• Authors:
    • Beach,R. H.
    • Cai,Y.
    • Thomson,A.
    • Zhang,X.
    • Jones,R.
    • McCarl,B. A.
    • Crimmins,A.
    • Martinich,J.
    • Cole,J.
    • Ohrel,S.
    • Deangelo,B.
    • McFarland,J.
    • Strzepek,K.
    • Boehlert,B.
  • Source: Environmental Research Letters
  • Volume: 10
  • Issue: 9
  • Year: 2015
  • Summary: Increasing atmospheric carbon dioxide levels, higher temperatures, altered precipitation patterns, and other climate change impacts have already begun to affect US agriculture and forestry, with impacts expected to become more substantial in the future. There have been numerous studies of climate change impacts on agriculture or forestry, but relatively little research examining the long-term net impacts of a stabilization scenario relative to a case with unabated climate change. We provide an analysis of the potential benefits of global climate change mitigation for US agriculture and forestry through 2100, accounting for landowner decisions regarding land use, crop mix, and management practices. The analytic approach involves a combination of climate models, a crop process model (EPIC), a dynamic vegetation model used for forests (MC1), and an economic model of the US forestry and agricultural sector (FASOM-GHG). We find substantial impacts on productivity, commodity markets, and consumer and producer welfare for the stabilization scenario relative to unabated climate change, though the magnitude and direction of impacts vary across regions and commodities. Although there is variability in welfare impacts across climate simulations, we find positive net benefits from stabilization in all cases, with cumulative impacts ranging from $32.7 billion to $54.5 billion over the period 2015-2100. Our estimates contribute to the literature on potential benefits of GHG mitigation and can help inform policy decisions weighing alternative mitigation and adaptation actions. © 2015 IOP Publishing Ltd.
  • Authors:
    • Haudenshield, J. S.
    • Bowen, C. R.
    • Hartman, G. L.
    • Fox, C. M.
    • Cary, T. R.
    • Diers, B. W.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Diseases and pests of soybean [ Glycine max (L.) Merr.] often reduce soybean yields. Targeted breeding that incorporates known genes for resistance and non-targeted breeding that eliminates susceptible plants in breeding populations reduces the impact of soybean pathogens and pests. Maturity group (MG) III soybean cultivars released from 1923 through 2008 were grown in three field environments to determine if disease and insect ratings were associated with year of cultivar release. Disease and pest ratings were evaluated on 40 soybean cultivars at one location (Urbana, IL) planted in two rotation treatments in 2010 and on 59 cultivars in two locations (Urbana and Arthur) in 2011. During the season, foliar disease symptoms and insect foliar feeding damage were recorded. At harvest maturity, stem diseases were assessed. In at least one environment, foliar incidence reached 100% for bacterial diseases, brown spot ( Septoria glycines Hemmi), and insect foliar feeding damage and 100% incidence for anthracnose [ Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore], Cercospora stem blight ( Cercospora kikuchii T. Matsumoto & Tomoy.), and charcoal rot [ Macrophomina phaseolina (Tassi) Goid.] on stems for all cultivars. For the nine different disease and pest severity assessments in 2010, seven had a significant ( P<0.05) negative correlation to year of cultivar release indicating that cultivars more recently released had lower severity ratings than cultivars with older release dates. This study demonstrated that incidence and severity of diseases were less pronounced on more newly-released soybean cultivars, showing that decades of breeding has resulted in increased disease resistance in modern soybean cultivars.
  • Authors:
    • Maxted, N.
    • Kang, D.
    • Wei, W.
    • Ford-Lloyd,B.
    • Chen, B.
    • Qin, H.
    • Kell, S.
