Young soils are present on new or disturbed areas of land – where there is erosion or sediments being deposited, or on steep slopes, rocky outcrops, coastal sand dunes, flood plains, near active volcanoes, in tidal estuaries, and in cities.
Raw soils cover 3% of New Zealand. These are infant soils that will probably never grow old because they occur where there is constant erosion or sediment build-up. The topsoil is missing or very thin. These soils are not farmed, as the frequent disturbance prevents plant growth, and fertility is limited by the lack of sufficient organic matter to produce nitrogen and other nutrients.
Recent soils cover 6% of New Zealand. They occur where erosion and sediment build-up are low enough to allow well-developed topsoils to form. However, subsoils usually show very little development. Many of New Zealand’s most versatile soils are Recent soils. They are usually fertile and allow plant roots to penetrate deeply, unless rock or dense clay is present.
Anthropic soils cover less than 1% of the country. They are created when people deposit rubbish in land fills, strip away the natural soil, or carry out earth works. Most extensive in urban areas, these soils are also common anywhere the land has been mined.