Freshwater

Water use

There are many pressures on farms to improve the water use efficiency of their crops. Optimising water management on a farm utilises best practice methods, which may change over time as our understanding evolves. Tools such as soil-water sensors are useful to identify the current soil water status. Partial rootzone drying is a technique developed for viticulture which deliberately exposes a plant to water stress to bring about physiological changes that can improve the efficiency of water use.

In 2011 the Government introduced the National Policy Statement for Freshwater Management (NPSFM). Regional Councils have been tasked with implementing the purpose of the Freshwater NPS is to safeguard the life-supporting capacity of water and its associated ecosystems, while providing for economic growth and the efficient use of water resources. It also seeks to maintain or improve the overall water quality in the region and protect values of outstanding water bodies and wetlands.

Water quality

Measures required to address non-point source discharges from agriculture comprise of three categories: reduction at source, interception of pollutants on land, and interception or processing of pollutants in water. 4139

Seachange Hauraki Plains (Credit: Raewyn Peart)

Fertiliser and sediment can enter waterways directly or through ground seepage and soil erosion. Measures to reduce this problem include:

  • Ensuring that fertiliser application levels are within the carrying capacity of the catchment
  • Maintaining well vegetated riparian areas
  • Matching the quantity of fertiliser applied to plant requirements
  • Avoiding the application of fertiliser when grass growth is active
  • Avoiding fertiliser applications when rain is likely or when the water table is high
  • Constructing sediment ponds in areas where there is significant run-off
  • Constructing farm roads and tracks on stable low-gradient sites and including frequent cut-off channels
  • Constructing bridges and culverts at frequently used river crossings
  • Minimising cultivation of soil especially in erosion prone areas

The preparation and implementation of farm environmental management plans and nutrient budgets can enable the range of environmental impacts from a single farming operation to be identified and managed. However, the adoption of best practice farm management approaches at the individual farm level, will not necessarily be sufficient to reduce the impacts of farming activity at a catchment level, so that they are within the environmental carrying capacity of the catchment. This may require controls on the location of farming activity, on the use of fertilisers, and/or on stock numbers. 

Horticultural activities may result in nutrients from fertilisers leaching from the soil into freshwater. Such impacts can be reduced by carefully matching fertiliser use to plant requirements and maintaining riparian margins.  Practical and effective Nutrient Management Plans (NMP) are critical to this.  Farmers and regulators need to have confidence in these.  One way of ensuring this is to use a certified Nutrient Management Adviser.  These rural professionals have achieved an agreed standard to provide certified nutrient management advice.

Other resources include:

  1. R Davies-Colley , K Cameron, G Francis, V Bidwell, A Ball and L Pang, 2003, 13-14

Last updated at 11:04AM on November 27, 2015