• Authors:
    • Suh, S. W.
    • Yang, Y.
  • Source: Article
  • Volume: 20
  • Issue: 2
  • Year: 2015
  • Summary: Purpose: Previous estimates of carbon payback time (CPT) of corn ethanol expansion assumed that marginal yields of newly converted lands are the same as the average corn yield, whereas reported marginal yields are generally lower than the average yield (47-83% of average yield). Furthermore, these estimates assumed that the productivity of corn ethanol system and climate change impacts per unit greenhouse gas (GHG) emissions remain the same over decades to a century. The objective of this study is to re-examine CPT of corn ethanol expansion considering three aspects: (1) yields of newly converted lands (i.e., marginal yield), (2) technology improvements over time within the corn ethanol system, and (3) temporal sensitivity of climate change impacts. Methods: A new approach to CPT calculation is proposed, where changes in productivity of ethanol conversion process and corn yield are taken into account. The approach also allows the use of dynamic characterization approach to GHGs emitted in different times, as an option. Data are collected to derive historical trends of bioethanol conversion efficiency and corn yield, which inform the development of the scenarios for future biofuel conversion efficiency and corn yield. Corn ethanol's CPTs are estimated and compared for various marginal-to-average (MtA) yield ratios with and without considering technology improvements and time-dependent climate change impacts. Results and discussion: The results show that CPT estimates are highly sensitive to both MtA yield ratio and productivity of ethanol system. Without technological advances, our CPT estimates for corn ethanol from newly converted Conservation Reserve Program (CRP) land exceed 100 years for all MtA yield ratios tested except for the case where MtA yield ratio is 100%. When the productivity improvements within corn ethanol systems since previous CPT estimates and their future projections are considered, our CPT estimates fall into the range of 15 years (100% MtA yield ratio) to 56 years (50% MtA yield ratio), assuming land conversion takes place in early 2000s. Incorporating diminishing sensitivity of GHG emissions to future emissions year by year, however, increases the CPT estimates by 57 to 13% (from 17 years for 100% MtA yield ratio to 88 years for 50% MtA yield ratio). For 60 MtA yield ratio, CPT is estimated to be 43 years, which is relatively close to previous CPT estimates (i.e., 40 to 48 years) but with very different underlying reasons. Conclusions: This study highlights the importance of considering technological advances in understanding the climate change implications of land conversion for corn ethanol. Without the productivity improvements in corn ethanol system, the prospect of paying off carbon debts from land conversion within 100 years becomes unlikely. Even with the ongoing productivity improvements, the yield of newly converted land can significantly affect the CPT. The results reinforce the importance of considering marginal technologies and technology change in prospective life cycle assessment.
  • Authors:
    • Wang, E.
    • Luo, Z.
    • King, D.
    • Bryan, B. A.
    • Zhao, G.
    • Yu, Q.
  • Source: GCB Bioenergy
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: The use of crop residues for bioenergy production needs to be carefully assessed because of the potential negative impact on the level of soil organic carbon (SOC) stocks. The impact varies with environmental conditions and crop management practices and needs to be considered when harvesting the residue for bioenergy productions. Here, we defined the sustainable harvest limits as the maximum rates that do not diminish SOC and quantified sustainable harvest limits for wheat residue across Australia's agricultural lands. We divided the study area into 9432 climate-soil (CS) units and simulated the dynamics of SOC in a continuous wheat cropping system over 122years (1889 - 2010) using the Agricultural Production Systems sIMulator (APSIM). We simulated management practices including six fertilization rates (0, 25, 50, 75, 100, and 200kg Nha(-1)) and five residue harvest rates (0, 25, 50, 75, and 100%). We mapped the sustainable limits for each fertilization rate and assessed the effects of fertilization and three key environmental variables - initial SOC, temperature, and precipitation - on sustainable residue harvest rates. We found that, with up to 75kg Nha(-1) fertilization, up to 75% and 50% of crop residue could be sustainably harvested in south-western and south-eastern Australia, respectively. Higher fertilization rates achieved little further increase in sustainable residue harvest rates. Sustainable residue harvest rates were principally determined by climate and soil conditions, especially the initial SOC content and temperature. We conclude that environmental conditions and management practices should be considered to guide the harvest of crop residue for bioenergy production and thereby reduce greenhouse gas emissions during the life cycle of bioenergy production.
