Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Background

The soil's physical properties are vital to the ecological and economic sustainability of land.

They control the movement of water and air through the soil, and the ease with which roots can penetrate the soil. Damage to the soil can change these properties and reduce plant growth, regardless of nutrient status. Decline in the physical properties of the soil can take considerable expense and many years to correct, and can increase the risk of soil erosion by water or wind.

Soil profile
The primary functions of the soil are to provide plants with air, water, nutrients and a rooting medium for growth and physical support.

Safeguarding the soil resource for present and future generations is a key task of land managers. Loss of soil condition (soil degradation) can significantly affect the environmental sustainability of the soil, and the economic sustainability of farming businesses.

There is more to measuring soil condition than just assessing carrying capacity, crop yield or soil fertility. Often, not enough attention is given to:

  • the basic role of soil condition in efficient and sustained production
  • the effect of soil condition on the farm's gross profit margin
  • the long-term planning needed to sustain good soil condition
  • the need for land managers to be able to identify and predict the effects on soil of the condition of their short and medium-term land management decisions.

As a land manager, you need reliable tools to help you make decisions that will lead to sustainable land management. The way you manage your farm has profound effects on your soil, and your soil has profound effects on your long-term profit.

Many physical, biological and, to a lesser degree, chemical soil properties show up as visual characteristics. Changes in land use or land management can markedly alter these. Research in New Zealand and overseas shows that many of the visual indicators are closely related to key quantitative (measurement-based) indicators of soil condition.

Visual assessment provides an immediate, effective diagnostic tool to assess soil condition, and the results are easy to interpret and understand. Compare a soil under well-managed pastoral grazing, and under poorly managed long-term continuous cropping.

Visual assessment provides an immediate effective diagnostic tool to assess soil quality.

These relationships have been used to develop VSA. The VSA Field Guide has been developed to help land managers assess soil condition easily, quickly, reliably and cheaply on a paddock scale. It requires little equipment, training or technical skills. Assessing and monitoring soil condition on your farm with VSA, and following guidelines for prevention or recovery of soil degradation, can help you develop and implement sustainable land management practices.

VSA provides a useful educational and vocational training tool for those unfamiliar with soil science. It can bring a better understanding of soil condition and its fundamental importance to sustainable resource and environmental management. In particular, VSA can develop a greater awareness of the importance of soil physical properties (such as soil aeration) in governing soil condition and on-farm production.

VSA is based on the visual assessment of key soil 'condition' and plant 'performance' indicators of soil condition, presented on a score card. Soil condition is ranked by assessment of the soil indicators alone. It does not require knowledge of paddock history. Plant indicators, however, require knowledge of immediate crop and paddock history. Because of this, only those who have this information will be able to complete the plant indicator score card satisfactorily.

VSA provides a useful educational and vocational training tool for those unfamiliar with soil science.