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Both spikelet removal and low temperature stress largely reduced photosynthate allocation to wheat grain; the former stimulated the average N2O emissions by 31.3% and 33.2% under the field and pot conditions; the latter increased average N2O emission by 19.9% under pot condition. Spikelet removal and low temperature stress significantly reduced total plant N uptake, thereby increasing soil NO3–-N content, and increased root biomass. Our findings indicated that photosynthate allocation affects the soil N2O emissions from wheat fields through altering plant N uptake and root growth, and suggest that promoting photosynthate allocation to grain may not only benefit higher wheat yield but also mitigate greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Highlights • Sub-soiling with rotary tillage in wheat season reduced soil penetration resistance. • SR in wheat season promoted soil water usage of 60–140 cm layers. • N-SR promoted the contribution of post-anthesis biomass to grain. Abstract Significant efforts have been made on the assessment of tillage impacts on crop growth during the current season; however, few studies have quantified the impacts on the succeeding crop growth under multiple cropping systems. Based on a multiple-year field experiment under corn-wheat cropping system in North China Plain, therefore, we examined the integrative impacts of annual rotational tillage on wheat growth and soil properties. The annual rotational tillage treatments consisted of two tillage regimes (i.e. N: no-tillage; and SR: sub-soiling with rotary tillage) in the corn season followed by three tillage practices (i.e. sTR: strip rotary tillage; R: rotary tillage; and SR: sub-soiling with rotary tillage) in the wheat season, respectively. The results showed that the N-SR rotational tillage of N in the corn season and SR in the wheat season significantly reduced soil penetration resistance and promoted soil water usage of 60–100 cm soil layers during wheat season. Meanwhile, soil NO 3 −-N concentration in the depth of 40–140 cm was significantly lower under the N-SR than other tillage practices except for the N–R ( P < 0.01 ). Average results of two-year dry matter accumulation and translocation showed that N-SR stimulated wheat biomass production and promoted the contribution of post-anthesis dry matter to the grain ( P < 0.01 ). Consequently, wheat yield was the highest under the N-SR ( P < 0.01 ). Our findings indicate that the annual rotational tillage of no-tillage in the corn season and sub-soiling with rotary tillage in the wheat season can promote wheat growth through enhancing deep soil water and N uptake. [ABSTRACT FROM AUTHOR]

Ammonia (NH) is an important atmospheric pollutant that threatens ecosystem and human health. Synthetic nitrogen (N) fertilizer applications are a major source of atmospheric NH. Most of current bottom-up estimates assume that the NH emission response to increasing N application rates is linear, and thus constant emission factors (EFs) are used. However, increasing evidence suggests that NH emissions increase exponentially with increasing N inputs. In the present study, we conducted a meta-analysis to generalize the relationship between N inputs and NH emissions. Overall, the change in EF per unit of additional N fertilizer input (ΔEF) was positive from 70 experiments with at least three N application rates, suggesting that NH emissions in response to increasing N additions grow at a rate higher than linear. Compared to our ΔEF model, the 10% EF model used by Intergovernmental Panel on Climate Change overestimated NH emissions when fertilizer N is applied at low levels, but underestimated NH emissions when N is applied in excess. Therefore, our results suggest that replacing the constant EF with the N-rate-dependent EF could improve the accuracy of NH emission estimates. [ABSTRACT FROM AUTHOR]

Methyl jasmonate (MeJA) and its free-acid form, jasmonic acid (JA) are naturally occurring plant growth regulators widely distributed in higher plants. In order to improve the sensitivity for the analysis of MeJA at low levels in small amounts of plant samples, a monoclonal antibody (MAb) (designated as MAb 3E5D7C4B6) against MeJA was derived from a JA-bovine serum albumin (BSA) conjugate as an immunogen. The antibody belongs to the IgG1 subclass with a κ type light chain and has a dissociation constant of approximately 6.07 × 10−9 M. MAb3E5D7C4B6 is very specific to MeJA. It was used to develop a direct competitive enzyme-linked immunosorbent assay (dcELISA), conventional and simplified indirect competitive ELISAs (icELISA). JA was derivatized into MeJA for the ELISA analysis. The IC50 value and detection range for MeJA were, respectively, 34 and 4–257 ng/mL by the conventional icELISA, 21 and 3–226 ng/mL by the simplified icELISA and 5.0 and 0.7–97.0 ng/mL by the dcELISA. The dcELISA was more sensitive than either the conventional or simplified icELISA. The assays were used to measure the content of jasmonates as MeJA in tobacco leaves under drought stress or inoculated with tobacco mosaic virus and tomato leaves inoculated with tomato mosaic virus or Lirioinyza sativae Blanchard as compared with the corresponding healthy leaves. The increased jasmonates content indicated its role in response to the drought stress and pathogens. [ABSTRACT FROM AUTHOR]

• Straw incorporation in topsoil layer promoted soil temperature and total porosity. • Corn straw incorporation in topsoil layer increased straw decomposition rate. • Higher decomposition rate caused higher availability of mineral N and TOC. The effects of straw incorporation on soil characters are well known, however, straw incorporation depth impact on corn straw decomposition rate, microbial biomass carbon (MBC) & microbial biomass nitrogen (MBN), soil carbon (C) and nitrogen (N) concentration during straw decomposition have not been documented. A two-year field experiment was carried out in a wheat-corn cropping system to investigate the effects of straw incorporation depth on decomposition rate of corn straw and soil C and N release. The straw incorporation depths were: topsoil 0–10 cm (TI), medium depth 10–20 cm (MI), and deep depth 20–30 cm (DI). The results showed that corn straw decomposition rate was significantly higher in TI by 24.5 % and 16.5 % than in MI and DI treatments from October 2016 to August 2017. The average contents of MBC and MBN during the decomposition period of straw were higher in TI than in MI and DI treatments (P < 0.01). Additionally, the release of N and C from the corn straw was higher in TI, causing a significantly higher average concentration of NO 3 −–N (P < 0.01) and total organic carbon (P < 0.05) observation in this layer compared with MI and DI. Our results suggest that the corn straw incorporation in topsoil layer of 0–10 cm can decompose faster, and the higher decomposition rate may facilitate the release of C&N from the straw, causing the higher availability of mineral nitrogen and total organic carbon of this layer. [ABSTRACT FROM AUTHOR]

Crop straw and N fertilizer applications impact paddy rice yield and greenhouse gas (GHG) emissions. However, their interactive effects have not been well documented. This study investigated the effects of straw (S), no straw incorporation (NS), and three levels of N fertilization rates (N0, N1, and N2) on single rice (SR), double rice (DR), and rice-wheat (RW) cropping systems. Straw incorporation significantly increased total CH4 emissions by 118.6%, 8.0%, and 79.0% in the SR, DR, and RW, respectively, compared to the NS. The total GHG emissions in DR are significantly 72.6% and 83.5% higher than those in RW and SR, respectively. Compared to NS, straw incorporation significantly increased yield-scaled emissions by 27.8%, 15.0%, and 89.0% in SR, DR, and RW, respectively. Straw with N application significantly increased average rice yield over N1 and N2 by 39.4%, 50.0%, and 6.7% in SR, DR, and RW, respectively. There was a significant correlation between methyl coenzyme M reductase (mcrA) and CH4 emissions in rSR = 0.87 (p < 0.05) and rRW = 0.85 (p < 0.05), except in rDR = 0.06 (p > 0.05). This study scientifically supports straw incorporation combined with a moderate N application rate in rice-based cropping systems to maintain high rice yields and mitigate GHG emissions. [ABSTRACT FROM AUTHOR]

