Enhanced microbial respiration due to carbon sequestration in pruning litter incorporated soil reduced the net carbon dioxide flux from atmosphere to tea ecosystem

Abstract

BACKGROUND: Tea (Camellia sinensis L.) bushes are periodically (at 3-4 year intervals) pruned (cut from top) to maintain vegetative growth stage and constant height. Plant residues (prunings litter) generated after pruning are generally left in the field as a potential source of organic matter in soil. Organic carbon (C) sequestration due to pruning litter incorporation is expected to increase microbial activity in soil. Being an evergreen plant, tea bushes assimilate atmospheric carbon dioxide (CO 2 ) throughout the year; however, the relation between decomposition of pruning litters and net CO 2 flux for tea plantation have not been studied before. The objective of this experiment was to evaluate the relation between organic C accumulation and microbial respiration in pruning litters incorporated soil and its subsequent effect on the net CO 2 flux from the atmosphere to tea plantation. RESULTS: Tea bushes assimilated 1878.2-2371.2 kg CO 2 ha −1 from the atmosphere within December to November; however, pruned bushes assimilated 1451.7-1840.8 kg CO 2 ha −1 within the same period. Decomposition of pruning litters added organic matter in soil, which was mostly accumulated in larger soil aggregates having 2.0-0.25 mm size. Such organic matter accumulation significantly increased microbial respiration in those aggregates, which in turn increased the overall rate of CO 2 emission from soil to the atmosphere. CONCLUSION: Decomposition of pruning litters leads to emission of 426.5-530.4 kg CO 2 ha −1 from soil. Hence, pruned areas recorded relatively lower (16.0-27.4%) net CO 2 flux from the atmosphere to tea ecosystem as compared to unpruned tea bushes.

Soil greenhouse gas emissions and crop production with implementation of alley cropping in a Mediterranean citrus orchard

“…These authors concluded that increases in soil moisture were associated to significant increases in CO 2 emissions in irrigated orchards. On the contrary, the lack of differences in emissions between DIV and MC may indicate that current soil management in MC with frequent tillage and incorporation of pruning residues (Table S1) also contributes to high soil GHG emissions, as reported in literature (García-Orenes et al, 2010;Morell et al, 2010;Pramanik and Phukan, 2020). The lack of correlations between CO 2 emission and soil properties such as texture, pH, EC, TOC, Nt, nitrates and ammonium may suggest that climatic conditions and management are controlling CO 2 emissions by soil microbial activation through the presence of alley crops, tillage or pruning residues additions rather than inherent soil characteristics.…”