Nutrient budgets - a key indicator of soil sustainability

Abstract

Sustainable land management is now embedded in New Zealand law in the form of the Resource Management Act, 1991. Nutrient budgets and soil tests are seen as important tools for monitoring soil chemical sustainability. Nutrient budgets require that all inputs and outputs of nutrients from a farm are quantified. The aim is to ensure inputs and outputs are in balance thus producing a sustainable system. Recent experience suggests that using the study group (or Landcare group) approach is an effective way of introducing the nutrient budgeting approach to farmers. At the same time a computer software package ('Overseer') for assisting the calculations involved is being developed and tested. P nutrient budgets for two Waikato dairy farms suggest that surplus P is being produced. Such information provides a basis for future decisions on P fertiliser inputs to balance the P requirements for production against those for sustainable land management. Nutrient budgets can be aggregated to the regional and national level as required. By being able to calculate nutrient budgets in this way, New Zealand will be in a good position to _ demonstrate a commitment.to.nutrient.management~ thus ensuring continued and perhaps enhanced market access for our agricultural products. Keywords: dairying, nutrient budgets, study groups, sustainable land management