Distribution, prevalence and intensity of earthworm populations in arable land and grassland in Scotland

aporrectodea arable soils earthworms especies estructura del suelo fertilidad del suelo grassland soils labranza lumbricus oligochaeta population density soil fertility soil structure soil types sol arable sol d'herbages species structure du sol suelo de praderas suelos cultivables tillage tipos de suelos travail du sol type de sol