• Authors:
    • Vaivode, A.
    • Balodis, O.
    • Gaile, Z.
    • Kreita, D.
    • Malecka, S.
    • Skrabule, I.
    • Ruza, A.
    • Katamadze, M.
  • Source: Zinatniski praktiskas konference, "Zinatne Latvijas Lauksaimniecibas Nakotnei: Partika, Lopbariba, Skiedra un Energija"
  • Year: 2012
  • Summary: In order to obtain significant data about the plant nutrient utilization from mineral fertilizers and maximum allowed dosages of fertilizers, a project, financed by the Ministry of Agriculture of the Republic of Latvia, was started in the year 2008. The aim of the project was to determine the utilization indicators of mineral fertilization, mainly nitrogen fertilization, on different nitrogen fertilization application dosages, also the maximum limit of and economically substantiated nitrogen fertilization dosages in different regions of Latvia depending on the year under the variable meteorological conditions. Different important field crops were used within the project: winter rye, winter and spring wheat, winter and spring oilseed rape, spring barley and potatoes. Field trials were established in research stations in different regions of Latvia: at the Research and Study Farm 'Vecauce" of the Latvia University of Agriculture; at the Research and Study Farm 'Peterlauki' of the Latvia University of Agriculture; at State Stende Cereals Breeding Institute and State Priekuli Field Crops Breeding Institute. Plant nutrition nitrogen agronomic efficiency from mineral fertilizers changed depending on the nitrogen fertilizing norm and yield. The specific results were observed concerning the nitrogen and potassium utilization, also the result differed between crops.
  • Authors:
    • Drinkwater, L.
    • Schipanski, M.
  • Source: Plant and Soil
  • Volume: 357
  • Issue: 1/2
  • Year: 2012
  • Summary: Background and aims: The selection of legume species and species mixtures influences agroecosystem nitrogen (N) and carbon cycling. We utilized a fertility gradient to investigate the effects of plant species interactions on biological N fixation of an annual and perennial legume in response to shifting soil resource availability. Methods: Legume N fixation of annual field pea ( Pisum sativum) and perennial red clover ( Trifolium pratense) grown in monoculture and mixtures with oats ( Avena sativa) or orchardgrass ( Dactylis glomerata) was estimated using the 15N natural abundance method across 15 farm fields and we measured six soil N pools ranging from labile to more recalcitrant. Results: Evidence of complementary and facilitative species interactions was stronger for the perennial red clover-orchardgrass mixture than for the annual field pea-oat mixture (N Land Equivalency Ratios were 1.6 and 1.2, respectively). We estimated that the transfer of fixed N from red clover to orchardgrass increased aboveground N fixation estimates by 15% from 33 to 38 kg N ha -1. Despite a more than 2-fold range in soil organic matter levels and more than 3-fold range in labile soil N pools across field sites, the N fertility gradient was not a strong predictor of N fixation. While grass N assimilation was positively correlated with soil N pools, we found only weak, inverse correlations between legume N fixation and soil N availability. In grass-legume mixtures, soil N availability indirectly influenced N fixation through plant competition. Conclusions: These results suggest that increasing diversity of cropping systems, particularly through the incorporation of perennial mixtures into rotations, could improve overall agroecosystem N cycling efficiency.
  • Authors:
    • Szendrei, Z.
  • Source: Entomologia Experimentalis et Applicata
  • Volume: 143
  • Issue: 2
  • Year: 2012
  • Summary: Habitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds on M. quadrilineatus abundance was investigated experimentally in carrot [ Daucus carota L. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed-free plots. The preference of M. quadrilineatus for different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance of M. quadrilineatus in the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no-border treatment. However, spelt-bordered plots had 42% fewer M. quadrilineatus than three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affected M. quadrilineatus abundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf-weeds had about 59% fewer M. quadrilineatus compared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf-weeds repelled M. quadrilineatus relative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.
  • Authors:
    • Crosson, E.
    • Bandaru, V.
    • West, T.
