Yield effects of soil compaction after different wheeling intensities on a silt soil in Norway

Climate change with a higher amount of rain during harvesting increases the need for efficient harvesting and transport which leads to use of more effective and heavier machinery with an enhanced risk for compaction. Soil compaction is known to reduce the production capacity of a soil and can have severe negative ecological consequences and may reduce the production capacity of soils. Heavy loads can enhance subsoil compaction which is considered to be irreversible. The effect of contrasting wheeling frequency (1x; 10x) and different wheel loads on the bearing capacity of a silt soil was studied in cooperation project between NIBIO (Norway), Christian- Albrecht- Universität Kiel (Germany) and Norwegian University of Life Sciences (Norway). Furthermore it is examining the influence of the use of typical (Norwegian) transport equipment (cereals, potatoes) with differing loads (12Mg; 16Mg total weight) and inflation pressure on soil physical parameters and yields under the climatic conditions of SE Norway. Field measurements and sampling took place at Kongsvinger (60.25° N and 11.08° E) in SE Norway in June 2015. The soil is characterized as silt soil with 82% silt in the topsoil, overlying silt (84%). Unloaded reference plots and loaded wheel tracks were sampled by taking undisturbed and disturbed soil samples (20, 40, 60 cm depth) to determine soil physical parameters. Soil bearing capacity was measured by determining precompression (PC). Stress propagation during wheeling was measured with a Stress-state and displacement stress transducer systems (SST, DTS). Yields of barley yields were monitored on unwheeled and wheeled plots two years after compaction. We will present both the results from the soil physical analyses and use of the compaction verification tool (CVT) in addition to the results from the SST/ DTS measurements. The yield effect of compaction will be illustrated by showing the yield data (barley) for wheeled and unwheeled plots for the 2 years after the compaction. First results show that the compaction had significant effects on the yields, but may have a positive yield effect under certain condition

Regenerationswirkung im Unterboden eines Ackerstandortes in Südnorwegen fünf Jahre nach der Belastung

Im Jahr 2011 wurden Befahrungsversuche mit zwei unterschiedlich schweren Gespannen, bestehend aus Ackerschlepper und Güllefass, in Südnorwegen nahe der Stadt Sarpsborg durchgeführt. Neben unterschiedlichen Gewichten wurden zwei Befahrungshäufigkeiten (einfach und zehnfach Befahrung) und zwei Bodenbearbeitungsverfahren (konventionelle und konservierende Bodenbearbeitung) untersucht. Mit dem Compaction Verification Tool (CVT) wurde außerdem eine potenziell schadhafte Unterbodenverdichtung bewertet. An den in drei Tiefen (20 cm, 40 cm und 60 cm) entnommenen Zylinderproben wurden folgende Parameter analysiert: Luftkapazität, Gesamtporenvolumen, Trockenrohdichte, Vorbelastung, gesättigte Wasserleitfähigkeit und Luftleitfähigkeit. Die Ergebnisse zeigen, dass durch die Befahrung eine Zunahme der schadhaften CVT-Klasse IV bei beiden Varianten unabhängig von der Bodenbearbeitung beobachtet werde konnte. Nach einer fünf jährigen Regenerationsphase wurden für ausgewählten Varianten erneut Proben auf einer bereits in 2011 zusätzlich angelegten Fläche genommen. Die erhobenen Daten wurden mit den Ergebnissen aus 2011 verglichen und lassen auf einen Regenerationseffekt schließen. Die Ergebnisse verdeutlichen aber auch, dass viele Parameter ihren unbelasteten Ursprungszustand nicht wieder erreichen

Differences Found in the Macroinvertebrate Community Composition in the Presence or Absence of the Invasive Alien Crayfish, Orconectes hylas.

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish (Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O. hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O. hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O. hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities

List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.

<p>List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.</p

Statistical significance (Pr > F values) for interaction terms from analysis of site differences in metric values (non-parametric nested ANOVA, α = 0.05) for Crane Pond Creek, Iron County, Missouri, USA.

<p>Macroinvertebrates sampled in two habitats during four time periods in 2011. Metric abbreviations are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = not significant, P = Sampling Period (season), H = Habitat, S = Site.</p

Missouri Biotic Index of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Statistical significance (Pr> │+│from ANOVA, α = 0.05) in macroinvertebrate metrics between Site 1 (invaded) and Site 2 (control) in two habitats sampled from Crane Pond Creek, Iron County, Missouri, USA in Late Summer 2011.

<p>Metric abbreviations are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = Not Significant.</p

Percent (%) Chironomidae of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.</p