• Authors:
    • Kuhlmann, H.
    • Lammel, J.
    • Senbayram, M.
    • Lebender, U.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 100
  • Issue: 1
  • Year: 2014
  • Summary: Nitrogen fertilizers are a major source of nitrous oxide (N2O) emissions from arable soils. The relationship between nitrogen application rates and N2O emissions was evaluated during the growth period of winter wheat (similar to 140 days) at six field sites in north-western Germany. Nitrogen was applied as calcium-ammonium-nitrate, with application rates ranging between 0 and 400 kg N ha(-1). One trial was conducted in 2010, three trials in 2011 and two trials in 2012. Additionally, post-harvest N2O emissions were evaluated at two field sites during autumn and winter (2012-2013). The emission factors (during the growth period) varied between 0.10 and 0.37 %. Annual N2O emissions ranged between 0.46 and 0.53 % and were consistently lower across all sites and years than to the IPCC Tier 1 default value (1.0 %). Across all sites and years, the relationship between N2O and N application rate was best described by linear regression even if nitrogen amounts applied were higher than the nitrogen uptake of the crop. Additionally, annual N2O emissions per unit of harvested wheat grain were calculated for two field sites to assess the environmental impact of wheat grain production. Yield-scaled N2O emissions followed a hyperbolic function with a minimum of 177 and 191 g N2O-N t grain yield(-1) at application rates of 127 and 150 kg N ha(-1), followed by an increase at higher N application rates. This relationship indicates that wheat crop fertilization does not necessarily harm the environment through N2O emissions compared to zero fertilization. Thus, improving nitrogen use efficiency may be the best management practice for mitigating yield-scaled N2O emissions.
  • Authors:
    • Venterea, R. T.
    • Maharjan, B.
    • Rosen, C.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Irrigation and N fertilizer management are important factors affecting crop yield, N fertilizer recovery efficiency, and N losses as nitrous oxide (N 2O) and nitrate (NO 3-). Split application of conventional urea (split-U) and/or one-time application of products designed to perform as enhanced-efficiency N fertilizers may mitigate N losses. The objective of this study was to compare the effects of controlled-release polymer-coated urea (PCU), stabilized urea with urease and nitrification inhibitors (IU) and split-U on direct soil-to-atmosphere N 2O emissions, NO 3- leaching, and yield for fully irrigated and minimum-irrigated corn in loamy sand. Indirect N 2O emissions due to NO 3- leaching were estimated using published emission factors (EF 5). Split-U increased yield and N uptake compared with preplant-applied PCU or IU and decreased NO 3- leaching compared with PCU. Direct N 2O emissions were significantly less with IU or split-U than with PCU, and there was a trend for greater emissions with split-U than with IU ( P=0.08). Irrigation significantly increased NO 3- leaching during the growing season but had no significant effect on direct N 2O emissions. After accounting for significantly increased yields with irrigation, however, N losses expressed on a yield basis did not differ and in some cases decreased with irrigation. Post-harvest soil N and soil-water NO 3- in spring showed the potential for greater N leaching in minimum-irrigated than fully irrigated plots. Indirect emissions due to NO 3- leaching were estimated to be 79 to 117% of direct emissions using the default value of EF 5, thus signifying the potential importance of indirect emissions in evaluating management effects on N 2O emissions.
  • Authors:
    • Briggs, R. D.
    • Volk, T. A.
    • Pacaldo, R. S.
  • Source: Bio-energy Research
  • Volume: 7
  • Issue: 3
  • Year: 2014
  • Summary: Previous greenhouse gas (GHG) assessments for the shrub willow biomass crops (SWBC) production system lacked quantitative data on the soil CO 2 efflux (F c). This study quantifies the mean annual cumulative F c, the C sequestration in the above- and belowground biomass, and the carbon balance of the production system. We utilized four SWBC fields, which have been in production for 5, 12, 14, and 19 years. Two treatments were applied: continuous production (CP) - shrub willows were harvested, and stools were allowed to regrow, and tear-out (TO) (crop removal) - shrub willows were harvested, and stools were sprayed with herbicide following spring, crushed, and mixed into the soil. Mean annual cumulative F c were measured using dynamic closed chambers (LI-8100A and LI-8150). Across different age classes, the mean cumulative F c ranged from 27.2 to 35.5 Mg CO 2 ha -1 year -1 for CP and 26.5 to 29.3 Mg CO 2 ha -1 year -1 for TO. The combined carbon (C) sequestration of the standing above- and belowground biomass, excluding stems, ranged from 50.6 to 94.8 Mg CO 2 eqv. ha -1. In the CP treatment, the annual C sequestration in the fine roots and foliage offsets the annual cumulative F c. Across different age classes, C balances ranged from -21.5 to -59.3 Mg CO 2 ha -1 for CP and 26.5 to 29.3 Mg CO 2 ha -1 for TO. The GHG potential of SWBC is about -36.3 Mg CO 2 eqv. ha -1 at the end of 19 years, suggesting that the SWBC system sequesters C until termination of the crop.
