The impacts of ditch cuttings on weed pressure and crop yield in maize

The Flevoland Polder in The Netherlands is characterised by large agricultural fields separated by ditches. The vegetation in the ditches is typically cut twice a year to ensure sufficient drainage. Removal of the cuttings, primarily reed (Phragmites australis), results in a substantial increase in biodiversity. In many cases however, the cuttings are considered a waste product and the material is left on the spot. This paper focuses on a practical on-farm application for the cuttings that may stimulate farmers to remove the material from the ditches. Instead of treating the cuttings as a waste product they were used as green compost and ploughed into a maize field after the harvest. This study investigates the effect of the cuttings on weed pressure and crop yield for two weed control systems, integrated and mechanical, for 2 years. The cuttings (15 and 30 m3/ha) did not lead to a change in total weed cover in either weed control system. However, the cuttings did result in increased species richness of weeds early in the first season. This effect disappeared after weed control. Taraxacum officinale, Solanum nigrum and Urtica dioica all increased when cuttings were applied, but their cover remained relatively low. The abundance of potential diaspores of P. australis did not result in its presence in the maize field. Despite a slight increase in weed pressure and possible immobilisation of nitrogen due to decomposition of the cuttings, the cuttings did not affect maize yield.