of Ananindeua, located south of Mosqueiro. The samples were collected in a riverine environment, surrounding the islands, with the goal of better understanding the areas used by the local population. The study indicates that there is variability in the soil fertility of insular environments of Belém, including a signiicant difference between the archipelagos evaluated for calcium (Ca +2 ), magnesium (Mg +2 ), potassium (K + ) and aluminum (A +3 ), as well as the sum of bases (SB) and cation exchange capacity (CTC). No signiicant difference was observed for the values of available phosphorus (P). A gradient in the south-north direction was also observed for the elements K + , Mg +2 and Al +3 .

Chemical and textural properties of floodplain forest soils in the Eastern Amazon, Brazil

“…Because of the heterogeneity and hydromorphism of floodplain soils, samples differed greatly in morphological, physical, chemical, and mineralogical characteristics, being grouped into different classes with different limitations and uses (Gomes et al, 2006;Lima et al, 2007). High levels of Al 3+ (1.12 cmol c dm −3 ) in soil limit plant development, as stated by Silva et al (2018). The value observed in the current study was much higher than those reported by Fajardo et al (2009) and Magalhães and Gomes (2013), namely 0.08 and 0.00 cmol c dm −3 , respectively, but within the range of 0.19 to 2.50 cmol c dm −3 described by Teixeira et al (2019) and Lima et al (2005) for several types of floodplain soils.…”

“…The high variability of chemical and textural data is due to the fact that, although samples were collected on the banks of the Amazon River, collection points differed in vegetation and sediment discharges from tributaries and rivers that form the Amazon basin (Meade et al, 1979;Filizola and Guyot, 2011;Silva et al, 2005;Montanher et al, 2014;Silva et al, 2018).…”

“…The high dispersion in soil physical properties is explained by the fact that floodplain soils are sedimentary and subject to removal, transport, and deposition promoted by the water cycle (Silva et al, 2018).…”