Yield and stability of yield of single‐ and multi‐clover grass‐clover swards in two contrasting temperate environments

Abstract

Diversity of clovers in grass-clover swards may contribute to greater herbage yields and stability of yield. This possible effect was evaluated in an experiment carried out over three harvest years at two contrasting sites, differing in precipitation and soil composition, using mixed swards containing either one, two or three clover species sown together with timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis L.). The clover species were red clover (Trifolium pratense L.), white clover (Trifolium repens L.) and alsike clover (Trifolium hybridum L.) sown in various proportions in a total of ten treatments. All swards were fertilized with nitrogen with amounts that increased from year to year, and three harvests were taken in three consecutive years. There was a significant interaction between site and species mixture on total dry matter (DM) yields (range 27-32 tonnes ha )1 ) and DM yields of clovers (range 5-15 tonnes ha )1 ); red clover as a single species or in a mixture was superior at the dry site while multi-clover species mixtures were superior at the wet site. Alsike clover was the least productive species of clover. Stability of yield of clovers was generally higher by including white and red clover in the seed mixture but total DM yield was not.

Complementary effects of red clover inclusion in ryegrass–white clover swards for grazing and cutting

“…Frankow‐Lindberg et al . () also found a positive yield effect of red clover inclusion in a 3‐year study at two Swedish sites in the first production year and also partly in the second year, but not in the third year.…”

“…(). The depression of ryegrass occurred despite a very low content of red clover in the seed mixture (1 kg ha −1 ) compared with more commonly used seed rates of 2–6 kg ha −1 (Humphreys et al ., ; Frame, ; Frankow‐Lindberg et al ., ). Avoiding this assumed reduction in ryegrass plant density would require even lower seed rates of red clover with the probable consequence of lower first‐year yields in the three‐species mixture.…”

“…Grass–red clover mixtures have the additional advantage of improved nitrogen (N)‐use efficiency in ruminants due to their content of secondary compounds (Kleen et al ., ). There are very few reports in the literature on the inclusion of more than one clover species in temperate grass–clover mixtures (Frankow‐Lindberg et al ., ), but such a strategy could be a solution to achieve a flexible, high‐yielding sward suitable for both grazing and cutting in low‐input temporary grassland systems. The complementary growth of red clover and white clover could maximize yields and increase the persistence of the clover component under conditions that are not optimal due to the effects of grazing, cutting or fertilization.…”

Combining Ability in Mixtures of Prairie Grass and Clovers

“…Low clover growth rate, especially for white clover, affected initial harvests possibly due to its low competitive ability for light and low stolon density during its establishment [23]. In binary mixtures, white clover establishment is affected by grass density and maturity, a reduced sward density and early maturity would probably increase compatibility [24][25][26][27].…”

Conditions that favor clover establishment in permanent grass swards

“…Dry weather in 2010 impacted white clover more than red clover, and this has been shown in other studies (Frame ; Frankow‐Lindberg et al . ). Red clover produced 3× more biomass than white clover in 2010.…”