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  Environment » Natural Resources » Land and soil » All about soil

All about soil

Healthy, well managed soil is vital to the Waikato region’s economy. We have many different soils and it’s important we use them wisely. We describe soils in terms of their characteristics, quality and versatility. Different soils are suitable for different land uses.

Photograph of a soil profile.On this page: Soil supports our region’s prosperity, Soil – more than a load of dirt, Many different types of soil, Soil characteristics, Land capability, soil versatility, soil quality, What Waikato Regional Council is doing Find out more.

Soil supports our region’s prosperity

Soil forms the foundation for plant life on land. It’s one of four major life supports needed for our agricultural economy:

  • sunlight
  • air
  • water
  • soil.

Many of the Waikato’s soils are highly productive. They are a precious resource and need to be managed carefully so they remain productive now and in the future.

Soil – more than a load of dirt

Soil is alive and ever-changing. It extends from a few centimetres to several metres below the ground’s surface - varying from place to place.

Soil is made up of:

  • broken and weathered rock – containing minerals
  • organic matter – decomposed plant and animal remains
  • living organisms – for example, insect larvae, worms, and micro-organisms (such as bacteria and fungi)
  • spaces filled with water and air.

Different soils have different proportions of these basic components, and can be divided into two main groups:

  • Organic soils are made up of mostly organic matter - for example, peat.
  • Mineral soils have mostly mineral-based material, for example, from volcanic ash or rocks such as pumice.

A living layer

Healthy soil is teeming with life. For example, just one teaspoon of soil contains about 100 billion bacteria and about 15 kilometres of fungal threads. These tiny life forms play a vital role in decomposing plant and animal remains. They release valuable nutrients, making them available to plants.

Find out more about the importance of healthy soil and good soil management.

Many different types of soil

There are over 600 different soil types in the Waikato region. Different soils have different properties or characteristics. These characteristics mean that some soils will be more suitable for certain land uses than others. For example, some areas have soils and a climate particularly suited to growing pasture grasses, and others are more suited to growing fruit trees.

Soil characteristics

If you’ve ever dug a deep hole or trench, you may have noticed the soil changing the deeper you go. The upper part of soil contains most of the organic matter and is called the topsoil. Organic matter plays an important role in the health of topsoil because it:

  • contains nutrients that are released when it’s being decomposed
  • absorbs and stores moisture
  • binds soil particles together.

The soil underneath the topsoil is called the subsoil. The subsoil consists of different layers that extend downwards to the rock or ‘parent material’ below the soil. Subsoil can vary in depth from only a few centimetres to several metres.

We can tell different soils apart by looking at the differences in six key characteristics:

  1. Chemical characteristics – for example, the amount of nutrients in the soil or how acidic the soil is.
  2. Colour – often a good indication of drainage. For example, poorly drained soils are usually pale.
  3. Consistency – how well the soil is held together, for example, sticky, loose, or firm.
  4. Soil depth.
  5. Soil structure – the size and shape of soil aggregates, and the space inbetween.
  6. Texture – how the soil feels between your fingers. Texture differs depending on the proportions of sand, silt and clay in the soil.

Land capability, soil versatility, soil quality

There are different methods for working out what different soils can be best used for. Different soils have different characteristics and are located in different micro-climates (with varying amounts of rainfall and sunshine). This results in different limitations on what they can be used for. Find out about land capability classes - one way of assessing the limitations of your land and soil.

Soil versatility

Soil versatility provides a more precise way of finding out what land uses best suit your soil type. Soil versatility tests tell you how productive your soil is, based on:

  • the potential rooting depth for plants – the deeper their roots can go, the more nutrients plants can potentially take up
  • how well the soil can withstand traffic (from vehicles and animals) - related to soil structure and drainage
  • the potential loss of nutrients from the soil - for example, soils that lose a lot of nutrients via leaching may not be suitable for intensive cropping
  • the water deficit – whether there’s enough water in the soil for plants
  • soil drainage – a balance is needed between too much and too little drainage.

Highly versatile soils are suited to a wide range of uses – including cultivation and cropping, which are very demanding on soil. They often:

  • have a deep rooting depth for plants
  • can withstand a certain amount of traffic
  • lose minimal amounts of nutrients
  • have good drainage.

The most versatile soils in the Waikato region are found between Hamilton and Cambridge, and around Matamata and Reporoa. However, some of our most versatile soils are being used for urban development, particularly around Hamilton and Cambridge. Find out more about fragmenting rural land.

You can find out more about soil versatility in the Waikato Region using our soil versatility map.

Soil quality

Measuring soil quality is a way of finding out how healthy a soil is. Measures of quality relate to four main aspects of a soil:

  • fertility – what nutrients are available
  • the amount of organic material
  • physical condition – for example, whether it has become compacted
  • the presence of beneficial soil life, such as earthworms and bacteria.

Find out more about measuring and maintaining good soil quality.

What Waikato Regional Council is doing

The Waikato Regional Council measures soil quality as an environmental indicator for the Waikato region and contributes to a national soil monitoring project.

We also:

Find out more

Check out our publications on land and soil.

For policy information on protecting soil versatility and productivity check out our Regional Policy Statement/ Find out more about the land and soil provisions in Section 5 of our  Regional Plan.

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