Straw incorporation promotes rice productivity and soil fertility. However, the effects of tillage practice with straw on GHG emissions in paddy fields are not well documented. Under three rice-based cropping systems of China (single rice, double rice and rice-wheat cropping systems), we investigated rice yield, CH4, N2O, area and yield-scaled emissions arising from different straw-incorporated tillage patterns. Tillage with straw affected rice yield by −6.8~3.2%, −9.1~9.0% and −9.8~2.1% in single rice, rice-wheat and double rice cropping systems respectively. Straw impacted CH4 emission but tillage influenced its impact irrespective of the rice cropping system. The highest CH4 emissions occurred in RedT + S, RoT + S and RoT + S under single rice, rice-wheat and double rice cropping systems respectively. Cumulative CH4 emission of PT + S decreased by 46.8% (p < 0.05) compared to RedT + S in the single cropping system, while under rice-wheat and double rice cropping systems, cumulative CH4 emission of PT + S decreased by 19.0% (p < 0.05) and 13.2% (p > 0.05) respectively compared with RoT + S. Lower methanogenic abundance of PT + S translated into the lowest cumulative CH4, area and yield scaled emissions in single rice and double rice cropping systems. To maintain high rice yield and reduce GHG emissions from straw incorporation, PT + S is recommended for a rice-based cropping system. [ABSTRACT FROM AUTHOR]

Enhanced-efficiency nitrogen fertilizer (EENF) has gained considerable attention for improving nitrogen use efficiency and mitigating N 2 O emission in many agro-ecosystems. However, the effectiveness of EENF is highly variable under field condition. The factors influencing the efficacy of EENF are not well understood. Here, a meta-analysis was conducted to investigate the key factors affecting the efficacy of EENF in upland cropping systems. The effects of EENF were found to be similar among maize, wheat, and barley, while they varied among different EENF products. Inhibitors (IS), including nitrification inhibitors (NI), urease inhibitors (UI), and the combination of UI and NI, significantly mitigated N 2 O emission and increased crop yield, resulting in a greater reduction in yield-scaled N 2 O emission compared with slow- or control-releasing fertilizer (S/CRF). Reductions in yield-scaled N 2 O emission response to IS and S/CRF were both greater in arid regions than in humid regions. Soil pH and texture had less impact on the effect of IS than S/CRF. The efficacy of IS and S/CRF were not significant when N use rates were between 120 and 180 kg N ha −1 . Surface broadcasting were unfavorable for mitigating N 2 O emissions with both IS and S/CRF. The impact of tillage on the efficacy of IS and S/CRF was affected by climate. The effectiveness of S/CRF depended more on these factors than did IS. This meta-analysis highlighted the necessity to connect EENF products with specific climatic, soil, and agronomic attributes for predicting their effectiveness. [ABSTRACT FROM AUTHOR]

Soil nutrients in deep soils are important for nutrient cycling and plant growth. Organic amendments have been widely used for enhancing soil health and crop yield. However, little is known about the effects of organic amendments on the vertical distributions of soil nutrients. Based on a 32-year long-term organic amendment experiment, the objective of this study was to evaluate changes in the vertical distribution of nutrients in a soybean–wheat system Vertisol. The results showed that NPK with manure or straw application significantly increased soil organic carbon (SOC), total N, total P, alkali-hydrolyzable N, available P and available K above the 40 cm soil layer. Variations in soil micronutrients primarily occurred above the 20 cm soil layer, and the highest contents were observed for NPKWS and NPKPM, respectively. Nevertheless, large amounts of NO3−−N contents accumulated in the 120–200 cm depth with manure but not straw application, indicating a high potential risk of nitrate leaching in manure treatments. These findings suggested that the application of organic amendment (manure or straw) could be recommendable for improving soil nutrients along the soil profile. Straw incorporation could be used as an alternative option for sustainable agriculture in regions with inadequate manure resources or severe nitrate leaching. [ABSTRACT FROM AUTHOR]

Including green manure into a rice-based double-cropping system has effects on both crop production and greenhouse gas (GHG) emissions. Yet, few studies have considered the trade-off between crop productivity, profitability, and carbon footprint (CF) in this cropping system of China. Thus, the impacts of different cropping regimes on crop productivity, economic benefits, carbon footprint, and net ecosystem economic budget (NEEB) were investigated. The treatments were rice–wheat (R–W), rice–rape (R–R), rice–hairy vetch (R–H), rice–barley (R–B), rice–faba bean (R–F), and rice–fallow (R). Compared to R–W treatment, planting rape (R–R), green manure (R–F, R–H), or fallow (R) in winter season tended to improve rice yield, but they were not conducive to yield stability. Treatments of R–H, R–F, and R reduced both direct and indirect GHG emission, and thus mitigated the area-scaled carbon footprint by 34.4%, 44.2%, and 49.7%, respectively, compared to R–W treatment. The economic benefits under R–R, R–B, or R system were not different from those of R–W treatment, while R–H reduced the economic benefit by 70.1%. In comparison with R–W treatment, R–H treatment reduced the NEEB, while R–F significantly increased the NEEB by USD 4065 ha−1. The present results indicate that as a measure to realize the combination of food security and environmental cost reduction, substituting leguminous crops with wheat can mitigate carbon emissions while ensuring profitability, on the premise of yield stability. [ABSTRACT FROM AUTHOR]

Fertilization is an effective agronomic management technique for increasing crop production. However, the overuse of chemical fertilizer stimulates energy consumption and greenhouse gas (GHG) emissions, which are antagonistic to sustainable wheat production. In this study, we estimated the energy and GHG performances of different fertilization regimes based on a 32−year fertilization experiment. In this long−term experiment, there are five treatments: CK (no fertilizer with wheat residue removal), NPK (chemical fertilizer with wheat residue removal), NPKPM (chemical fertilizer and pig manure with wheat residue removal), NPKCM (chemical fertilizer and cattle manure with wheat residue removal), and NPKWS (chemical fertilizer with wheat residue retention). The results indicated that NPKCM and NPKPM consumed higher total energy than NPK and NPKWS, which was attributed to the extra energy usage of farmyard manure. Although NPKCM and NPKPM increased energy output by 4.7 and 2.8%, NPKWS stood out by delivering the highest energy use efficiency (EUE) of 6.66, energy productivity of 0.26 kg MJ−1, energy profitability of 5.66, net return of 1799.82 US$ ha−1 and lower specific energy of 3.84 MJ kg−1. Moreover, the yield scale carbon footprint of NPKWS decreased by 66.7 and 52.3% compared with NPKCM and NPKPM, respectively. This study shows that the application of chemical fertilizer in combination with wheat residue retention is a good strategy to increase EUE and economic benefits while decreasing the carbon footprint of wheat production. [ABSTRACT FROM AUTHOR]

Conservation tillage (e.g. no tillage, minimum tillage) is regarded as an effective way to maintain sustainable crop productivity and improve soil quality globally. However, the claim that conservation tillage could improve crop yield are still controversial. It is hypothesized that whether conservation tillage increase crop yield in comparison with conventional tillage (CT) depends on the different conservation tillage practices, for example, no tillage (NT) and strip tillage (ST), and different variables including in agronomic managements, climate conditions, and soil properties. Herein, a meta-analysis was conducted to evaluate how tillage practices affect crop yield and which factors dominate yield performance mostly. Based on the 53 published articles with 290 paired-comparisons across the world, the effects of ST vs. CT and ST vs. NT on crop yield were conducted. It was showed that crop yield under ST had an increasing trend compared to that under CT and NT. Especially, ST significantly increased crop yield by 4.81% in contrast with NT, which indicated that ST might be a promising practice of conservation tillage in terms of crop yield. Under the agronomic managements of continuous cropping, multiple cropping, graminaceous crops, and straw removing, ST significantly increased crop yields by 5.40%, 10.29%, 7.66%, and 7.60% compared to NT, respectively. ST achieved significantly higher crop yield by 5.68% on average and 11.63% as compared to NT under all soil texture and neutral soil. Concerning the climate conditions, crop yield significantly increased by 3.64% under ST as compared to NT in cooler area where mean annual temperature (MAT) was lower than 10°C. Importance analysis indicated that cropping system and MAT were the key factors affecting the performance of tillage practice on crop yield. Overall, present study revealed that ST might be a favorable conservation tillage practice in continuous and multiple cropping systems with graminaceous crop (e.g. maize) in cooler (MAT <10℃) region in terms of yield promotion. This meta-analysis study demonstrated the importance of conservation tillage optimization for food safety and sustainable development of agriculture. • 53 articles with 290 paired-comparisons are used to conduct a meta-analysis. • Strip tillage has similar crop yield in contrast with conventional tillage. • Strip tillage significantly increases crop yield by 4.81% compared with no tillage. • Cropping system and mean annual temperature affect tillage performance. [ABSTRACT FROM AUTHOR]

