Jure Čop

Ecosystem function enhanced by combining four functional types of plant species in intensively managed grassland mixtures: a 3‐year continental‐scale field experiment

1.A coordinated continental-scale field experiment across 31 sites was used to compare the biomass yield of monocultures and four species mixtures associated with intensively managed agricultural grassland systems. To increase complementarity in resource use, each of the four species in the experimental design represented a distinct functional type derived from two levels of each of two functional traits, nitrogen acquisition (N2-fixing legume or nonfixing grass) crossed with temporal development (fast-establishing or temporally persistent). Relative abundances of the four functional types in mixtures were systematically varied at sowing to vary the evenness of the same four species in mixture communities at each site and sown at two levels of seed density. 2.Across multiple years, the total yield (including weed biomass) of the mixtures exceeded that of the average monoculture in >97% of comparisons. It also exceeded that of the best monoculture (transgressive overyielding) in about 60% of sites, with a mean yield ratio of mixture to best-performing monoculture of 1·07 across all sites. Analyses based on yield of sown species only (excluding weed biomass) demonstrated considerably greater transgressive overyielding (significant at about 70% of sites, ratio of mixture to best-performing monoculture = 1·18). 3.Mixtures maintained a resistance to weed invasion over at least 3 years. In mixtures, median values indicate

Nitrogen mineralization in marsh meadows in relation to soil organic matter content and watertable level

The objective of the present study was to asses the effect of watertable level on N mineralization in a Histosol and a Humic Gleysol profile under natural meadows in Ljubljana marsh, Slovenia. The two soils differ significantly in organic matter content (27—40 % in Histosol and 14—20 % in Humic Gleysol) but not in C : N ratio (13—20) and pH (6.5—7.0). For each soil, the watertable was maintained at two levels (above or below 50 cm from the soil surface) for approximately one year. The four main plots, according to soil carbon content and watertable level were divided into 4 subplots, according to 4 fertilization treatments (unfertilized control, PK, PK + 50 kg N ha—1, PK + 3 × 50 kg N ha—1). Net N mineralization in unfertilized subplots was estimated from indices of N mineralization obtained by incubation of soil samples in the laboratory and by seasonal dynamics of mineral N content in the field. Annual uptake of N in herbage under the 4 fertilization treatments was also measured. Total mineral N content in topsoil was 20—80 % higher in Histosol than in Humic Gleysol. Similarly, aerobic N mineralization potentials along the entire soil profile (0—90 cm) were 20—130 % higher in Histosol than in Humic Gleysol. By contrast, anaerobic N mineralization potentials in subsoil were 10—60 % lower in Histosol than in Humic Gleysol. Both, aerobic and anaerobic N mineralization potentials strongly depended on watertable levels at sampling time. Seasonal dynamics of soil mineral N content as well as N mineralization potentials indicated that the N mineralization in the Histosol could be 10—40 % higher at low than at high watertable level. In the Humic Gleysol the N mineralization could be 10—100 % higher at high watertable level. Higher N availability in Histosol at low watertable and in Humic Gleysol at high watertable was also reflected in higher N uptake in herbage. These results indicate that N mineralization in Histosol and Humic Gleysol, was proportional to soil organic matter content, whereas in both soils, higher N mineralization rates can be expected at watertable levels between 40 and 60 cm below the soil surface, than at higher/lower watertable levels. Einfluss des Humusgehaltes und des Grundwasserspiegels auf die Stickstoffmineralisation in Boden aus Feuchtgebieten Ziel dieser Untersuchung war es, den Einfluss der Hohe des Grundwasserspiegels auf die N-Mineralisation in einem Histosol und einem Humic Gleysol unter Naturwiesen des Ljubljanaer Moors, Slowenien, festzustellen. Die zwei untersuchten Bodentypen unterscheiden sich signifikant im Gehalt der organischen Substanzen (27—40 % in Histosol und 14—20 % in Humic Gleysol), aber nicht im C : N-Verhaltnis und pH-Wert (6.5—7.0). In jedem Bodentyp wurden fur die Dauer von 1 Jahr kunstlich jeweils ein hoher und ein niedriger Grundwasserspiegel eingestellt. Jede der 4 daraus resultierenden Haupt-Versuchsparzellen wurde weiter geteilt in 4 Dungungs-Teilstucke: Ungedungt, PK, PK + 50 kg N ha—1 und PK + 3 × 50 kg N ha—1. Die Netto-N-Mineralisation auf ungedungten Teilstucken der Haupt-Versuchparzellen (2 Bodentypen, 2 Grundwasserspiegel) wurde bestimmt durch die N-Mineralisationspotenziale bei anaerober und aerober Inkubation der Bodenproben im Labor sowie durch die saisonale Dynamik des N-Gehaltes im Boden sowie durch den N-Entzug der Vegetation in 4 Dungungsvarianten. Wahrend der Messperiode lag der Gehalt am gesamten mineralischen Stickstoff in der oberen Bodenschicht des Histosol um 20 bis 80 % hoher als im Humic Gleysol. Ahnlich waren die aeroben N-Mineralisationspotenziale im Bodenprofil des Histosols um 20 bis 130 % hoher als im Humic Gleysol. Die anaeroben N-Mineralisationspotenziale waren dagegen in tieferen Bodenschichten des Histosol um 10 bis 60 % niedriger als im Humic Gleysol. Die Anderungen der Mineralisationspotenziale in aerob und anaerob inkubierten Bodenproben waren zugleich vom Grundwasserspiegel zur Zeit der Beprobung abhangig. Sowohl die zeitliche Dynamik des Gehaltes an mineralischem N in der Zeit als auch die aeroben und anaeroben N-Mineralisationspotenziale zeigen aber einheitlich, dass die N-Mineralisation im Histosol bei niedrigem Grundwasserspiegel um 10 bis 40 % groser sein kann, wahrend im Humic Gleysol die N-Mineralisation bei hohem Grundwasserspiegel um 10 bis 100 % groser sein kann. Hohere N-Verfugbarkeit im Boden widerspiegelt sich auch im hoheren N-Entzug durch die Vegetation. Die Ergebnisse dieser relativ kurzen Untersuchung zeigen, dass die N-Mineralisation in Histosol und in Humic Gleysol proportional dem Humusgehalt verlauft; in beiden Bodentypen kann bei Grundwasserspiegeln von 40—60 cm eine starkere N-Mineralisation erwartet werden als bei daruber oder darunter liegendem Wasserspiegel.

