Abstract
We studied the effect of soil dressing on crop productivities to establish an desirable management of organic matter in the field dressed with Pumice Flow Deposit (PFD). In the frame experiment, a decrease of crop yield may be mainly caused by dilution of soil chemical fertilities. The application of 40 Mg ha1 barnyard manure and green manure simultaneous with dressing recovered a decrease of crop yield. In the field experiment, changes of crop yield after dressing was influenced by the both of soil chemical and physical properties. The crop yield might not decrease in the field when the soil physical properties were well improved enough to compensate dilution of nutrients and in case that a-glucosidase activities did not decrease to the value estimated. In order to recover a decrease of crop yield, the application of 40 Mgha1 barnyard manure would be recommended. More significant effects were obtained in case that 80 Mgha'1 of barnyard manure was applied. Green manure should be additionally cultivated after dressing for the recovery of primary yield downfall. These effects of barnyard manure has continued at least for 3 years.