Abstract: To learn the historical response of cropping system to climate change will benefit the strategy decision of future cropping adaptation. In this paper, we conducted an integrated analysis of the climate records of seventy-two meteorological stations and the records of crop yields over the period 1970–2009 in Northeast China. It was found that over these forty years, the daily mean, maximum and minimum temperatures during crop growing season increased on average by 0.34°C, 0.28°C, 0.43°C every ten years, respectively. No significant change in the precipitation was found, although the differences between years were large. After de-trending the agronomic technique contributions to the increments of crop yields, the historical warming had led to great annually increments of 16.6kgha−1, 15.5kgha−1 and 3.2kgha−1 in rice, corn and soybean yields, respectively. According to the historical warming level, present cropping boundaries can be theoretically extended northward about 80km with a prolonged growing period by 10 days compared to the 1970s. Actually, the growth durations of newly approved varieties of rice, corn and soybean have really prolonged by 14.0 days, 7.0 days and 2.7 days since the 1950s, respectively. The actual growing periods of rice and corn have also respectively prolonged by 6 days and 4 days due to the adjustment of sown and harvest dates by the farmer since 1990s. The existing rice cropping region has been extended northward 80km in the 2006 compared to the 1970. These actual responses were consistent with the theoretical calculation according to the historical warming trends. Our results demonstrate that cropping system owns the potential to progressively and actively adapt to the global warming for high yield through a comprehensive strategy. [Copyright &y& Elsevier]

Abstract: Recent crop model projections have shown that crop production may benefit from warming, especially in the high latitudes, but hard evidence is limited. In this study we conducted correlation and regression analyses of climate records of seventy-two meteorological stations and records of corn yield over the period 1965–2008 in Northeast China. It was found that over these forty-four years, the diurnal mean, minimum and maximum temperatures during corn growing season increased on average by 0.31°C, 0.42°C and 0.23°C every ten years, respectively. No significant change in precipitation was found, although differences between years were large. The daily minimum temperature was the dominant factor to corn production. Corn yield was significantly correlated with the daily minimum temperature in May and September. According to a regression analysis of the anomalies of corn yield and air temperature, a 1.0°C increase in daily minimum temperature in May or September will lead to an increment of 303kgha−1 or 284kgha−1 in corn yield, respectively. Corn varieties with longer growth duration will profit most from the climatic changes but agronomic practices may have to be modified to address expected weather extremes such as droughts and periods with heavy rainfall. [Copyright &y& Elsevier]

Global agriculture is facing multiple challenges to meet the food demands, optimize resource utilization, and mitigate the climate change. A field study, combined with the life cycle assessment (LCA), was conducted to select the effective and sustainable cropping systems in northwestern China. The study compared four maize‐based intercropping and corresponding monoculture systems on crop yield, evapotranspiration (ET), water use efficiency (WUE), profitability, and carbon footprint (CF). Maize/wheat intercropping had the highest energy yield (532.5 GJ/ha, on average) and maize equivalent energy yield (MEEY) (522.3 G/ha, on average), followed by those from the maize/rape intercropping system, and the lowest by the sole potato system. The WUE of maize equivalent energy yield (WUEMEEY) was the highest (1.06 GJ ha−1 mm−1) for sole rape system, followed by those for the maize/wheat and maize/rape intercropping systems. Maize/potato intercropping had the highest benefit: cost ratio at 3.30, followed by those for the maize/wheat intercropping (2.58), sole potato (2.57), and maize/rape intercropping (2.53). Lower CF and higher net ecosystem economic budget (NEEB) were observed in maize‐based intercropping systems. The maize/wheat intercropping system had the lowest CF per maize equivalent energy yield (CFm) (10.7 kg CO2‐eq GJ−1 year−1), and the maize/potato intercropping system had the lowest CF per unit economic output (CFe) (0.14 kg CO2‐eq US$−1 year−1), and the highest NEEB (7,352.8 US$/ha). The data presented indicate that maize‐based intercropping system may be a viable practice for the synthesized goals of higher productivity and profitability while lesser environmental footprint in a water‐scarce region of northwest China. [ABSTRACT FROM AUTHOR]

Maize production is facing multiple challenges toward increasing crop productivity, enhancing resource utilization, and mitigating climate change nowadays. Climate-smart agriculture (CSA) is an emerging concept, which pursues the synthesis of higher crop productivity, lower carbon emissions, and improved soil resilience to the climate change. However, few studies have been done to evaluate the productivity and environmental consequences following the CSA of maize production. Herein, the effects of CSA practice on maize yield, nitrogen use efficiency (partial factor productivity, PFP N), soil organic carbon (SOC) sequestration, and carbon footprint (CF) were evaluated based on a nine-year in-situ field experiment in northeastern China. The experiment followed a randomized block design with three treatments including in traditional farmers' practices (FM), optimized agronomic practices (OPT, aiming to high grain yield and PFP N), and climate-smart agriculture practices (CSA, aiming to higher grain yield, PFP N , SOC stock, while lower CF). Compared with FM, OPT and CSA practices significantly increased grain yield and PFP N by 25.0%− 30.1% and 92.2%− 100.2% on average of experimental duration, respectively. CSA practice had significant higher global warming potential (GWP) but equivalent global warming potential intensity (GWPI) than these of FM and OPT practices during 2016 and 2017. Meanwhile, CSA practice also achieved the highest SOC sequestration in 0–40 cm soil depth compared to other treatments. Consequently, CF per hectare (CF a) of CSA significantly decreased by 41.4% on average than that of FM mainly due to higher SOC sequestration. Concerning the profit of cropping system, CSA had the highest net ecosystem economic budget (NEEB) of 2090.62 $ ha−1 among the treatments. Overall, CSA practice showed advantages in promoting maize yield while reducing carbon footprint by integrated agronomic management (e.g. dense planting, subsoiling tillage, manure amendments, nitrogen fertilizer optimization, and so on), which could be regarded as a promising practice towards food security and carbon emission mitigation. [Display omitted] • An integrated agronomic practice was setup aiming to climate-smart agriculture (CSA). • CSA practice increased maize yield and nitrogen use efficiency compared to business as usual management. • CSA practice reduced carbon footprint by enhancing soil organic carbon stock and reducing indirect greenhouse gas emission. • It was demonstrated that CSA practice achieves the synergy of sustainable maize productivity and lower environmental costs. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 (eCO2) generally increases carbon input in rice paddy soils and stimulates the growth of methane‐producing microorganisms. Therefore, eCO2 is widely expected to increase methane (CH4) emissions from rice agriculture, a major source of anthropogenic CH4. Agricultural practices strongly affect CH4 emissions from rice paddies as well, but whether these practices modulate effects of eCO2 is unclear. Here we show, by combining a series of experiments and meta‐analyses, that whereas eCO2 strongly increased CH4 emissions from paddies without straw incorporation, it tended to reduce CH4 emissions from paddy soils with straw incorporation. Our experiments also identified the microbial processes underlying these results: eCO2 increased methane‐consuming microorganisms more strongly in soils with straw incorporation than in soils without straw, with the opposite pattern for methane‐producing microorganisms. Accounting for the interaction between CO2 and straw management, we estimate that eCO2 increases global CH4 emissions from rice paddies by 3.7%, an order of magnitude lower than previous estimates. Our results suggest that the effect of eCO2 on CH4 emissions from rice paddies is smaller than previously thought and underline the need for judicious agricultural management to curb future CH4 emissions. [ABSTRACT FROM AUTHOR]

