Spatial Arrangement Affects Growth Characteristics of Barley-Pea Intercrops

The effect of spatial variation in the planting arrangement on characteristics of a 50:50 barley/pea intercrop mixture was studied. The three planting arrangements were (i) complete seed mixing within rows, (ii) the two species cross drilled at right angles and (iii) alternate pairs of rows of the two un-mixed species. Pure stands of barley and peas were included for comparison. In all cases, dry matter production from intercropping was greater than that from sole crops; however, planting arrangement did have a significant effect. Land equivalent ratio (LER) values were 1.26, 1.25 and 1.16 for the mixed row, cross drilled and alternate row arrangements, respectively. The alternative row strategy produced significantly less LER value than the other two arrangements. While, there was an increase in LER values in both the component species of the mixtures, the magnitude of effect was greater with the barley (average of 30.0% increase) than it was with the peas (average of 14.8% increase). Grain/seed yields of both components of the intercrop mixtures were greater than would be expected if these were expected to yield half that of the sole crops. The increases were brought about by an increase in the number of ears m-2 in barley and pods m-2 in peas. Analysis of N uptake suggests that greater N availability for the barley component of the mixture was the mechanism responsible for the increased barley yields. Improved pea growth is likely to have arisen from the support offered by the barley plants, which was greatest in the mixed and cross rows, but least in the pairs of alternate rows. © Friends Science Publishers