Abstract
Inadequate land use has been considered worldwide as the number one contributor to land degradation, water pollution, and global warming, which are the major threats to agricultural sustainability. The detrimental effect of soil tillage on soil structure has forced science to look for alternatives to slow down the process of soil degradation. Zero tillage practices are the most efficient practices for the purposes of soil and water conservation. These practices minimize soil disturbance and maintain as much residue cover as possible in order to conserve soil moisture by reducing surface runoff and evaporation, protect the soil surface from both water and wind erosion, and reduce the energy resource inputs. A zero tillage crop production system was initiated at Hokkaido University Farm in season 2006. Based on the experimental results of season 2006, further evaluation of the system performance on various soil strengths was needed. Therefore, the major objective of this study was to evaluate the influence of the initial soil strength on the establishment of soybean crop. Three plots of soil strength representing the three treatments (tilled field, medium soil strength, and high soil strength) were applied. Edible soybean (Soya hispida) (Japanese variety, Tasty) was used as the test crop. The results showed no significant differences in the population rate and plant height between the three treatments. Furthermore, the results showed no significant differences in the soybean yield dry weight, the number of pods per plant, the number of seeds per pod, the number of seeds per plant, and the shoot dry weight per plant. In summary, the results indicated that the establishment of soybean was not significantly influenced by the initial soil strength for the tested field conditions. Further research work on the performance of a zero tillage seeding machine is highly recommended.