  • Authors:
    • Yang, J.
    • Ren, W.
    • Lu, C.
    • Tao, B.
    • Tian, H.
    • Banger, K.
  • Source: Agronomy Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: To the best of our knowledge, no attempts have been made to understand how environmental changes that occurred in the 20th century have altered soil organic carbon (SOC) dynamics in India. In this study, we applied a process-based Dynamic Land Ecosystem Model (DLEM), to estimate the magnitude as well as to quantify the effects of climate change and variability, land cover and land-use change (LCLUC), carbon dioxide (CO2) concentration, atmospheric nitrogen deposition (NDEP), and tropospheric ozone (O3) pollution on SOC stocks in India during 1901-2010. The DLEM simulations have shown that SOC stocks ranged from 20.5 to 23.4 Pg C (1 Pg = 1015 g), majority of which is stored in the forested areas in the north-east, north, and few scattered regions in the southern India. During the study period, soils have sequestered SOC by 2.9 Pg C. Elevated CO2 concentration has increased total SOC stocks over the country by 1.28 Pg C, which was partially offset by climate change (0.78 Pg C) and tropospheric O3 pollution (0.20 Pg C) during 1901-2010. Interestingly, LCLUC increased SOC stocks by 1.7 Pg C thereby suggesting that SOC loss from deforestation was offset by the conversion of low productive fallow lands and other lands to croplands that received irrigation along with N fertilizers. Atmospheric nitrogen deposition (NDEP) has increased biomass production and SOC by 0.5 PgC over the country. This study has demonstrated that the benefits from elevated CO2 concentration, cropland management practices, and NDEP in sequestering SOC stocks were offset by climate change and tropospheric O3 pollution which should be curbed in India. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Hurisso,T. T.
    • Norton,J. B.
    • Mukhwana,E. J.
    • Norton,U.
  • Source: Soil Science Society of America Journal
  • Volume: 79
  • Issue: 3
  • Year: 2015
  • Summary: Soil organic matter (SOM) fractions were determined using extraction-, incubation-, and density-based fractionation techniques on samples collected from a range of furrow-irrigated sugar beet (Beta vulgaris L.) based rotations on the same soil series on farmers' fields in Wyoming. We hypothesized that extending the period of time between sugar beet crops in rotations beyond the 2-yr sugar beet-barley (Hordeum vulgare L.) (SB-BA) rotation by adding perennial or annual legumes would lead to higher levels of surface-soil (0-15-cm) organic C and N. Four rotations were compared: SB-BA, sugar beet-dry bean (Phaseolus vulgaris L.) (SB-DB), sugar beetbarley-dry bean (SB-BA-DB), and sugar beet-sugar beet-alfalfa (Medicago sativa L)-alfalfa (SB-SB-Alf-Alf). Soils under SB-BA and SB-DB rotations on average contained 607 g soil organic C (SOC) m-2 in the upper 15 cm, or 46% of the SOC found within SB-BA-DB and SB-SB-Alf-Alf soils. Potentially mineralizable C and N and microbial biomass C (MBC) were lower in SB-BA and SB-DB soils than SB-BA-DB and SB-SB-Alf-Alf soils, but, when normalized by SOC and total soil N (TSN), these labile C and N fractions were >1.5 times higher in SB-BA and SB-DB soils, suggesting greater SOM mineralization. Moreover, light-fraction C in SB-BA and SB-DB soils was about half that of SB-SB-Alf-Alf soils. Sugar beet sucrose yield was also higher in the SB-SB-Alf-Alf than any other rotation. There were strong linear relationships (r2 = 0.50-0.84) between sugar beet sucrose yield and TSN, SOC, and MBC across all four rotations. To conserve high surface-soil organic C and N fractions on furrow-irrigated farm fields without sacrificing sugar beet sucrose yield, extending the 2-yr SB-BA rotation by adding 2 yr of alfalfa is recommended. © Soil Science Society of America, 5585 Guilford Rd., Madison Wl 53711 USA.
