Variabilidade espacial e temporal das características térmico-hídricas do solo em cultivo da Palma de óleo no leste da Amazônia.

Abstract

Oil palm has great economic and environmental importance. The thermal and water study of the soil and its spatial and temporal variability, becomes important because the soils participate in the whole process of water and energy exchange between surface, biota and the atmosphere. The objective of the study was to characterize the spatial and temporal thermal-hydric variation of the soil, in oil palm cultivation with interspecific hybrid (Elaeis guineensis Jacq. x Elaeis oleifera (H. B. K.) Cortés), in a Yellow Latosol in eastern Amazonia. The study was conducted in a HIE plantation (01º51’43.2’’S, 48º36’52.2’’O) in the municipality of Moju, Pará, Brazil. The precipitation was obtained by a rain gauge installed in a tower of micrometeorological observations, and the microclimatic data of the soil such as volumetric moisture (θ), temperature (Tsolo) and soil heat flow (G) were obtained by means of instruments installed near the tower. These were installed vertically between two plants (EP), at points located at increasing distances from the plant stem: EP1 (0.5 m), EP2 (2 m) and EP3 (4 m). Additionally, also between two lines of plants (EL). Soil samples were collected in EP and EL, to perform physical analyzes such as granulometry, density, porosity and water retention in the soil. The time series used in this study covers the period from 2014 to 2017. Lower values of θ were observed in EP1, a place with a higher density of roots that absorb water and nutrients. And, the largest of θ in EP2 and EP3. It is very likely that due to the fact that EP3 deposits the leaves that are pruned, this has promoted an insulating effect, which can attenuate both heat exchanges with the surface and evaporation, keeping the soil more humid and with lower temperatures. Regardless of the period, rainy (CP) or less rainy (PMC), θ showed lower values in EL than in EP. Through the soil water retention curve (CRA), it was observed that there was less water retention, greater density and less total porosity in EL than in EP. The smallest variation of Tsolo and G occurred specifically in EP3, where there was the deposition of pruned leaves on the soil, in comparison with EL, in which the soil was uncovered.