1. Direct impacts of alternative energy scenarios on water demand in the Middle East and North Africa

• Authors:
  • Damerau,Kerstin
  • van Vliet,Oscar P. R.
  • Patt,Anthony G.
• Source: Climatic Change
• Volume: 130
• Issue: 2
• Year: 2015
• Summary: The Middle East and North Africa (MENA) region stands out globally both for the immensity of its energy resources, and the paucity of its freshwater resources. Most energy extraction and conversion technologies have associated freshwater demand, and in the MENA region these account for 2 % of the available sustainable supply. We examine how this demand could change over the 21st century, assuming growth in population and economic output, and considering three alternative pathways for energy efficiency, carbon intensity, and energy exports from the region. We find that in the pathway marked by improved efficiency, a transition to renewable energy sources, and declining energy exports, water consumption for energy is twice as high as today's values by the end of the century. By contrast, in the pathway marked by continued commitment to fossil resource extraction, use, and export, water demand for energy might rise by a factor of five. If the region were to maintain high levels of energy exports, but would substitute the export of fossil fuels by an equivalent amount of electricity derived from sunlight, a freshwater volume comparable to the household needs of up to 195 million people could be saved.

2. An uncertainty approach to assessment of climate change impacts on the Zambezi River Basin

• Authors:
  • Strzepek, K.
  • McCluskey, A.
  • Gebretsadik, Y.
  • Fant, C.
• Source: Article
• Volume: 130
• Issue: 1
• Year: 2015
• Summary: Many residents of the Zambezi River Valley are dependent on water-related resources. Greenhouse gas (GHG) emissions may cause a significant change to the climate in the Zambezi Basin in the future, but there is much uncertainty about the future climate state. This situation leaves policy makers at a state of urgency to prepare for these changes as well as reduce the impacts of the changes through GHG mitigation strategies. First and foremost, we must better understand the economic sectors most likely impacted and the magnitude of those impacts, given the inherent uncertainty. In this study, we present a suite of models that assess the effects of climate change on water resources for four countries in the Zambezi basin: Malawi, Mozambique, Zambia, and Zimbabwe. We use information from a large ensemble (6800) of climate scenarios for two GHG emission policies which represent a distribution of impacts on water-related sectors, considering emissions uncertainty, climate sensitivity uncertainty, and regional climate uncertainty. Two GHG mitigation scenarios are used to understand the effect of global emissions reduction on the River Basin system out to 2050. Under both climate polices, the majority of the basin will likely be drier, except for a portion in the north around Malawi and northern Zambia. Three Key Performance Indicators are used-flood occurrence, unmet irrigation demand, and hydropower generation-to understand the impact channels of climate change effects on the four countries. We find that floods are likely to be worse in Mozambique, irrigation demands are likely to be unmet in Mozambique and Zimbabwe, and hydropower generation is likely to be reduced in Zambia. We also find that the range of possible impacts is much larger under an unconstrained GHG emissions case than under a strict mitigation strategy, suggesting that GHG mitigation would reduce uncertainties about the future climate state, reducing the risks of extreme changes as compared to the unconstrained emissions case.

3. Mapping global cropland and field size

• Authors:
  • Aziz, S. A.
  • Gong, P.
  • Hansen, M.
  • Justice, C.
  • Becker-Reshef, I.
  • Herrero, M.
  • Wood-Sichra, U.
  • Thornton, P.
  • Mosnier, A.
  • Havlik, P.
  • Perger, C.
  • Schill, C.
  • Albrecht, F.
  • Duerauer, M.
  • Moltchanova, E.
  • Bun, A.
  • You, L.
  • McCallum, I.
  • See, L.
  • Fritz, S.
  • Cipriani, A.
  • Cumani, R.
  • Cecchi, G.
  • Conchedda, G.
  • Ferreira, S.
  • Gomez, A.
• Source: Journal Article
• Volume: 21
• Issue: 5
• Year: 2015
• Summary: A new 1 km global IIASA-IFPRI cropland percentage map for the baseline year 2005 has been developed which integrates a number of individual cropland maps at global to regional to national scales. The individual map products include existing global land cover maps such as GlobCover 2005 and MODIS v.5, regional maps such as AFRICOVER and national maps from mapping agencies and other organizations. The different products are ranked at the national level using crowdsourced data from Geo-Wiki to create a map that reflects the likelihood of cropland. Calibration with national and subnational crop statistics was then undertaken to distribute the cropland within each country and subnational unit. The new IIASA-IFPRI cropland product has been validated using very high-resolution satellite imagery via Geo-Wiki and has an overall accuracy of 82.4%. It has also been compared with the EarthStat cropland product and shows a lower root mean square error on an independent data set collected from Geo-Wiki. The first ever global field size map was produced at the same resolution as the IIASA-IFPRI cropland map based on interpolation of field size data collected via a Geo-Wiki crowdsourcing campaign. A validation exercise of the global field size map revealed satisfactory agreement with control data, particularly given the relatively modest size of the field size data set used to create the map. Both are critical inputs to global agricultural monitoring in the frame of GEOGLAM and will serve the global land modelling and integrated assessment community, in particular for improving land use models that require baseline cropland information. These products are freely available for downloading from the http://cropland.geo-wiki.org website.

