The principle of intercropping (mixed cultivation) is based upon the simultaneous cultivation of different plant species on the same acreage. In doing so, one obtains a main crop and a secondary crop (Fig. 1). Ideally, intercropping makes it possible to better exploit limited soil resources; at the same time, the absorption of nutrients can be improved and economically interesting effects achieved.
Materials and methods
This two-year investigation was carried out in Gand in the municipality of Martell (South Tyrol). The strawberry plants (Elsanta, type WB-Waiting Bed) and different complementary plants were transplanted in May of 2020 in a double row on raised beds under tunnel conditions, adopting an intercropping system and a monoculture.
The rows were divided up into parcels, each consisting of
18 strawberry plants (50,000 plants per hectare) and nine plants of each complementary crop (25,000 plants per hectare) (in a ratio of 2:1). In order to be able to compare this system with a crop grown in monoculture, separate parcels were also established exclusively with strawberry plants or with the given complementary crop. All strawberry plants were treated in pre-flowering with sulfur to limit the spread of powdery mildew..
Results
Generally, intercropping combinations did not increase the marketable yield of strawberry plants (Table 1). The only exception was a combination of strawberries and peppermint (+10% increase in yield). In all other combinations, the decline in yields can be attributed to the competitive effect between the different crops. This applies also to the usually smaller yield of the secondary crops. Peppermint and chives represented the only exception, insofar as their yields increased by 20 to 40% with practice of intercropping as compared to monoculture.
Using the parameter of “Land Equivalent Ratio” (LER), production results can be examined in greater detail. The LER indicates the relative surface area which would have to be cultivated in monocropping in order to achieve the same yield as in intercropping. As Table 2 indicates, all plant combinations – except for strawberry and calendula – had an LER of more than 1; this indicates a more efficient utilization of soil in intercropping systems.
