Division of Agricultural Chemistry, Gyeongsang National University, Jinju 52828, Republic of Korea.
Korea Biochar Research Center, APRU Sustainable Waste Management Program and Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.
Sci Total Environ. 2022 Jun 25;827:154344. doi: 10.1016/j.scitotenv.2022.154344. Epub 2022 Mar 4.
Biochar and compost were accepted as a stable organic amendment to increase soil C stock as well as to decrease greenhouse gas (GHG) emissions in rice paddy soils. However, in most studies, their effect on GHG flux was evaluated only within the cropping boundary without considering industrial processes. To compare the net effect of these organic amendment utilizations on global warming within the whole rice cropping system boundary from industrial process to cropping, fresh, compost, and biochar manures were applied at a rate of 12 Mg ha (dry weight) in a rice paddy, and total GHG fluxes were evaluated. Compared with fresh manure, compost utilization decreased net global warming potential (GWP) which summated GHG fluxes and soil C stock change with CO equivalent by 43% within rice cropping boundary, via a 25% decrease of CH flux and 39% increase of soil C stock. However, 34 Mg CO-eq. of GHGs were additionally emitted during composting to make 12 Mg of compost and then increased the net GWP by 34% within the whole system boundary. In comparison, biochar changed paddy soil into a GHG sink, via 56% decrease of CH flux and 13% increase of soil C stock. However, pyrolysis emitted a total of 0.08 and 19 Mg CO-eq. of GHGs under with and without syngas recycling system, respectively, to make 12 Mg of biochar. As a result, biochar utilization decreased net GWP by approximately 28-70% over fresh manure within the whole system boundary. Rice grain productivity was not discriminated between biochar and compost manures, but compost considerably increased grain yield over fresh manure. Consequently, biochar utilization significantly decreased GHG intensity which indicates net GWP per grain by 33-72% over fresh manure, but compost increased by 22%. In conclusion, biochar could be a sustainable organic amendment to mitigate GHG emission impact in the rice paddy, but compost should be carefully selected.
生物炭和堆肥被认为是一种稳定的有机改良剂，可以增加土壤碳储量，并减少水稻土中的温室气体（GHG）排放。然而，在大多数研究中，仅在作物边界内评估了它们对 GHG 通量的影响，而没有考虑工业过程。为了比较这些有机改良剂在整个水稻种植系统边界内从工业过程到种植利用的净增温效应，在水稻田中以 12 Mg ha（干重）的速率施用新鲜、堆肥和生物炭肥料，并评估了总 GHG 通量。与新鲜肥料相比，堆肥利用减少了净全球变暖潜势（GWP），即在水稻种植边界内，通过减少 CH 通量 25%和增加土壤碳储量 39%，将 GHG 通量和土壤碳储量变化与 CO 当量求和。然而，在制作 12 Mg 堆肥的过程中，额外排放了 34 Mg CO-eq 的 GHG，从而使整个系统边界内的净 GWP 增加了 34%。相比之下，生物炭通过减少 CH 通量 56%和增加土壤碳储量 13%，将稻田变成了 GHG 汇。然而，在没有和有合成气回收系统的情况下，热解分别排放了总共 0.08 和 19 Mg CO-eq 的 GHG，以生产 12 Mg 的生物炭。因此，与新鲜肥料相比，生物炭利用在整个系统边界内降低了约 28-70%的净 GWP。生物炭和堆肥肥料对水稻籽粒生产力没有区别，但堆肥肥料显著增加了新鲜肥料的籽粒产量。因此，与新鲜肥料相比，生物炭利用使 GHG 强度降低了 33-72%，而堆肥增加了 22%，这意味着每粒谷物的净 GWP。综上所述，生物炭可以作为一种可持续的有机改良剂，以减轻水稻田 GHG 排放的影响，但堆肥应谨慎选择。