4. Does nitrogen fertilizer application rate to corn affect nitrous oxide emissions from the rotated soybean crop?

• Authors:
  • Sawyer, J. E.
  • Miguez, F.
  • Barker, D. W.
  • Mitchell, D. C.
  • Iqbal, J.
  • Pantoja, J.
  • Castellano, M. J.
• Source: Web Of Knowledge
• Volume: 44
• Issue: 3
• Year: 2015
• Summary: Little information exists on the potential for N fertilizer application to corn ( Zea mays L.) to affect N 2O emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects N 2O emissions during subsequent crops in rotation, we measured N 2O emissions for 3 yr (2011-2013) in an Iowa, corn-soybean [ Glycine max (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha -1, the recommended rate of 135 kg N ha -1, and a high rate of 225 kg N ha -1); soybean received no N fertilizer. We further investigated the potential for a winter cereal rye ( Secale cereale L.) cover crop to interact with N fertilizer rate to affect N 2O emissions from both crops. The cover crop did not consistently affect N 2O emissions. Across all years and irrespective of cover crop, N fertilizer application above the recommended rate resulted in a 16% increase in mean N 2O flux rate during the corn phase of the rotation. In 2 of the 3 yr, N fertilizer application to corn (0-225 kg N ha -1) did not affect mean N 2O flux rates from the subsequent unfertilized soybean crop. However, in 1 yr after a drought, mean N 2O flux rates from the soybean crops that received 135 and 225 kg N ha -1 N application in the corn year were 35 and 70% higher than those from the soybean crop that received no N application in the corn year. Our results are consistent with previous studies demonstrating that cover crop effects on N 2O emissions are not easily generalizable. When N fertilizer affects N 2O emissions during a subsequent unfertilized crop, it will be important to determine if total fertilizer-induced N 2O emissions are altered or only spread across a greater period of time.

5. Increasing precision in agronomic field trials using Latin square designs.

• Authors:
  • Woodward, R.
  • Jones, M.
  • Stoller, J.
• Source: Agronomy Journal
• Volume: 107
• Issue: 1
• Year: 2015
• Summary: Spatial variation from soil and related factors often affects the outcome of agronomic field experiments. The randomized complete block (RCB) is the most prevalent design despite inefficiencies that can result in inflated error terms. Experimental designs such as the Latin square (LS) allow for bidirectional blocking and offer the potential to account for spatial variability better. The objectives of this research were to investigate the occurrence of two-way gradients in agronomic field trials and compare the estimated relative efficiency (ERE) of a LS to a RCB. Thirty LS trials were evaluated in 10 states during 2013 across the midwestern United States investigating crop yields of corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and sorghum [ Sorghum bicolor (L.) Moench]. The results show that 47% of the trials exhibited a two-way gradient, indicating this characteristic is widespread across a large geographic region. Overall, the ERE was increased in 70% of the trials by using the LS design. A lower ERE occurred in 7% of the trials conducted using a LS. Multiple gradients appear common in agronomic field plot trials and enough variation existed between the two blocking directions to justify the use of a LS design. Our data indicate the LS offers a low risk, high reward option of experimental design for controlling spatial heterogeneity and increasing precision. When possible, the LS design should be used in field experiments where the trial area appears uniform and gradients to block against are not obvious.

