Correction: Lee et al. Reducing Methane Emissions with Humic Acid–Iron Complex in Rice Cultivation: Impact on Greenhouse Gas Emissions and Rice Yield. Sustainability 2024, 16, 4059

The authors would like to make the following corrections to the published paper [1], as they overlap with a publication from Joe et al., 2024 [2]. The changes are as follows:

(1)

The email of the author So-Hyeon Eom has been changed to god5425um@naver.com.

(2)

To clearly indicate the greenhouse gas results, replace the following original sentence in the “Abstract”:

The results demonstrated that the treatment plots with rice straw and the humic acid–iron complex significantly reduced methane emissions (563 ± 113.9 kg ha⁻¹) by 34.4% compared to plots treated with rice straw alone (859 ± 126.4 kg ha⁻¹).

with the corrected version, as follows:

The results demonstrated that the treatment plots with rice straw and the humic acid–iron complex reduced total greenhouse gas emissions (12.0 ± 2.49 Mg CO₂-eqv. ha⁻¹) by 33.9% compared to plots treated with rice straw alone (18.3 ± 2.74 Mg CO₂-eqv. ha⁻¹).

(3)

Delete both “Figure 5” and Figure 6” in “Section 3.3. Greenhouse Gas Emissions” and also delete the related figure citations, which show methane and carbon dioxide emissions.

(4)

The authors wish to add the new reference to clarify the following sentences in “Section 3.3. Greenhouse Gas Emissions”, paragraph 1:

• Regarding methane emissions, all treatment groups showed a gradual increase in CH₄ concentration following rice transplantation, with almost no emissions observed after complete drainage (DAT 106). Notably, the highest CH₄ concentration (65.9 ± 18.22 mg m⁻² h⁻¹) was observed 23 days after transplantation in the rice straw-treated plots. In contrast, the NPK, HA, and Biochar treatment groups exhibited a similar trend with the highest CH₄ concentrations observed around 70 days post transplantation. NPK and HA-Fe treatments exhibited relatively lower CH₄ emissions compared with other rice straw-mixed treatments after 50 days of transplantation [26]. The change in carbon dioxide emissions did not show any particular trend during the flooding period across all treatment groups. However, HA-Fe-treated plots maintained higher levels of CO₂ concentration than other treatments [26]. After complete drainage for harvest (DAT 106), CO₂ emissions sharply increased in all treatment groups. Nitrous oxide emission changes increased during the application of basal dressing (DAT 15) and panicle fertilizer (DAT 70), with a sharp increase in N₂O concentration in all treatment groups after the soil became reductive following complete drainage.

(5)

To clearly indicate the results, the authors wish to add an explanation along with a reference in “Table 5” Notes.

Replace the original version, as follows:

Notes: Mean ± SD (n = 3), NPK, application of N-P₂O₅-K₂O fertilizer; ST, application of straw; HA, application of humic acid; HA-Fe, application of humic acid–iron complex; Biochar, application of biochar; different letters following each value in the same column indicate significant difference at p < 0.05.

with the following:

Notes: Mean ± SD (n = 3), NPK, application of N-P₂O₅-K₂O fertilizer; ST, application of straw; HA, application of humic acid; HA-Fe, application of humic acid–iron complex; biochar, application of biochar. Different letters following each value in the same column indicate significant difference at p < 0.05. Some methane and carbon dioxide data were quoted from [26].

(6)

To clearly indicate the greenhouse gas results, the authors wish to add an explanation along with a reference in “Section 3.3. Greenhouse Gas Emissions”.

Replace the original version, as follows:

The total quantitative analysis of CH₄ emissions revealed that the amount was highest in the following order: ST, ST+HA, ST+HA-Fe, HA, NPK, and Biochar. Methane emissions were significantly decreased (34.4%) when rice straw was treated with the HA-Fe compared with rice straw alone. Biochar treatment resulted in a 9% decrease compared with NPK treatment, but the difference was not statistically significant. A significant reduction in methane was observed when the HA-Fe was added to rice straw treatments (34.4% decrease). Total CO₂ quantitative analysis indicated that emissions were highest in the following order: ST, ST+HA-Fe, ST+HA, HA, Biochar, and NPK. CO₂ emissions were higher in the treatments in which rice straw was applied (ST, ST+HA, ST+HA-Fe) compared with those without straw application (NPK, Biochar, HA). There was a statistically significant difference between groups treated with and without rice straw, but no difference within the groups. Total N₂O quantitative analysis showed emissions in the following order: NPK, Biochar, HA, ST+HA, ST+HA-Fe, and ST, but no significant difference was observed between the treatment groups (p = 0.105) (Figure 6).

with the following:

The total quantitative analysis of CH₄ emissions revealed that the amount was highest in the following order: ST (859 ± 126.4 kg ha⁻¹), ST+HA (796 ± 80.0 kg ha⁻¹), ST+HA-Fe (563 ± 113.9 kg ha⁻¹), HA (276 ± 50.7 kg ha⁻¹), NPK (217 ± 32.8 kg ha⁻¹), and biochar (198 ± 13.1 kg ha⁻¹) [26]. Methane emissions were significantly decreased (34.4%) when rice straw was treated with the HA-Fe complex compared with rice straw alone. Biochar treatment resulted in a 9% decrease compared with NPK treatment, but the difference was not statistically significant. A significant reduction was observed when the HA-Fe was added to rice straw treatments (34.4% decrease). Total CO₂ quantitative analysis indicated that emissions were highest in the following order: ST (4750 ± 473.4 3 kg ha⁻¹), ST+HA-Fe (4347 ± 1033.3 kg ha⁻¹), ST+HA (4055 ± 49.8 kg ha⁻¹), HA (2446 ± 727.7 kg ha⁻¹), biochar (2363 ± 471.6 kg ha⁻¹), and NPK (2079 ± 1013.5 kg ha⁻¹) [26]. CO₂ emissions were higher in the treatments in which rice straw was applied (ST, ST+HA, ST+HA-Fe) compared with those without straw application (NPK, biochar, HA). There was a statistically significant difference between groups treated with and without rice straw, but no difference within the groups. Total N₂O quantitative analysis showed emissions in the following order: NPK (0.9 ± 0.38 kg ha⁻¹), biochar (1.3 ± 0.66 kg ha⁻¹), HA (1.7 ± 0.54 kg ha⁻¹), ST+HA (2.0 ± 0.77 kg ha⁻¹), ST+HA-Fe (0.8 ± 0.29 kg ha⁻¹), and ST (1.1 ± 0.18 kg ha⁻¹), but no significant difference was observed between the treatment groups (p = 0.105).

(7)

To clearly indicate the greenhouse gas results, replace the following original sentence in “Section 5. Conclusions”:

Treating paddies with both the HA-Fe and rice straw led to a 34.4% reduction in methane emissions without decreasing rice yield, compared to treatment with rice straw alone.

with the following:

Treating paddies with both the HA-Fe complex and rice straw led to a 33.9% reduction in total greenhouse gas emissions without decreasing rice yield compared to treatment with rice straw alone.

The authors state that the scientific conclusions are unaffected. This correction was approved by the academic editor. The original publication has also been updated.