    • Andrews, A.
    • Lauvaux, T.
    • Davis, K.
    • Richardson, S.
    • Miles, N.
  • Source: Journal of Geophysical Research-Biogeosciences
  • Volume: 117
  • Issue: G1
  • Year: 2012
  • Summary: This study presents observations of atmospheric boundary layer CO2 mole fraction from a nine-tower regional network deployed during the North American Carbon Program's Mid-Continent Intensive (MCI) during 2007-2009. The MCI region is largely agricultural, with well-documented carbon exchange available via agricultural inventories. By combining vegetation maps and tower footprints, we show the fractional influence of corn, soy, grass, and forest biomes varies widely across the MCI. Differences in the magnitude of CO2 flux from each of these biomes lead to large spatial gradients in the monthly averaged CO2 mole fraction observed in the MCI. In other words, the monthly averaged gradients are tied to regional patterns in net ecosystem exchange (NEE). The daily scale gradients are more weakly connected to regional NEE, instead being governed by local weather and large-scale weather patterns. With this network of tower-based mole fraction measurements, we detect climate-driven interannual changes in crop growth that are confirmed by satellite and inventory methods. These observations show that regional-scale CO2 mole fraction networks yield large, coherent signals governed largely by regional sources and sinks of CO2.
  • Authors:
    • Moudry, J.
    • Jelinkova, Z.
    • Moudry, J.,Jr.
    • Konvalina, P.
  • Source: Lucrari Stiintifice, Universitatea de Stiinte Agricole Si Medicina Veterinara "Ion Ionescu de la Brad" Iasi, Seria Agronomie
  • Volume: 55
  • Issue: 2
  • Year: 2012
  • Summary: Potatoes are cultivated in conventional as well as in organic farming systems and although the production area itself is not large as compared to other crops (e.g. 1.17% of arable land in the Czech Republic, 2.14% in Germany, but also 14.89% in the Netherlands), in terms of production and subsequent food usage they belong to the most important crops not only in Europe. Farming system, which is used for their cultivation, can be one of the main factors affecting the production of greenhouse gases. The work is focused on monitoring and calculating the value of emissions expressed in CO 2 equivalent (CO 2-eqv=1x CO 2+23x CH 4+298x N 2O) which is produced within the cultivation of potatoes in conventional and organic farming system. The results show that when comparing emission load within the agricultural production of potatoes there is an evident difference between conventional and organic farming systems, while different values can be observed in all parameters (field emission, planting, fertilizing, agrotechnical operations, pesticides). Although agrotechnical procedures themselves, including fertilization, are very similar in conventional and organic farming, the emission load produced per one kilogram of conventional potatoes is 0.145 kg CO 2e while the load produced per one kilogram of ecological potatoes is for the amount of 0.126 kg CO 2e by around 13% lower.
  • Authors:
    • Miller, R.
    • Rothstein, D.
    • Nikiema, P.
  • Source: Biomass & Bioenergy
  • Volume: 39
  • Year: 2012
  • Summary: We assessed the short-term effects of converting pastureland to hybrid poplar and willow bioenergy plantations on soil greenhouse gas (GHG) fluxes and nitrogen (N) leaching in northern Michigan, USA. We used static chambers to measure soil carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) efflux, and tension lysimeters to measure nitrate (NO3-) leaching, in newly-established poplar and willow plantation plots, and in reference pasture plots. Emissions of N2O increased markedly following cultivation with cumulative direct N2O emissions of 0.3, 4.6 and 5.9 Mg ha(-1) of CO2 equivalents (CO(2)eq) in the reference, willow and poplar plots, respectively. Similarly, land conversion resulted in large increases of NO3 leaching with losses of 2.6, 38.8 and 53.9 kg ha(-1) of N from the reference, willow and poplar plots, respectively. Soil CO2 fluxes were significantly affected by land-use conversion; soils from willow and poplar plots emitted 29-42% less CO2 relative to the reference plots. Greater root respiration in the pastureland likely explained the greater soil CO2 efflux in these plots. Estimates of the net GHG emissions due to land-use conversion were strongly influenced by assumptions regarding the root contribution (RC) to total soil CO2 efflux. Assuming an RC = 50%, we estimate that pastureland conversion at this site incurred GHG debts of 7.4 and 11.6 Mg ha(-1) y(-1) as CO(2)eq for willow and poplar, respectively, during the establishment year. These results demonstrate the need to include soil disturbance impacts on the N cycle in future life cycle assessment of these bioenergy crops. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Romic, D.
