ADVANCES IN AGRONOMY Advisory Board PAUL M BERTSCH RONALD L PHILLIPS University of Kentucky University of Minnesota KATE M SCOW LARRY P WILDING University of California, Davis Texas A&M University Emeritus Advisory Board Members JOHN S BOYER KENNETH J FREY University of Delaware Iowa State University EUGENE J KAMPRATH MARTIN ALEXANDER North Carolina State University Cornell University Prepared in cooperation with the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America Book and Multimedia Publishing Committee DAVID D BALTENSPERGER, CHAIR LISA K AL-AMOODI CRAIG A ROBERTS WARREN A DICK MARY C SAVIN HARI B KRISHNAN APRIL L ULERY SALLY D LOGSDON Academic Press is an imprint of Elsevier 525 B Street, Suite 1900, San Diego, CA 92101-4495, USA 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 32 Jamestown Road, London, NW1 7BY, UK Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands First edition 2010 Copyright # 2010 Elsevier Inc All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (+44) (0) 1865 843830; fax (+44) (0) 1865 853333; email: permissions@elsevier.com Alternatively you can submit your request online by visiting the Elsevier web site at http://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made ISBN: 978-0-12-381023-6 ISSN: 0065-2113 (series) For information on all Academic Press publications visit our website at elsevierdirect.com Printed and bound in USA 10 11 12 10 CONTRIBUTORS Numbers in Parentheses indicate the pages on which the authors’ contributions begin S Anthony (83) ADAS, Wolverhampton, Woodthorne, Wolverhampton, United Kingdom Jeff Baldock (173) CSIRO Land and Water, PMB2, Glen Osmond, SA, Australia R Bol (47, 83) Biogeochemistry of Soils and Water group, North Wyke Research, Okehampton, Devon, United Kingdom Bhagirath S Chauhan (221) Crop and Environmental Sciences Division, International Rice Research Institute, Metro Manila, Philippines H Cover (117) Vistronix, Inc., Portland, Oregon, USA J A Delgado (117) USDA-ARS-Soil Plant Nutrient Research Unit, Fort Collins, Colorado, USA Matthew Forbes (173) Natural Resources Branch, Department of Conservation and Environment, Locked Bag 104, Bentley Delivery Centre, WA, Australia P Gagliardi (117) USDA-ARS-Soil Plant Nutrient Research Unit, Fort Collins, Colorado, USA S J Granger (83) Biogeochemistry of Soils and Water group, North Wyke Research, Okehampton, Devon, United Kingdom C M Gross (117) USDA-NRCS, WNTSC, Beltsville, Maryland, USA P M Haygarth (83) Centre for Sustainable Water Management, Lancaster Environment Centre, Lancaster University, Lancaster, Lancashire, United Kingdom vii viii Contributors E Hesketh (117) USDA-NRCS, WNTSC, Amherst, Massachusetts, USA David E Johnson (221) Crop and Environmental Sciences Division, International Rice Research Institute, Metro Manila, Philippines E Krull (47) CSIRO Land and Water, PMB2, Glen Osmond, Australia H Lal (117) USDA-NRCS, WNTSC, Portland, Oregon, USA E Lopez-Capel (47) The Swan Institute, University of Newcastle, Newcastle upon Tyne, United Kingdom S P McKinney (117) USDA-NRCS, WNTSC, Portland, Oregon, USA P N Owens (83) University of Northern British Columbia, Prince George, British Columbia, Canada W A Payne (1) Assistant Director for Research, Norman E Borlaug Institute of International Agriculture, and Professor of Crop Physiology, Texas A&M University System, College Station, Texas, USA M J Shaffer (117) USDA-ARS (Retired), Fort Collins, Colorado, USA S P Sohi (47) School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom, and Department of Soil Science, Rothamsted Research, Harpenden, Herts, United Kingdom Murray Unkovich (173) School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, SA, Australia S M White (83) Cranfield University, Cranfield, Bedfordshire, United Kingdom PREFACE Volume 105 contains six outstanding reviews dealing with nutrient cycling, soil and water resources, climate change, and crop management Chapter is a thought provoking commentary on the impacts of biofuels on sustainability of soil and water resources Chapter discusses the potential effect of biochar on climate change and carbon cycling, crop productivity, and resource management Chapter is a thorough review on water pollution from intensively managed grasslands Pollution pathways and ways to minimize contamination from them are also discussed Chapter is a contemporary review on the use of an innovative GIS Nitrogen Trading Tool for conserving and reducing nitrogen losses in the environment Chapter discusses the impact of harvest index variability of grain crops on carbon accounting, with application to Australian agriculture Chapter deals with the role of seed ecology in enhancing weed management in the tropics I appreciate the excellent reviews of the authors DONALD L SPARKS Newark, Delaware, USA ix C H A P T E R O N E Are Biofuels Antithetic to Long-Term Sustainability of Soil and Water Resources? W A Payne*,† Contents 7 13 13 14 15 16 16 17 21 22 22 24 29 33 41 43 Introduction Some History 2.1 Ethanol as a fuel 2.2 Soil and oil 2.3 Charting our future in the past An Overview of Biofuels 3.1 Ethanol 3.2 Biodiesel 3.3 Cellulosic ethanol 3.4 Biofuel feedstocks and conversion to biofuel 3.5 Bioenergy and biofuel potential on a global scale Sustainability Issues 4.1 Favorable economics? 