[en] Several crop heights, row patterns and planting sequences have been compared in intercropping studies in North Carolina. Grain yields were maximal with 170-180 kg N/ha and there were no significant N rate cropping pattern interactions. Productivity of land was increased 20 to 50% by planting soybeans or snapbeans into corn. Increases up to 80% were achieved by relay interplanting a second snapbean crop into the maturing corn. The increased production was attributed to a leaf canopy being maintained over the soil for a longer period of time. The leaf area duration (LAD) was doubled from 150 to 300 m²-days/m²-land when soybean was interplanted into corn and allowed to mature. The areas where research knowledge is inadequate were outlined, and the role of isotopes in providing the information was discussed. (author)