  • Source: Science Article
  • Volume: 209
  • Year: 2015
  • Summary: The potentially devastating impacts of climate change on crop production and food security are now widely acknowledged. An important component of efforts to mitigate these impacts is the production of new varieties of crops which will be able to thrive in more extreme and changeable environmental conditions. There is therefore an urgent need to find new sources of genetic diversity for crop improvement. Wild plant species closely related to crops (crop wild relatives) contain vital sources of such genes, yet these resources themselves are threatened by the effects of climate change, as well as by a range of other human-induced pressures and socio-economic changes. The flora of China comprises more than 20,000 native higher plant species, a proportion of which have known or potential value as gene donors for crop improvement. However, until now, the full range of these valuable crop wild relative species had not been identified. In this paper we present a methodology for creating a checklist of, and prioritizing China's crop wild relatives, and reveal that 871 native species are related to crops that are of particularly high socio-economic importance in China-including rice, wheat, soybean, potato, sweet potato, millet and yam-crops which are also of notably high value for food and economic security in other parts of the world. Within this list we have identified species that are in particular need of conservation assessment based on their relative Red List status and potential for use in crop improvement programs. Endemic species that have particularly high economic value potential in China and that are under severe threat of genetic erosion and thus in need of urgent conservation action include wild relatives of tea ( Camellia fangchengensis S. Yun Liang et Y.C. Zhong and C. grandibracteata H.T. Chang et F.L. Yu), apple ( e.g., Malus honanensis Rehder, M. ombrophila Hand.-Mazz. and M. toringoides (Rehder) Hughes), and pear ( Pyrus pseudopashia T.T. Yu). We provide recommendations for developing a systematic and comprehensive national CWR conservation strategy for China, highlighting the challenges and requirements of taking the strategy forward to the implementation phase.
  • Authors:
    • Rathmann, R.
    • Soria, R.
    • Portugal-Pereira, J.
    • Schaeffer, R.
    • Szklo, A.
  • Source: Article
  • Volume: 81
  • Year: 2015
  • Summary: This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO 2e and could reach 64 million tonne CO 2e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers.
  • Authors:
    • Rochette, P.
    • Morel, C.
    • Lalande, R.
    • Gagnon, B.
    • Angers, D. A.
    • Ziadi, N.
    • Chantigny, M. H.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Adoption of conservation practices can induce beneficial changes to soil properties and related crop yields in which magnitude varies according to soil and climatic conditions but usually increases with time. A long-term field experiment was initiated in 1992 at L'Acadie in southern Quebec on a clay loam soil to evaluate the effect of tillage [mouldboard plow (MP) vs. conservation (CT)], synthetic N fertilization (0, 80, and 160 kg N ha -1) and synthetic P fertilization (0, 17.5, and 35 kg P ha -1) on soil functioning and grain yields of a corn-soybean rotation. Soil tillage was performed every year while synthetic fertilizers were applied only to the corn. Results obtained 12 to 20 yr after initiation of the study indicated that CT enhanced organic C accumulation, NO 3-N, P and K availability, microbial biomass and activity, and microbial community structure in the upper soil layer, likely due to leaving crop residues at the soil surface. The MP practice resulted in greater organic C content deeper, near the bottom of the plow layer, which promoted soil microbial activity at that depth. However, soil N 2O emissions were not affected by tillage. The N and P fertilization increased the availability of these nutrients, but had no significant effect on the soil microbial biomass, activity, and structure. Linear relationships were established between soil available P and cumulative P budgets obtained under MP or 0 kg P ha -1 under CT. Crop yields varied by year in this study but on average, MP yielded 10% more corn and 13% more soybeans than CT. Corn yield increased linearly with added synthetic N each year, whereas soybean yield was little affected by residual N, and both crops did not respond to fertilizer P. Response to N fertilization did not differ due to tillage or P. Despite higher costs associated with plowing, the profitability of MP was greater than CT on this clay loam soil due to greater yields. Specialized management practices (e.g., delayed planting, better herbicide selection, fall cover crop, in-row tillage) might help to improve CT performance on these cool, humid fine-textured soils.
  • Authors:
    • Basanta, M.
    • Costantini, A.
    • Alvarez, C. R.