6. Sugarbeet yield and quality when substituting compost or manure for conventional nitrogen fertilizer

• Authors:
  • Johnson-Maynard, J. L.
  • Lentz, R. D.
  • Brown, B.
  • Lehrsch, G. A.
  • Leytem, A. B.
• Source: Agronomy Journal
• Volume: 107
• Issue: 1
• Year: 2015
• Summary: To grow sugarbeet ( Beta vulgaris L.) profitably, producers must effectively manage added N, whether from inorganic or organic sources. Our objective was to determine if equivalent sugarbeet root and sucrose yields could be achieved when substituting dairy cattle ( Bos spp.) manure, either composted or stockpiled, for conventional N (urea) fertilizer. First-year treatments at Site A (Parma, ID) included a control (no N), urea (202 kg N ha -1), compost (218 and 435 kg estimated available N ha -1), and manure (140 and 280 kg available N ha -1). Site B (Kimberly, ID) treatments were a control, urea (82 kg N ha -1), compost (81 and 183 kg available N ha -1), and manure (173 and 340 kg available N ha -1). Compost and manure were incorporated into two silt loams, a Greenleaf (fine-silty, mixed superactive mesic Xeric Calciargid) at Parma in fall 2002 and 2003 and a Portneuf (coarse-silty, mixed superactive, mesic Durinodic Xeric Haplocalcid) at Kimberly in fall 2002. Sugarbeet was planted the following spring. Sucrose yield averaged across years and organic N rates at Site A was 12.24 Mg ha -1 for urea, 11.88 Mg ha -1 for compost, and 11.20 Mg ha -1 for manure, all statistically equivalent. Doubling the organic N rates at Site A increased the yield of roots up to 26% and sucrose up to 21%. Applying organic amendments in place of urea affected neither root nor sucrose yields but, at one location, decreased sugarbeet quality, though without hindering sucrose recovery. Sugarbeet producers can use compost or manure to satisfy crop N needs without sacrificing sucrose yield.

7. Carbon stock and its responses to climate change in Central Asia

• Authors:
  • QiFe, H.
  • Luo GePing
  • Madaminov, A. A.
  • Maisupova, B.
  • Chen, X.
  • Zhang, C.
  • Li, C.
  • Djenbaev, B. M.
• Source: Primary Research Article
• Volume: 21
• Issue: 5
• Year: 2015
• Summary: Central Asia has a land area of 5.6*10 6 km 2 and contains 80-90% of the world's temperate deserts. Yet it is one of the least characterized areas in the estimation of the global carbon (C) stock/balance. This study assessed the sizes and spatiotemporal patterns of C pools in Central Asia using both inventory (based on 353 biomass and 284 soil samples) and process-based modeling approaches. The results showed that the C stock in Central Asia was 31.34-34.16 Pg in the top 1-m soil with another 10.42-11.43 Pg stored in deep soil (1-3 m) of the temperate deserts. They amounted to 18-24% of the global C stock in deserts and dry shrublands. The C stock was comparable to that of the neighboring regions in Eurasia or major drylands around the world (e.g. Australia). However, 90% of Central Asia C pool was stored in soil, and the fraction was much higher than in other regions. Compared to hot deserts of the world, the temperate deserts in Central Asia had relatively high soil organic carbon density. The C stock in Central Asia is under threat from dramatic climate change. During a decadal drought between 1998 and 2008, which was possibly related to protracted La Nina episodes, the dryland lost approximately 0.46 Pg C from 1979 to 2011. The largest C losses were found in northern Kazakhstan, where annual precipitation declined at a rate of 90 mm decade -1. The regional C dynamics were mainly determined by changes in the vegetation C pool, and the SOC pool was stable due to the balance between reduced plant-derived C influx and inhibited respiration.

