Consensus,uncertainties and challenges for perennial bioenergy crops and land use

Perennial bioenergy crops have significant potential to reduce greenhouse gas (GHG) emissions and contribute to climate change mitigation by substituting for fossil fuels; yet delivering significant GHG savings will require substantial land‐use change, globally. Over the last decade, research has delivered improved understanding of the environmental benefits and risks of this transition to perennial bioenergy crops, addressing concerns that the impacts of land conversion to perennial bioenergy crops could result in increased rather than decreased GHG emissions. For policymakers to assess the most cost‐effective and sustainable options for deployment and climate change mitigation, synthesis of these studies is needed to support evidence‐based decision making. In 2015, a workshop was convened with researchers, policymakers and industry/business representatives from the UK, EU and internationally. Outcomes from global research on bioenergy land‐use change were compared to identify areas of consensus, key uncertainties, and research priorities. Here, we discuss the strength of evidence for and against six consensus statements summarising the effects of land‐use change to perennial bioenergy crops on the cycling of carbon, nitrogen and water, in the context of the whole life‐cycle of bioenergy production. Our analysis suggests that the direct impacts of dedicated perennial bioenergy crops on soil carbon and nitrous oxide are increasingly well understood and are often consistent with significant life cycle GHG mitigation from bioenergy relative to conventional energy sources. We conclude that the GHG balance of perennial bioenergy crop cultivation will often be favourable, with maximum GHG savings achieved where crops are grown on soils with low carbon stocks and conservative nutrient application, accruing additional environmental benefits such as improved water quality. The analysis reported here demonstrates there is a mature and increasingly comprehensive evidence base on the environmental benefits and risks of bioenergy cultivation which can support the development of a sustainable bioenergy industry.     

A comparison of canopy evapotranspiration for maize and two perennial grasses identified as potential bioenergy crops

In the Midwestern US, perennial rhizomatous grasses (PRGs) are considered one of the most promising vegetation types to be used as a cellulosic feedstock for renewable energy production. The potential widespread use of biomass crops for renewable energy production has sparked numerous environmental concerns, including the impacts of land‐use change on the hydrologic cycle. We predicted that total seasonal evapotranspiration (ET) would be higher for PRGs relative to maize resulting from higher leaf area and a prolonged growing season. We further predicted that, compared with maize, higher aboveground biomass associated with PRGs would offset the higher ET and increase water‐use efficiency (WUE) in the context of biomass harvests for liquid biofuel production. To test these predictions, ET was estimated during the 2007 growing season for replicated plots of Miscanthus×giganteus (miscanthus), Panicum virgatum (switchgrass), and Zea mays (maize) using a residual energy balance approach. The combination of a 25% higher mean latent heat flux (λET) and a longer growing season resulted in miscanthus having ca. 55% higher cumulative ET over the growing season compared with maize. Cumulative ET for switchgrass was also higher than maize despite similar seasonal‐mean λET. Based on total harvested aboveground biomass, WUE was ca. 50% higher for maize relative to miscanthus; however, when WUE calculated from only maize grain biomass was compared with WUE calculated from miscanthus harvested aboveground biomass, this difference disappeared. Although WUE between maize and miscanthus differed postsenescence, there were no differences in incremental WUE throughout the growing season. Despite initial predictions, aboveground biomass for switchgrass was less than maize; thus WUE was substantially lower for switchgrass than for either maize scenario. These results indicate that changes in ET due to large‐scale implementation of PRGs in the Midwestern US would likely influence local and regional hydrologic cycles differently than traditional row crops.     

Carbon sequestration potential in perennial bioenergy crops: the importance of organic matter inputs and its physical protection

