Intercropping with Lolium spp. instead of applying soil-active herbicides confined weeds in three years of continuous maize cropping

Abstract

Owing to its high yields and carbohydrate content, maize is cropped continually to produce biomass for silage, but herbicides are commonly used to control weeds. In a proof of concept approach, continuous maize cropping systems were investigated to identify whether intercropping with annual grasses and adapted herbicide use could replace the soil-active herbicide S-Metolachlor. An experiment in nine maize fields conducted from 2017 to 2019 contrasted the current practice without intercropping but with the soil-active herbicide S-Metolachlor with two systems of intercropping (Festuca spp. And Lolium spp.) and adapted herbicide use. The Festuca spp. Intercrop was sown together with maize and foliar herbicides against dicots only were used. The Lolium spp. Intercrop was sown later and thus herbicides against dicot and monocot weeds were used prior to sowing.Over this three-year period, the cropping system with Lolium spp. As the intercrop confined weeds as effectively as the common practice using herbicides, but the cropping systems differed in their control of Echinochloa crus-galli and Poa annua. The densities of the summer annual E. crus-galli increased in the treatment with Festuca spp. As the intercrop and no chemical control of monocot weeds.Control of the species P. annua that exhibits year-round germination depended on the herbicide treatment and competition with the intercrop. Densities in P. annua were lowest in the cropping system with Lolium spp. As the intercrop in all years. The cover of the Lolium spp. Intercrop was negatively correlated with weed cover, but this was not the case with the Festuca spp. Intercrop. There were no differences in yield between the cropping system treatments. Dry matter content was significantly higher in the Festuca spp. Cropping system in each year.In continuous maize intercropping with Lolium spp. Together with adapted herbicide use allows to omit the soil active herbicide S-Metolachlor. This system confined the densities of most weed species. However, the tendency for E. crus-galli to increase means that this finding cannot be extended beyond the period investigated.