Key points

Losses of the nutrients nitrogen (mainly via leaching) and phosphorus (mainly via runoff) to water bodies contribute to algal growth, which leads to a decline in water quality. Nitrogen may also contaminate groundwater, making it unsuitable for drinking. Nutrient losses generally rise with increasing fertiliser use or excessive soil fertility. While soil nutrient levels should be maintained to ensure sustainable pastoral farming, excessive nutrient inputs should be avoided. Conversely, adding too little nutrient to the soil will result in exhausted, unproductive soils. Monitoring of nutrient inputs (such as fertiliser addition) and losses allows us to determine the optimum soil nutrient requirements and assess the risks to water quality.

• Nitrogen fertiliser use on sheep/beef and dairy farms in the Waikato region is increasing, with dairy farms tending to use more nitrogen fertiliser than sheep/beef farms.
• Nitrogen leaching is increasing at a similar level for sheep/beef and dairy farms.
• On average, phosphorus fertility on dairy farms is near the maximum for a high producing farm. Many soil samples from volcanic and sedimentary material show excessive phosphorus fertility. Fewer sheep/beef farms have excess phosphorus fertility.

Source: Environment Waikato

What agencies are doing

• Environment Waikato tracks changes in fertiliser use and nutrient loss to update this indicator and to assist with policy making and resource consent decisions. Find out more about the rules for fertiliser use in our Regional Plan.
• We are working to reduce phosphorus content in runoff, through soil conservation programmes and the Clean Streams project.
• We support voluntary guidelines and codes of practice such as the NZ Fertiliser Manufacturer’s Research Association Code of Practice for Nutrient Management.
• We provide staff time and expertise to support landcare groups in the region that are involved in riparian management such as planting and fencing.
• We provide environmental information including reports on practical land management guidelines.
• We encourage the use of nutrient budgeting.
• We regularly monitor levels of nitrate and phosphate in groundwater and surface water. These are indicators of the amount of nutrient lost from the land.

What you can do to help

• Get your fertiliser representative or farm advisor to do a farm nutrient budget so as to avoid applying unnecessary fertiliser and thus save money.
• Ask your farm advisor about modern farming practices that can be used to reduce nutrient leaching and nutrient runoff. Modern practices include a nutrient budget, a farm nutrient management plan, strategic grazing, nitrification inhibitors, altering the feed composition and alternative fertiliser products.
• Waterway margins form an important barrier between land and water. Fence off and protect drains, wetlands and other wet areas. These can act as buffer zones, remove nitrogen from the water before it reaches streams. Fence near streams and rivers to allow a thick grass sward to develop on the stream edge. The sward will help filter out dirty runoff containing nutrients.
• Avoid pugging in paddocks adjacent to streams.

More information

More detail on this indicator, including how and where this information is collected, is available here.

What we want to achieve

The community outcome we are seeking to achieve by monitoring fertiliser use on farms is:

• We use land management practices that protect and sustain our soil and land.