To date, only few studies have compared the soil organic carbon (SOC) sequestration potential between perennial woody and herbaceous crops. The main objective of this study was to assess the effect of perennial woody (poplar, black locust, willow) and herbaceous (giant reed, miscanthus, switchgrass) crops on SOC stock and its stabilization level after 6 years from plantation on an arable field. Seven SOC fractions related to different soil stabilization mechanisms were isolated by a combination of physical and chemical fractionation methods: unprotected (cPOM and fPOM), physically protected (iPOM), physically and chemically protected (HC‐μs + c), chemically protected (HC‐ds + c), and biochemically protected (NHC‐ds + c and NHC‐μs + c). The continuous C input to the soil and the minimal soil disturbance increased SOC stocks in the top 10 cm of soil, but not in deeper soil layers (10–30; 30–60; and 60–100 cm). In the top soil layer, greater SOC accumulation rates were observed under woody species (105 g m^?2 yr^‐1) than under herbaceous ones (71 g m^?2 yr^‐1) presumably due to a higher C input from leaf‐litter. The conversion from an arable maize monoculture to perennial bioenergy crops increased the organic C associated to the most labile organic matter (POM) fractions, which accounted for 38% of the total SOC stock across bioenergy crops, while no significant increments were observed in more recalcitrant (silt‐ and clay‐sized) fractions, highlighting that the POM fractions were the most prone to land‐use change. The iPOM fraction increased under all perennial bioenergy species compared to the arable field. In addition, the iPOM was higher under woody crops than under herbaceous ones because of the additional C inputs from leaf‐litter that occurred in the former. Conversion from arable cropping systems to perennial bioenergy crops can effectively increase the SOC stock and enlarge the SOC fraction that is physically protected within soil microaggregates.     

A critical review of the impacts of cover crops on nitrogen leaching,net greenhouse gas balance and crop productivity

Cover crops play an increasingly important role in improving soil quality, reducing agricultural inputs and improving environmental sustainability. The main objectives of this critical global review and systematic analysis were to assess cover crop practices in the context of their impacts on nitrogen leaching, net greenhouse gas balances (NGHGB) and crop productivity. Only studies that investigated the impacts of cover crops and measured one or a combination of nitrogen leaching, soil organic carbon (SOC), nitrous oxide (N₂O), grain yield and nitrogen in grain of primary crop, and had a control treatment were included in the analysis. Long‐term studies were uncommon, with most data coming from studies lasting 2–3 years. The literature search resulted in 106 studies carried out at 372 sites and covering different countries, climatic zones and management. Our analysis demonstrates that cover crops significantly (p < 0.001) decreased N leaching and significantly (p < 0.001) increased SOC sequestration without having significant (p > 0.05) effects on direct N₂O emissions. Cover crops could mitigate the NGHGB by 2.06 ± 2.10 Mg CO₂‐eq ha^?1 year^?1. One of the potential disadvantages of cover crops identified was the reduction in grain yield of the primary crop by ≈4%, compared to the control treatment. This drawback could be avoided by selecting mixed cover crops with a range of legumes and non‐legumes, which increased the yield by ≈13%. These advantages of cover crops justify their widespread adoption. However, management practices in relation to cover crops will need to be adapted to specific soil, management and regional climatic conditions.     

Implications of emissions timing on the cost‐effectiveness of greenhouse gas mitigation strategies: application to forest bioenergy systems

Conventional cost‐effectiveness calculations ignore the implications of greenhouse gas (GHG) emissions timing and thus may not properly inform decision‐makers in the efficient allocation of resources to mitigate climate change. To begin to address this disconnect with climate change science, we modify the conventional cost‐effectiveness approach to account for emissions timing. GHG emissions flows occurring over time are translated into an ‘Equivalent Present Emission’ based on radiative forcing, enabling a comparison of system costs and emissions on a consistent present time basis. We apply this ‘Present Cost‐Effectiveness’ method to case studies of biomass‐based electricity generation (biomass co‐firing with coal, biomass cogeneration) to evaluate implications of forest carbon trade‐offs on the cost‐effectiveness of emission reductions. Bioenergy production from forest biomass can reduce forest carbon stocks, an immediate emissions source that contributes to atmospheric greenhouse gases. Forest carbon impacts thereby lessen emission reductions in the near‐term relative to the assumption of biomass ‘carbon neutrality’, resulting in higher costs of emission reductions when emissions timing is considered. In contrast, conventional cost‐effectiveness approaches implicitly evaluate strategies over an infinite analytical time horizon, underestimating nearer term emissions reduction costs and failing to identify pathways that can most efficiently contribute to climate change mitigation objectives over shorter time spans (e.g. up to 100 years). While providing only a simple representation of the climate change implications of emissions timing, the Present Cost‐Effectiveness method provides a straightforward approach to assessing the cost‐effectiveness of emission reductions associated with any climate change mitigation strategy where future GHG reductions require significant initial capital investment or increase near‐term emissions. Timing is a critical factor in determining the attractiveness of any investment; accounting for emissions timing can better inform decisions related to the merit of alternative resource uses to meet near‐, mid‐, and long‐term climate change mitigation objectives.     

