• Authors:
    • Humphreys, J.
    • Casey, I.
    • Necpalova, M.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 95
  • Issue: 3
  • Year: 2013
  • Summary: This study evaluated the effect of grassland renovation on soil total N, soluble N, N leaching to groundwater and nitrous oxide (N2O) fluxes from poorly drained clay loam soils on a dairy farm in Ireland. The experimental area was divided into six blocks. In June 2008, one paddock in each block was ploughed and reseeded, and subsequently compared with a permanent grassland paddock. Nitrogen in groundwater was determined in a dense network of piezometers. Soil total N along with soluble N assessed in KCl extracts were determined at three depths to 0.9 m. The N2O fluxes were measured using the static chamber technique. Renovation decreased topsoil total N and soluble organic N (P 3 t N ha(-1)), the proportion lost via N leaching and N2O emissions was unsubstantial (27.11 kg N ha(-1) y(-1)) and represented only 4.8 and 0.49 % of the N input to renovated grassland, respectively. This was likely a result of soil inherent properties and anoxic status of the soils, which likely promoted complete denitrification. Since this study was a single site study and the measurements started only months after the renovation and were relatively short term, there is some uncertainty in the results.
  • Authors:
    • Paterson, E.
    • Sim, A.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 5
  • Year: 2013
  • Summary: Soil organic matter (SOM) mineralization processes are central to the functioning of soils in relation to feedbacks with atmospheric CO 2 concentration, to sustainable nutrient supply, to structural stability and in supporting biodiversity. Recognition that labile C-inputs to soil (e.g. plant-derived) can significantly affect mineralization of SOM ('priming effects') complicates prediction of environmental and land-use change effects on SOM dynamics and soil C-balance. The aim of this study is to construct response functions for SOM priming to labile C (glucose) addition rates, for four contrasting soils. Six rates of glucose (3 atm% 13C) addition (in the range 0-1 mg glucose g -1 soil day -1) were applied for 8 days. Soil CO 2 efflux was partitioned into SOM- and glucose-derived components by isotopic mass balance, allowing quantification of SOM priming over time for each soil type. Priming effects resulting from pool substitution effects in the microbial biomass ('apparent priming') were accounted for by determining treatment effects on microbial biomass size and isotopic composition. In general, SOM priming increased with glucose addition rate, approaching maximum rates specific for each soil (up to 200%). Where glucose additions saturated microbial utilization capacity (>0.5 mg glucose g -1 soil), priming was a soil-specific function of glucose mineralization rate. At low to intermediate glucose addition rates, the magnitude (and direction) of priming effects was more variable. These results are consistent with the view that SOM priming is supported by the availability of labile C, that priming is not a ubiquitous function of all components of microbial communities and that soils differ in the extent to which labile C stimulates priming. That priming effects can be represented as response functions to labile C addition rates may be a means of their explicit representation in soil C-models. However, these response functions are soil-specific and may be affected by several interacting factors at lower addition rates.
  • Authors:
    • Niklaus, P. A.
    • Back, F.
    • Marhan, S.
    • Poll, C.
    • Kandeler, E.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 165
  • Year: 2013
  • Summary: Modifications in temperature and precipitation due to climate change will likely affect carbon cycling and soil respiration in terrestrial ecosystems. Despite the important feedback mechanism of ecosystems to climate change, there is still a lack of experimental observation in agricultural ecosystems. In July 2008, we established the Hohenheim Climate Change (HoCC) experiment to investigate effects of elevated temperature and altered precipitation on soil respiration in an arable soil (mean annual temperature and precipitation 8.7°C and 679 mm, respectively). We elevated soil temperature to 4 cm depth by 2.5°C, reduced the amount of summer precipitation by 25%, and extended dry intervals between precipitation events. For two years, CO 2 fluxes were measured weekly and aboveground plant biomass and soil microbial biomass was determined. The results of the two-year study underline the importance of soil moisture as a driving factor in ecosystem response to climate change. Soil warming did not increase soil respiration in the first year; in the second year, a 27% increase was measured. The differential response of soil respiration to warming was most likely driven by soil moisture. In summer 2009, water limitation reduced microbial biomass in the heated plots thereby suppressing the stimulatory effect of elevated temperature on soil microorganisms. In summer 2010, the reduction in soil moisture was less pronounced and microbial biomass and respiration were not affected by water limitation. Temperature elevation significantly reduced Q10 values of soil respiration by 0.7-0.8. Altered precipitation showed only minor effects during the first two years of the experiment. We conclude from our study that the moisture regime of soils under elevation of temperature will largely determine whether different soils will serve either as carbon sources or as carbon sinks.