    • Rengel, Z.
    • Ondrasek, G.
    • Savic, R.
  • Source: European Journal of Soil Science
  • Volume: 63
  • Issue: 5
  • Year: 2012
  • Summary: Soil degradation processes, such as organic matter (OM) depletion, accompanied by metal contamination and salinization are becoming a serious threat to crop production and human food security. A glasshouse study was conducted to assess a factorial combination of salinity (0, 20, 40 and 60 mm NaCl) and cadmium (Cd) (0.3, 2.5 and 5.4 mg Cd kg-1) in organic soil (>90% OM) and their influence on dissolved organic carbon (DOC) in the rhizosphere and phyto-accumulation in radish (Raphanus sativus L. var. sativus). A 34-day exposure to increasing NaCl salinity significantly decreased DOC concentration in the radish rhizosphere solution and increased trace element (copper, Cu; zinc, Zn; and Cd) concentrations in the rhizosphere as well as in leaf/fruit tissues of radish. Soil contamination by Cd progressively raised concentrations in soil solution, but markedly reduced total concentration of Cu and Zn in the rhizosphere and leaves of radish. The NICA-Donnan chemical speciation/distribution modelling confirmed the predominance of dissolved organic reactive surfaces (from fulvic acid for example) in Cu and Cd chemisorption/complexation processes over the whole range of applied NaCl and Cd treatments. In contrast, Zn speciation was dominated by an organically-complexed pool at low salinity (020 mm NaCl), and free Zn2+ was the most important species at increased salinity (=40 mm NaCl). In conclusion, because of the diminished pool of DOC under excessive salinity, the biogeochemistry of Cu, Zn and Cd in the rhizosphere can be affected in a way that would enhance solubility and phyto-accumulation of these trace metals in food crops.
  • Authors:
    • Rytter, R.
  • Source: Biomass & Bioenergy
  • Volume: 36
  • Year: 2012
  • Summary: A large share, estimated at 12-25%, of the annual anthropogenic greenhouse gas emissions is attributed to global deforestation. Increasing the forested areas therefore has a positive impact on carbon (C) sequestration and mitigation of high atmospheric CO2 concentrations. Fast-growing species, such as willow and poplar, are of high interest as producers of biomass for fuel, but also as C sinks. The present study estimated the rate of C sequestration in biomass and soil in willow and poplar plantations. Calculations were based on above- and below-ground biomass production data from field experiments, including fine root turnover, litter decomposition rates, and production levels from commercial plantations. Accumulation of C in woody biomass, above and below ground, was estimated at 76.6-80.1 Mg C ha(-1) and accumulation of C in the soil at 9.0-10.3 Mg C ha(-1) over the first 20-22 years. The average rates of C sequestration were 3.5-4.0 Mg C ha(-1) yr(-1) in woody biomass, and 0.4-0.5 Mg C ha(-1) yr(-1) in the soil. If 400,000 ha of abandoned arable land in Sweden were planted with willow and poplar, about 1.5 Tg C would be sequestered annually in woody biomass and 0.2 Tg C in soils. This would be nearly one tenth of the annual anthropogenic emissions of C in Sweden today. These calculations show the potential of fast-growing plantations on arable land to mitigate the effect of high CO2 concentrations over a short time span. Knowledge gaps were found during the calculation process and future research areas were suggested. (C) 2011 Elsevier Ltd. All rights reserved.
  • Authors:
    • Caesar, A.
    • Caesar-TonThat, T.
