Effects of continuous application of rice [Oryza sativa] straw compost on growth of spring harvest cabbage [Brassica oleracea] and chemical properties of andosol

In order to clarify effects of continuous application of rice straw compost to a reclamation field on the growth of spring harvested cabbages and chemical properties of Ando soil, the process of fertilization by successive applications of the compost was investigated for 11 years beginning 1981. After that, the capability of nitrogen release from fertilized soil was estimated by the combined treatments of successive applications of the compost and the rate of synthetic fertilizer for 11 years beginning 1992. The results obtained are summarized as follows; 1. As a result of continuous application of compost and plowing-in of plant residue to the reclamation field, the growth of cabbages was improved and head weight became larger. This tendency was remarkably observed in the year when the growth was delayed generally by the climate condition and the head formation took place at the late spring in which it was not easily influenced by the temperature condition. 2 . Simultaneously humus content and CEC in the soil were increased by both continuous applications of compost and plowing-in of plant residue and the available phosphorus content was increased by the plowing-in. 3. As a result of combination of continuous compost application and standard fertilization to the fertiled field, the growth of cabbages progressed and head weight became larger. This tendency was remarkably observed in the year in which the head was formed at the late spring which growth was generally overdue from a climate factor and was not easily influenced of temperature during head formation period. This tendency was also remarkably observed in the year when growth, the head formation period, and the harvesting time became delayed generally in all treatments. 4. In the year in which the growth in the early stage was promoted, head weight became larger because the head formation took place at a relatively high temperature as the result of delayed head formation due to the reduced application rate of the synthetic fertilizer. 5. High humus content induced by successive application of compost resulted in retention of nitrogen and phosphorus in the soil, and subsequently made the total and available nitrogen content and the available phosphorus content increased. Moreover, high CEC in the soil might made the exchangeable K, Ca, Mg contents increased. Eutrophication of such soil might influence the initial growth and head weight.