  • Authors:
    • Buerkert, Andreas
    • Bruentrup, Michael
    • Lamers, John P. A.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 1
  • Year: 2015
  • Summary: Low concentrations of phosphorus (P) also limit crop production on the acid, sandy soils in Sudano-Sahelian West Africa (SSWA). An increased P-use is thus a key leverage for enhancing food security and alleviating poverty. Therefore, P-imports into the predominating agro-pastoral farming systems are indispensable, but most smallholders are cash-poor and risk averse, face labor-constraints, and P-fertiliser responses are site-specific. Key to the adoption of any new technology is a high financial performance with low risk levels of failure, low demands of labor and cash, and adaptation to the prevailing farming systems. Financial performances were assessed from nine, annually applied fertilising practices during 4 years in five SSWA zones. Information about the farming systems, labor demands, and input-output prices stem from secondary sources. The profitability largely depended on rainfall and location-specific soil conditions, but those of annually repeated mineral and organic P-strategies increased over time. Several P-fertilisations were profitable on a per land unit basis, but could not compete with farmers' practices on a per labor unit basis. Mulching with and without P (13 kg P ha(-1)) were not financially superior, but the broadcast application of 13 kg P ha(-1) became profitable over time. Hill-placed P (4 kg P ha(-1)), also known as micro-dosing, was a profitable alternative to farmers' practices particularly in the intermediate rainfall zone. The results showed the importance of recommendations following rainfall zones, which are of interest across a spectrum of users including policy makers, land use practitioners, private firms, NGOs and research for development implementers.
  • Authors:
    • Normand,F.
    • Lauri,P. E.
    • Legave,J. M.
  • Source: Acta Horticulturae
  • Volume: 1075
  • Year: 2015
  • Summary: Climate change is becoming an observed reality, very likely due to the increase of anthropogenic greenhouse gas concentration. Since a few decades, several research teams around the world carry out a huge work to model the future climatic change during the 21st century, based on several scenarios of greenhouse gas emission. We have to expect rise in average temperatures, in atmospheric CO 2 concentration, in soil salinity in some areas, and lower and more irregular rainfall. The climate variability and the frequency of extreme events (scorching heat, heavy rainfall, drought, hurricane) are also expected to rise. Climate change is therefore a great concern for agriculture. Mango is one of the most widely cultivated and popular fruits in these regions for its economic and nutritional values. It is the fifth most cultivated fruit in the world. It is consequently justified to wonder about the impact of climate change on the mango tree and about the consequences on mango production and cultivation. The lack of crop model for mango prevents the prediction of the effects of climate change on mango tree development and production. They are then assessed on the basis of our current knowledge on the influence of climatic variables on mango tree development and production. We describe the influence of climatic variables on processes of agronomical importance for the mango tree: photosynthesis, vegetative and reproductive development, fruit quality. We then review the climate changes predicted for two areas of mango production and draw the possible consequences for mango cultivation. Finally, we propose some research ways to adapt mango cultivation to climate change in the coming decades, such as cultivar and rootstock selection, and improvement of cultural practices. The interest of developing a mango crop model is discussed.
  • Authors:
    • O'Dea,Justin K.
    • Jones,Clain A.
    • Zabinski,Catherine A.
    • Miller,Perry R.