A long-term field experiment was performed to assess the effects of fertilization regimes on greenhouse gas emissions, soil properties, soil denitrifies, and maize (Zea mays) grain yield on Mollisols of Northeastern China. Chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers plus pig manure (MNPK) treatment significantly increased soil N2O emissions by 29.9–226.4% and global warming potential (GWP) by 29.8–230.7% compared to unfertilized control (CK), chemical N fertilizer only (N), chemical N, P, and K fertilizers (NPK) and chemical N, P, and K fertilizers plus corn straw (SNPK) treatments. However, the MNPK treatment yielded similar greenhouse gas intensity (GHGI) as compared with other treatments, mainly due to higher maize grain yield. There were also higher gene copy numbers of nirK, nirS, and nosZ in topsoil (0–20 cm depth) under MNPK treatment. Automatic linear modeling analysis indicated that main factors influencing soil N2O emissions were soil organic carbon (SOC), NO3− content, and nirK gene abundance. Although the application of chemical fertilizers plus organic manure increases N2O emissions due to higher N and C availability and nirK gene activity in the soil, this is still a promising fertilizer management due to its notable enhancement of maize grain yield and SOC content. [ABSTRACT FROM AUTHOR]

Green manure crops play an important role in reducing chemical fertilizer applications while enhancing soil fertility. However, the effects of winter-planted green manure crops on rice paddy greenhouse gas (GHG) emissions are poorly understood. Based on a 35 years experiment, we analyzed the impacts of a rice-rice-green manure cropping system on rice yield and GHG emissions during both rice and winter-green manure seasons. Our experiment consisted of four treatments: ryegrass-rice-rice (Ry-R-R), milkvetch rice-rice (Mv-R-R), rapeseed-rice-rice (Rp-R-R) and fallow-rice-rice (Fa-R-R), arranged in a completely randomized design. Incorporation of winter-planted green manure had more impacts on yield and CH 4 emission in the early rice season than in the late rice season. Compared to the Fa-R-R, the Mv-R-R, Rp-R-R, and Ry-R-R systems increased annual yield by 15.4%, 11.8%, and 6.1%, respectively. However, Ry-R-R and Rp-R-R significantly increased annual CH 4 emissions by 116.73% and 52.45%, respectively, while Mv-R-R reduced CH 4 emissions by 16.3%, compared to Fa-R-R. The CH 4 emissions showed significant positive correlations with dissolved organic carbon, as well as the biomass and C/N ratio of the incorporated green manure plant materials. Although green manuring reduced N 2 O emissions in both winter and rice seasons, there was no significant difference in annual cumulative N 2 O emissions among the treatments. Ry-R-R and Rp-R-R increased annual yield-scaled GWP by 102.6% and 34.8%, respectively, while Mv-R-R was 27.8% lower, compared to the Fa-R-R. Our results suggest that Mv-R-R is the best choice of cropping system for yield sustainability and eco-friendly rice production over the long-term. • The impact of green manure crops on greenhouse gas emissions was studied. • Ry-R-R and Rp-R-R significantly increased CH 4 emissions by 116.73% and 52.45%, respectively. • Mv-R-R significantly increased rice yield by 15.4% and reduced CH 4 emission. • Mv-R-R is the most suitable cropping system for higher rice yield and lower CH 4 emission. [ABSTRACT FROM AUTHOR]

Highlights • Global warming frequently induces extreme temperatures in rice cropping. • Extreme HT impacts severely on rice yield and quality than the LT. • The most responding stage to quality at the 2nd week of post-heading period. Abstract Extreme temperatures will likely occur with greater frequency and intensity under the conditions of climatic warming, presenting a serious challenge for future crop development. The responses of rice yield and quality to extreme high (HT) and low temperature (LT) during precise reproductive periods are still unclear. Therefore, we conducted a walk-in climate chamber experiment with two indica cultivars and three temperature treatments –CK: 20–28 °C, LT: 12–20 °C and HT: 28–36 °C as the mean values of night-day temperatures– for seven days in four key periods –the last week of pre-heading, and the first, second and third week of post-heading–, respectively. Extreme temperatures reduced rice leaf chlorophyll fluorescence, photosynthetic rate and dry matter translocation, consequently decreasing the grain yield by 5–13 percent under LT and 12–15 percent under HT. The most sensitive periods of rice yield to extreme temperatures were found during the last week of pre-heading and the first week of post-heading. Extreme temperatures significantly declined the grain appearance, milling and cooking quality traits with inversely enhanced chalkiness, broken rice and gelatinization temperature. The most responsive period of rice quality to extreme temperatures occurred during the second week of post-heading. HT exhibited a more severe impact on rice quality than by LT. Our results indicate that the responses of rice yield and quality to extreme temperatures are different among reproductive periods. [ABSTRACT FROM AUTHOR]

Rice is a staple food for nearly half of the world's population, but rice paddies constitute a major source of anthropogenic CH4 emissions. Root exudates from growing rice plants are an important substrate for methane‐producing microorganisms. Therefore, breeding efforts optimizing rice plant photosynthate allocation to grains, i.e., increasing harvest index (HI), are widely expected to reduce CH4 emissions with higher yield. Here we show, by combining a series of experiments, meta‐analyses and an expert survey, that the potential of CH4 mitigation from rice paddies through HI improvement is in fact small. Whereas HI improvement reduced CH4 emissions under continuously flooded (CF) irrigation, it did not affect CH4 emissions in systems with intermittent irrigation (II). We estimate that future plant breeding efforts aimed at HI improvement to the theoretical maximum value will reduce CH4 emissions in CF systems by 4.4%. However, CF systems currently make up only a small fraction of the total rice growing area (i.e., 27% of the Chinese rice paddy area). Thus, to achieve substantial CH4 mitigation from rice agriculture, alternative plant breeding strategies may be needed, along with alternative management. Breeding efforts optimizing photosynthate allocation to grains, i.e., increasing harvest index (HI), are widely expected to reduce CH4 emissions from rice cultivation. Here we show, by combining a series of experiments, meta‐analyses, and an expert assessment, that the potential of CH4 mitigation from rice paddies through HI improvement is actually small. We estimate that future HI improvement will reduce CH4 emissions in continuously flooded systems (CF) by 4.4% at most. Furthermore, HI improvement did not affect CH4 emissions in systems with intermittent irrigation (II); these systems make up a large part of the China's rice growing area and are becoming increasingly popular. [ABSTRACT FROM AUTHOR]

Fertilizer application often significantly affects soil quality and crop productivity, thus, can affect soil greenhouse gas (GHG) emissions and nitrogen use efficiency (NUE) as well. However, the impacts have not been well documented under double maize cropping system in subtropical China. Based on a thirty-year field experiment with five fertilization treatments (i.e. no fertilizer (CK), organic manure (OM), N, NPK and NPK plus OM (NPKM)), maize cultivar (Yedan 13) was planted both at the early maize season and late maize season, we assessed the impacts of different fertilizer application on nitrous oxide (N 2 O) and methane (CH 4 ) emissions, grain yield and NUE. Compared to the NPK, manure application (i.e. OM and NPKM) significantly increased N 2 O emissions, and maize yield. Nevertheless, there was no significant difference in yield–scaled global warming potential (GWP) among NPK, OM, and NPKM. Manure application increased soil pH, soil organic carbon, and soil total N, suggesting it can improve soil quality. The NPKM treatment had the highest N uptake, but in terms of NUE, it was lower than OM, due to double N application. Our results suggest that manure application can compensate its negative impacts on N 2 O emission through improving soil quality, maize yield and N use efficiency. [ABSTRACT FROM AUTHOR]

