• Authors:
    • Bohm, H.
    • Gronle, A.
  • Source: Julius-Kühn-Archiv
  • Volume: 1
  • Issue: 434
  • Year: 2012
  • Summary: The reduction of soil tillage depth is of special interest in organic farming. However, shallow ploughing often results in higher weed abundances in comparison to deep ploughing. Thus, the objective of this study was to evaluate whether the high weed suppressive ability of spring and winter pea-cereal intercrops can compensate for the higher weed growth in shallow ploughing compared to deep ploughing in organic farming. Peas and cereals were grown as sole crops and intercrops under shallow and deep ploughing in experiments on a sandy loam soil in Northern Germany in 2009, 2010 and 2011. Semi-leafless spring peas-oats, semi-leafless winter peas-triticale and regular-leaf type winter peas-triticale intercrops were examined. At harvest, weed shoot biomass in semi-leafless spring and winter pea sole crops under deep ploughing were slightly higher than those of the corresponding intercrops under shallow ploughing. Whereas weed shoot biomass in semi-leafless winter peas-triticale intercrops under deep ploughing was comparable to shallow ploughing, the cultivation of spring peas-oats intercrops under shallow ploughing led to a significantly higher weed growth than did deep ploughing. The regular-leaf type winter pea grown as a sole crop, or an intercrop with triticale, showed a higher weed suppressive ability than the semi-leafless peas. The tillage system had no significant influence on the weed infestation of sole and intercropped regular-leaf type winter peas. Semi-leafless spring peas-oats and winter peas-triticale intercrops could compensate for weed infestation differences under shallow ploughing compared to the corresponding pea sole crops under deep ploughing. Due to the high weed suppressive ability of regular-leaf type winter peas, shallow ploughing and deep ploughing, as well as sole cropping and intercropping, led to comparable weed infestation.
  • Authors:
    • Naunheim, P.
    • Kerlen, D.
  • Source: Julius-Kuhn-Archiv
  • Volume: 2
  • Issue: 434
  • Year: 2012
  • Summary: Cadou FORTE (flufenacet; flurtamone; diflufenican) is a new cereal herbicide with efficacy against blackgrass ( Alopecurus myosuroides), loose silky-bentgrass ( Apera spica-venti L.), annual meadow-grass ( Poa annua L.) and a broad spectrum of dicot weeds. Cadou FORTE can be used in winter wheat, winter barley, winter rye, winter triticale and spelt for pre and post emergence application in autumn. This publication focuses on efficacy trials from three years of autumn application with Cadou FORTE.
  • Authors:
    • Schenke, E.
  • Source: Julius-Kuhn-Archiv
  • Volume: 2
  • Issue: 434
  • Year: 2012
  • Summary: Early autumn herbicide application in winter cereals is in many areas a reasonable agronomic procedure. ADDITION with the well-known active ingredients diflufenican (40 g/l) and pendimethalin (400 g/l) is a new combination for weed control in winter wheat, barley, rye and triticale. Early post emergence application of 2.5 l/ha includes these advantages: unrestricted selectivity to various application conditions for all kinds and varieties of winter cereals and wide efficacy spectrum to broad-leaved weeds. The specific feature of ADDITION is a complementary and overlapping efficacy spectrum. Within the overlapping spectrum diflufenican and pendimethalin affect the same weed varieties with different modes and on different sites of action. HRAC rates diflufenican to group F1 and pendimethalin to group K1. These different modes of action are the basis for variety specific resistance management. According to increasing discussions of weed resistance, ADDITION is a strong partner to set up a successful long term resistance management. Favorable restrictions are allowing a wide application range of ADDITION.
  • Authors:
    • Fleige, H.
    • Zink, A.
    • Hartmann, P.
