Why is LandFarming Required?

Drilling for oil and gas produces significant quantities of drilling cuttings. This waste must be disposed of responsibly and sustainably. Sometimes waste is reinjected deep into old wells that have been assigned the purpose of storing waste. Sometimes the best alternative way to dispose of the waste is to use landfarming. Oil & Gas companies who own drill sites that create drill waste must apply for resource consent to dispose of this waste.

During drilling, the slurry is collected and is temporarily stored at the well site.

What's in the Cuttings?

Drilling cuttings consists of:

  • Sedimentary rock – as found underground in locale specific combinations
  • Clay, knows as bentonite clays
  • Hydrocarbons (oil and gas)
  • Minerals and salts – varying concentrations of minerals that are found underground including: barium sulphate.

While there may be other components involved, such as drilling liquids or additives, these are understood to be present at such low concentrations that they do not contribute to the toxicity of the waste.

Transport & Storage

The cuttings are transported from the drill site to the land farming location.

Before landfarming begins, baseline data is collected for surface water and groundwater quality, flow paths and soil characteristics. This information provides an assessment of the site suitability for a landfarming operation. If resource consent is granted, monitoring by the regional council ensures consdent conditions are complied with.

The cuttings are usually stored at the land farm until the correct volume of material is ready to be distributed over the land. It is stored in lined pits to ensure the material is contained prior to distribution over the land.

Spreading & Fallow

The cuttings are spread over the land, using trucks, and dug into the soil by tractors.

The land is left for a period of time to allow naturally occurring microbes to breakdown the organic compounds found in the waste – particularly the hydrocarbons, which of all the contents of drilling cuttings are the most likely to contribute to observed toxicity.


The land is tested to ensure soil quality falls within approved levels of mineral and other content. Testing is monitored by regional council staff to ensure the activity meets with resource consent considerations.

What's the value of LandFarming?


Landfarming achieves the best return of value to the farmer if it’s done on ‘marginal’ land - like sandy soils near the coast. In their original state these fields are relatively unproductive and of low per hectare value.

Research suggests dollar values of previously marginal land increase from around $3,000 - $5,000 per hectare to $30,000 or $40,000 per hectare once subject to landfarming. This represents major added value for the farmer.

Is LandFarming Safe?

According to all reports and testing to date, Landfarming is a safe and sustainable way of disposing of drilling cuttings, and of enriching less productive, marginal farming land.

Landfarming as a practice is controlled under the RMA, as administered by local councils.

In Taranaki, there are specific resource consent conditions to minimise negative environmental impacts.

  • All waste must be stored onsite in lined pits to reduce risk of rain-effected run off
  • Groundwater monitoring must take place

Oil and Gas drilling waste slurry does include deposits of minerals that in concentrated form can be toxic to the environment, animals and people.

However, according to research the presence of these minerals is so low there is no evidence that landfarming adversely effects levels of toxicity in pasture.

If landfarming does take place, the Ministry of Primary Industries advises that the land is not stocked and crops not harvested until the concentration of hydrocarbons in the soil are at or below the values specified.

Landcare Research analysis has determined that, once these values have been reached, no risk to food safety or animal welfare exists as a result of spreading rocks and minerals on the land, and the land can be used for any purpose, including for stock or crops to produce meat, milk, fruit or vegetables.

Additionally, ‘landfarming is a valid and environmentally acceptable means of waste treatment with appropriate controls. There is no reason why such landfarming should not continue, subject to controls being imposed by means of consent conditions appropriate to each site and the waste being handled.’

Some Issues around LandFarming

In 2013, Fonterra published its decision to not take milk from stock grazing on new landfarms.

In their decision, Fonterra made no reference to any proof that stock or milk products from that stock were in any way adversely affected by toxicity from landfarming, blaming instead the high cost of testing.

“…given the high costs of testing [for petrochemical contaminants](around NZ$80, per annum) we made the decision earlier this year that no supply will be accepted from any further dairy farms where land-farming is proposed.

Fonterra also noted ‘The area of NZ dairy farm land associated with land-farming is extremely low with only two farms supplying Fonterra. We have completed a thorough assessment of the practice, including specific residue testing, and we’re confident that it poses no risk to the integrity of our milk’