Seed rate companion on establishment of herbs E17
Younie, D.1 & Umrani, A. P.2
1) Ferguson Building, Scottish Agricultural College, Craibstone Bucksburn, Aberdeen, AB21 9YA, UK; 2) MacRobert Building, Department of Agriculture, Aberdeen University, 581 King Street, Aberdeen AB24 5UA, UK
|Forage herbs are mineral rich and deep rooting
plants, providing higher levels of essential minerals to livestock and improved soil
structure compared with perennial ryegrass (PRG) swards. These advantages have been
observed recently in grazing swards in Australia and New Zealand under non-organic farming
conditions. However, the agronomic requirements for consistent and reliable herb-based
forage systems in northern European conditions are not known.
In the present study, two forage herbs chicory (Cichorium intybus) and ribwort plantain (Plantago lanceolata) were sown at Craibstone, Aberdeen, north-east Scotland under organic farming conditions. Three seed rates (1.5 and 20 kg/ha) of each herb were sown with either no companion species or with PRG (cv Merlinda) or PRG/white clover (WC) cv Menna in April 1995. The effects of treatments on plant population density, root length, root and shoot dry matter (DM) were observed in June, July September 1995 and April 1996.
The higher herb seed rates increased herb plant population and herb DM weight/m2 significantly at all sampling dates, but there was a marked reduction (average 700% and 500% in chicory and ribwort, respectively) in population density in all treatments between June and September 1995. Only at first sampling date, when herb population was at its maximum, the highseed rates had a negative effect on individual plant weight. Companion species had greater negative effect on individual plant size than on plant population of herbs on September 1995. Companion treatments had the highest herbage biomass/m2 but reduced the herbage contribution to biomass. Weeds invasion was also significantly less where companion species were sown.
These results suggest that early establishment of forage herbs is more dependent on environment factors and intraspecific competition than companions, but later in the establishment phase, when growth rate is fast, companion species have a more marked effect on herbs than seed rates.