19722015
  • Authors:
    • Katterer, T.
    • Oborn, I.
    • Sundberg, C.
    • Tidaker, P.
    • Bergkvist, G.
  • Source: Agricultural Systems
  • Volume: 129
  • Year: 2014
  • Summary: Rotational perennial grass/clover has multiple effects in cropping systems dominated by cereals. This study evaluated the environmental impact of rotational grass/clover ley for anaerobic digestion in a cereal-dominated grain production system in Sweden. Life cycle assessment (LCA) methodology was used to compare two scenarios: (i) a cropping system including only spring barley and winter wheat; and (ii) a cropping system including 2-year grass/clover ley in combination with spring barley and winter wheat. The functional unit was one tonne of grain. The two main functions of the grass/clover crop were to provide feedstock for biogas production and to act as an organic fertiliser for allocation among the cereal crops in the rotation. Special consideration was given to nitrogen (N) management and the rotational effects of the grass/clover ley. In total, 73% of the N requirement of cereals in the ley scenario was met through symbiotic N fixation. Replacing diesel with biogas and mineral fertiliser with digested grass/clover biomass (digestate) reduced the use of fossil fuels substantially, from 1480 MJ per tonne in the reference scenario to -2900 MJ per tonne in the ley scenario. Potential eutrophication per tonne grain increased in the ley scenario, mainly owing to significantly higher ammonia emissions from spreading digestate and the larger area required for producing the same amount of grain. Potential acidification also increased when N mineral fertiliser was replaced by digestate. Crops relying on symbiotic N fixation are a promising feedstock for reducing the use of non-renewable energy in the production chain of farm-based bioenergy, but careful handling of the N-rich digestate is required. Replacing cereals intended for feed or food with bioenergy crops leads to indirect land use changes (iLUC) when the displaced crops must be produced elsewhere and the benefits obtained when biofuels replace fossil fuels may thereby be outweighed. In this study, the iLUC factor assumed had a critical effect on global warming potential in the ley scenario. However, carbon sequestration and the higher yield potential of subsequent cereal crops can mitigate greenhouse gas emissions from iLUC to a varying extent. We recommend that crop sequences rather than single crops be considered when evaluating the environmental impact of production systems that include perennial legumes for food, feed and bioenergy.
  • Authors:
    • Greve, M. B.
    • Kheir, R. B.
    • Minasny, B.
    • Hartemink, A. E.
    • Adhikari, K.
    • Greve, M. H.
  • Source: PLOS ONE
  • Volume: 9
  • Issue: 8
  • Year: 2014
  • Summary: Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories.
  • Authors:
    • Kebreab, E.
    • Gao, X. P.
    • Flaten, D. N.
    • Tenuta, M.
    • Asgedom, H.
  • Source: Web Of Knowledge
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Soil N 2O emissions vary with N source. A study was undertaken on a clay soil in the Red River Valley, Manitoba, Canada, to determine the effect of granular N fertilizers and dairy manure on N 2O emissions from a field cropped to rapeseed ( Brassica napus L.) in 2009 and spring wheat ( Triticum aestivum L.) in 2010. Treatments included an unamended control, granular urea, controlled-release urea (ESN), stabilized urea (SuperU), and solid dairy manure added at rates to achieve a total of 140 kg available N ha -1 (product plus soil N test). The N fertilizers were broadcast and shallowly incorporated each spring before planting; the manure was broadcast incorporated the previous fall. Nitrous oxide emissions were monitored from planting to freeze in fall and during spring thaw in 2011 using static-vented chambers. In both years, N 2O emissions occurred within 4 to 5 wk of planting but not in fall after manure application. Area-scale cumulative N 2O emissions (SigmaN 2O, kg N ha -1) from planting to freeze were control < ESN=manure < urea=SuperU. Nitrous oxide emission factors were 0.017 kg N 2O-N kg -1 available N added for urea and SuperU and 0.007 kg N 2O-N kg -1 available N for ESN. Seventy-eight percent of the variation in SigmaN 2O could be explained by NO 3- intensity, an integration of soil NO 3- concentrations during the study periods. Greater SigmaN 2O were also associated with higher yields. These findings suggest that N release rates, as indicated by NO 3- intensity and yield, determined N 2O emissions. The results highlight the challenge of meeting crop demand yet reducing N 2O emissions by selection of an N source.
  • Authors:
    • Gundersen, P.
    • Stefansdottir, H. M.
    • Vesterdal, L.
    • Kiar, L. P.
    • Barcena, T. G.
