Intercropping potatoes in early spring in a temperate climate. 2. radiation utilization

Three experiments on intercopping potatoes with cabbage are reported in which the cabbage crop was transplanted between rows of potatoes prior to planting. The cabbages were removed before the canopies of the component crops overlapped, but comparison with sole crops showed that the ground cover of both crops had been retarded. This early competition affected both the amount of radiation intercepted by the potato crop and its efficiency of conversion into dry matter. As a result the sum of the radiation intercepted by the intercrops in no instance exceeded that of the sole potato crops. The evidence suggests that largely before any significant competition for light due to mutual shading, competition for water, nitrogen and possibly other essential elements, took place, with repercussions for canopy growth for the remainder of the growing season.