| If native soils on the filter strip site are highly compacted, or of such low fertility that vegetation cannot become established, they should be tilled to a depth of 300 mm and amended with [[compost]] to achieve an [[organic matter]] content of 8 - 15 %. | | If native soils on the filter strip site are highly compacted, or of such low fertility that vegetation cannot become established, they should be tilled to a depth of 300 mm and amended with [[compost]] to achieve an [[organic matter]] content of 5 - 15 %. |