供氮水平对爬山虎(Parthenocissus tricuspidata Planch)生物量及养分分配的影响

爬山虎是典型的亚热带木本攀援植物,在垂直绿化、植被恢复和水土保持等方面的应用日益普遍,而营养元素对爬山虎生长的影响还缺乏研究,这不利于爬山虎的生长调控与合理应用。通过水培试验,对不同氮素水平(0、0.15、0.3、0.45、0.6、0.75g.L-1)条件下爬山虎幼苗生长、氮磷钾营养分配和利用状况作了研究。结果表明:供氮水平的提高能显著促进植株的生物量增加,并影响茎叶的生物量分配比例,供氮处理的叶生物量占总生物量的50%以上;供氮水平的提高能增加植株根、茎、叶的氮含量,对磷含量影响不显著,对茎叶中的钾含量有一定的稀释作用;叶片是主要的氮养分贮存器官,叶片氮累积量达到整个植株总氮累积量的60%以上;供氮水平的增加,降低了爬山虎的氮利用率,提高了磷钾的利用率。     

An estimate of greenhouse gas (N2O and CO2) mitigation potential under various scenarios of nitrogen use efficiency in Chinese croplands

It is well recognized that improving nitrogen use efficiency (NUE) can directly reduce nitrous oxide (N₂O) emission in cropland and indirectly reduce carbon dioxide (CO₂) release from nitrogen (N) production, while such a reduction has not been well quantified in China. We estimated the greenhouse gas (GHG; N₂O and CO₂) mitigation potential (MP) from Chinese cropland and its regional distribution by quantifying NUE and determining the amount of over‐applied synthetic N under various scenarios of NUE. We estimated that synthetic NUE in the late 1990s was 31±11% (mean±SD) for rice, 33±13% for wheat, and 31±11% for maize cultivation. Improving NUE to 50% could cut 6.6 Tg of synthetic N use per year, accounting for 41% of the total used. As a result of this reduction, the direct N₂O emission from croplands together with CO₂ emission from the industrial production and transport of synthetic N could be reduced by 39%, equivalent to 60 Tg CO₂ yr^?1. The MP was probably underestimated because organic N supply was not taken into account when estimating NUE. It was concluded that improving N management can greatly reduce GHG (N₂O and CO₂) emissions in Chinese croplands, and mitigation in the Jiangsu, Henan, Shandong, Sichuan, Hubei, Anhui, and Hebei provinces should be given priority.     

Potential trade‐offs of employing perennial biomass crops for the bioeconomy in the EU by 2050: Impacts on agricultural markets in the EU and the world

Perennial biomass crops (PBC) are considered a crucial feedstock for sustainable biomass supply to the bioeconomy that compete less with food production compared to traditional crops. However, large‐scale development of PBC as a means to reach greenhouse gas (GHG) mitigation targets would require not only the production on land previously not used for agriculture, but also the use of land that is currently used for agricultural production. This study aims to evaluate agricultural market impacts with biomass demand for food, feed, and PBC in four bioeconomy scenarios (“Business as usual,” “Improved relevance of bioeconomy,” “Extensive transformation to a bioeconomy,” “Extensive transformation to a bioeconomy with diet change”) to achieve a 75% GHG reduction target in the emission trading sector of the EU until 2050. We simulated bioeconomy scenarios in the energy system model TIMES‐PanEU and the agricultural sector model ESIM and conducted a sensitivity analysis considering crop yields, PBC yields, and land use options of PBC. Our results show that all bioeconomy scenarios except the one with diet change lead to increasing food prices (the average food price index increases by about 11% in the EU and 2.5%–3.0% in world markets). A combination of the transformation to a bioeconomy combined with diet change toward less animal protein in the EU is the only scenario that results in only moderately increasing food prices within the EU (+3.0%) and even falling global food prices (–6.4%). In addition, crop yield improvement and cultivation of PBC on marginal land help to reduce increases in food prices, but higher land prices are inevitable because those measures have only small effects on sparing agricultural land for PBC. For a transition to a bioeconomy that acknowledges climate mitigation targets, counter‐measures for those substantial direct and indirect impacts on agricultural markets should be taken into account.     