Understanding the actual impacts of climatic warming on winter-sown wheat production will benefit cultivar breeding efforts and agronomic innovations and may help to improve food security. Therefore, we conducted a comprehensive study across the main Chinese winter wheat cropping regions, comprising field warming experiments at four locations and an analysis of 36 years of winter wheat yield data. In the field warming experiments, an increase of 1.0 °C in nighttime temperature enhanced wheat yield by 10.1% on average ( P < 0.05 ). Warming-induced enhancement of 1000-grain weight explained most of these yield increases. Warming shortened the length of pre-flowering phase by 5.4 days, while it prolonged the length of post-flowering phase by 3.8 days. Grain yield increases with warming were similar across experimental sites, even though warming-induced changes in the length of growth periods decreased with increasing ambient temperature. Our analysis of the historical data set was consistent with our field warming experiments; between 1980 and 2015, the major Chinese cropping regions experienced significant warming, especially in daily minimum temperature. Across the historical data set, daily minimum temperature was positively correlated with wheat yield (142.0 kg ha −1 °C −1 ). Our findings are inconsistent with previous reports of yield decreases with warming and may help to inform policy decisions and agronomic innovations of Chinese wheat production to better cope with future climate warming. [ABSTRACT FROM AUTHOR]

Great efforts have been made on the assessment of the effects of straw managements or tillage practices on rice yield and greenhouse gas (GHG) emissions. However, their interactive effects were not well documented. Based on a seven-year field experiment under a double rice system, we tested the effects of rotary tillage (RT) vs. plough tillage (PT) on rice yield, methane (CH 4 ) and nitrous oxide (N 2 O) emissions with or without straw incorporation. As compared to straw removal, straw incorporation increased rice yield by 12.7% and 1.3% under the PT and the RT, respectively. Straw incorporation significantly stimulated CH 4 emissions under both tillage regimes in the late rice season, while no significant effect occurred in the early rice season. Compared to the RT, PT significantly decreased DOC concentrations and methanogen abundances, resulting in a reduction in CH 4 emission. The PT decreased yield-scaled global warming potential (GWP) with or without straw incorporation by 31.0% and 15.5%, respectively, as compared to the RT. Together, our results indicate that straw incorporation with plough tillage benefits rice production for higher-yield with less GHG emissions in double rice cropping areas. [ABSTRACT FROM AUTHOR]

Breeding high-yielding rice cultivars through increasing biomass is a key strategy to meet rising global food demands. Yet, increasing rice growth can stimulate methane ( CH4) emissions, exacerbating global climate change, as rice cultivation is a major source of this powerful greenhouse gas. Here, we show in a series of experiments that high-yielding rice cultivars actually reduce CH4 emissions from typical paddy soils. Averaged across 33 rice cultivars, a biomass increase of 10% resulted in a 10.3% decrease in CH4 emissions in a soil with a high carbon (C) content. Compared to a low-yielding cultivar, a high-yielding cultivar significantly increased root porosity and the abundance of methane-consuming microorganisms, suggesting that the larger and more porous root systems of high-yielding cultivars facilitated CH4 oxidation by promoting O2 transport to soils. Our results were further supported by a meta-analysis, showing that high-yielding rice cultivars strongly decrease CH4 emissions from paddy soils with high organic C contents. Based on our results, increasing rice biomass by 10% could reduce annual CH4 emissions from Chinese rice agriculture by 7.1%. Our findings suggest that modern rice breeding strategies for high-yielding cultivars can substantially mitigate paddy CH4 emission in China and other rice growing regions. [ABSTRACT FROM AUTHOR]

Many efforts have been made to learn the fertilization effects on greenhouse gas (GHG) emissions in the current crop season of multiple cropping systems, however, residual effects on the succeeding crop season are not clear. Based on a thirty-year fertilization experiment, we investigated the impacts of wheat fertilization on GHG emissions in the succeeding soybean season. There were five fertilization regimes for the wheat-soybean cropping system, including sole organic manure (M), balanced chemical NPK fertilizer (NPK), chemical NPK plus manure (NPKM), chemical NP plus wheat straw (NPS), and no fertilizer application (CK). Fertilization significantly affected GHG emissions not only in the current fertilizing season of winter wheat but also in the non-fertilizing season of summer soybean. Compared to the NPK treatment, the M and NPKM treatments stimulated annual soil CO 2 and N 2 O emissions, and reduced CH 4 emissions. The M and NPKM treatments also significantly increased soil organic C and total N contents, soil microbial biomass C and N, and NH 4 N and NO 3 N concentrations, especially in the soybean season. Although fertilizers were only applied in wheat season, the emissions of CO 2 and N 2 O were higher in the soybean season. At the cropping system scale, the treatments of M and NPKM significantly increased annual global warming potential (GWP) by 75.5% and 38.3%, respectively, compared to the NPK. Sole manure application (M) significantly increased greenhouse gas intensity (GHGI) in comparison with the NPK, while there was no significant increment in the GHGI caused by the treatments of chemical fertilizer plus manure (NPKM) and crop straw (NPS). [ABSTRACT FROM AUTHOR]

China is the largest country in grain production and consumption with the greatest emission of greenhouse gas (GHG) in the world. To learn the historical changes and regional differences in GHG emission of the major grain crop production can provide important references to the mitigation of GHG emission in the country and other similar countries. Therefore, we quantified the carbon footprints of rice ( Oryza sativa L.), wheat ( Triticumaestivum L.) and maize ( Zea mays L.) production based on agricultural inputs in the country over the period of 1978–2012. The results showed that area-scaled carbon footprint of rice, wheat and maize production increased gradually from 1286, 937 and 895 kg carbon dioxide equivalent (CO 2 -eq) ha −1 in 1978–2682, 2978 and 2294 kg CO 2 -eq ha −1 in 2012, respectively, and the average increase rates for the three crops were correspondingly 41, 60 and 41 kg CO 2 -eq ha −1 a −1 . During the last ten years, however, all the average yield-scaled carbon footprints of rice, wheat and maize decreased by 0.11 kg CO 2 -eq kg −1 10a −1 . Chemical fertilizer contributed the largest ratio to the total GHG emission by 66, 68 and 76% for rice, wheat and maize, respectively. Significant increasing contribution ratio to the carbon footprint was found in the electricity used for crop irrigation. There were large differences in both the area- and yield-scaled carbon footprints among the cropping regions with the lowest GHG emission occurring in the major cropping regions. Our findings indicate a great potential to reduce GHG emission of grain production through optimizing the spatial layout of cropping region and enhancing chemical fertilizer use efficiency. Further efforts also need to be made on water-saving irrigation to decrease the electricity usage. [ABSTRACT FROM AUTHOR]

Great attentions have been taken to the effects of climatic warming on crop production, however, fewer were known about the actual impacts of nighttime warming under different cropping systems. Therefore, a three-year field experiment with a passive nighttime warming (PNW) facility and a one-year field experiment with free air temperature increase (FATI) facility were conducted in major Chinese rice cropping systems. Four-year field observations from different rice cropping systems all showed that nighttime warming less than 1.0 °C could shorten the length of crop pre-flowering phase period while prolonged the length of post-flowering phase period, resulting in insignificant reduction in the length of crop entire growth period. The temperature increase caused significant increments in grain yields by 16.2, 12.7 and 12.0% for late rice in the rice–rice cropping system, wheat in the rice-wheat cropping system and rice in the single rice cropping system, respectively. However, this warming declined grain yields significantly by 4.5 and 6.5% for early rice in the rice–rice cropping system and rice in the rice-wheat cropping system, respectively. Since warming-induced yield reduction was less than warming-induced increment in each cropping system, the annual yields was higher in the warmed plots than the non-warmed under all systems. Our findings can provide important references to cropping system adjustment for coping with global warming in China and other regions. [ABSTRACT FROM AUTHOR]

