Waterway contamination

Waterway contamination

Waterway contamination

Water can be contaminated by a number of elements, chemicals and waste products from the farm as well as direct access by deer.  (Link to DFLM).  Many of these contaminants have the potential to kill aquatic plants and animals.  However the biggest issue facing sustainable deer farming is nutrient leakage from farmland as the nutrients encourage algal growth.  Algae cause serious deterioration of water quality. The New Zealand public abhorrence to decline of water quality drives political and regulatory impositions on farming. Regional councils monitor water quality and report to other government agencies on water quality status. See also http://www.mfe.govt.nz/environmental-reporting/fresh-water/index.html   

Information on Protecting waterways from wallow and feed pad run-off is available in a convenient DINZ Deer Fact sheet. Print off your own copy here >>

Contamination-causing nutrients

The primary nutrients that affect water quality are also the primary nutrients that are the basis to profitable production on the deer farm: nitrogen and phosphorus. Some nutrient leakage from farming to waterways is inevitable. The challenge to deer farmers is to use the LEP system to minimize all possible avenues of nutrient loss from the deer farm to minimize downstream effects on water quality.    

Nitrogen and phosphorus loss pathways are quite different. Nitrogen generally moves off the farm as leachate sourced from animal urine patches (as nitrate - NO3) passing through soil to underground water aquifers.  Phosphorous is typically lost from the farm in overland runoff during storm events (See also DFLM CSA P-loss pg 30 link). Understanding these different loss pathways for nitrogen and phosphorus is essential to minimizing and intercepting their loss from the deer farm. Deer urine patches are relatively small, like those of sheep, so unlike cattle and dairy cows which have large concentrated urine patches, nitrate leaching from deer is not usually a major issue. However, deer do generally have a relatively high phosphorous loss compared to other species of grazed animals. Phosphorous attaches to soil particles so it is primarily soil disturbance and runoff of ‘dirty water’ that results in high phosphorous-loss from deer farms.

Managing nutrient loss
Nutrient loss from the farm to waterways is influenced by many factors of farm management and the best way to organize an effective approach to dealing with this issue is to- 

  • firstly complete a comprehensive Nutrient Budget (NB) (see pg86 DFLM Link); and 
  • secondly use the NB information to derive a Nutrient Management Plan (NMP) that is an essential part of your Land and Environment Plan (LEP). 

Both the NB and NMP tools are reliant on OVERSEER®.  OVERSEER® is an agricultural management tool which assists farmers and their advisers in examining nutrient use and movements within a farm to optimise production and environmental outcomes.  OVERSEER® estimates the nutrient flows in a productive farming system and identifies risk for environmental impacts through nutrient loss, including run-off and leaching.

Further sources of advice


 Source of advice

Nutrient budget

Fertiliser company representative

courses on Nutrient Management 


nutrient budgeting and proficient with the use of OVERSEER®

Your Fertiliser company representative; or 

independent nutrient consultant

Nutrient management techniques capable of integration into your LEP's Nutrient Management Plan, including recommendations for minimizing nitrogen loss and phosphorous loss from fertilizer to waterways

Landcare Manual pgs 29 -30 

 Methods to limit contamination of waterways by deer

Landcare Manual section 3(b) to 3(d) of the DFLM pgs 20 &21

Best practice management practices for fertiliser application

7 step process for preparing a Nutrient Management Plan for your farm

14 relevant fact sheets

Fertiliser Association of New Zealand's Code of Practice for Nutrient Management

Show me the science

The efficacy of strategies to mitigate the loss of phosphorus from pastoral land use in the catchment of Lake Rotorua McDowell 2010