    • Sigurdsson, B. D.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 8
  • Year: 2014
  • Summary: Northern Europe supports large soil organic carbon (SOC) pools and has been subjected to high frequency of land-use changes during the past decades. However, this region has not been well represented in previous large-scale syntheses of land-use change effects on SOC, especially regarding effects of afforestation. Therefore, we conducted a meta-analysis of SOC stock change following afforestation in Northern Europe. Response ratios were calculated for forest floors and mineral soils (0-10 cm and 0-20/30 cm layers) based on paired control (former land use) and afforested plots. We analyzed the influence of forest age, former land-use, forest type, and soil textural class. Three major improvements were incorporated in the meta-analysis: analysis of major interaction groups, evaluation of the influence of nonindependence between samples according to study design, and mass correction. Former land use was a major factor contributing to changes in SOC after afforestation. In former croplands, SOC change differed between soil layers and was significantly positive (20%) in the 0-10 cm layer. Afforestation of former grasslands had a small negative (nonsignificant) effect indicating limited SOC change following this land-use change within the region. Forest floors enhanced the positive effects of afforestation on SOC, especially with conifers. Meta-estimates calculated for the periods 30 years since afforestation revealed a shift from initial loss to later gain of SOC. The interaction group analysis indicated that meta-estimates in former land-use, forest type, and soil textural class alone were either offset or enhanced when confounding effects among variable classes were considered. Furthermore, effect sizes were slightly overestimated if sample dependence was not accounted for and if no mass correction was performed. We conclude that significant SOC sequestration in Northern Europe occurs after afforestation of croplands and not grasslands, and changes are small within a 30-year perspective.
  • Authors:
    • Cihacek, L. J.
    • DeSutter, T. M.
    • Rahman, S.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: The 11 major electricity-generating coal combustion stations in the northern Great Plains have the potential to produce almost 1 million Mg of flue gas desulfurization gypsum (FGDG) annually, which is a very attractive fertilizer (Ca and S) and amendment for sodic and acid soils. The potential environmental impacts of applying FGDG to soils in this region have not been fully investigated. The objectives of this research were to determine the influence of FGDG on soil chemical characteristics and to determine the impact that FGDG has on hard red spring wheat ( Triticum aestivum L.) yields and element analysis of the grain. Flue gas desulfurization gypsum and commercial gypsum were applied at rates of 0, 2.24, 11.2, and 22.4 Mg ha -1 to two soils in southwestern North Dakota in the spring of 2007. Soil and grain chemistries were monitored for two growing seasons. Wheat grain yields and elemental analysis of the grain were generally not affected by the gypsum treatments, indicating that the gypsum products did not negatively affect plant productivity. In addition, soil elemental analysis was similar across the treatments at both sites in both years. The results from this study indicate that its application to soil at rates used for sodic soil remediation (Mg ha -1) did not negatively affect the chemistries of either the soils or the wheat evaluated in this study compared with a commercial gypsum product or control soils.
  • Authors:
    • Verhallen, A.
    • Hayes, A.
    • Congreves, K. A.
    • Eerd, L. L. van
    • Hooker, D. C.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Long-term studies allow for quantification of the effects of crop production practices, such as tillage and crop rotation, on soil quality and soil C and N stores. In two experiments at Ridgetown, ON, we evaluated the long-term (11 and 15 yr) effect of tillage system and crop rotation on soil quality via the Cornell Soil Health Assessment (CSHA) at 0-15 cm and soil organic C (SOC) and total N at 5-, 10-, and 20-cm increments to 120 cm depth. The CSHA soil quality score and SOC and total N were higher with no-till (NT) than fall moldboard plough with spring cultivation (conventional tillage, CT) and rotations with winter wheat [soybean-winter wheat (S-W) and soybean-winter wheat-corn (S-W-C)] compared with rotations without winter wheat. In both long-term trials, NT had ca. 21 Mg ha -1 more or 14% higher SOC than CT in the 0- to 100-cm soil profile, a trend which contrasts previous research in eastern Canada. Thus, the two long-term trial results at Ridgetown suggest that to improve soil quality and storage of C and N, growers on clay loam soil in southwestern Ontario should consider adopting NT production practices and including winter wheat in the rotation.
  • Authors:
    • Regina, K.
    • Palosuo, T.
    • de Gerenyu, V. L.
    • Kurganova, I.
    • Heikkinen, J.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: The collapse of Soviet Union in early 1990s led to abandonment of large area of arable land which is assumed to act as a carbon (C) sink. We studied the ability of two dynamic soil C models (Yasso07 and RothC) to predict changes in soil C content after cropland abandonment. The performance of the models was compared using the results of a long-term experiment in Pushchino, Moscow region (54A degrees 50'N, 37A degrees 35'E) in Russia. The experiment was divided in four combinations of fertilizer or mowing treatments on former cropland soil. The soil C content was determined in the year of establishment (1980) and thereafter in 1999 and 2004. The soil C stocks increased by about 1.5- to 1.8-fold during the study period. Both models predicted the overall change in soil C relatively well (modelling efficiency of Yasso07 and RothC were 0.60 and 0.73, respectively). According to the models, the soil gained on average 140-150 g C m(-2) year(-1) during the first 5 years after conversion of cropland to grassland. The C sequestration rate decreased to 40-50 g C m(-2) year(-1) after 20 years of land use change. The sequestration rates estimated in this study are comparable to the rates observed in other studies.
