19862015
  • Authors:
    • Kludze, H.
    • McDonald,I.
    • Dadfar, H.
    • MacLean, H. L.
    • Dias, G.
    • Deen, B.
    • Sanscartier, D.
  • Source: GCB Bioenergy
  • Volume: 6
  • Issue: 4
  • Year: 2014
  • Summary: Replacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas (GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (-90-170 kg CO(2)eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (-20-190 g CO(2)eq kWh(-1)) compared with coal-generated electricity (1130 g CO(2)eq kWh(-1)). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production.
  • Authors:
    • Retore, M.
    • Silva, W. M.
    • Concenco, G.
    • Zanatta, J. A.
    • Tomazi, M.
    • Mercante, F. M.
    • Salton, J. C.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 190
  • Issue: SI
  • Year: 2014
  • Summary: Performance of soil management systems was initiated in 1995 in a field experiment in Dourados, MS, Brazil, with the following systems: CS - conventional tillage; NTS - no-tillage; ICLS - integrated crop-livestock with soybean (Glycine max (L) Merr.) and pasture under no-till, rotating every two years, and PP - permanent pasture. Pastures (Brachiaria decumbens) were grazed by heifers with stocking rate adjusted to constant supply of forage. The hypothesis was that rotation of crops and pastures would be more efficient and present beneficial effects to the environment. More complex and diversified production systems may exhibit synergism between components to result in better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. Better soil conditions in ICLS allowed greater resilience; over the years of assessment soybean and pasture yields were less affected by drought and frost. The ICLS was very efficient, accumulating soil C and reducing emissions of greenhouse gases. Soil quality was improved in integrated systems with larger number of components and greater interaction between these components (ICLS) compared to simple systems. Based on soil attributes, we affirmed in this long-term study that the ICLS system is agronomically and environmentally efficient and sustainable. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Korth, K.
    • Chen, P.
    • Gbur, E. E.
    • Brye, K. R.
    • Smith, F.
  • Source: Soil Science
  • Volume: 179
  • Issue: 3
  • Year: 2014
  • Summary: One of the most significant contributors to the greenhouse effect is carbon dioxide (CO2) gas in the atmosphere. Soil respiration, the combined production of CO2 from soil, as a result of root and microorganism respiration, is the largest flux of CO2 from the terrestrial ecosystem to the atmosphere. Considering land use can greatly impact soil C storage and cycling, agricultural management practices can also greatly affect soil respiration and CO2 emissions. Therefore, the effects of long-term residue management (i.e., residue burning and nonburning, and conventional [CT] and no-tillage [NT]) and residue level (i.e., high and low) on soil respiration during the soybean [Glycine max (L.) Merr.] growing season were examined over 2 consecutive years (i.e., 2011 and 2012) in a wheat (Triticum aestivum L.)-soybean, double-crop system in a silt-loam soil (Aquic Fraglossudalf) in the Mississippi River Delta region of eastern Arkansas after more than 9 years of consistent management. Soil respiration rates from individual plots ranged from 0.53 to 40.7 and from 0.17 to 13.1 mol CO2.m(-2).s(-1) throughout the 2011 and 2012 soybean growing seasons, respectively, and differed (P < 0.05) among treatment combinations on two and five of nine and 11 measurement dates in 2011 and 2012, respectively. Regardless of residue level, soil respiration was generally greater (P < 0.05) from CT than NT. Estimated season-long CO2 emissions were 10.2% less (18.5 Mg CO2 ha(-1)) from residue burning than from non-burning (20.6 Mg CO2.ha(-1); P = 0.032). Averaged over years and all other field treatments, estimated season-long CO2 emissions were 15.5% greater from CT (21.0 Mg CO2 ha(-1)) than from NT (18.1Mg CO2 ha(-1); P = 0.020). Understanding long-term management effects on soil C losses, such as soil respiration, from common and widespread agricultural systems, such as the wheat-soybean, double-crop system, in eastern Arkansas can help improve policies for soil and environmental sustainability throughout the lower Mississippi River Delta region.
  • Authors:
    • Cecagno, D.
    • Costa, S. E. V. G. de A.
    • Martins, A. P.
    • Anghinoni, I.
    • Assmann, J. M.
    • Carlos, F. S.
    • Carvalho, P. C. de F.
  • Source: Web Of Knowledge
  • Volume: 190
  • Year: 2014
  • Summary: Managing grazing stocks in integrated crop-livestock (ICL) systems under no-tillage is a key variable for reaching equilibrium in soil C and N budgets. Understanding how different plant and animal residues affect soil C and N stocks in these systems goes beyond soil dynamics since these elements are crucial for the functioning of the soil-plant-atmosphere system. The objective of this research was to determine soil C and N fractions, stocks, budgets and the carbon management index as affected by nine years of ICL with grazing intensities under no-tillage conditions. The experiment established in May 2001 in a Rhodic Hapludult (Oxisol) of southern Brazil was composed of black oat ( Avena sativa) plus ryegrass ( Lolium multiflorum) pasture in winter and soybean ( Glycine max) crop in summer. Treatments were regulated by grazing pressures to maintain forage at 10, 20, 30 and 40 cm high (G10, G20, G30 and G40, respectively). Non-grazed (NG) treatment was the control. Changes in soil C and N stocks and fractions (particulate and mineral-associated) were assessed in the ninth year of the experiment. Moderate and light grazing intensities (G20, G30 and G40) resulted in similar increases in total organic C, particulate organic C, total N, and particulate organic N compared with NG treatment. Soil C additions ranged from 0.54 to 8.68 Mg ha -1 from NG to the other grazing treatments. The G10 led to a soil N loss of 1.17 Mg ha -1 due to soil organic matter degradation. The carbon management index (CMI) values, compared with native forest (NF) as a reference, indicated soil quality loss and degradation under high grazing intensity (G10). For a positive contribution to the soil system, ICL must be managed with moderate grazing intensities and adjustment of N additions through N fixation or fertilization.