    • Keren,Ilai N.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 2
  • Year: 2015
  • Summary: In the North American northern Great Plains (NGP), legumes are promising summer fallow replacement/cropping intensification options that may decrease dependence on nitrogen (N) fertilizer in small grain systems and mitigate effects of soil organic matter (SOM) losses from summer fallow. Benefits may not be realized immediately in semiarid conditions though, and longer-term effects of legumes and intensified cropping in this region are unclear, particularly in no-till systems. We compared effects of four no-till wheat (Triticum aestivum L.) cropping systems-summer fallow-wheat (F-W), continuous wheat (CW), legume green manure (pea, Pisum sativum L.)-wheat (LGM-W), and pea-wheat (P-W)-on select soil attributes in an 8-year-old rotation study, and N fertilizer effects on C and N mineralization on a duplicate soil set in a laboratory experiment. We analyzed potentially mineralizable carbon and nitrogen (PMC and PMN) and mineralization trends with a nonlinear model, microbial biomass carbon (MB-C), and wet aggregate stability (WAS). Legume-containing systems generally resulted in higher PMC, PMN, and MB-C, while intensified systems (CW and P-W) had higher WAS. Half-lives of PMC were shortest in intensified systems, and were longest in legume systems (LGM-W and P-W) for PMN. Nitrogen addition depressed C and N mineralization, particularly in CW, and generally shortened the half-life of mineralizable C. Legumes may increase long-term, no-till NGP agroecosystem resilience and sustainability by (1) increasing the available N-supply (similar to 26-50 %) compared to wheat-only systems, thereby reducing the need for N fertilizer for subsequent crops, and (2) by potentially mitigating negative effects of SOM loss from summer fallow.
  • Authors:
    • Rati Mukteshawar
    • Shehrawat,P. S.
  • Source: Annals of Biology
  • Volume: 31
  • Issue: 1
  • Year: 2015
  • Summary: As we know, that agriculture has been an important profession for Indian as well as for the people of the world. The world's population is growing at an alarming rate with corresponding increase in demand for food goods and natural resources, so it directly burdens the agriculture to meet the consumption needs, farmers really more depend upon inorganic farm inputs. As a consequence of increase in inorganic farm inputs consumption, vast quantities of gases and effluents are discharged that may change the climate composition of the atmosphere and its capacity to regulate its temperature that's why world agriculture is facing numerous newly emerged challenges, the most prominent challenges are such as climate change and effect of greenhouse gases on agricultural practice. Mostly scientists now agree that rising atmospheric concentrations of GHG threaten to have severe impacts on food production, natural ecosystems and human health. Now-a-days, the agricultural scientists and extension clienteles have preference for demand driven and participatory approaches. The need to provide up-to-date information by the extension workers regarding to causes of GHG emissions and how it affects the agricultural production. Due and focuses efforts have to be made regarding the transfer of new agricultural technologies efficiently and effectively. A total number of eight villages were selected randomly. From each village, 15 farmers were selected randomly. Hence, a total number of 120 farmers were interviewed. The study revealed that farmers had awareness about GHG (65.00%), followed by knowledge about GHG (39.16%), major source of GHG emissions (73.33%), livestock also emit GHG (35.83%) and losses due to GHG in agriculture (68.33%). Whereas farmers were not aware regarding attending any meeting/workshop/training regarding sequestration of GHG (67.50%), farmers changed their cropping patterns (50.00%) and observation regarding deterioration in quality of crop produce (42.50%). The study further revealed that farmers were found agreed about change in current farm management practices (85.00%), change in season length (89.16%), altering the farming practices of field operations (97.50%), change in seasonal temperature (91.66%), changes in time of precipitation (82.00%), increase in flood and drought (72.50%) and 'fluctuation in ground water table' (88.33%). Whereas farmers were found undecided about emission of GHG which is not a problem for agricultural practices (82.50%), no effect of GHG emission on crop production (64.16%) and no effect of GHG emission on livestock production (70.00%). Farmers' were found disagreed regarding no effect of GHG emission on bio-diversity (33.33%), change in timing of precipitation (17.50%) and increase the incidence of falling hail (14.16%).
  • Authors:
    • Singh,R. J.
    • Ahlawat,I. P. S.
