Weed competition and biomass production of maize and sorghum under different herbicide intensity level

• Main Authors: Söchting, Hans-Peter, Zwerger, Peter
• Format: Article
• Language: deu
• Published: Julius Kühn-Institut 2012-03-01
• Series: Julius-Kühn-Archiv
• Subjects: Biodiversität; Energiepflanzen; Ertrag; Unkrautdeckungsgrad; biodiversity; energy crops; weed coverage; yield

The production of biogas still gains importance with maize being the most important crop for bioenergy production. However, the increasing area planted with maize has been considered as not being only beneficial. The question therefore arises whether the growing cultivation of maize can be conducted in a more environmentally sustainable way and to which degree a certain level of weed infestation can be tolerated in fields used for biomass production. As weeds may also contribute to the amount of biomass produced on a field and increase the in-field biodiversity, a certain weed infestation in maize for biogas production might be tolerable. Under these aspects, a field trial was conducted on the experimental fields of the JKI near Braunschweig between 2008 and 2010. Three maize cultivars and two sorghum cultivars (Sorghum bicolor and Sorghum bicolor x Sorghum sudanense) were sown at normal seeding densities with four replicates. At growth stage BBCH 13-14 of the sorghum-plants, the herbicide Gardo Gold (terbuthylazin 187,5 g/l + S-metolachlor 312,5 g/l) was applied at the registered dose (4 l/ha) or half-dose (2 l/ha). An untreated plot without any herbicide application was included. The aim of the experiment was to investigate differences in the development of the weed infestation level and the biomass yields of the crops. Assessments of the weed species and weed coverage were carried out at several times during the growing season. At the end of the experiment, the dry matter/m2 of the crops and weeds were determined. The results of the three years showed a higher biomass yield for the maize cultivars compared with the sorghum cultivars (not always significant). Regarding the effect of the herbicide application on the biomass yields, a clear difference between the variants was observed only in 2008 and 2009 with the highest yield under the registered application rate of 4 l/ha Gardo Gold (one exception). In 2009 and 2010, the results were more complex and the maximum biomass yield was not necessarily reached in the variants with the highest herbicide rate.