    • Horn, R.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: In this study we determined wheeling (external loads of 6.3. Mg by 10 times wheeling) and tillage effects (conventional and conservation tillage) on the soil hydraulic properties of Stagnic Luvisols in Northwest Germany and modeled the soil water balance's reaction on both loading and changing climatic conditions. Due to the mechanical stress applied by loading, physical properties changed distinctly in the top Ap-horizons and the subsequent Eg-horizons at both tillage systems. Especially pore size distributions and soil hydraulic conductivities were affected. The Btg horizons did not show changes due to loading. Soil water balance was measured with soil tensiometers during one growing period and the following autumn and was modeled with Hydrus 1D for loaded and unloaded conditions under winter wheat for three different periods (1991-2000; 2051-2060; 2091-2100) based on a regional A1B climate scenario. At the loaded sites we found an increase of actual transpiration rates in the growing period. As a consequence of stronger drying and changed hydraulic properties, rewetting in autumn and winter was retarded and less complete on average. Furthermore, simulations indicated an increase of the variability of matric potentials. Consequently, compaction might result in a higher drought risk and a higher susceptibility for water logging in spring, which may result in less favorable soil conditions and plant growth. Reactions of soil water balance on changing climatic conditions were comparable for all loading variants and tillage systems. Predicted changes in precipitation (in general: summer -, winter +) and temperature (+) would result in a reduction of transpiration rates in the growing period while the climatic water balance in autumn and winter would increase distinctly. © 2012 Elsevier B.V.
  • Authors:
    • Fiener, P.
    • Reichenau, T. G.
    • Schmidt, M.
    • Schneider, K.
  • Source: Agricultural and Forest Meteorology
  • Volume: 165
  • Issue: November
  • Year: 2012
  • Summary: Arable land occupies large areas of global land surface and hence plays an important role in the terrestrial carbon cycle. Therefore agro-ecosystems show a high potential of mitigating greenhouse gas emissions while optimizing agricultural management. Hence, there is a growing interest in analyzing and understanding carbon fluxes from arable land as affected by regional environmental as well as management conditions. The major goal of this study is to use a two year data set of eddy covariance measurements (October 2007 to October 2009) on a winter wheat field located in Western Germany to assess the seasonal and inter-annual variability of carbon fluxes as affected by meteorological variables and land management. During the study period, which was comprised of two full growing seasons, eddy covariance measurements together with measurements of various soil, plant, and meteorological data were performed. Flux partitioning and gap filling methods including uncertainty estimates were applied to derive complete time series of net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (R-eco). Despite different management dates and slightly different meteorological conditions, annual NEE resulted in 270 g C m(-2) in both years. Although the period from sowing to harvesting was more than 20 days shorter in the first year, due to the later start of senescence, GPP was higher by 220 g C m(-2). In the annual carbon budget this was compensated by a stronger heterotrophic respiration after the harvest of sugar beet grown on the field before the study period. Taking into account the carbon losses due to removal of biomass during harvest, the winter wheat field acts as a carbon source with respective net biome productivities (NBP) of 246 and 201 g C m(-2) a(-1). To complete the carbon balance, releases due to energy consumption associated with crop production are taken into account. However, the relatively large carbon loss was probably, to a large extent, compensated by carbon input from plant residues left on the field after preceding sugar beet harvest. This underlines the importance of multi-annual measurements taking full crop rotations into account. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Joergensen, R. G.
    • Schweinsberg-Mickan, M. S. Z.
