The abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) has increased in coastal grasslands in Norway over recent decades, and their spread has coincided with increased precipitation in the region. Especially in water‐saturated, peaty soils, it appears from field observations that productive grasses cannot compete effectively with such rapidly growing rush plants. In autumn–winters of 2012–2013 and 2013–2014, a four‐factor, randomised block greenhouse experiment was performed to investigate the effect of different soil moisture regimes and organic matter contents on competition between these rush species and smooth meadow‐grass (Poa pratensis). The rush species were grown in monoculture and in competition with the meadow‐grass, using the equivalent of full and half the recommended seed rate for the latter. After about three months, above‐ and below‐ground dry matter was measured. J. effusus had more vigorous growth, producing on average 23–40% greater biomass in both fractions than J. conglomeratus. The competitive ability of both rush species declined with decreasing soil moisture; at the lowest levels of soil moisture, growth reductions were up to 93% in J. conglomeratus and 74% in J. effusus. Increasing water level in peat–sand mixture decreased competivitiveness of meadow‐grass, while pure peat, when moist, completely impeded its below‐ground development. These results show that control of rush plants through management may only be achieved if basic soil limitations have been resolved.
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AC/DC-weeds: Applying and Combining Disturbance and Competition for an agro-ecological management of creeping perennial weeds
Målsetningen med prosjektet AC/DC-weeds er å utvikle metoder for bærekraftig kontroll av flerårig vandrende ugras (rotugras) som kveke, åkerdylle og åkertistel i landbruket. Målet er å redusere behovet for intensiv jordarbeiding som pløying og å finne alternativer til bruk av ugrasmiddelet glyfosat. Nye metoder for bærekraftig kontroll av rotugras krever at en kombinerer flere typer av både forebyggende og direkte bekjempingstiltak. Kunnskap fra prosjektet vil formidles til viktige målgrupper som rådgivere, bønder og andre relevante mottakere. Rostock Universitet (Tyskland) ved Prof. Dr. Bärbel Gerowitt er prosjektkoordinator. NMBU ved Prof. Dr. Lars Olav Brandsæter administrerer aktiviteten i Norge.