Effect of Traditional Cultivation on Dynamics of Seed bank in Soil Depth and on The Occurrence of Weed Species with Crops

Abstract

   The dynamics of weed seedbank movement in the soil layer 0-40 cm were  studied  under the effect of conventional cultivation at two different locations during three subsequent seasons. Weed seeds were separated from the soil samples by flotation method and then classified. So, the species and numbers of seeds which form the soil seedbank were determind. Results showed that a significant reduction of seed numbers of common weed were found in the deeper layer 20-40 cm of the soil compared with the upper layer 0-20 cm. Most of the seedlings that appeared with subsequent crops germinated from seeds present in the upper layer 0-20 cm. Seed germination is related to buried depth, and the seeds in the upper layer germinate more readily. Also, a positive correlation was found between the seed number at various depths during several seasons. A larg variation was found in the random distribution of weed seeds in the horizontal and vertical soil profile. Therefore, studying the dynamics of the weed seedbank movement in the soil for many seasons can help in determining the flora of the field, and monitoring the infestation of expected occurrence of different weed species with associated crops in a specific growing season. Different formulae to explain the shift of seeds in soil were suggested in this study. These formulae suggest that traditional cultivation may be a useful management tool, as it will alter the periodicity of weed emergence allowing use of more effective control options and may simplify choosing the proper herbicide in order to project an integrated control program.