Dense planting and less basal nitrogen (N) fertilization have been recommended to further increase rice ( Oryza sativa L.) grain yield and N use efficiency (NUE), respectively. The objective of this study was to evaluate the integrative impacts of dense planting with reduced basal N application (DR) on rice yield, NUE and greenhouse gas (GHG) emissions. Field experiments with one conventional sparse planting (CK) and four treatments of dense planting (increased seedlings per hill) with less basal N application were conducted in northeast China from 2012 to 2013. In addition, a two-factor experiment was conducted to isolate the effect of planting density and basal N rate on CH 4 emission in 2013. Our results show that an increase in planting density by about 50% with a correspondingly reduction in basal N rate by about 30% (DR1 and DR2) enhanced NUE by 14.3–50.6% and rice grain yield by 0.5–7.4% over CK. Meanwhile, DR1 and DR2 reduced GWP by 6.4–12.6% and yield-scaled GWP by 7.0–17.0% over CK. According to the two-factor experiment, soil CH 4 production and oxidation and CH 4 emission were not affected by planting density. However, reduced basal N rate decreased CH 4 emission due to it significantly reduced soil CH 4 production with a smaller reduction in soil CH 4 oxidation. The above results indicate that moderate dense planting with less basal N application might be an environment friendly mode for rice cropping for high yield and NUE with less GHG emissions. [ABSTRACT FROM AUTHOR]

Rice cropping innovations for high yield with high N use efficiency (NUE) and low greenhouse gas (GHG) emissions are significant in ensuring food security and coping with climate change. The objective of this study was to investigate the comprehensive effects of dense planting with less basal N application (DR) on rice yield, NUE and GHG emissions. Field experiments were conducted at three sites in China: Shenyang, Danyang and Jinxian representing annual single rice cropping system, wheat-rice cropping system and double rice cropping system, respectively. Four planting densities with 25, 50, 75 and 100% higher each time correspondingly with about 25, 50, 75 and 100% less in basal N rate (i.e., DR1, DR2, DR3 and DR4 correspondingly) relative to traditional cropping for high yield (CK). Across three tested sites, the DR1 mode showed a large potential of NUE enhancement by 19.6% and GHG emissions mitigation by 12.2% at area-and yield-scaled with similar rice yield compared to the CK. However, further increase in planting density and decrease in basal N application caused a significant reduction in rice yield with a large increase in GHG emissions. Our results will provide important reference to rice cropping innovations for the integrated goals of food security, environmental health and climate change mitigation in China. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]

High-yield varieties with low methane emissions will benefit sustainable rice ( Oryza sativa L.) production. However, no specific plant characteristics have been identified to be primarily responsible for rice variety impacts on the CH 4 emission. We conducted a comprehensive study through comparing effects of 66 varieties on CH 4 under both greenhouse and field conditions to identify rice plant characteristics that may significantly affect soil CH 4 emission. Although there were significant differences in CH 4 emissions among the tested rice varieties, no significant and consistent relationships were observed between aboveground traits and CH 4 fluxes or dissolved CH 4 concentrations in soil solutions. Yet dissolved CH 4 concentrations were significantly correlated with the mean CH 4 flux over the growing season. In addition, cutting rice plants 5 cm off above the floodwater did not increase CH 4 fluxes, indicating that the CH 4 transport through the removed part of rice plant contributed little to the total CH 4 emission. Taken together, our results indicate that differences in CH 4 emissions among rice varieties primarily stem from the differential effects of rice plants on the belowground CH 4 production and oxidation. Aboveground plant traits do not provide reliable predictions of variety effects on CH 4 emissions. Future efforts should be focused on understanding belowground processes and the underlying mechanisms that govern rice variety impacts on the CH 4 emission. [ABSTRACT FROM AUTHOR]

Atmospheric CO 2 concentrations and water management practices both affect greenhouse gas (GHG) emissions from rice paddies, but interactive effects between these two factors are still unknown. Here, we show the first study to compare the impact of elevated atmospheric CO 2 (eCO 2) on GHG emissions under continuously flooded irrigation (CF) and under intermittently flooded (IF) conditions. Elevated CO 2 stimulated CH 4 emissions under CF by 50% in a field experiment and by 46% in a pot experiment, but it had no effect under IF in both experiments. Elevated CO 2 had no effect on N 2 O emissions in either the field or pot experiment. Rice root biomass, aboveground biomass and grain yield increased with eCO 2 , but were not affected by water management. Elevated CO 2 only stimulated the abundance of methanogens under CF, suggesting that increased soil O 2 availability with IF limited methanogenic activity under eCO 2. Our findings suggest that estimates of CH 4 emissions from global rice agriculture with eCO 2 need to account for recent changes in water management. • The first study to compare the effect of elevated CO 2 on GHG emissions under CF and IF. • Elevated CO 2 stimulated CH 4 emissions under CF, but had no effect under IF. • Elevated CO 2 did not affect N 2 O emissions under CF and IF. • Elevated CO 2 increased the abundance of methanogens under CF only. • Current estimates of CO 2 effects on CH 4 emissions from rice paddies may be too high. [ABSTRACT FROM AUTHOR]

Mechanical planting is replacing manual transplanting in the major Asian rice cropping areas, however, few are known about the impacts of mechanical planting on rice yield and greenhouse gas (GHG) emission. Therefore, a two-year experiment was conducted to examine the impacts of dry direct-seeding (MDS), wet direct-seeding (MWS) and transplanting (MTP) in Jianghuai area, China. The results showed that CH 4 emission was significantly lower in the MDS than the MWS and MTP both with and without straw incorporation. No significant difference in N 2 O emission was found among the planting methods. Straw incorporation significantly stimulated CH 4 emission in the MWS and MTP, but not in the MDS. The lowest rice yield was found in the MWS, while there was no significant difference in grain yield between the MDS and MTP methods. The area-scaled emission of CH 4 and N 2 O in CO 2 -equivalent unit was respectively 78.5 and 89.6% lower in the MDS than those in the MWS and MTP without straw incorporation, and 87.7 and 94.1% lower with straw incorporation. The yield-scaled emission was correspondingly 80.4 and 88.1% lower without straw incorporation, and 89.0 and 93.4% lower with straw incorporation, respectively. Our results indicate that MDS can get an acceptable yield with a large reduction in GHGs emissions in the test location. [ABSTRACT FROM AUTHOR]

Studies on greenhouse gas (GHG) emissions from paddy field have primarily focused on the post-transplanting period, however, recent researches raise new concerns about GHGs emission from rice nursery. In this study, CH 4 and N 2 O fluxes were determined from different nurseries under major rice cropping systems in China. The tested nurseries included flooded nursery (FN), moist nursery (MN) and dry nursery (DN). Methane emissions from FN were significantly higher than those from MN and DN under all the rice cropping systems. When comparing with FN, MN decreased total CH 4 emissions by 74.2%, 72.1% and 49.6% under the rice–upland rotation cropping system (RUR), and the double rice cropping system for the early rice (EDR) and the late rice (LDR), respectively. DN decreased CH 4 emissions by 99.2%, 92.0%, 99.0% and 78.6% compared to FN under the single rice cropping system (SR), RUR, EDR and LDR, respectively. When comparing with FN, MN and DN increased N 2 O emissions by 58.1–134.1% and 28.2–332.7%, respectively. Ultimately, compared with FN across the cropping systems, MN and DN decreased net global warming potentials (GWPs) of CH 4 and N 2 O by 33–68% and 43–86%, respectively. The mitigating effect of MN and DN on total GWPs varied greatly across the systems, ranging from 30.8% in the LDR to 86.5% in the SR. Chinese actual emission from rice nurseries was reduced to 956.66 × 10 3 t CO 2 eq from the theoretical estimate of 2242.59 × 10 3 t CO 2 eq if under the flooded nursery scenario in 2012. Taking into account the large rice nursery area (2032.52 × 10 3 ha) in China, the results of this study clearly indicate the importance to estimate and mitigate GHGs emission from flooded rice nursery. Being effective to reduce GHG emissions and increase rice yield, dry nursery technique is a promising candidate for climate smart rice cropping. [ABSTRACT FROM AUTHOR]

