 By contrast , fishing has declined in Orkney since the 19th century and the impact of the oil industry has been much less significant . However , the soil of Orkney is generally very fertile and most of the land is taken up by farms , agriculture being by far the most important sector of the economy and providing employment for a quarter of the workforce . More than 90 % of agricultural land is used for grazing for sheep and cattle , with cereal production utilising about 4 % ( 4 @,@ 200 hectares ( 10 @,@ 000 acres ) ) , although woodland occupies only 134 hectares ( 330 acres ) . 