模拟氮沉降对藏北高寒草甸温室气体排放的影响

目前,高寒草甸对全球温室效应的贡献仍具有不确定性,而随着N沉降的增加,该系统温室体气排放也必将发生变化。为揭示高寒草甸对N沉降的响应机制,探讨其对全球变化的反馈作用,利用人工添加氮素的方法,于2014年生长季(6-9月)在那曲地区那曲县设置不同水平N添加梯度(0、7、20kg hm~(-2)a~(-1)和40 kg hm~(-2)a~(-1)),模拟氮沉降增加对藏北高寒草甸温室气体排放的影响。经过1a的研究结果表明:1)施氮显著促进了CO_2排放但对CH_4的吸收和N_2O的排放无显著影响。总体而言,添加氮素明显增加了温室气体排放总量,其中N2O处理下高寒草甸温室气体排放总量最高。2)回归分析结果表明,CO_2与NPP(总生物量)和TOC(土壤有机碳)线性相关(P0.05),而与TN(总氮)、NH_4~+-N和NO_3~--N均无显著相关关系(P0.05),CH_4与TN/NPP/TOC/NH_4~+-N/NO_3~--N均不相关(P0.05),N_2O与NPP/TOC/NO_3~--N均显著线性相关(P0.05),而与TN/NH_4~+-N不相关。综合初步研究结果,未来氮沉降增加条件下,藏北高寒草甸温室气体排放通量将有可能明显增加,从而对气候变化产生重要的反馈作用。     

不同氮肥对东北春玉米农田温室气体周年排放的影响

为探明不同氮肥条件下高纬度农田土壤的温室气体排放特性,采用静态箱-气相色谱法研究了常规施氮(CN)、施用缓释肥(SLN)、尿素添加硝化抑制剂和脲酶抑制剂(NIUI)、不施氮肥(NN)对东北春玉米农田土壤温室气体排放的影响.结果表明: CN、SLN和NIUI处理产量分别为9618、9376和9645 kg·hm^-2.与CN处理相比,SLN促进了玉米生长季土壤N₂O的排放,降低了非生长季土壤N₂O的排放;NIUI处理N₂O累积排放量比CN降低了39.0%;各处理土壤CO₂周年累积排放通量无显著差异;东北春玉米田是大气中CH₄的弱汇,NIUI处理较CN促进了玉米生长季土壤对CH₄的吸收.综上,尿素添加脲酶抑制剂和硝化抑制剂可以在实现玉米高产的同时有效减少土壤温室气体排放.     

Life cycle greenhouse gas emissions of furniture and bioenergy production from oil palm trunks

The palm oil industry constantly attempts to increase the sustainability along the entire palm oil value chain. One important strategy is to utilize all co‐products. Oil palm trunks, which become available upon replanting of existing plantations, represent an important and increasing flow of underexploited biomass. In recent years, innovative technologies are emerging to use them for producing furniture or plywood or providing bioenergy. We assessed the life cycle greenhouse gas emissions of such products and the greenhouse gas emission savings due to replaced alternative products. Although challenging material properties result in a relatively high energy demand and related greenhouse gas emissions in the oil palm wood processing, substantial reductions in greenhouse gas emissions can arise from producing furniture or bioenergy from oil palm trunks, especially if the process energy demand is met by the energy recovery from oil palm wood‐processing residues.     

耕作和培肥对豫中区小麦-玉米轮作系统土壤氮平衡和温室气体排放的影响

豫中区作为黄淮海平原粮食的主产地,节能、减排和增效是该区农业发展的重要方向.本研究基于2010年耕作与培肥定位试验,在2018-2019年探究了 3种耕作方式(深耕、浅耕和免耕)和2种培肥模式(氮肥和氮肥+有机肥)对土壤氮平衡和温室气体排放的影响.结果表明:增施有机肥能增加土壤全氮积累量;在小麦和玉米成熟期,0～60 ...     

Greenhouse gas emissions from four bioenergy crops in England and Wales: Integrating spatial estimates of yield and soil carbon balance in life cycle analyses

Accurate estimation of the greenhouse gas (GHG) mitigation potential of bioenergy crops requires the integration of a significant component of spatially varying information. In particular, crop yield and soil carbon (C) stocks are variables which are generally soil type and climate dependent. Since gaseous emissions from soil C depend on current C stocks, which in turn are related to previous land management it is important to consider both previous and proposed future land use in any C accounting assessment. We have conducted a spatially explicit study for England and Wales, coupling empirical yield maps with the RothC soil C turnover model to simulate soil C dynamics. We estimate soil C changes under proposed planting of four bioenergy crops, Miscanthus ( Miscanthus × giganteus ), short rotation coppice (SRC) poplar ( Populus trichocarpa Torr. & Gray × P. trichocarpa , var. Trichobel), winter wheat, and oilseed rape. This is then related to the former land use – arable, pasture, or forest/seminatural, and the outputs are then assessed in the context of a life cycle analysis (LCA) for each crop. By offsetting emissions from management under the previous land use, and considering fossil fuel C displaced, the GHG balance is estimated for each of the 12 land use change transitions associated with replacing arable, grassland, or forest/seminatural land, with each of the four bioenergy crops. Miscanthus and SRC are likely to have a mostly beneficial impact in reducing GHG emissions, while oilseed rape and winter wheat have either a net GHG cost, or only a marginal benefit. Previous land use is important and can make the difference between the bioenergy crop being beneficial or worse than the existing land use in terms of GHG balance.     