Organic amendment often affects both crop yield and greenhouse gas (GHG) emission. Yet the impact of organic amendment on yield gains and GHG emissions is still unclear, particularly in long-term soybean-wheat cropping system. Based on a 30-year soybean-wheat cropping system experiment, the impact of organic amendments (i.e. straw and manure) on soil properties, crop yield, N 2 O and CH 4 emissions, and net ecosystem economic budget (NEEB) were investigated. The treatments were: chemical NPK fertilizer (NPK), chemical NPK plus low amount of wheat straw (NPKLS), chemical NPK plus high amount of wheat straw (NPKHS), chemical NPK plus pig manure (NPKPM), chemical NPK plus cattle manure (NPKCM), and a control with no fertilizer applied (CK). The long-term straw and manure amendments enhanced soybean yield by 13.1% and 44.0%, and improved wheat yield by 6.4% and 9.9%, respectively. Meanwhile, they stimulated N 2 O emissions by 25.1% and 49.0% respectively, without significant effect on CH 4 emissions, compared to the chemical NPK fertilizer treatment (NPK). The results of structural equation model showed that soil properties tested explained 76% of the variations observed in N 2 O emissions, which were directly affected by soil nitrification capacity, pH and denitrification capacity. Although straw and manure amendments increased the total GHG emissions investigated by 25.7% and 48.6% respectively, they showed insignificant effects on the greenhouse gas intensity (GHGI), and increased NEEB by 8.6% and 21.1%, respectively, compared to the NPK treatment. This indicates that the benefits arising from crop yield improvement through the use of organic amendments can cover the carbon fees caused by increased GHG emissions. Our findings suggest that organic amendment can be an effective strategy to simultaneously increase crop yield while mitigating greenhouse gas emissions from the perspective of carbon fees. [Display omitted] • Organic amendments stimulated total GHG emissions of N 2 O and CH 4. • Soil properties tested explained 76% of the variation in N 2 O emissions. • Organic amendments improved yield without increasing the greenhouse gas intensity. • Straw and manure amendments increased the net ecosystem economic budget. [ABSTRACT FROM AUTHOR]

Green manure is important for crop yield sustainability. However, its impact on methane (CH 4) emissions in paddy soils is poorly understood. Based on a 37-year experiment, we linked methanogenic and methanotrophic communities to CH 4 emissions under a green manure-based double rice cropping system. The treatments were: ryegrass-rice-rice (R), milk vetch-rice-rice (M) and fallow-rice-rice (F). The early and late rice yield where within the range of 3760.0 and 4933.3 kg ha−1, and 5040.0 and 6373. 3 kg ha−1, respectively. Meanwhile, the CH 4 fluxes ranged from, 0.02–168.71 mg m−2 h−1. Green manure increased annual rice yield by 16.1–25.3%, as against F (P < 0.05). However, R increased cumulative CH 4 emissions by 90.2% (P < 0.05) whereas M showed no significant stimulation, relative to F. The total CH 4 emissions notably correlated with dissolved organic carbon (DOC) (r = 0.80, P < 0.01) and the gene copy numbers of mcrA (r = 0.78, P < 0.05), but not pmoA (r = 0.65, P > 0.05). The relative abundances of acetoclastic methanogens belonging to the family Methanosarcinaceae , and hydrogenotrophic methanogens of the orders Methanocellales and Methanobacteriales , were lower in M, as against R (P < 0.05), and correlated with the total CH 4 emissions (r = 0.90, 0.84, 0.96, respectively, P < 0.01). Our findings suggest that leguminous green manure improves rice yield, and mitigates CH 4 emissions by regulating both acetoclastic and hydrogenotrophic methanogenic communities. • Green manuring significantly increased annual rice yield by 16.1–25.3%. • R significantly increased total CH 4 emissions, relative to M and F. • Methanosarcinaceae , Methanocellales and Methanobacteriales were significantly lower in M, as against R. • Legume green manuring is a good approach for increasing rice yield and mitigating CH 4 emission. [ABSTRACT FROM AUTHOR]

• Rotation regimes led to significant differences of soil macrofaunal community. • SOC was the most important factor for shaping soil macrofaunal community. • The green manure and fallow fields held higher soil macrofaunal biodiversity. • Land use intensity reduction increased the complexity of trophic structure. Crop production has negative effect on the biodiversity in farmlands because of less crop varieties and intensive soil disturbance. Macrofauna are important components of the belowground biodiversity, and contribute to the soil ecosystem functions and soil processes. The response of soil macrofauna to cropping pattern is crucial for understanding the soil ecological dynamics and biodiversity conservation. Herein, we established an experiment of rice (Oryza sativa L.)-based double cropping system in Jiangsu Province, China since 2016 to evaluate the effects of rotation regimes on soil properties and soil macrofauna communities. The rice-based double cropping system included rice–wheat (Triticum aestivum L.), rice-oilseed rape (Brassica campestris L.), rice-tiny vetch (Vicia hirsuta L.), rice-broad bean (Vicia faba L.), and rice-fallow. After 3-year rotations, soil macrofaunal biodiversity and trophic structure varied significantly with soil properties. The higher biodiversity indices were found in the tiny vetch (used as green manure in situ) and fallow fields. In addition, soil organic carbon (SOC), the main factor for shaping the soil environment and regulating the soil macrofaunal communities, was improved. While soil water content and pH were selected to predict each trophic richness and density in most of the optimal regression models, changes in soil macrofaunal communities should also be considered as comprehensive responses to the soil environments (food resources, microhabitats etc.) co-varying rotation regimes. Crop rotation with lower intensity of land use increased the complexity of soil macrofaunal trophic structure. Green manure fields or fallow after rice plantation promoted soil macrofaunal biodiversity in the rice-based cropping system. [ABSTRACT FROM AUTHOR]

Climatic warming is often predicted to reduce wheat yield and grain quality in China. However, direct evidence is still lacking. We conducted a three-year experiment with a Free Air Temperature Increase (FATI) facility to examine the responses of winter wheat growth and plant N accumulation to a moderate temperature increase of 1.5°C predicted to prevail by 2050 in East China. Three warming treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming) were applied for an entire growth period. Consistent warming effects on wheat plant were recorded across the experimental years. An increase of ca. 1.5°C in daily, daytime and nighttime mean temperatures shortened the length of pre-anthesis period averagely by 12.7, 8.3 and 10.7 d (P<0.05), respectively, but had no significant impact on the length of the post-anthesis period. Warming did not significantly alter the aboveground biomass production, but the grain yield was 16.3, 18.1 and 19.6% (P<0.05) higher in the AW, DW and NW plots than the non-warmed plot, respectively. Warming also significantly increased plant N uptake and total biomass N accumulation. However, warming significantly reduced grain N concentrations while increased N concentrations in the leaves and stems. Together, our results demonstrate differential impacts of warming on the depositions of grain starch and protein, highlighting the needs to further understand the mechanisms that underlie warming impacts on plant C and N metabolism in wheat. [ABSTRACT FROM AUTHOR]

