Date: 2/2022

Growers have several options when deciding to renew their grassland once the presence of weeds in the sward reduces the productivity of the crop to an unacceptable level. At low numbers of weeds a simple and cheap annual over-seeding is sufficient most of the time, however a severe infestation of weeds will require a ploughing and re-sowing of the field.

Many weeds of grassland such as common couch are edible for livestock and so judging the productivity of your land based on the species present alone is difficult. To understand how couch will affect the grassland manager DSV has made an investigation on our forage innovation trial fields, measuring the yield and analysing the forage quality of weed species and comparing them to modern varieties.

The species common couch (Elytrigia repens) is an unwanted visitor often found in dryer fields after several years of cultivation. This grass can spread in mats from underground structures called rhizomes, quickly gaining more and more space in the field and pushing out the more productive species such as perennial ryegrass (Lolium perenne). Results from our controlled trial plots show a couch dry matter yields are 15% lower than perennial ryegrass.

In the real world grazing situation this is actually much lower as the cow has fine taste and will selectively eat her favourite grasses before the hard and sharp-leaved couch, allowing the invader to conquer the space occupied by the defoliated ryegrass. Once begun this vicious cycle will continue without intervention from the farmer.

Our laboratory analyses show couch has a 60% lower sugar (WSC) content than perennial ryegrass, 16% lower digestibility (OMD) and 50% more tough lignin (ADL). From these basic components of the grass plant we can calculate a value called net energy for lactation (NEL), which is the usefulness of the feed to the animal. In our studies we calculate the NEL of couch is 5.1, one whole point lower than perennial ryegrass (6.1).

So if you spot that your fields are harbouring more and more of that unwanted visitor couch grass, react with a re-seed of a mixture containing top-quality newly varieties from DSV.