Maize is one of the most difficult field crops in terms of weed management. The low number of plants per m2 and the relatively long time the crop requires to cover the soil surface encourage the growth of summer weeds and increase water evaporation.
The mentioned problems can be avoided by sowing maize in a no-till system into a mulched cover crop. This method requires mechanical termination of the cover crop that precedes the maize crop with a roller-crimper, and, for sowing maize, a no-till planter is needed.
The mulch cover will control weeds during the initial growth phase of the maize crop and reduce water loss by evaporation. If leguminous cover crops are used, important amounts of nitrogen can be collected.
In a Northern Italian context, a field pea cover crop was tested as mulch for the maize crop. The roller crimper effectively terminated the cover crop (15 t per ha of wet biomass). However, the mulch did not last long enough, probably due to a narrow C/N-ratio and biologically active soil. The maize plants did not have enough time to develop and shade the entire soil surface. Weeds started to sprout through the decomposing mulch. For the test conditions, this cover crop has proven unsuitable as a long-lasting mulch to control weeds. No fertilization and no irrigation were applied. The maize yields amounted to about 5 t per ha.
• The cover crop needs to be sown as accurately as the main crop. Poor cover crop stands do not result in good mulches.
• The effectiveness of the mulch depends on the amount of mulch biomass. However, more biomass also means more difficulty for the planter.
• On soils with low organic matter content, additional nitrogen fertilisation should be considered.