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Mixed Swards (mixed + sward)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Effects of potassium carbonate as an alternative de-icer on ground vegetation and soil

ANNALS OF APPLIED BIOLOGY, Issue 3 2000
E ERHART
Summary The effects of the new de-icer potassium carbonate on the growth and species composition of a mixed sward and on the pH and electrical conductivity of the soil were examined in a four-year field trial and compared with sodium chloride. There were small positive effects of K2CO3 on the biomass yield of the sward at application rates up to 200 g m,2 yr,1, while effects were less negative than those of NaCl at annual application rates of 200 , 400 g m,2 yr,1. The species composition of the sward changed considerably with K2CO3 application, Agropyron repens becoming the dominant species. The pH was elevated slightly more by K2CO3 than by NaCl application. Electrical conductivity as an index of soil salinity was increased by both de-icers. K2CO3 was more adsorbed to soil colloids than NaCl, so that the rise in E.C. resulting from application of the former was restricted to the uppermost 10 cm of soil. [source]

Effects of white clover cultivar and companion grass on winter survival of seedlings in autumn-sown swards

GRASS & FORAGE SCIENCE, Issue 2 2003
A. Elgersma
Abstract The aim was to study the effects of white clover cultivar and combinations with perennial ryegrass cultivars on seedling establishment in autumn-sown swards and on winter survival of seedlings. Large-leaved white clover cv. Alice and small-leaved white clover cv. Gwenda, and an erect and a prostrate perennial ryegrass cultivar were sown in autumn in pure stands and as four binary grass-clover mixtures. Mixtures of white clover cv. Huia and Aberherald with perennial ryegrass were also sown. Companion grasses had no significant impact on the establishment of white clover. The number of seedlings of white clover cv. Alice in mixtures (335 m,2) was higher than cv. Gwenda (183 m,2) and pure swards had similar white clover population densities as mixed swards. White clover cv. Huia tended to have more seedlings than Aberherald (355 and 205 m,2 respectively). No stolons were produced prior to a severe winter, because of the late sowing date. Winter survival of clover seedlings was 0·56 in mixtures and 0·69 in pure stands, irrespective of white clover or companion grass cultivar. Stolon development of white clover in autumn is often considered essential for overwintering survival and spring growth. In this study, there was considerable survival of the non-stoloniferous tap-rooted seedlings of all four clover cultivars despite a severe winter. [source]

The effect of accumulation period and harvest date in spring on dry-matter yield and forage quality in mixed swards containing Lolium spp. and Trifolium subterraneum in Western Australia

GRASS & FORAGE SCIENCE, Issue 1 2001
M. N. Callow
The object of this study was to determine the effect of closing date and date of harvest for conservation (accumulation period), on dry-matter (DM) yield and forage quality of annual pasture in Western Australia. The field study comprised 48 plots, 2 m × 2 m, sown with either annual ryegrass (Lolium rigidum Gaud.) or Italian ryegrass (L. multiflorum Lam.), and mixed with subterranean clover (Trifolium subterraneum L.). Defoliation of swards until the end of winter was at the three leaves tiller,1 stage. In spring, once stem nodal development had commenced, swards were defoliated every 3,4 weeks. Swards were defoliated either twice with three leaves tiller,1 (accumulation period 1 commenced on 15 August); twice with three leaves tiller,1 and then once after 4 weeks (accumulation period 2 commenced on 11 September); twice with three leaves tiller,1 and then twice after 4-week intervals (accumulation period 3 commenced on 9 October) or; twice with 3 leaves tiller,1 and then twice after 4-week intervals and then once after 3 weeks (accumulation period 4 commenced on 30 October). From the commencement of the accumulation period, tiller density, DM yield and forage quality were determined weekly for up to 10 weeks. There was a positive quadratic association between DM yield and days after the commencement of the accumulation period. Yields were maximized from accumulation period 1 with 5·3, 6·6 and 9·5 t DM ha,1, and growth rates were 140, 128 and 145 kg DM ha,1 d,1, for Wimmera annual ryegrass and Richmond and Concord cultivars of Italian ryegrass respectively. In contrast, in vitro dry-matter digestibility (IVDMD) and crude protein (CP) content were negatively associated with days after the commencement of the accumulation period, and initial values were greater than 0·80 and 180 g kg DM,1 for IVDMD and CP content respectively. The rate of decline in IVDMD d,1 for Wimmera annual ryegrass was 0·005, 0·019 and 0·012 d,1 for accumulation periods 1, 2 and 3, respectively, while for Italian ryegrass cultivars Richmond was 0·015, 0·011, 0·02 and 0·012 d,1 and Concord was 0·014, 0·009, 0·013 and 0·01 d,1, for the 4 accumulation periods respectively. It is recommended that annual and Italian ryegrass pastures be harvested between 10% and 20% inflorescence emergence when IVDMD will exceed 0·70 regardless of cultivar and/or defoliation practice prior to the commencement of the accumulation period. [source]

Evaluation of the effects of resistance to stem nematode (Ditylenchus dipsaci) in white clover (Trifolium repens L.) under sheep grazing and cutting

PLANT BREEDING, Issue 4 2007
T. A. Williams
Abstract Two field experiments were carried out to analyze the performance of white clover varieties differing in their resistance to stem nematode. Varieties were compared under grazing and cutting regimes in mixed swards with or without the addition of nematode and dry matter yields of white clover and perennial ryegrass recorded over a 3-year period. The resistant variety did not show a yield advantage in the absence of nematode but did so in the presence of nematode in the first year and for several of the sampling dates in the second year. White clover yields under grazing were significantly less than under cutting in both experiments. The hypothesis that the additional stress of grazing would increase the benefits of resistance relative to a cutting management was not supported. [source]