Abstract
A laboratory incubation experiment is conducted for 90 days under controlled conditions where either pruning residue or its biochar is applied to determine which application generates the lowest amount of greenhouse gas from tea plantation soil. To study the effect of incorporation depth on soil N2O and CO2 emissions, experiment 1 is performed with three treatments: (1) control; (2) tea pruning residue; and (3) residue biochar mixed with soil from two different depths (0–5 cm and 0–10 cm layers). In experiment 2, only the 0–10 cm soil layer is used to study the effect of surface application of tea pruning residue or its biochar on soil N2O and CO2 emissions compared with the control. The results show that biochar significantly increases soil pH, total C and C/N ratio in both experiments. The addition of pruning residue significantly increases soil total C content, cumulative N2O and CO2 emissions after 90 days of incubation. Converting pruning residue to biochar and its application significantly decreases cumulative N2O emission by 17.7% and 74.2% from the 0–5 cm and 0–10 cm soil layers, respectively, compared to their respective controls. However, biochar addition increases soil CO2 emissions for both the soil layers in experiment 1. Surface application of biochar to soil significantly reduces both N2O and CO2 emissions compared to residue treatment and the control in experiment 2. Our results suggest that converting pruning residue to biochar and its addition to soil has the potential to mitigate soil N2O emissions from tea plantation.
Highlights
Nitrous oxide (N2 O) is a potent greenhouse gas (GHG) and the single most important ozone depleting compound currently emitted to the atmosphere [1]
Pruning residue amendment showed the highest emission peak followed by the control and the lowest peak was observed in biochar amendment
The results of this study showed that residue biochar addition to different soil layers significantly decreased cumulative N2 O emissions from tea plantation soil compared to the control and residue treatment in experiment 1 (Figures 1a,b and 2)
Summary
Nitrous oxide (N2 O) is a potent greenhouse gas (GHG) and the single most important ozone depleting compound currently emitted to the atmosphere [1]. Atmospheric N2 O concentrations have increased by 19% since pre-industrial times, with an average increase of 0.77 ppbv yr−1 for the period 2000–2009 [2]. Agricultural soil is the single largest source of global anthropogenic N2 O emissions, accounting for approximately 59% of anthropogenic emissions [3]. N2 O emissions from agriculture can be tackled by improving. N fertilizer and manure management technology, practicing cover crops, reduced till or no till, and crop residue and biochar amendment. Crop residues are a major component of biomass production in agriculture. 3.8 billion tonnes of crop residues are produced annually from cereal, sugar, legumes, tuber and oil crops [6]
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