Preprint Article Version 1 This version is not peer-reviewed

Response of Carbon Exchange and Growth Analysis in Tropical Pastures to Distinct Irrigation Levels

Version 1 : Received: 4 September 2018 / Approved: 6 September 2018 / Online: 6 September 2018 (06:13:09 CEST)

How to cite: Pereira-Flores, M.E.; Justino, F.; Boehringer, D.; Martins Melo, A.A.; Gazolla Cursi, A.; da Costa Pereira, V.; Gomes Pereira, O.; Ruiz-Vera, U.M. Response of Carbon Exchange and Growth Analysis in Tropical Pastures to Distinct Irrigation Levels. Preprints 2018, 2018090112 (doi: 10.20944/preprints201809.0112.v1). Pereira-Flores, M.E.; Justino, F.; Boehringer, D.; Martins Melo, A.A.; Gazolla Cursi, A.; da Costa Pereira, V.; Gomes Pereira, O.; Ruiz-Vera, U.M. Response of Carbon Exchange and Growth Analysis in Tropical Pastures to Distinct Irrigation Levels. Preprints 2018, 2018090112 (doi: 10.20944/preprints201809.0112.v1).

Abstract

This study explores the effect of seasonality on soil carbon efflux and pasture growth based on field and lysimeter experiments during summer-fall and winter-spring in two years. Focus is also pointed on irrigation strategies to alleviate the crop response to seasonal fluctuations in precipitation and surface temperatures. Soil respiration, soil and air temperature, leaf photosynthesis, plant dry weight and leaf area index were quantified and analyzed. It has been found significant differences in the CO2 efflux between the two growing season. Emission of soil CO2 allowed to characterize and to prioritize the temperature and rain influence in seasonal brachiaria response. During the seasons, the transient variation of CO2 efflux was highly correlated with rainfall (r = 0.87, P < 0.05), and poorly correlated with soil temperatures (r = 0.5, P < 0.05). The CO2 efflux and plant response to different level of reposition of evapotranspiration demonstrated that irrigation during fall mitigates the reduction of growth conditioned by drying soil and the lower temperatures. The lower temperatures are limiting only when the soil moisture is below 32% of the field capacity. Thus, we propose to keep the soil moisture around 50% during the fall as a key practices for mitigating the effect of seasonality and its intensification with the climate change, even more if added to management routine practices the soil and water conservation.

Subject Areas

tropical pasture seasonality; soil carbon dioxide emission; irrigation management strategy

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