    • Sainju, U. M.
  • Source: Soil and Tillage Research
  • Volume: 118
  • Issue: January
  • Year: 2012
  • Summary: Portable chamber provides simple, rapid, and inexpensive measurement of soil CO2 flux but its effectiveness and precision compared with the static chamber in various soil and management practices is little known. Soil CO2 flux measured by a portable chamber using infrared analyzer was compared with a static chamber using gas chromatograph in various management practices from May to October 2008 in loam soil (Luvisols) in eastern Montana and in sandy loam soil (Kastanozems) in western North Dakota, USA. Management practices include combinations of tillage, cropping sequence, and N fertilization in loam and irrigation, tillage, crop rotation, and N fertilization in sandy loam. It was hypothesized that the portable chamber would measure CO2 flux similar to that measured by the static chamber, regardless of soil types and management practices. In both soils, CO2 flux peaked during the summer following substantial precipitation and/or irrigation (>15 mm), regardless of treatments and measurement methods. The flux varied with measurement dates more in the portable than in the static chamber. In loam, CO2 flux was 14-87% greater in the portable than in the static chamber from July to mid-August but 15-68% greater in the static than in the portable chamber from late August to October in all management practices. In sandy loam, CO2 flux was 10-229% greater in the portable than in the static chamber at all measurement dates in all treatments. Average CO2 flux across treatments and measurement dates was 9% lower in loam but 84% greater in sandy loam in the portable than in the static chamber. The CO2 fluxes in the portable and static chambers were linearly to exponentially related (R-2 = 0.68-0.70, P < 0.01, n = 40-56). Although the trends of CO2 fluxes with treatments and measurement dates were similar in both methods, the flux varied with the methods in various soil types. Measurement of soil CO2 flux by the portable chamber agreed more closely with the static chamber within 0-10 kg C ha(-1) d(-1) in loam soil under dryland than in sandy loam soil under irrigated and non-irrigated cropping systems. Published by Elsevier B.V.
  • Authors:
    • Phillips, R. L.
    • Tanaka, D. L.
    • Hendrickson, J. R.
    • Liebig, M. A.
    • Schmer, M. R.
  • Source: Biomass and Bioenergy
  • Volume: 45
  • Issue: October
  • Year: 2012
  • Summary: Switchgrass (Panicum virgatum L.) is being evaluated as a bioenergy crop for the northern Great Plains. Field measurements of CO2, CH4, and N2O flux are needed to estimate the net greenhouse gas (GHG) balance of this biofeedstock. The study objective was to determine effects of recommended Nitrogen (N) fertilization (67 kg ha(-1) of N applied) and unfertilized switchgrass on growing season soil-atmosphere CO2, CH4, and N2O flux using static chamber methodology. Mean hourly CO2 flux was greatest during periods of active switchgrass growth and was similar between N fertilizer treatments (P = 0.09). Mean hourly N2O flux was consistently greater under N fertilization than without N throughout the growing season. Overall, N fertilization of switchgrass affected cumulative growing-season N2O flux (27.6 kg ha(-1) +/- 4.0 kg ha(-1) vs. 86.3 kg ha(-1) +/- 14.3 kg ha(-1) as CO2 equivalents (CO(2)eq) for 0 kg ha(-1) and 67 kg ha(-1) of N applied, respectively; P < 0.01), but not cumulative CO2 or CH4 flux (P = 0.08 and 0.51, respectively). Aboveground biomass production was greater with N application (6.8 Mg ha(-1) +/- 0.5 Mg ha(-1) dry matter) than without N (3.2 Mg ha(-1) +/- 0.5 Mg ha(-1)) (P < 0.05). Net greenhouse gas intensity (GHGI; kg GHG flux kg(-1) harvest yield as CO(2)eq) for switchgrass production was similar between N treatments (0.71 vs. 0.44 for 0 kg ha(-1) and 67 kg ha(-1) of N applied, respectively; P = 0.18). Published by Elsevier Ltd.