  • Authors:
    • Okruszko, T.
    • Acreman, M. C.
    • Laize, C. L. R.
    • Piniewski, M.
    • Schneider, C.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: Environmental flows-the quantity of water required to maintain a river ecosystem in its desired state-are of particular importance in areas of high natural value. Water-dependent ecosystems are exposed to the risk of climate change through altered precipitation and evaporation. Rivers in the Narew basin in northeastern Poland are known for their valuable river and wetland ecosystems, many of them in pristine or near-pristine condition. The objective of this study was to assess changes in the environmental flow regime of the Narew river system, caused by climate change, as simulated by hydrological models with different degrees of physical characterization and spatial aggregation. Two models were assessed: the river basin scale model Soil and Water Assessment Tool (SWAT) and the continental model of water availability and use WaterGAP. Future climate change scenarios were provided by two general circulation models coupled with the A2 emission scenario: IPSL-CM4 and MIROC3.2. To assess the impact of climate change on environmental flows, a method based conceptually on the "range of variability" approach was used. The results indicate that the environmental flow regime in the Narew basin is subject to climate change risk, whose magnitude and spatial variability varies with climate model and hydrological modeling scale. Most of the analyzed sites experienced moderate impacts for the Generic Environmental Flow Indicator (GEFI), the Floodplain Inundation Indicator, and the River Habitat Availability Indicator. The consistency between SWAT and Water GAP for GEFI was medium: in 55 to 66% of analyzed sites, the models suggested the same level of impact. Hence, we suggest that state-of-the-art, high-resolution, global- or continental-scale models, such as WaterGAP, could be useful tools for water management decision-makers and wetland conservation practitioners, whereas models such as SWAT should serve as a complementary tool for more specific, smaller-scale, local assessments.
  • Authors:
    • Hatfield, P. G.
    • Lenssen, A. W.
    • Barsotti, J. L.
    • Sainju, U. M.
  • Source: Nutrient Cycling in Ecosystems
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: Sheep (Ovis aries L.) grazing, a cost-effective method of weed control compared to herbicide application and tillage, may influence N cycling by consuming crop residue and weeds and returning N through feces and urine to the soil. The objective of this experiment was to evaluate the effect of sheep grazing compared to tillage and herbicide application for weed control on soil particulate and active soil N fractions in dryland cropping systems. Our hypothesis was that sheep grazing used for weed control would increase particulate and active soil N fractions compared to tillage and herbicide application. Soil samples collected at the 0-30 cm depth from a Blackmore silt loam were analyzed for particulate organic N (PON), microbial biomass N (MBN), and potential N mineralization (PNM) under dryland cropping systems from 2009 to 2011 in southwestern Montana, USA. Treatments were three weed management practices [sheep grazing (grazing), herbicide application (chemical), and tillage (mechanical)] as the main plot and two cropping sequences [continuous spring wheat (Triticum aestivum L.; CSW) and spring wheat-pea (Pisum sativum L.)/barley (Hordeum vulgare L.) mixture hay-fallow; W-P/B-F] as the split-plot factor arranged in randomized complete block with three replications. The PON and MBN at 0-30 cm were greater in the chemical or mechanical than the grazing treatment with CSW. The PNM at 15-30 cm was greater in the chemical or mechanical than the grazing treatment in 2009 and 2011 and at 5-15 cm was greater with W-P/B-F than CSW in 2010. From 2009 to 2011, PON at 0-30 cm and PNM at 15-30 cm reduced from 2 to 580 kg N ha(-1) year(-1) in the grazing and chemical treatments, but the rate varied from -400 to 2 kg N ha(-1) year(-1) in the mechanical treatment. Lower amount of labile than nonlabile organic matter returned to the soil through feces and urine probably reduced soil active and coarse organic matter N fractions with sheep grazing compared to herbicide application and tillage for weed control. Reduction in the rate of decline in N fractions from 2009 to 2011 compared to the herbicide application treatment, however, suggests that sheep grazing may stabilize N fractions in the long-term if the intensity of grazing is reduced. Animal grazing may reduce soil N fractions in annual cropping systems in contrast to known increased fractions in perennial cropping systems.
  • Authors:
    • Grant, C. A.
    • Burton, D. L.
    • Miller, J. J.
    • Zebarth, B. J.
