Li Jin-Qiu, Shao Xiao-Hui, Gou Guang-Lin, Deng Yi-Xin, Tan Shi-Min, Xu Wen-Xian, Yang Qiu, Liu Wen-Jie, Wu Yan-Zheng, Meng Lei, Tang Shui-Rong
College of Tropical Crops, Hainan University, Haikou 570228, China.
College of Ecology and Environment, Hainan University, Haikou 570228, China.
Huan Jing Ke Xue. 2021 Jul 8;42(7):3458-3471. doi: 10.13227/j.hjkx.202011181.
Paddy soils are widely considered a main source of methane (CH) and nitrous oxide (NO). Comprehensively evaluating CH and NO emissions from double-rice systems in tropical regions with different water irrigation and fertilizer applications is of great significance for addressing greenhouse gas emissions from such systems in China. In this study, eight treatments were evaluated:conventional irrigation-PK fertilizer (D-PK), conventional irrigation-NPK fertilizer (D-NPK), conventional irrigation-NPK+organic fertilizer (D-NPK+M), conventional irrigation-organic fertilizer (D-M), continuous flooding-PK fertilizer (F-PK), continuous flooding-NPK fertilizer (F-NPK), continuous flooding-NPK+organic fertilizer (F-NPK+M), and continuous flooding-organic fertilizer (F-M). CH and NO emissions in double-rice fields in tropical region of china were monitored in situ by closed static chamber-chromatography method and crop yields as well as global warming potential (GWP) and greenhouse gas intensity (GHGI) were determined. The results show that:① The cumulative CH emissions from early rice and late rice are 10.3-78.9 kg·hmand 84.6-185.5 kg·hm, respectively. Compared with F-PK and F-NPK treatments, F-NPK+M and F-M treatments significantly increased the cumulative emissions of CH from early rice season. Under the same fertilizer conditions, the cumulative CH emissions under continuous flooding condition were significantly higher than that under conventional irrigation condition. Irrigation and fertilization had extremely significant effects on CH emission in the early rice season. ② The cumulative NO emissions across all treatments were 0.18-0.76 kg·hm in early rice season and 0.15-0.58 kg·hmin late rice season, respectively. During early rice season, compared with F-PK, F-NPK significantly increased the cumulative NO emission; however, compared with D-PK, D-NPK, D-NPK+M, and D-M treatments significantly increased the cumulative NO emissions. Compared with F-PK, other three treatments under continuous flooding condition significantly increased NO cumulative emission in late rice season; compared with D-PK, D-NPK, and D-M treatment significantly increased the cumulative NO emission. Irrigation and fertilization had significant impacts on NO emissions in late rice season, and fertilization had significant impacts on NO emission in early rice season. ③ Early and late rice yields were 7310.7-9402.4 kg·hm and 3902.8-7354.6 kg·hm, respectively. Early rice yields in both F-NPK and F-M treatments were significantly higher than those in F-PK, D-PK, and D-NPK treatments. Compared with PK, the other three fertilization treatments under the same irrigation condition significantly increased late rice yield. The GWP and GHGI in early rice season were 580.8-2818.5 kg·hmand 0.08-0.30 kg·kg, respectively. There was no significant difference in GWP among four fertilizer treatments under conventional irrigation condition in the early rice season. However, F-NPK+M and F-M treatments had a significant increase in GWP compared with F-PK. The GHGI in F-NPK+M and F-M treatments were significantly higher than that in other treatments. The GWP and GHGI in late rice season were 3091.6-6334.2 kg·hm and 0.50-1.23 kg·kg, respectively. Irrigation significantly affected GWP and GHGI in both early and late rice seasons but fertilization had no significant impact on GWP and GHGI in late rice season. ④ Correlation analysis results showed that soil NH-N content and soil temperature below 5 cm soil layer had an extremely significant negative correlation with CH emissions. Soil pH was extremely significant positive correlated with CH emissions but significantly negatively correlated with NO emission. Soil NH-N and NO-N concentrations were extremely significantly negatively correlated with NO emission. Given crop yield, GWP, GHGI, and D-NPK+M can be recommended for local water and fertilizer management to reduce greenhouse gas emissions while maintaining rice yields.
稻田被广泛认为是甲烷（CH₄）和一氧化二氮（N₂O）的主要来源。全面评估热带地区不同水分灌溉和施肥方式下双季稻系统的CH₄和N₂O排放，对于应对中国此类系统的温室气体排放具有重要意义。本研究评估了8种处理：常规灌溉-PK肥（D-PK）、常规灌溉-NPK肥（D-NPK）、常规灌溉-NPK+有机肥（D-NPK+M）、常规灌溉-有机肥（D-M）、淹灌-PK肥（F-PK）、淹灌-NPK肥（F-NPK）、淹灌-NPK+有机肥（F-NPK+M）和淹灌-有机肥（F-M）。采用密闭静态箱-色谱法原位监测中国热带地区双季稻田的CH₄和N₂O排放，并测定作物产量以及全球增温潜势（GWP）和温室气体强度（GHGI）。结果表明：①早稻和晚稻的CH₄累积排放量分别为10.3-78.9 kg·hm⁻²和84.6-185.5 kg·hm⁻²。与F-PK和F-NPK处理相比，F-NPK+M和F-M处理显著增加了早稻季CH₄的累积排放量。在相同施肥条件下，淹灌条件下的CH₄累积排放量显著高于常规灌溉条件。灌溉和施肥对早稻季CH₄排放有极显著影响。②所有处理早稻季的N₂O累积排放量为0.18-0.76 kg·hm⁻²，晚稻季为0.15-0.58 kg·hm⁻²。早稻季，与F-PK相比，F-NPK显著增加了N₂O累积排放量；然而，与D-PK、D-NPK、D-NPK+M和D-M处理相比，D-NPK显著增加了N₂O累积排放量。与F-PK相比，淹灌条件下的其他三种处理显著增加了晚稻季N₂O累积排放量；与D-PK相比，D-NPK和D-M处理显著增加了N₂O累积排放量。灌溉和施肥对晚稻季N₂O排放有显著影响，施肥对早稻季N₂O排放有显著影响。③早稻和晚稻产量分别为7310.7-9402.4 kg·hm⁻²和3902.8-7354.6 kg·hm⁻²。F-NPK和F-M处理的早稻产量均显著高于F-PK、D-PK和D-NPK处理。与PK相比，相同灌溉条件下的其他三种施肥处理显著提高了晚稻产量。早稻季的GWP和GHGI分别为580.8-2818.5 kg·hm⁻²和0.08-0.30 kg·kg⁻¹。早稻季常规灌溉条件下的四种施肥处理间GWP无显著差异。然而，与F-PK相比，F-NPK+M和F-M处理的GWP显著增加。F-NPK+M和F-M处理的GHGI显著高于其他处理。晚稻季的GWP和GHGI分别为3091.6-6334.2 kg·hm⁻²和0.50-1.23 kg·kg⁻¹。灌溉对早稻季和晚稻季的GWP和GHGI均有显著影响，但施肥对晚稻季的GWP和GHGI无显著影响。④相关分析结果表明，土壤铵态氮（NH₄⁺-N）含量和5 cm土层以下土壤温度与CH₄排放呈极显著负相关。土壤pH与CH₄排放呈极显著正相关，但与N₂O排放呈显著负相关。土壤铵态氮和硝态氮（NO₃⁻-N）浓度与N₂O排放呈极显著负相关。考虑作物产量、GWP、GHGI，推荐D-NPK+M用于当地水肥管理，以在维持水稻产量的同时减少温室气体排放。