    • Mueller, T.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 175
  • Issue: 5
  • Year: 2012
  • Summary: A greenhouse rhizobox experiment was carried out to investigate the fate and turnover of 13C- and 15N-labeled rhizodeposits within a rhizosphere gradient from 08?mm distance to the roots of wheat. Rhizosphere soil layers from 01, 12, 23, 34, 46, and 68?mm distance to separated roots were investigated in an incubation experiment (42 d, 15 degrees C) for changes in total C and N and that derived from rhizodeposition in total soil, in soil microbial biomass, and in the 0.05 M K2SO4extractable soil fraction. CO2-C respiration in total and that derived from rhizodeposition were measured from the incubated rhizosphere soil samples. Rhizodeposition C was detected in rhizosphere soil up to 46?mm distance from the separated roots. Rhizodeposition N was only detected in the rhizosphere soils up to 34?mm distance from the roots. Microbial biomass C and N was increased with increasing proximity to the separated roots. Beside 13C and 15N derived from rhizodeposits, unlabeled soil C and N (native SOM) were incorporated into the growing microbial biomass towards the roots, indicating a distinct acceleration of soil organic matter (SOM) decomposition and N immobilization into the growing microbial biomass, even under the competition of plant growth. During the soil incubation, microbial biomass C and N decreased in all samples. Any decrease in microbial biomass C and N in the incubated rhizosphere soil layers is attributed mainly to a decrease of unlabeled (native) C and N, whereas the main portion of previously incorporated rhizodeposition C and N during the plant growth period remained immobilized in the microbial biomass during the incubation. Mineralization of native SOM C and N was enhanced within the entire investigated rhizosphere gradient. The results indicate complex interactions between substrate input derived from rhizodeposition, microbial growth, and accelerated C and N turnover, including the decomposition of native SOM (i.e., rhizosphere priming effects) at a high spatial resolution from the roots.
  • Authors:
    • Bakken, L.
    • Budai, A.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Issue: January
  • Year: 2012
  • Summary: Amending agricultural soils with organic residues is frequently recommended to improve soil fertility and to sequester carbon for counteracting global warming. However, such amendments will enhance microbial respiration, hence denitrification. Therefore, the assessment of effects on global warming must take N2O emission and the N2O/(N2O + N-2) product ratio of denitrification into account. There are some indications that the product ratio of denitrification is positively correlated with the ratio of available NO3- and available organic C in soils, but more research is needed to unravel quantitative relationships in well defined experiments. We conducted two laboratory incubation experiments, with the objective (i) to test the impact of the application of various N containing organic substrates including biogas residue on the denitrification rate and on N2O emission, and (ii) to investigate the effect of various NO3- concentrations on the denitrification rate and the N2O/(N2O + N-2) product ratio under standardized anoxic conditions in soils collected from long-term organic or inorganic fertilizer plots. In experiment 1, we found that biogas residue was more recalcitrant than maize straw, despite a high concentration of soluble organic C. High respiration (treatments with maize straw and sucrose) resulted in a transient peak in N2O emission, declining rapidly towards zero as nitrate concentrations reached less than 20 mg NO3--N kg(-1) dry soil. Application of biogas residue had a more moderate effect on soil respiration and denitrification, and resulted in a more long lasting peak in N2O emission. The results were interpreted as a result of a gradual increase in the relative activity of N2O reductase (thus lowering of the N2O/(N2O + N-2) product ratio of denitrification) throughout the incubation, most likely controlled by concentration of available NO3- in soil. In the second experiment, we found low N2O/(N2O N-2) product ratios for the treatment where NO3- concentrations were = 10 mM NO3-, and the ratios were remarkably independent of the soil's fertilizer history. We conclude that (i) in N-fertilized agricultural soils, application of organic matter with high contents of labile C may trigger denitrification-derived N2O emission whereas (ii) in soils with low NO3- contents such application may substantially lower the N2O/(N2O + N-2) product ratio and hence N2O emission. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Juszczak, R.
    • Augustin, J.
    • Yeluripati, J.
    • Smith, P.
    • Smith, J.
    • Jones, E.
    • Bell, M. J.
    • Olejnik, J.
    • Sommer, M.