  • Authors:
    • Mahanta, D.
    • Tuti, M. D.
    • Gupta, H. S.
    • Bhatt, J. C.
    • Bisht, J. K.
    • Pandey, S. C.
    • Bhattacharyya, R.
    • Mina, B. L.
    • Singh, R. D.
    • Chandra, S.
    • Srivastva, A. K.
    • Kundu, S.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 1
  • Year: 2013
  • Summary: Carbon retention is a critical issue in arable farming of the Indian Himalayas. This study, conducted from 2001 through 2010 on a sandy clay loam soil, evaluated the effect of tillage alterations (conventional tillage [CT] and zero tillage [ZT]) and selected irrigation treatments (I1: pre-sowing, I2: pre-sowing + active tillering or crown root initiation, I3: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering, and I4: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering + grain filling), applied at the critical growth stages to rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) on soil organic C (SOC) retention and its pools, soil aggregation, and aggregate-associated C contents in the 0- to 30-cm soil layer. Results indicate that the plots under ZT had nearly 17 and 14% higher total SOC and particulate organic C contents compared with CT (~9.8 and 3.6 g kg -1 soil) in the 0- to 5-cm soil layer after 9 yr of cropping, despite similar mean aboveground biomass yields of both crops on both CT and ZT plots. Tillage had no effect on C pools in the subsurface layers. Irrigation had positive impact on SOC content in the 0- to 5- and 5- to 15-cm layers. Although the labile pools of SOC were positively affected by ZT, the recalcitrant pool was not. Plots under ZT and I4 also had higher large and small macroaggregates and macroaggregate-associated SOC. Thus, adoption of ZT is the better management option for soil C improvement than CT, and irrigation generally enhances the positive impacts.
  • Authors:
    • Schilling, B.
    • Reischl, A.
    • Hangen, E.
    • Geuss, U.
    • Sporlein, P.
    • Barthold, F.
    • Hubner, R.
    • Wiesmeier, M.
    • Lutzow, M. von
    • Kogel-Knabner, I.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 176
  • Year: 2013
  • Summary: Agricultural soils have a high potential for sequestration of atmospheric carbon due to their volume and several promising management options. However, there is a remarkable lack of information about the status quo of organic carbon in agricultural soils. In this study a comprehensive data set of 384 cropland soils and 333 grassland soils within the state of Bavaria in southeast Germany was analyzed in order to provide representative information on total amount, regional distribution and driving parameters of soil organic carbon (SOC) and nitrogen (N) in agricultural soils of central Europe. The results showed that grassland soils stored higher amounts of SOC (11.8 kg m -2) and N (0.92 kg m -2) than cropland soils (9.0 and 0.66 kg m -2, respectively) due to moisture-induced accumulation of soil organic matter (SOM) in B horizons. Surprisingly, no distinct differences were found for the A horizons since tillage led to a relocation of SOM with depth in cropland soils. Statistical analyses of driving factors for SOM storage revealed soil moisture, represented by the topographic wetness index (TWI), as the most important parameter for both cropland and grassland soils. Climate effects (mean annual temperature and precipitation) were of minor importance in agricultural soils because management options counteracted them to a certain extent, particularly in cropland soils. The distribution of SOC and N stocks within Bavaria based on agricultural regions confirmed the importance of soil moisture since the highest cropland SOC and N stocks were found for tertiary hills and loess regions, which exhibited large areas with potentially high soil moisture content in extant floodplains. Grassland soils showed the highest accumulation of SOC and N in the Alps and Pre-Alps as a result of low temperatures, high amounts of precipitation and high soil moisture content in areas of glacial denudation. Soil class was identified as a further driving parameter for SOC and N storage in cropland soils. In total, cropland and grassland soils in Bavaria store 242 and 134 Mt SOC as well as 19 and 12 Mt N down to a soil depth of 1 m or the parent material, respectively.
  • Authors:
    • Hulugalle, N. R.