4.2 Conservation of resources 4.3 Preservation of ecology 4.4 Social justice Summary References Abstract Sustainability of biofuels is a contentious but old topic that has reemerged with increased use of crops as feedstocks There are vastly different land requirements for different feedstocks, and disagreement on the energy balance of their conversion to biofuel To be sustainable, biofuel systems should (1) have favorable economics, (2) conserve natural resources, (3) preserve ecology, and (4) promote social justice With the possible exception of sugarcane * Assistant Director for Research, Norman E Borlaug Institute for International Agriculture, Texas A&M University System, College Station, Texas, USA Professor of Crop Physiology, Texas A&M University System, College Station, Texas, USA { Advances in Agronomy, Volume 105 ISSN 0065-2113, DOI: 10.1016/S0065-2113(10)05001-7 # 2010 Elsevier Inc All rights reserved W A Payne production in Brazil, it seems unlikely that ethanol production from crops will be economically viable without government support Less is known on cellulosic feedstock economics because there are no commercial-scale plants Natural resources that may be affected include soil, water, and air In the United States, agricultural intensification has been associated with greater soil conservation, but this depended on retaining residue that may serve as cellulosic feedstocks The ‘‘water footprint’’ of bioenergy from crops is much greater than for other forms of energy, although cellulosic feedstocks would have a smaller footprint Most studies have found that first-generation biofuels reduce greenhouse gas emissions 20–60%, and second generation ones by 70–90%, if effects from land-use change are excluded But land-use change may incur large carbon losses, and can affect ecological preservation, including biodiversity Social justice is by far the most contentious sustainability issue Expanding biofuel production was a major cause of food insecurity and political instability in 2008 There is a large debate on whether biofuels will always contribute to food insecurity, social justice, and environmental degradation in poor countries Introduction The cacophony of responses to a recent New York Times article (NYT, 2009a,b) in which New Mexico Senator Bingaman suggested further government help for the ailing ethanol industry illustrates what an emotionally and politically charged topic that biofuel has become (Table 1) One can find similar spirited exchanges on biofuel articles at the Christian Science Monitor, The Economist, and other newspapers Some of the hot button issues that biofuels and especially ethanol raise include patriotism, pro- and antiwar sentiment, terrorism, xenophobia, engine and conversion efficiencies, food for the poor, environmental protection, fair trade, energy independence, urban vs rural America, big oil companies, and government spending of taxpayers’ dollars How can scientists possibly make sense of this when, after all, they themselves are not free from partisanship (Clair, 2009; Guston et al., 2009)? There is not even a strong consensus within the scientific community on whether the overall energy output from ethanol and biodiesel production is greater than the input (Liska et al., 2008; Pimentel and Patzek, 2005) Add to that all the other sociopolitical aspects, and one truly has a (metaphorically) volatile mixture Because of the many biophysical but especially sociopolitical uncertainties and complexities involved, it should come as no surprise that, whether for good-faith or simply politically motivated reasons, there are many contentious views on the topic of biofuels and sustainability In large part, the topic is linked with that of global climate change, which itself is Are Biofuels Antithetic to Long-Term Sustainability of Soil and Water Resources? Table Posted reader comments to New York Times article on proposed increased support to the