供氮水平对爬山虎（Parthenocissus tricuspidata Planch）生物量及养分分配的影响

爬山虎是典型的亚热带木本攀援植物,在垂直绿化、植被恢复和水土保持等方面的应用日益普遍,而营养元素对爬山虎生长的影响还缺乏研究,这不利于爬山虎的生长调控与合理应用。通过水培试验,对不同氮素水平（0、0.15、0.3、0.45、0.6、0.75 g•L-1）条件下爬山虎幼苗生长、氮磷钾营养分配和利用状况作了研究。结果表明：供氮水平的提高能显著促进植株的生物量增加,并影响茎叶的生物量分配比例,供氮处理的叶生物量占总生物量的50%以上;供氮水平的提高能增加植株根、茎、叶的氮含量,对磷含量影响不显著,对茎叶中的钾含量有一定的稀释作用;叶片是主要的氮养分贮存器官,叶片氮累积量达到整个植株总氮累积量的60%以上;供氮水平的增加,降低了爬山虎的氮利用率,提高了磷钾的利用率。     

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Cropping is responsible for substantial emissions of greenhouse gasses (GHGs) worldwide through the use of fertilizers and through expansion of agricultural land and associated carbon losses. Especially in sub‐Saharan Africa (SSA), GHG emissions from these processes might increase steeply in coming decades, due to tripling demand for food until 2050 to match the steep population growth. This study assesses the impact of achieving cereal self‐sufficiency by the year 2050 for 10 SSA countries on GHG emissions related to different scenarios of increasing cereal production, ranging from intensifying production to agricultural area expansion. We also assessed different nutrient management variants in the intensification. Our analysis revealed that irrespective of intensification or extensification, GHG emissions of the 10 countries jointly are at least 50% higher in 2050 than in 2015. Intensification will come, depending on the nutrient use efficiency achieved, with large increases in nutrient inputs and associated GHG emissions. However, matching food demand through conversion of forest and grasslands to cereal area likely results in much higher GHG emissions. Moreover, many countries lack enough suitable land for cereal expansion to match food demand. In addition, we analysed the uncertainty in our GHG estimates and found that it is caused primarily by uncertainty in the IPCC Tier 1 coefficient for direct N₂O emissions, and by the agronomic nitrogen use efficiency (N‐AE). In conclusion, intensification scenarios are clearly superior to expansion scenarios in terms of climate change mitigation, but only if current N‐AE is increased to levels commonly achieved in, for example, the United States, and which have been demonstrated to be feasible in some locations in SSA. As such, intensifying cereal production with good agronomy and nutrient management is essential to moderate inevitable increases in GHG emissions. Sustainably increasing crop production in SSA is therefore a daunting challenge in the coming decades.     

Simulation of greenhouse gases following land‐use change to bioenergy crops using the ECOSSE model: a comparison between site measurements and model predictions

This article evaluates the suitability of the ECOSSE model to estimate soil greenhouse gas (GHG) fluxes from short rotation coppice willow (SRC‐Willow), short rotation forestry (SRF‐Scots Pine) and Miscanthus after land‐use change from conventional systems (grassland and arable). We simulate heterotrophic respiration (R_h), nitrous oxide (N₂O) and methane (CH₄) fluxes at four paired sites in the UK and compare them to estimates of R_h derived from the ecosystem respiration estimated from eddy covariance (EC) and R_h estimated from chamber (IRGA) measurements, as well as direct measurements of N₂O and CH₄ fluxes. Significant association between modelled and EC‐derived R_h was found under Miscanthus, with correlation coefficient (r) ranging between 0.54 and 0.70. Association between IRGA‐derived R_h and modelled outputs was statistically significant at the Aberystwyth site (r = 0.64), but not significant at the Lincolnshire site (r = 0.29). At all SRC‐Willow sites, significant association was found between modelled and measurement‐derived R_h (0.44 ≤ r ≤ 0.77); significant error was found only for the EC‐derived R_h at the Lincolnshire site. Significant association and no significant error were also found for SRF‐Scots Pine and perennial grass. For the arable fields, the modelled CO₂ correlated well just with the IRGA‐derived R_h at one site (r = 0.75). No bias in the model was found at any site, regardless of the measurement type used for the model evaluation. Across all land uses, fluxes of CH₄ and N₂O were shown to represent a small proportion of the total GHG balance; these fluxes have been modelled adequately on a monthly time‐step. This study provides confidence in using ECOSSE for predicting the impacts of future land use on GHG balance, at site level as well as at national level.     

