The beginners guide to soils in New Zealand

Allan Hewitt of Landcare Research in New Zealand has prepared this beginners guide.  It is a great pespective on soils. Enjoy!

 The soil is called a Pallic Soil because of its pale colour.

Some soils are made of dust

This soil in New Zealand is made of rock dust produced about more than 18 000 years ago in glaciers. Rocks trapped by glacial ice were ground up into powder ,which was picked up by strong winds and blown across the land.

The soil is called a Pallic Soil because of its pale colour.

In the middle of the soil a hard layer stops the penetration of roots and the drainage of water. This reduces the versatility of land use on this soil. It is mostly used for sheep grazing.

 The soil is called a Podzol Soil and exists in areas with very high rainfall. The material in which the soil has formed is from pumice. Soil as sour as a lemon

This is a very acid soil – about as acid as a sour lemon.
It got this way because acid producing trees have been growing in it.

The layers show one of the effects of the acidity. The top layer is black because it has a concentrated organic matter. The white layer below it is has been bleached because rain has washed the acid thru the soil and removed the coloured minerals. Underneath, the brown colours show where the coloured minerals accumulated. The acidity is associated with very low fertility, which is quite acceptable to many New Zealand native forest species.   

The soil is called a Podzol Soil and exists in areas with very high rainfall. The material in which the soil has formed is from pumice.

 

 The soil is called a Recent Soil – meaning that it was recently formed. It Layers of fertility

Layers in the bottom of this soil are a record of alternating floods of sand and silt, deposed from flood waters from a nearby river. These layers are usually obliterated through mixing by roots, insects and worms. The fact that we can still see them means that the soil is young. In the upper part of the soil the black streaks are worm burrows. Here their mixing action has already churned and destroyed the original layering.

The soil is called a Recent Soil – meaning that it was recently formed. It is highly fertile because the natural fertility has not yet been washed out by rain. It is also fertile because the soil is soft and roots can potentially explore all of the volume of the soil.  It has much soil organic matter which provides good storage of phosphorus. It also is excellent for filtering pollutants out of contaminated water.

thirsty soil  Sign of a thirsty soil This Semiarid Soil is formed in stony alluvium deposited about 10,000 year ago by a river that has now gone.The white layer is made of lime (calcium carbonate) but is not formed from limestone. It formed in the soil by a reaction between calcium weathered out of the stony alluvium, and carbon dioxide contributed from the breath of microbes living in the pores of the soil. For soils in wet places this lime is washed away by rain water, but here there is so little rain that the lime remains.The soil is poor for crops because of the low rainfall, and also because the many stones reduce the amount of good fine soil available for trapping any rain that does fall. Stored water for roots to suck on is greatly limited.
 tidy pedologist

A tidy pedologist

A truly remarkable sight. Normally a dirty job, this pedologist has dug a neat pit that exposes all the important features of the soil, and is now describing it. He is using a standard colour book to measure the colours.

Colour is an important soil property as it indicates the soil age, wetness, the amount of soil organic matter, and thickness of the various layers. This along with other properties (e.g. structure and texture) will be entered into a database to make soil maps that will assist good soil management.  

We hope the pit was as neatly filled in when he was finished.