ethanol industry (NYT, 2009a,b) I think this is a terrible idea, every single subsidized program has been a terrible money draining failure from airlines to welfare Basically we’re supporting high commodity prices by pushing this plan This hurts foreign competition and disrupts food markets, we should not be burning food until we can end world hunger Of course there are also various environmental concerns, the increased fertilizer runoff, by-products from factories and the stuff is less safe than gasoline since it is less stable The claim that the problems of the ethanol industry are attributable to the recession is dishonest The ethanol industry is in terrible shape because corn ethanol makes no sense economically or environmentally, and there is no known method for producing cellulosic ethanol on a commercial scale Please not prop up corn ethanol The environmental consequences of growing so much corn conventionally (read mono-crop, petroleum intensive, chemical dependent agriculture) easily cancel out the benefits of ethanol blends Because we heartlessly treat food as a global free market commodity exposed to the whims of speculation, ethanol production has spiked corn prices and in classic domino effect caused the prices of other staples to ride a roller-coaster as well This has led to wide spread hunger, food riots and instability Congressmen, many of whom are deep in the pocket of mega-agribusiness, need to step back for a moment and realize the dangerous consequences of burning food as fuel Contact your Senators and Representatives and tell them that corn ethanol fuel is a terrible idea both for the economy and the environment Wow! You mean the government mandated something without making sure it was technologically and economically feasible first? Ethanol uses up as much fuel as it is supposed to save or more, according to recent studies It makes us more dependent to foreign oil, raises food prices, reduces gas mileage and engine performance, damages the environment If it wasn’t for .lobbyists, congress would have never given those multibillion dollar corporations our tax dollars to subsidize this lunacy Corn-based ethanol is the ONLY renewable fuel that is available today and is the foundation for the next generation ethanol (cellulosic) of tomorrow The notion that corn-based ethanol being the culprit for increased food prices has been completely debunked, leaving the GMA and other antiethanol groups with absolutely no credibility America’s corn growers have just completed one of the largest harvests of corn in our country’s history, with an average of 154 bushels of corn per acre With continued improvements in agriculture, that yield is expected to double, ON THE SAME AMOUNT OF LAND, over the next decade This country MUST continue to support corn-based ethanol to get to cellulosic and, more importantly, to reduce our addiction to foreign oil (continued) W A Payne Table (continued) In addition to the economic failure of corn ethanol, the environmental costs include using limited water supplies Ethanol plants are more water efficient than they were, but still have huge water requirements According to the Feb 2007 Ethanol Producer Magazine it takes 150–300 million gallons of water to produce 100 million gallons of ethanol When the water tables are depleted and we cannot get water for food crops, drinking and other activities, where are the tankers of water going to come from? I love how 99% of the people bashing ethanol have never driven a car with ethanol (besides E10), but will quickly attest to how terrible it supposedly is by pointing to bogus studies that use ethanol data in excess of years old Besides, I’d rather buy my fuel from Farmer Bob down the road than some sheik in the mideast that’s funneling money to terrorist organizations The price difference makes up for your lost mileage because of very large subsidies and indirect costs that are paid by other consumers and taxpayers If you want to pay more money to Farmer Bob for ethanol, then by all means so—but pay him with your own money, not money confiscated from others And while you’re at it, add on a few bucks per gallon for the environmental damage that you’re inflicting In short is it not the myth of ‘‘renewable, corn base ethanol’’ that both science and the market place has debunked? Ethanol from corn is not renewable because the energy inputs are roughly the size of what you get out in usable liquid fuels, and the greenhouse gas savings are nil There is no scientific doubt about these statements, the literature is full of them There is also no doubt that cellulosic ethanol, if