    • Alvarez, C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 142
  • Year: 2014
  • Summary: Soil management affects distribution and the stocks of soil organic carbon and total nitrogen. The aim of this study was to evaluate the effect of different crop sequences and tillage systems on the vertical distribution and stocks of soil carbon and nitrogen. We hypothesized that no-tillage promotes surface organic carbon and total nitrogen accumulation, but does not affect the C and N stocks, when compared with reduced tillage. In addition, the incorporation of maize in the crop sequence increases total organic carbon and total nitrogen stocks. Observations were carried out in 2010 in an experiment located in the semiarid Argentine Pampa, on an Entic Haplustoll. A combination of three tillage systems (no tillage, no tillage with cover crop in winter and reduced tillage) and two crop sequences (soybean-maize and soybean monoculture) were assessed. After 15 years of management treatments, soil samples to a depth of 100. cm at seven intervals, were taken and analyzed for bulk density, organic carbon and total nitrogen. Total organic carbon stock up to a depth of 100. cm showed significant differences between soils under different tillage systems (reduced tillage. <. no tillage = no tillage with cover crop), the last ones having 8% more than the reduced tillage treatment. Soybean-maize had 3% more organic C up to 100. cm depth than the soybean monoculture. Total nitrogen stock was higher under no-till treatments than under reduced tillage, both at 0-50 and 0-100. cm depths. Total organic carbon stratification ratios (0-5. cm/5-10. cm) were around 1.6 under no-till and lower under reduced tillage. The stratification ratio explains less than 40% of soil carbon stock. Tillage system had a greater impact on soil carbon stock than crop sequence. © 2014 Elsevier B.V.
  • Authors:
    • Al-Kaisi, M. M.
    • Guzman, J. G.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 2
  • Year: 2014
  • Summary: Agriculture management practices can significantly affect soil C storage through changes in C inputs and losses. This study investigated the shortterm effects of tillage (no-tillage [NT] and conventional tillage [CT]), residue removal (0, 50, and 100%), and N rates of 0, 170, and 280 kg N ha-1 on soil C storage. Studies were established in 2008 to 2011 on a Nicollet clay loam (fine-loamy, mixed superactive, mesic Aquic Hapludolls) and Canisteo clay loam (Fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) soil association at Ames, central Iowa site (AC) and a Marshall silty clay loam (Fine-silty, mixed, superactive, mesic Typic Hapludolls) soil association at Armstrong, southwest Iowa site (ASW) in continuous corn (Zea Mays L.). Findings from the C budget show that under CT and N rate of 170 kg N ha-1 in continuous corn, there was no significant change in net soil C with no residue removal. Increasing N rate from 170 to 280 kg N ha-1 resulted in greater potential C inputs from above and belowground biomass, although C losses were not significantly different, especially with NT. Thus, a portion of soil surface residue could be removed without causing a net loss of soil C. Converting from CT to NT led to lower soil C losses, but C inputs varied due to soil temperature and water content differences and seasonal variability in a given year. Consequently, averaged across both tillage systems and at 280 kg ha-1 N rate for continuous corn approximately 5.10 and 4.18 Mg ha-1 of the residue should remain on the field to sustain soil C in 2010 and 5.23 and 5.18 Mg ha-1 in 2011 for AC and ASW sites, respectively. These finding suggest that residue removal needs to be approached on yearly basis with particular consideration to site's yield potential and weather condition as the residue biomass production can be variable. © Soil Science Society of America.
  • Authors:
    • Kaspar, T. C.
    • Wiedenhoeft, M. H.
    • Moore, E. B.