林龄对红松和落叶松人工林土壤温室气体通量的影响

探讨人工林发育过程中土壤温室气体排放及其机制,可为森林温室气体通量估算提供理论依据.采用室内培养方法研究了黑龙江省帽儿山地区不同林龄(15、30和50年生)红松(Pinus koraiensis)和落叶松(Larix gmelinii)人工林土壤温室气体排放/吸收速率及其调控因素.结果 表明:30年生红松和落叶松人工林...     

增密减氮对东北水稻产量、氮肥利用效率及温室效应的影响

水稻生产正向资源节约和环境友好的方向转型,常规高产稻作技术亟待创新.本研究以粳稻辽星1号为试材,在2012、2013年研究密度增加、基蘖肥减少、穗肥稳定的“增密减氮”栽培模式对东北水稻产量和氮肥利用效率及温室效应的影响.结果表明： 与常规高产栽培模式相比,在基本苗增加33.3%和基蘖肥施氮量减少20.0%的条件下,氮肥农学效率和氮肥偏生产力两年平均分别提高49.6%(P<0.05)和20.4%(P<0.05),单位面积和单位产量的温室效应两年平均分别下降9.9%和12.7%(P<0.05).虽然水稻有效穗数和总生物量下降,但结实率和收获指数提高,所以产量基本稳定甚至提高.增密减氮降低了土壤NH₄⁺-N和NO₃^--N浓度,提高了氮素回收效率.表明适度增密减氮可兼顾水稻高产、氮肥高效利用和温室气体减排.     

Cropland intensification mediates the radiative balance of greenhouse gas emissions and soil carbon sequestration in maize systems of sub-Saharan Africa

Sub-Saharan Africa (SSA) must undertake proper cropland intensification for higher crop yields while minimizing climate impacts. Unfortunately, no studies have simultaneously quantified greenhouse gas (GHG; CO₂, CH₄, and N₂O) emissions and soil organic carbon (SOC) change in SSA croplands, leaving it a blind spot in the accounting of global warming potential (GWP). Here, based on 2-year field monitoring of soil emissions of CO₂, CH₄, and N₂O, as well as SOC changes in two contrasting soil types (sandy vs. clayey), we provided the first, full accounting of GWP for maize systems in response to cropland intensifications (increasing nitrogen rates and in combination with crop residue return) in SSA. To corroborate our field observations on SOC change (i.e., 2-year, a short duration), we implemented a process-oriented model parameterized with field data to simulate SOC dynamic over time. We further tested the generality of our findings by including a literature synthesis of SOC change across maize-based systems in SSA. We found that nitrogen application reduced SOC loss, likely through increased biomass yield and consequently belowground carbon allocation. Residue return switched the direction of SOC change from loss to gain; such a benefit (SOC sequestration) was not compromised by CH₄ emissions (negligible) nor outweighed by the amplified N₂O emissions, and contributed to negative net GWP. Overall, we show encouraging results that, combining residue and fertilizer-nitrogen input allowed for sequestering 82–284 kg of CO₂-eq per Mg of maize grain produced across two soils. All analyses pointed to an advantage of sandy over clayey soils in achieving higher SOC sequestration targets, and thus call for a re-evaluation on the potential of sandy soils in SOC sequestration across SSA croplands. Our findings carry important implications for developing viable intensification practices for SSA croplands in mitigating climate change while securing food production.     

有机无机肥配施对双季稻轮作系统产量、温室气体排放和土壤养分的综合效应

本研究开展了连续3年(2017-2019年)的田间试验,通过设置不施肥(CK)、单施化肥(F)、等氮条件下有机肥配施化肥(FM)(有机肥全部于早稻季施用)3个处理,对双季稻轮作系统作物产量、土壤肥力进行分析,并连续2年(2018-2019年)对单施化肥和有机肥配施化肥处理的CH4和N20排放进行监测.结果表明:施肥可以...