made right, or the kinds of advanced biofuels Berkeley, Stanford and other institutions are working on, MIGHT give true relief on the oil front and the CO2 front But no responsible scientist, economist or politician (oxymoron) believes cellulosic ethanol or any other biofuel will be cheap, even compared to $100/bbl oil, when all the costs are counted I challenge you to forego the tax subsidies and shift to a tax on oil, and a tax on carbon, and let the market decide how well ethanol from corn can compete with other fuels, more efficient cars, and less driving Corn also requires nitrogen fertilizing that is being blamed for increasing dead zones in the Gulf of Mexico and elsewhere If we want 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cultivations Weed Res 15, 249–258 Woolley, J T., and Stoller, E (1978) Light penetration and light-induced seed germination in soil Plant Physiol 61, 597–600 Yenish, J P., Doll, J D., and Buhler, D D (1992) Effects of tillage on vertical distribution and viability of weed seed in soil Weed Sci 40, 429–433 Yenish, J P., Fry, T A., Durgan, B R., and Wyse, D L (1996) Tillage effects on seed distribution and common milkweed (Asclepias syriaca) establishment Weed Sci 44, 815–820 Zimdahl, R L (1988) The concept and application of the critical weed-free period In ‘‘Weed Management in Agroecosystems: Ecological Approaches’’ (M A Altieri and M Liebman, Eds.), pp 145–155 CRC, Boca Raton, FL Index A Agricultural non-point source pollution (AGNPS) model, 143 Agriculture applications crop productivity impacts, 65–67 greenhouse gas balance impact, 70–72 resource implications cation exchange capacity (CEC), 68–69 charcoal, 67 mineral ash, 70 soil chemistry, 69 soil organic matter, 68 terra preta fertile, 64–65 Agriculture Research Service Soil Plant Nutrient Research Unit (ARS-SPNR), 125 Australian field crops barley yield, 200 carbon balances, 207–208 cereal breeding, 180–181 cropping system, 176 dryland crops, 193, 195 nitrogen availability, 187–188 oilseed poppies, 206 pest and diseases, 181 rice yield, 204 seed production cost vs harvest index, 192, 194 temperature extremes, 182 varied climatic condition, 176 water use, 183–186 wheat yield, 199 Avena fatua, 223, 243 B Barley dry matter and grain yield, 200 frequency distribution, 200–201 Biochar agriculture applications crop productivity impacts, 65–67 greenhouse gas balance impact, 70–72 resource implications, 67–70 terra preta fertile, 64–65 batch process, 51 characterization bulk soil sample, 61 chemical composition, 63–64 quantification, 61–63 scanning electron microscopy (SEM), 64 climate change, 48 gas turbine/engines, 49 global carbon cycle biomass stabilization effects, 56 black carbon cycle, 56 climate forcing measure, 57 fertilization, 55 organic resource/wastes, 55 photosynthesis, 54 initial feedstock mass, 50 oil production, 53 policy context, 53–54 potential win–win strategy, 48 process parameters, 50 production and deployment carbon storage, 57 closed-loop system, 58 land-use impacts, 59 pyrolysis, 49 research priorities barriers and limitations, 75–76 biochar fate, 73 nutrient efficiency, 73 physiological plant response, 74 properties, qualities, and environmental risks, 74 soil–biochar system, modeling capacity, 74–75 soil microbial communities, 72–73 soil nitrous oxide and methane emission impacts, 73 soil physical effects, 73 surface interactions, 73 research-scale pyrolysis, 51 thermal conversion, 52 trading and acceptability issues agronomic function, 59 key elements, 60 PAH profile, 61 renewable energy, 59 toxic compounds, 60 Biofuel carbon debt, 31 Biofuels, 22 agricultural development, 40 biodiesel, 16 bioenergy, 21–22 biomass sources, 14–15 263 264 Index Biofuels (cont.) cellulosic ethanol, 16–17 classification, 15 cropping system, 39 environmental benefits and impacts, 37 ethanol, 15 feedstocks, 17–21 biodiesel production, 17–18 crop-based ethanol, 20 crop yield estimation, 19 energy requirement, 18 ethanol production, 17, 21 FAO report, 19 fossil energy balance estimation, 20 large-scale production model, 38 promising biofuel species, 39 tariff barrier, 38 C Carbon accounting average (site x year) values, 207 shoot:root ratios, 175 single value approach, 207–208 Carbon balance, 174, 176, 207–208 Clean development mechanism (CDM), 54 Convention on Biological Diversity, 29 D Denitrification erosion N loss pathways, 151–152 estimation, 147 gaseous pathway management practices, 147–149 NH3-N volatilization, 149–150 nutrient farming concept, 149 IPCC methodology, 146 NO3-N leaching pathways, 150–151 reactive N reduction, 145 Diffuse agricultural