  • Source: Crop and Pasture Science
  • Volume: 64
  • Issue: 8
  • Year: 2013
  • Summary: Partial mitigation of global warming caused by accelerated emissions of greenhouse gases such as carbon dioxide may be possible by storing atmospheric carbon in soils. Carbon storage is influenced by processes and properties that affect soil aggregation, such as clay and silt concentrations and mineralogy, intensity and frequency of wet/dry cycles, and microbial activity. Microbial activity, in turn, is influenced by factors such as temperature, nutrient and water availability, and residue quality. The objective of this study was to assess the influence of average annual maximum temperature on soil carbon storage in Vertosols under cotton-based farming systems. This paper reports a re-evaluation of results obtained from a series of experiments on cotton-farming systems conducted in eastern Australia between 1993 and 2010. The experimental sites were in the Macquarie and Namoi Valleys of New South Wales, and the Darling Downs and Central Highlands of Queensland. Average soil organic carbon storage in the 0-0.6m depth was highest in a Black Vertosol in Central Queensland and lowest in a Grey Vertosol that was irrigated with treated sewage effluent at Narrabri. At other sites, average values were generally comparable and ranged from 65 to 85 t C/ha. Climatic parameters such as ambient maximum temperature, T-max, and rainfall at rainfed sites (but not irrigated sites) were also related to soil organic carbon storage. At most sites, variations in carbon storage with average ambient maximum temperature were described by Gaussian models or bell-shaped curves, which are characteristic of microbial decomposition. Carbon storage occurred at peak rates only for a very limited temperature range at any one site, with these temperatures increasing with decreasing distance from the equator. The exception was a site near Narrabri that was irrigated with treated sewage effluent, where the relationship between soil organic carbon and T-max was linear. The decrease or absence of change in soil carbon storage with time reported in many Australian studies of annual cropping systems may be due to carbon storage occurring within a limited temperature range, whereas intra-seasonal average maximum temperatures can range widely. Further research needs to be conducted under field conditions to confirm these observations.
  • Authors:
    • Jayet, P.-A.
    • Castell, J.-F.
    • Szopa, S.
    • Clerino, P.
    • Leconte-Demarsy, D.
    • Humblot, P.
  • Source: ECOLOGICAL ECONOMICS
  • Volume: 85
  • Year: 2013
  • Summary: As a result of anthropogenic activities, ozone is produced in the surface atmosphere, causing direct damage to plants and reducing crop yields. By combining a biophysical crop model with an economic supply model we were able to predict and quantify this effect at a fine spatial resolution. We applied our approach to the very varied French case and showed that ozone has significant productivity and land-use effects. A comparison of moderate and high ozone scenarios for 2030 shows that wheat production may decrease by more than 30% and barley production may increase by more than 14% as surface ozone concentration increases. These variations are due to the direct effect of ozone on yields as well as to modifications in land use caused by a shift toward more ozone-resistant crops: our study predicts a 16% increase in the barley-growing area and an equal decrease in the wheat-growing area. Moreover, mean agricultural gross margin losses can go as high as 2.5% depending on the ozone scenario, and can reach 7% in some particularly affected regions. A rise in ozone concentration was also associated with a reduction of agricultural greenhouse gas emissions of about 2%, as a result of decreased use of nitrogen fertilizers. One noteworthy result was that major impacts, including changes in land use, do not necessarily occur in ozone high concentration zones, and may strongly depend on farm systems and their adaptation capability. Our study suggests that policy makers should view ozone pollution as a major potential threat to agricultural yields. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Hauggard-Nielsen, H.
    • Jensen, E. S.
    • Carter, M. S.
    • Johansen, A.
    • Ambus, P.