  • Authors:
    • Gao, Z. Q.
    • Yang, W. S.
    • Li, P.
    • Ju, H.
    • Merchant, A.
    • Ma, Z. Y.
    • Han, X.
    • Gao, J.
    • Hao, X. Y.
    • Lin, E.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 192
  • Year: 2014
  • Summary: Investigations across the world have elucidated common chemical and physiological responses of plants to the influence of elevated atmospheric CO 2 concentration ([CO 2]). Focus is now turning to the influence of elevated [CO 2] on yield quality among a number of globally important crops including soybean ( Glycine max (L.) Merr). Soybean cv. Zhonghuang 35 was grown in a free-air CO 2 enrichment (FACE) field experiment at Changping-Beijing (China) under ambient (41516 mol mol -1) and elevated (55019 mol mol -1) CO 2 concentrations. Results showed that elevated [CO 2] increased the yields of soybean seeds (g m -2) by 26% and 31% respectively, in 2009 and 2011. Total protein concentration in seeds was significantly reduced by 3.3% under CO 2 enrichment, but oil concentration increased by 2.8%. Accordingly, most proteinogenic amino acid concentrations were significantly reduced under elevated [CO 2], whilst two fatty acids (linoleic acid and palmitic acid) increased in concentration. The protein and oil yield per unit ground area increased by 24.5% and 32.0%, respectively. Results indicate that whilst future elevated atmospheric [CO 2] may improve the oil quantity of soybean, corresponding reductions in the nutritive value are likely to occur.
  • Authors:
    • Miao, S. J.
    • Han, X. Z.
    • Doane,T. A.
    • Qiao, Y. F.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 12
  • Issue: 2
  • Year: 2014
  • Summary: The impact of long-term fertilizer application on greenhouse gas emission and global warming potential (GWP) is not well documented. A long-term fertilizer experiment, located at the Hailun State Key Agro-ecological Experiment Station, Hailun County, Heilongjiang Province, China, was used in this study to completely account for emission of CO 2 and N 2O from maize-soybean rotation systems. Five treatments were implemented, including nitrogen and potassium (NK), nitrogen and phosphorus (NP), balanced inorganic fertilizer (NPK), combined inorganic/organic fertilizer (NPKM), and no fertilizer (Cont.). CO 2 and N 2O fluxes were measured using a closed-chamber method from May 2006 to April 2007, and net GWP was estimated using emission data and considering CO 2 fixed by crops. With the exception of NK in soybean, long-term fertilizer application significantly increased crop biomass in all treatments and both crops compared to Cont. plots. Long-term inorganic fertilizer application tended to decrease total CO 2 emission and increase total N 2O emission. Inorganic/organic combination fertilizer significantly increased CO 2 and N 2O emission by 41% and 388% compared to the Cont., respectively. Compared with the Cont., inorganic fertilizer application significantly decreased total net GWP by 179%; in contrast, net GWP was increased 82% by inorganic/organic combination fertilizer application. The results of this study indicate that reduction of GWP and agricultural economic gain can be simultaneously achieved by appropriate fertilizer application.
  • Authors:
    • Carvalho, P. C. de F.
    • Anghinoni, I.
    • Assmann, J. M.
    • Ferreira, A. O.
    • Amado, T. J. C.
    • Silva, F. D. da
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 190
  • Year: 2014
  • Summary: Brazil has the world's second-largest cattle herd and second-largest no-till grain crop area. However, these activities are not frequently integrated because there is a widespread perception that cattle have a negative effect on cropping, especially when high crop yields are a goal. This misunderstanding of the synergy between pastures, livestock and crops is linked to overgrazing at the pasture rotation phase, which causes a decline in soil quality. Few studies have investigated the effect of pasture grazing intensities on soil carbon (C) balance and soil quality in subtropical environments. This work assessed the effects of different grazing intensities (0.10, 0.20, 0.30 and 0.40 m sward height) on soil C indices and animal productivity in a clay Haplorthox. The crop-livestock system model was a soybean/ryegrass plus black oat annual rotation managed for 10 years, using a randomized complete block design with three replications. Grazing intensity affected the quantity and composition of soil C input. Under heavy grazing with limited soil C input, there was a decrease in pasture and an increase in soybean participation in total C input. Soil organic C (0-0.20 m) under different grazing intensities had a linear relationship with C stratification ratio, C management index (CMI) and C pool index. Our results suggest that integrated crop-livestock systems could act as atmospheric C sources or sinks, depending on the grazing intensity. Pastures managed at 0.20 and 0.40 m height had the best balance between CMI and animal daily gain. The best balance between CMI and live weight gain per unit area occurred in sward height of 0.20 m.
