Kimani Samuel Munyaka, Bimantara Putu Oki, Hattori Satoshi, Tawaraya Keitaro, Sudo Shigeto, Xu Xingkai, Cheng Weiguo
The United Graduate School of Agricultural Sciences, Iwate University, Morioka, 020-8550, Japan.
Graduate School of Agricultural Sciences, Yamagata University, Tsuruoka, 997-8555, Japan.
Heliyon. 2020 Sep 28;6(9):e05042. doi: 10.1016/j.heliyon.2020.e05042. eCollection 2020 Sep.
Poultry-litter biochar and Azolla as green manure amendments are reported to enhance paddy soil fertility and rice yields. However, whether their co-application in lowland rice paddies has synergistic effects and whether those benefits are accompanied by greenhouse gas (GHG) emissions remains unknown. The objective of this study was to determine the effects of poultry-litter biochar (hereafter: biochar) and its co-application with Azolla as green manure (hereafter: Azolla), on the simultaneous methane (CH) and nitrous oxide (NO) emissions from a lowland paddy soil planted with rice during a single rice growing season in Tsuruoka, Yamagata, Japan. Biochar and Azolla amendments were applied once before rice was transplanted at a density of 20 t ha and 133.9 kg N ha, respectively. Compared with NPK, NPK + biochar, and Azolla only treatments, Azolla and biochar co-application (i.e., Azolla + biochar) significantly increased CH emissions by 33%-197.6% in the early stages of rice growth (before 63 days after transplanting, DAT), but did not significantly influence CH emissions at both late rice growth stages (after 63 DAT,) and whole rice growth period (112 DAT). Conversely, Azolla + biochar significantly reduced NO emissions by 83.0%-97.1% before 63 DAT, and by 76.4%-95.9% during the whole rice growth period at 112 DAT, with a significantly high interaction between biochar and fertilizer amendments. There were no significant NO emission differences among all treatments after 63 DAT. Additionally, Azolla + biochar significantly increased rice grain yield by 27.3%-75.0%, and consequently, decreased both yield-equivalent CH emissions by 24.7%-25.0% and NO emissions by 81.8%-97.7%. Our findings suggest that the co-application of poultry-litter biochar and Azolla as green manure offers a novel approach to increase rice yield while reducing the emissions of non-carbon dioxide greenhouse gases.
据报道，家禽粪便生物炭和满江红作为绿肥改良剂可提高稻田土壤肥力和水稻产量。然而，它们在低地稻田中的共同施用是否具有协同效应，以及这些益处是否伴随着温室气体（GHG）排放，仍然未知。本研究的目的是确定家禽粪便生物炭（以下简称：生物炭）及其与满江红作为绿肥的共同施用（以下简称：满江红）对日本山形县鹤冈市单季水稻生长季节种植水稻的低地稻田中同时产生的甲烷（CH）和一氧化二氮（NO）排放的影响。生物炭和满江红改良剂在水稻移栽前分别以20吨/公顷和133.9千克氮/公顷的密度施用一次。与仅施用氮磷钾（NPK）、氮磷钾+生物炭和仅满江红处理相比，满江红和生物炭共同施用（即满江红+生物炭）在水稻生长早期（移栽后63天之前，DAT）显著增加CH排放33%-197.6%，但在水稻生长后期（63 DAT之后）和整个水稻生长周期（112 DAT）对CH排放没有显著影响。相反，满江红+生物炭在63 DAT之前显著减少NO排放83.0%-97.1%，在整个水稻生长周期112 DAT时减少76.4%-95.9%，生物炭与肥料改良剂之间存在显著的高相互作用。63 DAT之后所有处理之间的NO排放没有显著差异。此外，满江红+生物炭显著提高水稻籽粒产量27.3%-75.0%，因此，使产量当量CH排放降低24.7%-25.0%，NO排放降低81.8%-97.7%。我们的研究结果表明，家禽粪便生物炭和满江红作为绿肥的共同施用提供了一种增加水稻产量同时减少非二氧化碳温室气体排放的新方法。