  • Source: Applied Soil Ecology
  • Volume: 63
  • Issue: January
  • Year: 2013
  • Summary: Anaerobic digestion of animal manure and crop residues may be employed to produce biogas as a climate-neutral source of energy and to recycle plant nutrients as fertilizers. However, especially organic farmers are concerned that fertilizing with the digestates may impact the soil microbiota and fertility because they contain more mineral nitrogen (N) and less organic carbon (C) than the non-digested input materials (e.g. raw animal slurry or fresh plant residues). Hence, an incubation study was performed where (1) water, (2) raw cattle slurry, (3) anaerobically digested cattle slurry/maize, (4) anaerobically digested cattle slurry/grass-clover, or (5) fresh grass-clover was applied to soil at arable realistic rates. Experimental unites were sequentially sampled destructively after 1, 3 and 9 days of incubation and the soil assayed for content of mineral N, available organic C, emission of CO2 and N2O, microbial phospholipid fatty acids (biomass and community composition) and catabolic response profiling (fiinctional diversity). Fertilizing with the anaerobically digested materials increased the soil concentration of NO3- ca. 30-40% compared to when raw cattle slurry was applied. Grass-clover contributed with four times more readily degradable organic C than the other materials, causing an increased microbial biomass which depleted the soil for mineral N and probably also O-2. Consequently, grass-clover also caused a 10 times increase in emissions of CO2 and N2O greenhouse gasses compared to any of the other treatments during the 9 days. Regarding microbial community composition, grass-clover induced the largest changes in microbial diversity measures compared to the controls, where raw cattle slurry and the two anaerobically digested materials (cattle slurry/maize, cattle slurry/grass-clover) only induced minor and transient changes. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Laerke, P. E.
    • Elsgaard, L.
    • Kandel, T. P.
  • Source: GCB Bioenergy
  • Volume: 5
  • Issue: 5
  • Year: 2013
  • Summary: Cultivation of bioenergy crops has been suggested as a promising option for reduction of greenhouse gas (GHG) emissions from arable organic soils (Histosols). Here, we report the annual net ecosystem exchange (NEE) fluxes of CO2 as measured with a dynamic closed chamber method at a drained fen peatland grown with reed canary grass (RCG) and spring barley (SB) in a plot experiment (n=3 for each cropping system). The CO2 flux was partitioned into gross photosynthesis (GP) and ecosystem respiration (R-E). For the data analysis, simple yet useful GP and R-E models were developed which introduce plot-scale ratio vegetation index as an active vegetation proxy. The GP model captures the effect of temperature and vegetation status, and the R-E model estimates the proportion of foliar biomass dependent respiration (R-fb) in the total R-E. Annual R-E was 1887 +/- 7 (mean +/- standard error, n=3) and 1288 +/- 19g CO2-Cm-2 in RCG and SB plots, respectively, with R-fb accounting for 32 and 22% respectively. Total estimated annual GP was -1818 +/- 42 and -1329 +/- 66g CO2-Cm-2 in RCG and SB plots leading to a NEE of 69 +/- 36g CO2-C m(-2)yr(-1) in RCG plots (i.e., a weak net source) and -41 +/- 47g CO2-C m(-2)yr(-1) in SB plots (i.e., a weak net sink). Standard errors related to spatial variation were small (as shown above), but more significant uncertainties were related to the modelling approach for establishment of annual budgets. In conclusion, the bioenergy cropping system was not more favourable than the food cropping system when looking at the atmospheric CO2 emissions during cultivation. However, in a broader GHG life-cycle perspective, the lower fertilizer N input and the higher biomass yield in bioenergy cropping systems could be beneficial.
  • Authors:
    • Govindaraj, M.
    • Prabukumar, G.
    • Arunachalam, P.
    • Kannan, P.
  • Source: African Journal of Agricultural Research
  • Volume: 8
  • Issue: 21
  • Year: 2013
  • Summary: Atmospheric rise of CO 2, N 2O and CH 4 over years, accelerated increase in global temperature, has led to uncertainty in monsoon rainfall and also leading to recurrence of drought, which in turn is severely affecting crop productivity and livelihood security of the farmers in Semi Arid Tropics. Agriculture contributes considerable amount of CO 2, N 2O and CH 4 emission into the atmosphere through different soil and crop management practices. Nevertheless agricultural activities contribute to global warming. The medium of crop production, soil is one of the major sinks of global warming gaseous and it helps to sequester more carbon and cut the N 2O emission by adopting smart soil and crop management techniques. Biochar is one of the viable organic amendments to combat climate change and sustain the soil health with sustainable crop production. It is an anaerobic pyrolysis product derived from organic sources and store carbon on a long term basis in the terrestrial ecosystem and also capable of reducing greenhouse gases (GHG) emission from soil to the atmosphere. Biochar application improved the soil health, increase the carbon capture and storage, reduce the GHG emission and enhance the crop yield with sustained soil health, which enables to meet out the food grain needs of the ever growing population.