GRAIN-YIELD AND WEED BIOMASS OF A WHEAT-LENTIL INTERCROP

Intercropping cereal with pulse crops often increases total grain production in subtropical regions, Our objective was to determine if a yield advantage resulted when lentil (Lens culinaris Medik.) was intercropped with wheat (Triticum aestivum L, emend. Thell.) in a cool semiarid region. A held experiment was conducted during 1989, 1990 and 1991 under dryland management in south central North Dakota. Lentil and hard red spring wheat were each sown alone and intercropped in different planting patterns and populations. Plants were hand clipped at the soil surface and threshed to provide grain yield estimates in an 3 yr. In 1991, grain was also harvested with a research combine to assess if intercrops could be harvested mechanically. Grain yield of wheat was unaffected by intercropping (P < 0.05). Intercropping reduced grain yield of lentil by 87 to 95% when yield estimates were based on samples harvested manually, and by 70 to 85% when samples were harvested mechanically. The increased height at which pods formed on intercropped compared with sole-cropped lentil plants and subsequent enhancement in mechanical harvestability of grain in intercrops partially explains this difference in yield estimates between harvesting methods. The land equivalent ratio was 1.15 for grain yield across intercrop treatments with mechanical harvest, and 1.03 for the intercrop treatments when grain was harvested manually. While harvestability of the short-statured lentil aas enhanced in this investigation by intercropping, the low lentil yield under intercropping suggests that wheat-lentil mixtures are probably not adapted to cool semiarid regions.