The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands

Kirwan, L., Connolly, J., Brophy, C., Baadshaug, O. H., Belanger, G., Black, A., Carnus, T., Collins, R. P., Cop, J., Delgado, I., De Vliegher, A., Elgersma, A., Frankow-Lindberg, B. E., Golinski, P., Grieu, P., Gustavsson, A., Helgadottir, A., Hoglind, M., Huguenin-elie, O., Jorgensen, M., Kadziuliene, Z., Lunnan, T., Luscher, A., Kurki, P., Porqueddu, C., Sebastia, M. T., Thumm, U., Walmsley, D. & Finn, J. A. (2014). The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands. Ecology, 95 (9), [2680]

The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands Ecological Archives

Kirwan, L., Connolly, J., Brophy, C., Baadshaug, O. H., Belanger, G., Black, A., Carnus, T., Collins, R. P., Cop, J., Delgado, I., De Vliegher, A., Elgersma, A., Frankow-Lindberg, B. E., Golinski, P., Grieu, P., Gustavsson, A., Helgadottir, A., Hoglind, M., Huguenin-elie, O., Jorgensen, M., Kadziuliene, Z., Lunnan, T., Luscher, A., Kurki, P., Porqueddu, C., Sebastia, M. T., Thumm, U., Walmsley, D. & Finn, J. A. (2014). The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands. Ecology, 95 (9), [2680]