water pollution aquatic ecosystems, 85 conceptual framework ammonium, 96–97 delivery aspects, 90–92 faecal pathogens, 100–101 fine-grained sediment, 94–96 mobilization aspects, 88–90 nitrate, 97–98 nitrite, 98 phosphorus, 98–99 pollutant transport, 92–94 source aspects, 87–88 source–mobilization–delivery (SMD) pollutant, 87 generic functional classification, 106 HOST classification system, 86 intensively managed grassland systems, 107–109 multipollutant approach, 86 potential pollutant SMD scenarios concentration and discharge, 103–106 diffuse pollution loss, 103 drainage water entrainment, 102 inorganic fertilizer, 101 research gap identification, 110 surface water eutrophication, 84 water body effects, 85 E Echinochloa crus-galli, 243 Energy investment, harvest index carbon cost, 177–179 C3 cereal crops, 179 protein content, 180 Energy Tax Act, European Economic Community (EEC), 85 F Fire effect, weed seed germination high temperature, 230–231 physiological effect, 231 Food security and biofuel biodiesel production, 36 food price, 34 global grain supplies, 37 IFPRI estimation, 34 sustainable development, 37 G Global Forest Coalition Report, 40 Global position system (GPS), 139 H Harvest index, grain crops barley dry matter and grain yield, 200 frequency distribution, 200–201 breeding, 180–181 C accounting average (site x year) values, 207 single value approach, 207–208 canola, 203–204 chickpea, 202 cost, seed production, 192, 194 database apparent harverst index, 189 lupin crop, various sample, 190–191 moisture content, 189–190 pot-grown chickpea, 190–191 short-statured crops, 191–192 small plot experiments, 189 dataset mean, 192 energy investment 265 Index carbon cost, 177–179 C3 cereal crops, 179 protein content, 180 environmental impacts, 182 faba bean, 203 factors, 188 field pea, 202–203 lentil, 205–206 lower limits, 192 lupin, 201 maize, 206 oilseed poppies, 206–207 peanut, 206 pest and diseases effects, 181 pre:postanthesis water use fertilizer, N, 184 field experiment, 184 glasshouse-grown lentil, 185–186 pot cultured wheat, 183 seed yield reduction, water stress, 186 rice, 204–205 soil mineral nitrogen, wheat climate variability, 188 N fertility, 187 postanthesis water stress, 188 weak negative relationship, 187 sorghum, 202 sunflower, 205 upper limits, 194 variablity, flowering, 181 wheat dry matter yield, 199 grain yield, 199 seasonal treatment, 199–200 I Integrated weed management (IWW) program, 248 Intensively managed grassland systems, 107–109 International Panel on Climate Change (IPCC), 146 L Long Island Sound (LIS) basin, 158 M Moisture stress, weed germination See Salt and moisture stress N National Biodiesel Board, 35 Natural Resources Conservation Service (NRCS), 125 Nitrate leaching and economic analysis package (NLEAP), 142 Nitrification inhibitors (NI), 137 Nitrogen management and trading bank balance account, NTT-DNLreac, 124 carbon and nitrogen sequestration, 153–154 carbon contribution, 126–127 definition, 124 denitrification, 146–152 internet prototype, 125 limited irrigation, 131–132, 134–135 mass balance approach, 124 N inputs amount of, 132, 134, 136 crop rotations, 143–145 methods and time, 138 models and index, 142 precision farming techniques, 139–142 spatial and temporal variability, 143 types, 134, 136–138 nitorgen use efficiency, 123–124 nitrogen pools, 152–153 N2O emissions, 154 nutrient trading concept, 124 principles, 123 vs soil–crop–hydrologic cylce denitrification process, 122, 128 hydrologic groups, 128–130 NO3-N leaching, 128 precipiation, seasonla timing, 128, 131 surface runoff, 128 water-logged conditions, 127 stand-alone prototype, 125–126 web-based prototype, 125 Nitrogen trading tool (NTT) agricultural systems high water use efficiency, 120 nitrogen inputs, 118 application and trends air quality, 159 water quality, 158–159 erosion N loss pathways, 151–152 estimation, 147 gaseous pathways, 147–150 GIS concept evaluation irrigated systems, 157 manure applications, midwest region, 157–158 no-till systems, north atlantic region, 157 management and trading bank balance account, NTT-DNLreac, 124 carbon and nitrogen sequestration, 153–154 carbon contribution, 126–127 definition, 124 denitrification, 146–152 internet prototype, 125 limited irrigation, 131–132 mass balance approach, 124 N inputs, 132–145 nitorgen use efficiency, 123–124 266 Index Nitrogen trading tool (NTT) (cont.) nitrogen pools, 152–153 N2O emissions, 154 nutrient trading concept, 124 principles, 123 vs soil–crop–hydrologic cylce, 127–131 soil nitrogen pool, 123 soil organic matter, 126 stand-alone prototype, 125–126 web-based prototype, 