Objective  Means to utilize straws of tomato and chili pepper plants after harvest on solanaceous vegetable fields were explored.

  Method  Pot experiments were conducted to study the effects of crushed fresh straws, crushed sun-dried straws, and composted straws from tomato and chili pepper plants for fertilization/soil conditioning on the seedling growth of solanaceous vegetables (i.e., tomato, chili, and eggplant) and the allelopathy of the vegetable field.

  Result  Application of the crushed fresh straws not only significantly inhibited the seedling growth but also induced a significant negative allelopathic effect on the soil. The effect was particularly pronounced in 30 d after the straws were turned into the ground where same family of vegetables was planted. Whereas, when the crushed sun-dried straws were applied, a negative allelopathic effect on the 3 solanaceous vegetables also appeared in 10 d but dissipated after 30 d and followed by a significantly vigorous root growth of the seedlings. On the other hand, the composted straws showed a positive allelopathic effect immediately after the application that continued to enhance with time.

  Conclusion  For solanaceous vegetable farming, tomato and chili straws after composting could conceivably be returned to the field for desirable results. The crushed sun-dried waste material could be added to the soil at least 30 d after seedling planting to mitigate the negative effect. Using the fresh straws, however, would require further study to firstly resolve the harms brought about by the direct application.