Liu Feng, Wang Yun-Qiu, Zhang Yun, Zhu Zhen-Ke, Wu Jin-Shui, Ge Ti-da, Li Yu-Hong
College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China.
Key Laboratory of Subtropical Agriculture Ecology, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Huan Jing Ke Xue. 2022 Aug 8;43(8):4372-4378. doi: 10.13227/j.hjkx.202112040.
Long-term straw returning to the field changes the environmental conditions of rice paddy soil, which affects the mineralization and priming effect of residual rice roots in the soil, but the direction and intensity of its influence is not clear. Therefore, based on a long-term fertilization field experiment, C-CO isotopic labeling technology and laboratorial incubation were used to analyze the characteristics of mineralization of rice roots and native soil organic carbon, the intensity and direction of the priming effect, and the source partitioning of CO emissions in three treatments, consisting of no fertilization (CK), chemical fertilizer (CF), and straw returning with chemical fertilizer (CFS). The results showed that after 120 days of flooding incubation, the root residue (R) increased the cumulative CO emissions by 617.41-726.27 mg·kg. The cumulative CO emissions from roots and root mineralized proportions in the CFS+R and CF+R treatments were 470.82 and 444.04 mg·kg, respectively, and 18.8% and 17.8%, respectively. These were significantly higher than those in the CK+R treatment (384.19 mg·kg, 15.4%). There was no significant difference in the cumulative CO emissions from native soil organic carbon among the three treatments. However, the mineralized proportion of native soil organic carbon in the CFS+R treatment (4.2%) was significantly lower than that in the CF+R and CK+R treatments (5.4% and 5.8%). The priming effect in the CFS+R treatment was 29.6%, which was significantly lower than that in the CK+R treatment (42.5%) and higher than that in the CF+R treatment (14.4%). A total of 23.47% to 27.59% of the cumulative CO emission of the flooded paddy soil was from the roots, and the remainder was from the soil. In addition, the proportion of CO emission caused by the priming effect was smaller in the CFS+R treatment than that in the CK+R treatment and larger than that in the CF+R treatment. In summary, the long-term straw returning in the flooded paddy soil will increase the mineralization potential of rice roots, but it is more conducive to the stability of the native soil organic carbon.
长期秸秆还田改变了稻田土壤的环境条件，影响了土壤中残留稻根的矿化和激发效应，但其影响方向和强度尚不清楚。因此，基于一项长期施肥田间试验，采用C-CO同位素标记技术和实验室培养方法，分析了不施肥（CK）、化肥（CF）和化肥配施秸秆还田（CFS）三种处理下稻根和土壤原生有机碳的矿化特征、激发效应的强度和方向以及CO排放的源分配。结果表明，淹水培养120天后，根残体（R）使累积CO排放量增加了617.41-726.27 mg·kg。CFS+R和CF+R处理中根的累积CO排放量和根矿化比例分别为470.82和444.04 mg·kg，分别为18.8%和17.8%。这些显著高于CK+R处理（384.19 mg·kg，15.4%）。三种处理下土壤原生有机碳的累积CO排放量无显著差异。然而，CFS+R处理中土壤原生有机碳的矿化比例（4.2%）显著低于CF+R和CK+R处理（5.4%和5.8%）。CFS+R处理的激发效应为29.6%，显著低于CK+R处理（42.5%），高于CF+R处理（14.4%）。淹水稻田土壤累积CO排放总量的23.47%至27.59%来自根系，其余来自土壤。此外，CFS+R处理中激发效应引起的CO排放比例小于CK+R处理，大于CF+R处理。综上所述，淹水稻田长期秸秆还田会增加稻根的矿化潜力，但更有利于土壤原生有机碳的稳定性。