125 nutrient cycles, 118–119 technology tier approaches, 154–155 web-based and stand-alone modeling approaches, 155–156 Normalized difference vegetation index (NDVI), 141 N reflectance index (NRI), 141 O Oregon Department of Environmental Quality (OR-DEQ), 159 Oryza sativa, 223 P Pennsylvania Department of Environmental Protection (Penn-DEP), 158–159 Pollutant concentration, 91 Precision agricultural–landscape modeling system (PALMS), 143 Presidedress soil NO3-N test (PSNT), 142 R Remote-sensing technique, 141 S Salt and moisture stress A fatua and E crus-galli, 243–244 osmotic potential, 243 sodium chloride concentration, 242–243 soil salinity, 242 Seed burial depth effects factors, 233 seedling emergence, 233–235 vs seed weight, 233, 235 soil compaction, 236 Seed ecology See Weed seed germination Seed scarification, germination farming system, 230 hard-coated seeds, 229 Site-specific management zone (SSMZ), 139 Soil and water assessment tool (SWAT) model, 143 Soil organic matter (SOM), 126 Source–mobilization–delivery (SMD) pollutant, 87, 93 Surface mulches chemical effect, 241–242 cover crop, 239 crop residues, 239, 242 residues effects, various species, 240 seed size, 241 weed suppression, 241 Sustainability, soil and water resources agricultural market, 23 agricultural product, 24 air resources, 28–29 biodiversity, 29–30 cellulosic biofuel feedstock, 26 corn stover, 26 crop production, 14 CRP land harvest, 27 The Economist article, 23 emission reduction, 43 energy components, 41 energy consumption, 25 ethanol as fuel energy information administration (EIA), fuel demand, 12 internal combustion engine, legislative action, 12 usage timeline, 8–12 ethanol industry support, 3–7 ethanol production cost vs USDA’s supply control program cost, 13 food security and biofuel biodiesel production, 36 food price, 34 global grain supplies, 37 IFPRI estimation, 34 sustainable development, 37 fossil fuel balance estimation, 42 grain-based ethanol, 28 impacts, 25 integrated system, 22 oil price, 24 petroleum-based fuel, 22 sensitive lands and land-use change loss carbon estimation, 31 FAO project, 32–33 greenhouse emission, 31 wheat production potential, 32 social justice issues, 40–41 sociopolitical uncertainties, soil erosion rate, 25 US agricultural production, 41 US Energy Policy Act, 22 US legislation, 13 water footprint, 27, 42 T Tillage systems, weed seed germination conservation, 250 267 Index dry- and wet-land conditions, 236–239 seed scarification, 230 shallow operations, 248 vertical seed distribution effect, 232 Trading and acceptability issues, biochar carbon agronomic function, 59 key elements, 60 PAH profile, 61 renewable energy, 59 toxic compounds, 60 W Water Quality Trading Program, 159 Weed seed germination decision-making tools, 251–252 developing integrated crop management, 250–251 fire effect high temperature, 230–231 physiological effect, 231 flooding, 244–247 light exposure ‘‘depth indicator,’’ 228 effects, specific species, 226, 228 photoblastic seeds, 227 mulch and herbicide interaction, 250 salt and moisture stress A fatua and E crus-galli, 243–244 osmotic potential, 243 sodium chloride concentration, 242–243 soil salinity, 242 seed bank, 249–250 seed burial depth effects factors, 233 seedling emergence, 233–235 vs seed weight, 233, 235 soil compaction, 236 seed ecology, population environmental factors, 226–227 germination pattern, 226 seed bank, 224–225 seed dormancy, 225 seed scarification farming system, 230 hard-coated seeds, 229 surface mulches chemical effect, 241–242 cover crop, 239 crop residues, 239, 242 residues effects, various species, 240 seed size, 241 weed suppression, 241 weed management, tropics crop establishing methods, 224 herbicide resistance, 223–224 integrated weed management (IWW) program, 248 Wheat dry matter yield, 199 grain yield, 199 seasonal treatment, 199–200 soil mineral nitrogen climate variability, 188 N fertility, 187 postanthesis water stress, 188 weak negative relationship, 187 World Resource Institute (WRI), 154 ... gallon subsidy for every gallon of ethanol blended into gasoline  Marketing of commercial alcohol-blended fuels began Amoco Oil Company began marketing commercial alcohol-blended fuels, followed... represent only a small fraction of total plant mass, which is mostly composed of cellulose, hemicellulose, and lignin Cellulose and hemicellulose can be also converted into ethanol after they... Table 2007 ethanol and biodiesel production of the world and selected countries Country/country grouping Ethanol (millions of l) Biodiesel (millions of l) Brazil Canada China India Indonesia Malaysia