Highlights: [•] Corn yield is affected by climate patterns in cool-high latitude rainfed area. [•] Flat planting increases topsoil water storage and minimum temperature at early stage. [•] Ridge planting can reduce waterlogging risk at middle and later growth stages. [•] Flat planting with ridge at V6 stage achieves higher corn yield due to improved soil moisture and temperature conditions. [Copyright &y& Elsevier]

Arbuscular mycorrhizal fungi (AMF), which form symbiotic associations with 80% of land plants, provide host plants with soil phosphorus (P) and nitrogen (N) in exchange for carbon. The AMF often reduces nitrous oxide (N 2 O) emissions from soils with non-legume plants, as they acquire N from soils to plants. However, the effect of AMF on soil N 2 O emissions is still unknown in the legume system, a major source of this potent greenhouse gas. Therefore, we conducted the field and pot experiments to investigate the effects of AMF on plant growth and soil N 2 O emissions in legume systems. The results showed that AMF significantly increased soil N 2 O emissions from soils with soybean by 39% in the field experiment and by 63% in the pot experiment. The AMF significantly enhanced the root biomass, aboveground biomass, grain yield, plant N uptake, plant P uptake, and the nodule numbers. The AMF increased soil extractable N concentrations and DOC concentrations, but reduced soil available P concentrations. The AMF stimulated the N 2 O-producing microbes (nirS - and nirK -type) whereas they did not affect the N 2 O-consuming (nosZ -type) denitrifiers. The AMF reduced the yield-scaled N 2 O emissions in the field experiment and increased the net ecosystem economic budget. Our findings indicate that AMF increase soil N 2 O emissions from legume system through enhancing P acquisition for biological N 2 fixation and suggest that AMF benefit crop production for higher-yield with less N 2 O emissions. • The first study of N 2 O emissions from legume systems as affected by AMF. • AMF significantly increased soybean yields and soil N 2 O emissions in soybean systems. • AMF increased N 2 O-producing microbes mainly due to higher biological N 2 fixation. • AMF increased net ecosystem economic budget. [ABSTRACT FROM AUTHOR]

Increasing crop biodiversity often increases agro-ecosystem services, however, the effects of crop biodiversity on crop yield and environmental benefits are still unclear. Thus, we conducted a 4-yr field experiment in northeastern China including continuous maize (CM), continuous soybean (CS), maize and soybean rotation (M-S), and maize and soybean intercropping (M/S) to evaluate the crop productivity, economic returns, carbon footprint (CF) and carbon sustainability index (CSI) among the cropping system regimes. Compared with CM treatment, M-S and M/S achieved lower energy yield (EY) and maize equivalent economic yield (MEEY), but higher economic returns. The mean annual net revenue of M-S treatment was 7.2% higher, and the mean annual benefit: cost ratio of M-S and M/S treatments were 12.0% and 8.8% higher than those of CM treatment. Based on the life cycle assessment (LCA), lower CFs were observed in the M-S and M/S systems. The CF per unit of area (CF A) of M-S and M/S treatments was 21.4% and 51.3% lower than that of the CM treatment, respectively. The CF per kg of energy yield (CF EY) of M/S treatment was 35.4% lower, compared with that of the CM treatment. The CF per kg of maize equivalent economic yield (CF MEEY) under M/S treatment was 44.0% lower, than that of the CM treatment. Moreover, CF per unit of economic output (CF E) of M/S treatment was 45.0% lower than that of the CM treatment. The highest CSI was observed in M-S treatment, and it was 61.4% higher than that of CM treatment. Our findings indicate that diversified crop practice (e.g. maize-soybean intercropping and rotation systems) could achieve lesser carbon footprint and higher profitability, however, might compromise grain or energy yield. [Display omitted] • The productivity, profitability, and environmental costs of different cropping systems were evaluated. • Diversified crop practice had lesser carbon footprint and higher profitability. • Maize-soybean intercropping systems is an alternative to the traditional maize monoculture system in northeastern China. [ABSTRACT FROM AUTHOR]

Abstract: Recently increasing studies suggest that a comprehensive assessment of cropping practices impacts on greenhouse gas (GHG) emissions at yield-scale will benefit cropping technique innovation and policy selection for higher-yield with less-emissions. In this paper, we conducted a meta-analysis to quantify the impacts of rice cropping practices on the global warming potential (GWP) of GHG emissions at yield-scale rather than area-scale in China. The results showed that the yield-scaled GWP of Chinese major rice cropping systems during rice growing season was in the order: double rice cropping system (1188.9kg CO2 equiv.Mg−1)>rice-upland crop rotation system (777.0kg CO2 equiv.Mg−1)>single rice cropping system (346.7kg CO2 equiv.Mg−1). Nitrogen fertilization (50–300kgNha−1) significantly increased rice yield with slight increments in the GWP of CH4 and N2O emissions, resulting in significant reductions in the yield-scaled GWP. The greatest reduction occurred at the application rate of 150–200kgNha−1 by 37% as compared to the non-fertilization control. For organic amendments, biogas residue application had no significant effect on the yield-scaled GWP, while manure application and straw recycling significantly increased the yield-scaled GWP by 54% and 154%, respectively. Intermittent irrigation significantly reduced yield-scaled GWP by 59% largely because of a significant reduction in CH4 emission and a significant increment in rice yield. No-tillage showed lower CH4 emission with similar rice yield in comparison with the conventional tillage, resulting in a reduction in yield-scaled GWP by 20%. These results indicate that there is a great potential to meet the new objective of higher-yield with less-GHG emissions through innovating rice cropping technique. More efforts should be paid on the field observations of GHG emissions during non-rice growing season, so as to perform a life-cycling assessment of GHG emissions from rice fields at yield scale under different cropping systems. [Copyright &y& Elsevier]

Abstract: A five-year experiment with Free Air Temperature Increase facility was conducted to investigate the actual responses of winter wheat phenophase and yield to warming in Yangtze Delta Plain, China. Air temperature increase of around 1.5°C in wheat canopy advanced crop phenophases significantly, leading to a reduction in length of the entire growth period by 10 days (P <0.05). This reduction was mainly found in the length of pre-anthesis phase, while the length of post-anthesis phase was prolonged slightly. Warming increased grain yield by 16.3% (P <0.05) whereas no significant effects were found on the aboveground biomass. Warming tended to increase the numbers of productive spike and filled grain and the harvest index. The areas of flag leaf and total green leaf at anthesis and the 1000-grain weight were 36.0, 19.2 and 5.9% higher in the warmed plots than the un-warmed control (P <0.05), respectively. Warming stimulated the filling rate of inferior grain (P <0.05), while the rate of superior grain stayed almost unchanged. The above evidences suggest that anticipated warming may facilitate winter wheat production in East China. [Copyright &y& Elsevier]

Abstract: Increasing evidences have shown that dissolved organic components are responsible for the significant C and N exports from terrestrial ecosystems to the surrounding aquatic ecosystems and very sensitive to CO2 enrichment. However, there is still a lack of direct evidence about CO2-led effects on these components at the ecosystem scale, especially in wetlands. We, therefore, simultaneously investigated the contents of dissolved organic carbon (DOC) and dissolved nitrogen (DN) in the surface water and soil layer in a paddy field under FACE facility in Eastern China. Elevated CO2 significantly increased the contents of DOC and DN in the surface water by 18.0% and 14.3% on average. Elevated CO2 also increased DOC content in the soil, but decreased DN content. The contents of DOC and DN in the soil–water interface of 0–1cm soil layer were on average 22.4% and 47.5% higher than in the 5–15cm soil layer. Besides, significant higher DOC and DN contents existed in the soil porewater than in the surface water. Due to multiple drainage regime and rainstorm-induced runoffs in rice cropping regions, CO2-led DOC and DN increments in the surface water may increase C and N exports from paddies to the surrounding aquatic ecosystems under future climate patterns. [Copyright &y& Elsevier]