Earthworm and Enchytraeid Numbers in Soybean-Barley Fields under Till and No-Till Cropping Systems in Japan during Nine Years.

摘要

Over a period of 9 years, earthworm and enchytraeid numbers were measured in soybean-barley fields under different cropping systems in Japan. Throughout the surveyed period, there were no earthworms in the tilled field without mulch (CT) and a few inthe no-tillage field without mulch (NT-m). In the no-tillage field with organic mulch (NT+m), earthworms were first collected in the third year of treatment, and their number was small for the succeeding three years. The number increased from the seventhyear on, and reached its largest size in the ninth year. In this field, lumbricids were dominant in the first half of the surveyed period, and megascolecids in the latter half. The number of enchytraeids was smaller in the CT treatment field than in thetwo NT fields. During the summer or autumn months of the third year the number of enchytraeids in the three fields was at its largest, and then gradually decreased with the years. Especially in the NT-m field, its decline was steep. Seasonal fluctuations in the enchytraeid population of the two NT treated fields were not clearly defined, having one or more peaks in many years, and these fluctuations were strongly influenced by the population size of the dominant genus, Fridericia.