  • Authors:
    • Calegari, A.
    • Balota, E. L.
    • Nakatani, A. S.
    • Coyne, M. S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 197
  • Year: 2014
  • Summary: Soil degradation in Brazil is a concern due to intensive agricultural production. Combining conservation practice, such as no-tillage, with winter cover crops may increase microbial activity and enhance soil quality more than either practice alone. This research evaluated the benefits of long-term (23 years) winter cover crops and reduced tillage on soil microbial quality indicators in an Oxisol from Parana State, Southern Brazil. The winter cover treatments were: fallow, black oat, wheat, radish, blue lupin, and hairy vetch in conventional (plow) or no-tillage management; the summer crop was a soybean/maize rotation. Soil quality parameters included organic C, microbial biomass C and N, total and labile polysaccharide, easily extractable and total glomalin-related soil protein, and enzyme activity. Winter crops increased soil microbial quality parameters compared to fallow in both tillage systems, with greater relative increase in conventional than no-tillage. No-tillage had higher microbial biomass, polysaccharide, glomalin-related soil protein, and soil enzyme activity than conventional tillage. Including legumes in the crop rotation was important for N balance in the soil-plant system, increasing soil organic C content, and enhancing soil quality parameters to a greater extent than grasses or radish. The microbial parameters proved to be more sensitive indicators of soil change than soil organic C. Cultivating winter cover crop with either tillage is a beneficial practice enhancing soil microbial quality and also soil organic C stocks.
  • Authors:
    • Eisenhauer, D. E.
    • Gilley, J. E.
    • Blanco-Canqui, H.
    • Jasa, P. J.
    • Boldt, A.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: The benefits of grass barriers or hedges for reducing offsite transport of non-point-source water pollutants from croplands are well recognized, but their ancillary benefits on soil properties have received less attention. We studied the 15-yr cumulative effects of narrow and perennial switchgrass ( Panicum virgatum L.) barriers on soil organic C (SOC), total N, particulate organic matter (POM), and associated soil structural properties as compared with the cropped area on an Aksarben silty clay loam (fine, smectitic, mesic Typic Argiudoll) with 5.4% slope in eastern Nebraska. Five switchgrass barriers were established in 1998 at ~38-m intervals parallel to the crop rows in a field under a conventional tillage and no-till grain sorghum [ Sorghum bicolor (L.) Moench]-soybean [ Glycine max (L.) Merr.]-corn ( Zea mays L.) rotation. Compared with the cropped area, switchgrass barriers accumulated about 0.85 Mg ha -1 yr -1 of SOC and 80 kg ha -1 yr -1 of total soil N at the 0 to 15 cm soil depth. Switchgrass barriers also increased coarse POM by 60%. Mean weight diameter of water-stable aggregates increased by 70% at 0 to 15 cm and by 40% at 15 to 60 cm, indicating that switchgrass barriers improved soil aggregation at deeper depths. Large (4.75-8 mm) macroaggregates under switchgrass barriers contained 30% more SOC than those under the cropped area. Switchgrass-induced changes in SOC concentration were positively associated with aggregate stability ( r=0.89***) and porosity ( r=0.47*). Overall, switchgrass barriers integrated with intensively managed agroecosystems can increase the SOC pool and improve soil structural properties.
  • Authors:
    • Chen, P. Y.
    • Sinclair, T. R.
    • Devi, J. M.
    • Carter, T. E.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Breeding efforts in soybean [ Glycine max (L.) Merr.] have addressed the challenge of water-limited yields by incorporating parental stocks which exhibit drought-tolerant traits. Multiple cycles of empirical selection for improved yielding ability in water-deficient field environments have produced new generations of adapted breeding lines. However, the impact of this selection process on specific putative drought-tolerant traits is unknown. The objective of this study was to determine if breeders' selection of 10 elite lines for high seed yield under dry conditions is associated with the presence of physiological expression of three putative drought-tolerant traits: (i) limited transpiration rate under high vapor pressure deficit (VPD), (ii) early decrease in transpiration rate with soil drying, and (iii) drought-tolerant N 2 fixation. Greenhouse experiments were undertaken to characterize each genotypes for their phenotype of each of these three traits. Unlike most soybean cultivars, 9 of the 10 elite lines expressed a limited transpiration rate under elevated VPD. The VPD at which transpiration rate became limited was 1.9 kPa or less. There was no difference among genotypes in the threshold for decline in transpiration rate with soil drying, although all genotypes expressed high thresholds indicating an ability to conserve soil water. All lines expressed drought tolerance in their N 2 fixation rates, which was superior to that commonly observed in soybean. This study demonstrated that mating of parents that expressed a drought trait and multiple rounds of progeny selection based on improved yield under water-limited conditions resulted in the elite lines expressing improved drought traits.