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Straw returning usually gives rise to greenhouse gas (GHG) emissions from the soil, and thus negatively affects carbon footprint (CF) of crop production. Numerous studies reported the effects of straw returning on the CF from single crop production. However, little is known about the integrated effects of different levels of straw returning on the CF and net ecosystem economic benefits (NEEB) from rice-wheat rotation. Here, we investigated the effects of different amounts of straw returning on soil CH4 and N2O emissions, GHG emissions from agricultural inputs (AIGHG), CF, and NEEB from a 2-year cycle of rice-wheat rotation. The CF was determined based on the total GHG emissions associated with crop production inputs and services. Overall, straw returning significantly increased annual CH4 emissions by 5.4–72.2% and reduced annual N2O emissions by 3.3–31.4% compared with straw removal. Straw returning remarkably increased rice grain yields by 8.1–9.9% and wheat grain yields by 10.2–21.1% compared with straw removal. The average annual AIGHG from rice-wheat rotation ranged from 3579 to 4987 kg CO2-eq ha–1. Diesel consumption played a dominant role in the AIGHG. The annual CF ranged from 0.96 to 1.31 kg CO2-eq kg–1 and increased with increasing straw returning amounts. The NEEB, which ranged from 14161 to 17413 CNY ha–1, was significantly affected by the levels of straw returning. The treatment with returning of 1/3 of preceding crop straw to the field (2.19–2.47 kg ha−1 year−1 of rice straw in the wheat season and 1.38–1.68 kg ha−1 year−1 of wheat straw in the rice season) resulted in relatively higher grain yield, the lowest CF, and the highest NEEB among all treatments, and thus can reduce CF, and increase grain yields and NEEB, and thus can be recommended as a sustainable approach to mitigate GHG emissions and increase economic benefits from rice-wheat rotation. [ABSTRACT FROM AUTHOR]

Currently, the effects of different tillage modes on greenhouse gas (GHG) emissions, carbon footprint (CF), energy budget and net ecosystem economic efficiency (NEEE) in rice fields remain unclear. In the present study, three tillage modes were tested, including rice conventional cultivation with intensive till (CT), conventional flat cultivation with no-till (FNT) and ridge cultivation with no-till (RNT) in Dafasi town, Wuxue city, Hubei province, China. This study for the first time evaluates the effects of RNT on agricultural GHG emissions, grain yield, CF, energy budget and NEEE. Compared with CT and FNT, RNT reduced the soil CH 4 emissions by 29.5% and 9.9%, respectively. CT resulted in 15.8% and 23.1% lower total GHG emissions than FNT and RNT, respectively, due to lower soil CH 4 emissions. Moreover, RNT significant decreased the CF by 35.7% and 18.2% relative to CT and FNT, respectively. The net energy, energy efficiency and energy productivity under RNT were 41.2%, 25.0% and 26.7% higher than those under CT, respectively, while the specific energy under RNT was 24.7% lower than that under CT. The NEEE under RNT was 1.66 and 1.20 folds of that under CT and FNT, respectively. In conclusion, this study recommends that RNT is an environmentally safe tillage mode for reducing GHG emissions and CF, and improving energy use efficiency and NEEE for rice production in China and similar agro-eco-regions elsewhere in the world. [ABSTRACT FROM AUTHOR]

Numerous studies have reported effects of straws with microbial decaying agents on greenhouse gas emissions from rice fields. However, studies regarding the effects of microbial decaying agents on carbon footprint and economic profit under diverse water regimes remained unclear. A two-factor field experiment was adopted to assess effects of different straw treatments (straw returning alone abbreviated as S, and straw returning with microbial decaying agent abbreviated as SMD) on CH 4 and N 2 O emissions, rice yield, carbon footprint, economic profit and net ecosystem economic profit (NEEP) from paddy field under different water regimes (continuous flooding abbreviated as F, and alternation of wetting and drying abbreviated as AWD) in central China. Compared with S treatment, SMD treatment significantly enhanced the crop water productivity by 7.9%−8.4% and the rice yield by 7.3%−7.7%. Though SMD treatment increased the economic profit by 9.9%−18.5%, and the NEEP by 9.6%−18.0% relative to S treatment, it also resulted in higher the CH 4 emissions by 12.7%−32.4% and global warming potential by 11.2%−21.5% regardless of water regimes. Water regimes had significant effects on the crop water productivity, rice yield, CH 4 and N 2 O emissions, global warming potential, economic profit, NEEP and carbon footprint. Compared with F treatment, AWD treatment improved the crop water productivity by 51.7%−79.4%, maintained rice yield, increased N 2 O emissions by 17.7%−40.0%, and mitigated CH 4 emissions by 33.2%−75.1%, which therefore resulted in lower global warming potential by 31.5%−69.8% and carbon footprint by 32.7%−66.0%. Moreover, AWD treatment significantly increased the economic profit by 25.4%−41.9% and the NEEP by 28.8%−46.6% relative to F treatment. Overall, the straw incorporated with microbial decaying agents is not an environmental friendly practice for the tradeoff of mitigation of CH 4 emissions and increase in economic profit. It is necessary to further optimize straw treatment for mitigating CH 4 emissions in order to develop rice sustainable production. • AWD irrigation reduced carbon footprint while increased economic profit. • Straws with microbial decaying agents increased rice yield and economic profit. • Straws with microbial decaying agents did not affect carbon footprint. • Straws with microbial decaying agents boosted CH 4 emissions and GWP. [ABSTRACT FROM AUTHOR]

Background: Significant efforts have been devoted to assess the effects of the poly-gamma-glutamic acid (γ-PGA) on crop growth, yield and quality, soil water retention and fertilizer use efficiency. However, few studies have evaluated the effects of γ-PGA on greenhouse gas (GHG) emissions and grain yield from paddy fields with different rice varieties., Methods: In the present study, a split-plot field experiment was performed to comprehensively evaluate the effects of γ-PGA concentrations (i.e., no application [P0] and 25.0 kg ha -1 of γ-PGA fermentation solution [P1]) and rice varieties (i.e., conventional rice [Huanghuazhan, H], red rice [Gangteyou 8024, R] and black rice [Black indica rice, B]) on the grain yield, GHG emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), net ecosystem economic profit (NEEP) and carbon footprint (CF) during 2022 and 2023 rice-growing seasons in central China., Results: Application of γ-PGA significantly affected the GHGs emissions, NEEP and CF. Compared with P0 treatments, P1 treatments significantly increased the NEEP by 1.2-11.2 %, and decreased the GWP by 12.9-35.4 %, the GHGI by 16.5-35.9 % and the CF by 13.8-26.2 % in 2022-2023. Application of γ-PGA showed a tendency to increase the yield. Under γ-PGA application condition, R treatment exhibited the lowest GWP, GHGI and CF, and the highest yield and NEEP compared with B and H treatments., Conclusion: Our results suggest that γ-PGA application is an ecological agricultural management to increase rice yield, reduce greenhouse gas emission and increase economic benefit, and its advantage is more significant for red rice than for other rice varieties., Competing Interests: Declaration of competing interest The authors report no declarations of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)