Arthropod ecology and biodiversity in agroforestry versus conventional cropping practices

Our research involves examining the effects of alley cropping on insect biodiversity, crop yields, and small farm economics. We have investigated two alley cropping practices: a summer crop of alfalfa with black walnut and a winter crop rotation of canola and wheat with heartnut. We compared both practices at two alley widths to conventionally grown crops to determine which arrangement of crop and tree species produces the greatest return while providing the maximum ecological benefits. In the first practice with alfalfa, we found that alfalfa weevil mortality was significantly higher in alley cropped alfalfa compared to monocropped alfalfa, and that arthropod diversity was greater in alley cropped crops compared to conventionally grown crops. Alfalfa yield from wider alleyways was not significantly different from monocropped alfalfa. In the second practice with canola and wheat, alley cropping winter crops provided less competition with trees for water, nutrients and light while providing many of the same benefits found in the alfalfa-walnut system. Insect numbers followed a similar pattern as those found in the alfalfa walnut practice, with more predators in the alley crops than in the conventional crops.