A Field Technique for Separating Above- and Below-Ground Interactions in Intercropping: an Experiment With Pearl Millet/Groundnut

SUMMARY A field technique is described in which trenches were dug and vertical polythene partitions installed to eliminate below-ground interactions between component crops in intercropping. With pearl millet/groundnut the control intercrop (i.e. not dug out) gave a yield advantage of 22% compared with sole cropping. A treatment dug out but refilled without polythene partitions was very similar to the control intercrop, indicating that the digging procedure per se had little effect on growth. An intercrop treatment in which below-ground partitions were installed gave a yield advantage of 19% over sole cropping, suggesting that the main determinant of yield advantage was an above-ground interaction between the canopies. However, partitioning decreased millet yield and increased groundnut yield, indicating that below-ground interactions were important in determining the competitive balance of the two crops. It is concluded that the partitioning technique is promising.