Efeitos da aplicação do efluente da indústria de óleo de palma sobre o efluxo de CO2 e CH4 em plantio de palma de óleo

Abstract

The continuous increase of the global demand for palm oil has resulted in expansions in the planting areas of this oilseed. Aiming at the sustainability of the palm oil industry, and taking into account the large amount of residual biomass generated, the recycling of these by-products has been one of the proposed practices. In general, the application of part of this waste as organic fertilizer in agricultural systems has been common, for example, the liquid effluent - POME. The impact of this organic increment on soil organic matter (MOS) and, consequently, on greenhouse gas emissions (GHG’s) is little known. Thus, this study reports the results of CO2 and CH4 emissions in commercial planting of the interspecific hybrid (Elaeis guineensis Jacq. x Elaeis oleifera (Kunth) Cortés) from the gross application of the PMS over a six-month period. The addition of this organic compound increased considerably the CO2 emission rates, when compared to the control plots, but it did not have considerable effects on the methane emission. These soil respiration peaks may have been influenced by the increased organic matter content and, consequently, by microbial activity, which has been stimulated. Near the base of the plant the CO2 emission was higher and, as the sampling points moved away from the base of the plant, these emissions were reduced until it became insignificant. However, the relationship between CO2 and CH4 flows and soil temperature and humidity was weak and even non-existent, which may be associated with the low variability of these variables in oil palm planting. Thus, long-term studies are needed to assess the impacts of this application on soil C dynamics and, concomitantly, other factors that can regulate these flows, such as root biomass, microbial activities, the nutritional and physicalstatus of the soil to ensure whether this practice favors the maintenance and quality of the MOS.