A. Elgersma

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

Comparison of the fatty acid composition of fresh and ensiled perennial ryegrass (Lolium perenne L.), affected by cultivar and regrowth interval

Two experiments were conducted to evaluate the effects of grass cultivar and regrowth stage on the fatty acid (FA) profile in fresh and ensiled perennial ryegrass (Lolium perenne L.). The Experiment 1 compared the composition of fresh grass with that of pre-wilted ensiled material of six cultivars, harvested after 25 days of regrowth at a dry matter (DM) yield of approximately 2000 kg DM ha(-1). The Experiment 2 compared fresh and ensiled grass of two cultivars, harvested after 23 and 33 days of regrowth. There were genetic differences in fatty acid profiles in fresh grass, but the physiological basis of these differences was not clear as management, growth conditions and leaf blade proportion were similar among cultivars. The concentrations of most FA declined with increasing regrowth stage. In fresh grass, 98% of the fat was present as esterified fatty acids (EFAs) but in silages, 27-73% of the total FA consisted of free fatty acids (FFAs). The largest changes in FA contents took place in the EFA. In pre-wilted ensiled grass, the contents of most FA were lower than in fresh grass, especially of C18:1 and C18:3

Effect of Rhizobium inoculation and phosphorus application on native Texas legumes grown in local soil

Greenhouse experiments were conducted to determine the effects of Rhizobium inoculation and addition of phosphorus to soil on the productivity and quality of the Texas range legumes Desmanthus illinoiensis (Michx.) MacMill. ex B.L. Rob. & Fernald, Desmanthus velutinus Scheele, Desmanthus virgatus (L.) Willd., and Neptunia lutea (Leavenw.) Benth. Phosphorus (P) fertilization was applied at 0, 40, 80, and 120 kg P ha−1 in Experiment 1 with half the pots also receiving D522-1/2 (a Desmanthus isolate). Experiment 2 consisted only the Desmanthus species and tested four different inoculant treatments (uninoculated control, inoculated with commercial cowpea Rhizobia, D522-1/2 from Desmanthus isolates, and L1145, a Leucaena isolate). Two soil treatments were used in Experiment 2, gamma radiation sterilized and unsterilized soil, to determine whether introduced Rhizobia were as effective as native populations. Shoot dry matter (DM) yield, root DM weight, and shoot nitrogen (N) and P concentration increased with increasing P application levels up to 80 kg P ha−1. Rhizobium strain D522-1/2 was an effective inoculant for all legumes when applied in combination with P fertilizer (Experiment 1). In sterilized P-deficient soil (Experiment 2), inoculation improved the parameters measured. In unsterilized soil, however, only D522-1/2 and L1145 improved shoot nitrogen concentration while the cowpea Rhizobium strain was detrimental in the case of D. velutinus. The low concentration of available soil P and the scarcity of active Rhizobium in the soil might be the cause of the slow establishment of native legume species in disturbed soils without native Rhizobia populations.

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]