Extending an organic rotation with intercropping of forage crops

Field experiment 8, Switzerland

Field experiment 8 trial overview. Photo: Maike Krauss

Field experiment 8 faba bean/oat intercrop. Photo: Maike Krauss

Trial location and duration

Location: Fislisbach, Switzerland (47°42’77’’, 8°29’05’’, 423 m a.s.l.)
Trial duration: 2018-2021

Objectives and research question

Intercropping with legumes is of interest in terms of reduced fertiliser input, better weed suppression and yield stability. We hypothesized that above- and belowground resources are more efficiently used resulting in higher overall yields with a good quality. We also hypothesized that spatial and temporal diversification creates a more attractive habitat for above- and belowground organisms.

Experimental design

The trial has four replications in a randomized block design with plots of the size 15x30 m (Figure 1). The three treatments are a Reference organic rotation (REF1), a diversified organic rotation with intercropping (DIV) and a maize/sorghum rotation (REF2). The crop rotation is shown in Table 1.

Figure 1: Spatial trial design of field experiment 8

Table 1: Crop rotations in field experiment 8

Field experiment 8 sorghum harvest. Photo: Maike Krauss

Main findings and highlights

Intercrops produced more yield per ha than single crops
Legumes in intercropped plots increased biological N fixation compared with single legumes
Intercrops were more resilient regarding diseases and lodging
Soil organic carbon levels did not change after four years
Earthworms in the diversified rotation had more offspring than in the organic rotation and both more than under short rotation

Main challenges

European corn borer forced to change from maize monoculture to maize/sorghum rotation
Unfavourable weather conditions caused non-emergence of undersown cover crop in 2019 and lodging of faba bean in 2020