Farms are complex systemswith nutrients from many sources cycling through the farm system in different waysA way we can measure and estimate these nutrient inputs and outputs is with a nutrient budget.

nutrient budget is prepared for regulatory purposes and takes into account a farm system’s nutrient inputs such as fertiliser, stock numbers, feed eaten and excreted and supplementary feed used on the property. When coupled with the farm’s location, climate, soil type and management data, OverseerFM can estimate the nutrient flows in and out of the system. This includes nutrient losses to ground and surface water (leaching and run-off), nutrients lost to the atmosphere and nutrients taken up by crops for production.  

Once these nutrients are modelled, changes can be made to the farm system to reduce nutrient losses.  

Why is a nutrient budget important? 

There are two main reasons why a nutrient budget is important. Firstly, a nutrient budget allows you to identify what blocks or paddocks are vulnerable to nutrient losses. Once the nutrient loss information is known, farm management scenarios can be modelled and assessed to find the most efficient solutions. This information can then be used in conjunction with financial and risk analysis to determine the best path of nutrient loss improvement. 

Secondly, a nutrient budget can be used to show compliance with regulations by meeting nitrogen loss thresholds. This is important because it can help determine whether a farm system can operate as a permitted activity (continue as is) or whether it may be required to apply for resource consent (permission required). 

It is important that farm systems are represented as accurately as possible in OverseerFM because modelled nutrient losses can have a significant impact on: 

  • Property values; sale and purchase prices; the lease value of property  
  • Demonstrating the property’s compliance with required nutrient loss values (i.e for an irrigation scheme or consent), as farm system changes occur over time
  • A farm's greenhouse gas profile and potential emissions.

What information is needed for a nutrient budget? 

The nutrient budget information required for input into OverseerFM will vary based on the area or region-specific constraints within which a farm operates (for example culturally sensitive areas, high P-loss risk areas, nutrient allocation zones, nitrate priority areas etc) as well as the farm system type. However, some of the basic information typically required includes: 

  • Farm details including address, owner, contact details and land information  
  • Farm climate data (NIWA 30-year average data is used) 
  • Maps including property, land status, soils, cropping, irrigation, effluent and drainage  
  • Blocking information including what was grown, irrigation, slope  
  • Cropping information including the crop or pasture sown and the fertiliser applied  
  • Animal information including stocking numbers and movements  
  • Supplementary feed and whether it was grown on-farm and/or imported; where it was fed  
  • Irrigation information including the type of irrigation and how much applied  
  • Drainage including the type and position on the property  
  • Fertiliser information including the type and where it was applied  
  • Any on-farm structures and effluent storage methods.  

All nutrient budget input data and nutrient loss information is unique to the farm system, property and period they have been calculated for. This information is collected directly from you, the farmer to ensure the information is as accurate as possible. Input data is ground-truthed at the farm visit via farmer records.