Effect of Row Orientation in Maize/ Faba Bean Strip Intercropping Systems on Above Ground Biomass, LAI and Light Interception

Crop Science, Intercropping Research

Productive agricultural systems are needed to feed a growing population. However, the intensification of agriculture brings with it ecological trade-offs. Therefore, agricultural systems must be intensified in a sustainable manner to improve ecosystem services while maintaining high productivity. In this context, intercropping systems (IC) can be part of the solution as a form of diversified cropping systems. Intercropping refers to the cultivation of at least two different crop species during the same growing season, either over a specific period of time or entirely simultaneously in the same field. Intercropping can achieve higher total yields and increase yield stability by minimizing the risks associated with monocultures (sole crops, SC). The Land Equivalent Ratio (LER) serves as an main index for comparing the productivity of intercropping systems with monocultures. Productivity advantages of intercropping systems over monocultures typically arise from the complementary use of resources in terms of time and space, for example through different strategies for light interception or nitrogen uptake (N acquisition). Yield formation in mixed cropping systems is influenced, among other factors, by the choice of planting geometry and row arrangement, as these regulate interspecific competition between plant species. Nevertheless, the extent to which general key processes determine the final yield advantage in many different intercropping combinations is not yet fully understood. Therefore, the systematic identification, quantification, and validation of the influence of key processes on yield in intercropping systems is of crucial importance.

The objective of this study is to quantify the influence of the cropping system (monoculture vs. strip cropping) as well as the row orientation of the cropping system (north-south vs. east-west) on the growth of maize and faba bean, as well as on yield of both species. The variables of interest include light interception, biomass (separated into leaves and shoots), LAI, the C/N ratio, and yield.

The study comprises two bachelor’s theses, which can be completed together or independently of one another. A field trial with maize and summer faba bean in a strip intercropping system is planned, which will take place between April and mid-October 2027. Measurements of biomass and LAI for both crops will be conducted at specific time points during the growing season. These include maize emergence, field bean flowering, maize flowering, and full maturity of both the faba bean and maize. Light interception on the other hand, will be measured continuously throughout the growth period from shooting to harvest (approximately every 2 weeks after faba bean elongation). Therefore, Bachelor’s thesis (1) would focus on fewer, labor-intensive measurements of biomass, LAI, and the C/N ratio, while Bachelor’s thesis (2) would focus on the more frequent, less labor-intensive measurements of light interception throughout the growth cycle of both crops using the SunScan. The yield of both crops is relevant to both theses and can therefore be determined together. The experiment is expected to be conducted at the CKA.

We expect that the variables will differ in both the monoculture and the strip intercropping system, and that row orientation will also have an influence.

The experiment will be conducted in 2027 between mid-April and mid-October.

English or German

Interest in strip intercropping systems, field experiments, and sustainable agriculture

Hanna Bernartz, Dominik Behrend

hanna.bernartz@uni-bonn.de, dbehrend@uni-bonn.de