    • Cambardella, C. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 3
  • Year: 2014
  • Summary: Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] farmers in the upper Midwest are showing increasing interest in winter cover crops. The effects of winter cover crops on soil quality in this region, however, have not been investigated extensively. The objective of this experiment was to determine the effects of a cereal rye (Secale cereale L.) winter cover crop after more than 9 yr in a corn silage-soybean rotation. Four cereal rye winter cover crop treatments were established in 2001: no cover crop, rye after soybean, rye after silage, and rye after both. Soil organic matter (SOM), particulate organic matter (POM), and potentially mineralizable N (PMN) were measured in 2010 and 2011 for two depth layers (0-5 and 5-10 cm) in both the corn silage and soybean phases of the rotation. In the 0- to 5-cm depth layer, a rye cover crop grown after both main crops had 15% greater SOM, 44% greater POM, and 38% greater PMN than the treatment with no cover crops. In general, the treatments that had a rye cover crop after both crops or after corn silage had a positive effect on the soil quality indicators relative to treatments without a cover crop or a cover crop only after soybean. Apparently, a rye cover crop grown only after soybean did not add enough residues to the soil to cause measureable changes in SOM, POM, or PMN. In general, rye cover crop effects were most pronounced in the top 5 cm of soil.
  • Authors:
    • Wight, J. P.
    • Hons, F. M.
    • Storlien, J. O.
    • Heilman, J. L.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 5
  • Year: 2014
  • Summary: Modern bioenergy feedstocks, such as bioenergy sorghum [Sorghum bicolor (L.) Moench], are being developed to supply future cellulosic biofuel demands. How these cropping systems impact greenhouse gas (GHG) emission of CO2and N2O from the soil is unknown and field research is necessary to elucidate the effects of agronomic management practices on soil trace gas emissions. We studied the effects of N fertilization (0 vs. 280 kg urea-N ha-1), residue management (0 vs. 50% of sorghum biomass returned), crop sequence (corn [Zea mays L.]-sorghum vs. sorghum-sorghum), and their interactions on CO2and N2O emissions from bioenergy production scenarios on a Weswood (finesilty, mixed, superactive, thermic Udifluventic Haplustept) silty clay loam soil in central Texas. Gas fluxes were measured approximately weekly throughout the 2010 and 2011 growing season and at a reduced rate during the fallow season with a photoacoustic gas analyzer integrated with a static chamber. Overall, CO2and N2O fluxes were relatively higher than those observed by others in the United States despite drought conditions throughout much of 2010 and 2011. Highest emissions of both gases were observed during the growing season, often following a precipitation-irrigation event and shortly after N fertilization. Residue return increased cumulative CO2emissions each year, probably due to increased heterotrophic microbial activity. Nitrogen addition significantly increased cumulative emissions of N2O both years but only impacted cumulative CO2emissions in 2011. While crop rotation impacted biomass yield, it had no significant effect on cumulative CO2or N2O emissions. Additional research is needed to identify the optimal N and residue application rates that provide high yields with minimal soil GHG emissions and aid in sustaining long-term soil quality.
  • Authors:
    • Taboada, M. A.
    • Scianca, C. M.
    • Varela, M. F.
    • Rubio, G.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: Cover crops (CC) provide many benefits to soils but their effect on decomposition of previous crop residues and release of nutrients in continuous no-tillage soybean [Glycine max (L.) Merr.] production are little known. Our objective was to quantify CC effects on decomposition and phosphorus (P) release from soybean residue using litterbags. Three CC species (oat, Avena sativa L.; rye, Secale cereal L.; and rye grass, Lolium multiflorum L.) and a no CC control were evaluated. Temperature, moisture content, microbial biomass and microbial activity were measured in the surface 2cm of soil and residues. Cover crops increased soybean residue decomposition slightly both years (8.2 and 6.4%). Phosphorus release from soybean residue did not show any significant differences. Cover crops increased microbial biomass quantity and activity in both soil and residue samples (p<0.001, p=0.049 for soil and residue microbial biomass; p=0.060, p=0.003 for soil and residue microbial activity, respectively). Increased residue decomposition with CC was associated with higher soil and residue microbial biomass and activity, higher near-surface (0-2cm) moisture content (due to shading) and soil organic carbon enrichment by CC. Even though CC increased soybean residue decomposition (233kgha-1), this effect was compensated for by the annual addition of approximately 6500kgha-1 of CC biomass. This study demonstrated another role for CC when calibrating models that simulate the decomposition of residues in no-tillage systems.