Abstract
Diversification through crop rotations, the third principle defining
Conservation Agriculture (CA), is key to supporting more diverse
above-ground arthropod populations. Furthermore, due to the higher
demand for crop production, CA farming systems must focus on supporting
natural services that can support yield and decrease the demand for
external agrochemical inputs. The crop rotation sequence could play a
role in supporting different groups of organisms, thereby promoting the
sustainability of whole cropping systems. The objectives of this study
were to investigate two crop rotation system treatments (i.e., A:
Wheat-Wheat-Wheat-Wheat and G: Canola-Medics-Wheat-Medics) as part of a
larger long-term trial on a CA farming system located in a wheat
producing region of South Africa. Each phase of the crop rotation
sequence was represented each year for crop rotation system G.
Arthropods were sampled using two sampling methods (i.e., pitfall and
sweep-net sampling) 90 days after plant emergence. The results indicated
that diversification through crop rotation positively affected the
diversity of above-ground arthropods, depending on the specific sampling
method used. Arthropods collected with pitfalls revealed less distinct
differences between crop rotation sequences. The sweep-net sampling
method indicated more crop-specific differences, which could relate to
the specific resources each phase provides within the crop rotation
sequence. By investigating each arthropod order separately, the results
indicated that diversification through crop rotations had a variable
effect on the different arthropod groups. Therefore, our study
highlights that different arthropod groups must be investigated to draw
conclusions regarding diversification within CA farming systems.