  • Authors:
    • Boettcher, J.
    • Kage, H.
    • Ratjen, A.
    • Heumann, S.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: Eliminating uncertainty in soil N supply could reduce fertilizer input, but the amount of N mineralized during plant growth is usually still unknown. We aimed to test the relatively simple two-pool net N mineralization model NET N that uses site-specific temperature and soil water functions as well as pedotransfer functions for deriving the pool sizes and was developed for NW Germany. The objectives were to (1) evaluate, if field net N mineralization under unfertilized winter wheat could be satisfactorily simulated, and to (2) examine the variation in time patterns of net N mineralization within years and sites and from two functional N pools: a rather small, fast mineralizable N pool (N-fast) and a much greater, slowly mineralizable N pool (N-slow). NET N simulations for 36 site-year-combinations and up to five dates within the growing season were evaluated with detailed N balance approaches (calculated from: soil mineral N contents, plant N uptake using estimates of green area index, simulated N leaching). Simulated net N mineralization was highly significantly correlated (r(2) = 0.58; root mean square error = 24.2 kg N ha(-1)) to estimations from the most detailed balance approach, with total simulated net N mineralization until mid August ranging from 62.1 to 196.5 kg N ha(-1). It also became evident that N mineralization from pool N-slow-in contrast to pool N-fast-was considerably higher for loess soils than for sandy or loamy soils. The results suggest that NET N was adequate for simulations in unfertilized winter wheat. However, further field studies are necessary for proving its applicability under fertilized conditions.
  • Authors:
    • Dick, W. A.
    • Ladwig, K.
    • Tian, Y. Q.
    • Guo, X. L.
    • Chen, L. M.
    • Kost, D.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: Gypsum (CaSO 4.2H 2O) is a quality source of Ca and S and has various beneficial uses that can improve agricultural production. This study was conducted to compare rates of flue gas desulfurization (FGD) gypsum and commercially available agricultural (i.e., mined) gypsum as soil amendments on soils typical of eastern Ohio or western Pennsylvania. Two field experiments were conducted, one involving a mixed grass hay field and the other corn ( Zea mays L.). Gypsum was applied once at rates of 0.2, 2.0, and 20 Mg ha -1 and a seventh treatment was a zero rate control. Corn grain yields response to gypsum was mixed with significant differences between low and high gypsum rates in 2010 but not between gypsum and no gypsum treatments. In the hay study, the low and intermediate gypsum rates generally did not result in any significant changes compared with the control treatment. At the high rate of 20 Mg ha -1, the following results were observed for the hay study: (i) both gypsums generally increased Ca, S, and soluble salts (electrical conductivity) in the topsoil and subsoil, when compared with the control; (ii) the FGD gypsum decreased Mg in soil when compared with all other treatments, and mined gypsum decreased Mg when compared with the control; and (iii) there were few effects on soil concentrations of trace elements, including Hg. Also at the high application rate, hay yield for the first cutting (May) in 2009 and 2010 was significantly less for mined and FGD gypsum compared with the control, but increased yields in subsequent cutting resulted in no significant treatment differences in total annual hay yield for 2008, 2009, or 2010 or cumulative yield for 2008 to 2010. Overall, for the hay study, the absence of significant soil chemical effects for the intermediate gypsum rate and the decrease in soil Mg concentrations for the high gypsum rate indicate that an application rate of approximately 2.0 Mg ha -1 would be optimal for this soil.
  • Authors:
    • Lopes de Gerenyu, V.
    • Kurganova, I.
    • Six, J.
    • Kuzyakov, Y.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 3
  • Year: 2014
  • Summary: The collapse of collective farming in Russia after 1990 and the subsequent economic crisis led to the abandonment of more than 45 million ha of arable lands (23% of the agricultural area). This was the most widespread and abrupt land use change in the 20th century in the northern hemisphere. The withdrawal of land area from cultivation led to several benefits including carbon (C) sequestration. Here, we provide a geographically complete and spatially detailed analysis of C sequestered in these abandoned lands. The average C accumulation rate in the upper 20 cm of mineral soil was 0.960.08 Mg C ha -1 yr -1 for the first 20 years after abandonment and 0.190.10 Mg C ha -1 yr -1 during the next 30 years of postagrogenic evolution and natural vegetation establishment. The amount of C sequestered over the period 1990-2009 accounts to 42.63.8 Tg C per year. This C sequestration rate is equivalent to ca. 10% of the annual C sink in all Russian forests. Furthermore, it compensates all fire and postfire CO 2 emissions in Russia and covers about 4% of the global CO 2 release due to deforestation and other land use changes. Our assessment shows a significant mitigation of increasing atmospheric CO 2 by prolonged C accumulation in Russian soils caused by collective farming collapse.