    • Sharifi, M.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: Long-term effects of fresh (FM) versus composted (CM) beef manure application to barley (Hordeum vulgare L.) on potentially mineralizable nitrogen (N (0) ), and mineralizable nitrogen (N) pools, were evaluated in a clay loam soil in southern Alberta, Canada. A suite of laboratory-based indices were evaluated for prediction of soil N supply. The treatments were three rates (13, 39, 77 Mg ha(-1) dry wt.) of FM or CM containing either straw or wood-chip bedding, 100 kg N ha(-1) as inorganic fertilizer, and an unfertilized control. Treatments were fall-applied annually for 8 years (1998-2005). Soil samples (top 15 cm) were collected in spring 2006. The medium and high rates of organic amendment resulted in increases in N (0) , and readily (Pool I) and intermediate (Pool II) mineralizable N pools in ranges of 140-355 % compared with the average of the fertilizer and control treatments. Fertilizer application had no significant effect on mineralizable N pools, but increased the mineralization rate constant (k) compared with the control. Application of FM and use of straw bedding resulted in a greater quantity of readily available and intermediate mineralizable N, and also increased the rate of N turn-over as indicated by greater values of k, compared with CM and wood-chip bedding. Among laboratory-based measures of soil N supply, CaCl2-NO3 (r(2) = 0.84) and NaHCO3-205 (r (2) = 0.79) were strong predictors of plant N uptake (PNU). Increased soil mineralizable N did not translate into greater barley dry-matter yield or PNU. Composted beef manure and use of wood-chip bedding can be recommended as alternatives to FM and use of straw bedding for barley production is Southern Alberta.
  • Authors:
    • Stoddard, F. L.
    • Makela, P.
    • Simojoki, A.
    • Tammeorg, P.
    • Alakukku, L.
    • Helenius, J.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 191
  • Year: 2014
  • Summary: Poor water retention capacity (WRC) and nutrient deficiency commonly limit crop yields in sandy soils. The use of biochar as a soil amendment has been previously reported to improve these limiting factors in subtropical and temperate soils. We studied the effects of biochar on soil properties and yield formation of spring wheat ( Triticum aestivum L.) when applied together with inorganic fertiliser or meat bone meal (MBM) to an Endogleyic Umbrisol with a loamy sand texture in boreal conditions. In a two-year field experiment, biochar was applied at 0, 5, 10, 20 and 30 t ha -1 combined with three fertiliser treatments (unfertilised control, MBM and inorganic fertiliser) providing equal amounts of nitrogen (N), phosphorus (P) and potassium (K). Soil WRC and fertility as well as wheat yield, yield components and quality were analysed. Soil moisture content, leaf area index and leaf chlorophyll values (SPAD) were monitored during the experiment. Biochar increased the plant-available water content of the topsoil in the first year and reduced the bulk density in the second year after application. It also increased the contents of easily soluble K and soil organic C (SOC) in the 20 cm of topsoil, but had no effects on other soil nutrients, pH or moisture content. Biochar amendment decreased the soil NO 3--N content below control values in the first year but increased it significantly in the second year. The addition of biochar did not significantly affect the nitrogen uptake, grain yield or quality of wheat, possibly because of its low nutrient availability and the high organic matter content of the soil.
  • Authors:
    • Amichev,Beyhan Y.
    • Hangs,Ryan D.
    • Konecsni,Sheala M.
    • Stadnyk,Christine N.
    • Volk,Timothy A.
    • Belanger,Nicolas
    • Vujanovic,Vladimir
    • Schoenau,Jeff J.
    • Moukoumi,Judicael
    • Van Rees,Ken C. J.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Willow (Salix spp.) short-rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and the northern United States, there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amounts of anthropogenic greenhouse gas emissions. A fundamental question concerning sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found that willow systems have relatively low nutrient demands, with minimal nutrient outputs other than in the harvested biomass. Our overall aim was to summarize the literature and present findings and data from ongoing research trials across Canada and the northern United States examining willow SRC system establishment and viability. The research areas of interest are the crop production of willow SRC systems, above-and belowground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budgets, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context.
  • Authors:
    • Aoun,W. B.
    • El-Akkari,M.
    • Gabrielle,B.
    • Flenet,F.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: Nitrogen fertilization practices have a significant effect on the LCA results of biodiesel chains, which warrants reliable inventory data. In this study focused on the Lorraine region (eastern France), we established a typology of oilseed rape fields based on fertilization practices, and used the agro-ecosystem model CERES-EGC in lieu of generic emission factors to simulate the productivity and externalities associated with oilseed farming. The results were subsequently used to generate an LCA of biodiesel from oilseed rape. We also tested the effect of improved practices on the LCA results. In Lorraine, oilseed rape crops appeared to be frequently over fertilized compared to best management practices. Switching to improved practices with optimal fertilization has a potential to reduce the GWP of 1 megajoule of biodiesel by around 6 gr CO 2eq, against a total life-cycle of 43.9 gr CO 2eq.
  • Authors:
    • Bjornsson,L.
    • Prade,T.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: In an analysis of climate effects, increased soil organic carbon will have a dual effect due to both increased soil fertility and carbon sequestration. Even so, soil carbon changes are neglected in many crop production LCAs. In the present study, the introduction of grass-clover crops in cereal-dominated crop production was evaluated. The grass-clover crops were used for biogas production, and the digested residue was recycled to the farm as biofertilizer. A shift from the cereal-dominated crop rotation to integrated production of food crops and one or two years of grass-clover crops used as biogas feedstock would result in avoided emissions of 2-3 t CO 2-eq. ha -1 a -1. Integrated food and energy crop production would in this case improve soil organic carbon content at the same time as resulting in considerably decreased greenhouse gas emissions from the cultivation system.