  • Source: Web Of Knowledge
  • Volume: 92
  • Issue: 2
  • Year: 2012
  • Summary: The global warming potential of nitrous oxide (N2O) and its long atmospheric lifetime mean its presence in the atmosphere is of major concern, and that methods are required to measure and reduce emissions. Large spatial and temporal variations means, however, that simple extrapolation of measured data is inappropriate, and that other methods of quantification are required. Although process-based models have been developed to simulate these emissions, they often require a large amount of input data that is not available at a regional scale, making regional and global emission estimates difficult to achieve. The spatial extent of organic soils means that quantification of emissions from these soil types is also required, but will not be achievable using a process-based model that has not been developed to simulate soil water contents above field capacity or organic soils. The ECOSSE model was developed to overcome these limitations, and with a requirement for only input data that is readily available at a regional scale, it can be used to quantify regional emissions and directly inform land-use change decisions. ECOSSE includes the major processes of nitrogen (N) turnover, with material being exchanged between pools of SOM at rates modified by temperature, soil moisture, soil pH and crop cover. Evaluation of its performance at site-scale is presented to demonstrate its ability to adequately simulate soil N contents and N2O emissions from cropland soils in Europe. Mitigation scenarios and sensitivity analyses are also presented to demonstrate how ECOSSE can be used to estimate the impact of future climate and land-use change on N2O emissions.
  • Authors:
    • Plieninger, T.
  • Source: Applied Geography
  • Volume: 32
  • Issue: 2
  • Year: 2012
  • Summary: This study explores the potential of historical maps to detect, measure and monitor changes of trees outside forests. The main goal is to assess local-level changes of scattered trees and orchards and their land-use determinants in two areas in Southern Germany between 1901/1905 and 2009. Firstly, overall landscape changes are recorded. Secondly, the spatial-temporal trajectories of scattered trees and their land-use determinants are identified. Thirdly, changes in quantity and fragmentation patterns of traditional orchards are analyzed in their relationship to overall land-cover change. The results confirm major losses in scattered trees, mainly due to urbanization, agricultural intensification, and land abandonment. They further reveal that, while orchards have persisted in total area, they have undergone critical changes toward a simplified landscape structure and loss of the traditional land-use mosaic, which is a characterizing feature of high nature value landscapes. Multi-temporal assessment showed that most trends have been continuous and did not change directions over time, but rather accelerated during periods of rapid change (most dramatically in the 1950-1990 period). The case of orchards and scattered trees illustrates a major problem of cultural landscapes in Europe: Semi-natural landscape features of high nature value are threatened by both intensification and abandonment of land uses. This makes their conservation a potentially costly enterprise, as both opportunity costs for lost alternative land uses and for conservation management costs arise. (C) 2011 Elsevier Ltd. All rights reserved.
  • Authors:
    • Koch, H. J.
    • Gajic, A.
  • Source: Journal of Environmental Quality
  • Volume: 41
  • Issue: 4
  • Year: 2012
  • Summary: Hydrothermal carbonization allows rapid conversion of biomass into a carbon-rich, lignite-like product (hydrochar). It is assumed to have beneficial effects on soil properties and plant growth, but detailed studies are lacking, especially in the field. The objective of our study was to investigate the effect of hydrochar incorporated into arable soils on soil mineral nitrogen (N min) content and sugar beet growth. In 2010-2011, a field and a pot trial were conducted. Hydrochars (field: 10 Mg ha -1; pot: equivalent to 30 Mg ha -1) processed from sugar beet pulp (HSP) and beer draff (HBD) were tested against an untreated control. As a second factor, mineral nitrogen (N) fertilizer level (field: 0, 50, 100, 150 kg N ha -1; pot: 0, 100, 200 mg N kg -1 soil) was varied. In both trials, hydrochars reduced initial sugar beet growth, especially when hydrochar with a high C/N ratio (38, HSP) was combined with a low N fertilizer level; high N supply partly compensated for the reduced seedling growth. Without N fertilization, no extractable N min was present at the end of the pot trial in the HSP treatment, whereas in HBD even more N min was extracted than in the control. This suggests remineralization of previously immobilized N when hydrochar with a low C/N ratio was applied (16, HBD). In the field, beet yield was equal at the high N fertilizer level in HSP and at all N levels in HBD treatment. Our results suggest that hydrochar can decrease plant-available N due to N immobilization. Other potential causes for the observed early growth reduction need to be studied more in detail.