  • Source: Environmental Monitoring and Assessment
  • Volume: 187
  • Issue: 5
  • Year: 2015
  • Summary: Two of the most pressing sustainability issues are the depletion of fossil energy resources and the emission of atmospheric green house gases like carbon dioxide to the atmosphere. The aim of this study was to assess energy budgeting and carbon footprint in transgenic cotton–wheat cropping system through peanut intercropping with using 25–50 % substitution of recommended dose of nitrogen (RDN) of cotton through farmyard manure (FYM) along with 100 % RDN through urea and control (0 N). To quantify the residual effects of previous crops and their fertility levels, a succeeding crop of wheat was grown with varying rates of nitrogen, viz. 0, 50, 100, and 150 kg ha-1. Cotton + peanut–wheat cropping system recorded 21 % higher system productivity which ultimately helped to maintain higher net energy return (22 %), energy use efficiency (12 %), human energy profitability (3 %), energy productivity (7 %), carbon outputs (20 %), carbon efficiency (17 %), and 11 % lower carbon footprint over sole cotton–wheat cropping system. Peanut addition in cotton–wheat system increased the share of renewable energy inputs from 18 to 21 %. With substitution of 25 % RDN of cotton through FYM, share of renewable energy resources increased in the range of 21 % which resulted into higher system productivity (4 %), net energy return (5 %), energy ratio (6 %), human energy profitability (74 %), energy productivity (6 %), energy profitability (5 %), and 5 % lower carbon footprint over no substitution. The highest carbon footprint (0.201) was recorded under control followed by 50 % substitution of RDN through FYM (0.189). With each successive increase in N dose up to 150 kg N ha-1 to wheat, energy productivity significantly reduced and share of renewable energy inputs decreased from 25 to 13 %. Application of 100 kg N ha-1 to wheat maintained the highest grain yield (3.71 t ha-1), net energy return (105,516 MJ ha-1), and human energy profitability (223.4) over other N doses applied to wheat. Application of 50 kg N ha-1 to wheat maintained the least carbon footprint (0.091) followed by 100 kg N ha-1 (0.100). Our study indicates that system productivity as well as energy and carbon use efficiencies of transgenic cotton–wheat production system can be enhanced by inclusion of peanut as an intercrop in cotton and substitution of 25 % RDN of cotton through FYM, as well as application of 100 kg N ha-1 to succeeding wheat crop. © 2015, Springer International Publishing Switzerland.
  • Authors:
    • Prasad,J. V. N. S.
    • Rao,Ch S.
    • Ravichandra,K.
    • Jyothi,Ch N.
    • Babu,M. B. B. P.
    • Babu,V. R.
    • Raju,B. M. K.
    • Rao,B. B.
    • Rao,V. U. M.
    • Venkateswarlu,B.
    • Devasree Naik
    • Singh,V. P.
  • Source: Journal of Agrometeorology
  • Volume: 17
  • Issue: 1
  • Year: 2015
  • Summary: Carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2O) are important biogenic green house gases (GHGSs) from agricultural sector contributing to global warming. Temperature and rainfall play an important role in GHGS fluxes and information on their role in rainfed crops and systems is very scanty. Field studies were conducted at Hyderabad, India during 2012 rainy season to quantify GHGSs fluxes from two important food crops grown widely in rainfed regions viz. sorghum and pigeonpea. Quantum of fluxes ranged from 26-85 mg CO 2 - C m -2 h -1 in case of CO 2 and 18-68 g N 2O-N m -2 h -1 in case of N 2O at different stages of crop growth. Cumulative seasonal fluxes are 1.18 and 1.24 Mg CO 2-C ha -1 and 0.78 and 0.94 kg N 2O-N ha -1, in sorghum and pigeonpea, respectively. Ambient temperature and rainfall significantly influenced CO 2 fluxes. CO 2 fluxes increased with increase in temperature from 25.9°C to 31°C and fluxes were highest at 28.4°C in pigeonpea and at 27.7°C in sorghum. Quantum of CO 2 fluxes were highest at grain filling stage in sorghum and grand growth period in pigeonpea. N 2O fluxes increased with increase in temperature and moisture availability. These results provide evidence that rainfed crops in semi-arid regions contribute significant CO 2 and N 2O fluxes which are influenced by temperature and rainfall, thus warrant further studies.