Buckwheat for couch grass control

Summary

Five organic vegetable growers will investigate the potential for including buckwheat into their horticultural rotations to reduce couch grass infestations.  They will compare the performance with their usual means of couch grass control.

The triallists are also keen to understand the costs and benefits of using buckwheat (as a potential crop or green manure) in the rotation.

The field lab group was formed with the support of Cotswold Seeds and the Organic Growers Alliance. Cotswold Seeds provided support in the form of free buckwheat seeds for all the trial hosts throughout the duration of the trial.

How it works

Couch grass or twitch (Elymus repens) is a common perennial weed which rapidly spreads by underground rhizomes. It can have significant negative effects on vegetable crop yields and is difficult to control once established, especially in organic systems.

Traditional organic control methods include repeated cultivations, harrowing and raking to bring rhizomes to the surface where they are then killed by desiccation, as well as ploughing to bury foliage and rhizomes. Whilst these methods can be effective, they are weather dependent and can also be damaging to the soil structure.

Buckwheat (Fagopyrum tataricum) is a fast-growing annual green manure or cover crop, useful for suppressing weeds, and as a food source for pollinators. There is also some evidence of allelopathic effects of buckwheat, which may also act as additional weed control.

Trial design

Trials will be carried out over a three growing seasons between 2017 and 2019.

Participating growers will carry out baseline sampling at the start of each year to determine the levels of couch grass infestation prior to any treatments being applied. The treatment will be a buckwheat crop, either on its own or as part of a mixture, and the control will be their normal farm practice.

Photographs will be taken throughout each growing season to monitor the treatments. Key dates and observations such as soil conditions and seed rates will be recorded. 

Couch grass levels will be assessed again at the end of each trial, and worm counts will be carried out to establish differences in soil health between the treatments.

The final report can be found under the results and reports tab.