8. Modeling biomass and soil carbon sequestration of indigenous agroforestry systems using CO2FIX approach

• Authors:
  • Kanninen, M.
  • Negash, M.
• Source: Article
• Volume: 203
• Year: 2015
• Summary: The fifth assessment report of the intergovernmental panel on climate change (IPCC) estimated that by 2040 agroforestry would offer high potential of carbon (C) sequestration in developing countries. However, the role of tropical agroforestry in C sequestration and in climate change mitigation has only recently been recognized by United Nations Framework Convention on Climate Change (UNFCCC). This is partly due to the lack of reliable estimates on the sequestration potential in biomass and soil carbon pools over time. The aim of this study was to analyze the changes in the biomass and soil carbon pools of three indigenous agroforestry systems in south-eastern Rift Valley escrapment of Ethiopia using CO2FIX (v. 3.2) model. The agroforestry systems studied were Enset ( Ensete ventricosum)-tree, Enset-coffee-tree, and Tree-coffee systems. To run the model, empirical data collected from 60 farms (20 farms for each agroforestry system) and literature were used as inputs to parameterize the model. Simulations were run over a period of 50 years. Average simulated total biomass C stocks was the highest for Tree-coffee system (122 Mg C ha -1), followed by the Enset-coffee-tree (114 Mg C ha -1) and Enset-tree system (76 Mg C ha -1). The tree cohort accounted for 89-97% of the total biomass C stocks in all the studied systems, and the reminder was shared by Enset and coffee cohorts. The total average simulated total C stocks (biomass and soil) were 209, 286 and 301 Mg C ha -1 for Enset-tree, Enset-coffee-tree and Tree-coffee systems, respectively. The soil organic carbon (SOC) stocks accounted for 60-64% of the total carbon in the studied systems. Model validation results showed that long-term (10-40 years) simulated biomass C stocks were within the range of measured biomass C stocks for Enset-tree and Enset-coffee-tree systems, but significantly differed for the Tree-coffee system. The simulated soil and total C stocks were within the range of measured values for all the three systems. The CO2FIX model accurately predicted the SOC and total C stocks in the studied indigenous agroforestry systems, but the prediction of the biomass C stocks could be improved by acquiring more accurate input parameter values for running the model.

9. Rising atmospheric CO 2: potential impacts on chickpea seed quality

• Authors:
  • Pal, M.
  • Chakraborty, D.
  • Sehgal,V. K.
  • Saha, S.
• Source: Agriculture Journal
• Volume: 203
• Year: 2015
• Summary: Experiments on chickpea ( Cicer arietinum L.) were performed in open-top chambers during 2010-11 and 2011-12 to assess effects of atmospheric CO 2 enrichment on the quality of seeds. Although no physical modification was observed, an increase in seed water uptake was recorded in plants grown under enriched atmospheric CO 2 condition. Germination of seeds reduced by 45-47%, while seed leachate conductivity increased by 10-17%. Seedling vigor decreased, although root and shoot lengths and seedling biomass showed negligible changes. Similarly, atmospheric CO 2 enrichment reduced field emergence of seedlings with no change in root characteristics of the emerged seedlings. A decrease in protease activity supports the reduced seed viability, although no change in grain phosphatase and alpha-amylase activities were recorded. Increase in carbon content in germinating seed-cotyledon along with decrease in N in cotyledon resulted in large increase in C:N ratio for the plants grown under enriched CO 2 condition. The starch content increased with no change in soluble sugar in germinating seed-cotyledons. This indicates more carbonaceous seeds from plants grown under enriched CO 2 environment. Results suggest that rising atmospheric CO 2 might have adverse impact on viability and germination of chickpea seeds, and cause nutritional imbalance through increase in C with dilution of N contents in germinating seed-cotyledons.

10. High carbon and biodiversity costs from converting Africa's wet savannahs to cropland

• Authors:
  • Rubenstein, D.
  • Notenbaert, A.
  • Beringer, T.
  • Thornton, P. K.
  • Estes, L.
  • Searchinger, T. D.
  • Heimlich, R.
  • Licker, R.
  • Herrero, M.
• Source: Article
• Volume: 5
• Issue: 5
• Year: 2015
• Summary: Do the wet savannahs and shrublands of Africa provide a large reserve of potential croplands to produce food staples or bioenergy with low carbon and biodiversity costs? We find that only small percentages of these lands have meaningful potential to be low-carbon sources of maize (1/42%) or soybeans (9.5-11.5%), meaning that their conversion would release at least one-third less carbon per ton of crop than released on average for the production of those crops on existing croplands. Factoring in land-use change, less than 1% is likely to produce cellulosic ethanol that would meet European standards for greenhouse gas reductions. Biodiversity effects of converting these lands are also likely to be significant as bird and mammal richness is comparable to that of the world's tropical forest regions. Our findings contrast with influential studies that assume these lands provide a large, low-environmental-cost cropland reserve. © 2015 Macmillan Publishers Limited. All rights reserved.