Effluent app aids nutrient loadings, application rates

Get it right and your farm will save fertiliser, improve soil condition, prevent animal health issues and comply with council rules or resource consent.

The key to all this to understand soil water deficit – essential to prevent ponding and run-off and to avoid applying effluent to saturated soils.

Soil water deficit is the amount of water, or effluent, which can be applied to the soil before it reaches field capacity (the amount of water held in the soil after excess water has drained away). 

If effluent is added at field capacity it will likely result in ponding, runoff or leaching.

According to DairyNZ, the average dairy cow produces about $25 worth of nutrients annually as farm dairy effluent (FDE) –  from a 400 cow dairy herd about $10,000 of nutrients annually. 

If these FDE nutrients are used effectively the fertiliser bill can be much reduced. 

The DairyNZ farm dairy effluent spreading calculator (an app) allows farmers to easily calculate nutrient loadings and application rates for dairy effluent based on a number of customisable inputs. 

This means farmers
can manage the application of their effluent nutrients with greater precision.

There are two calculators in this app: a quick calculator for spray irrigation systems such as travelling irrigators and sprinklers, and an advanced calculator for slurry tankers and muck spreaders. It is also available as an Excel spreadsheet if you prefer to use your computer.

Ask the right questions on soil, landscape

When deciding whether to install or upgrade a farm dairy effluent system it’s important to ask the right questions, gather information and take professional advice.

You want the system to work well for many milking seasons so consider the following:

• Find the right person for the job
• Establish your system requirements
• Make sure future plans are taken into account.

Most crucial is how landscape and climate affect effluent management. The main factors in the success of effluent application are:

• Soil drainage characteristics
• Landscape contour
• Rainfall and soil moisture deficits.

Management practices need to be matched to soil and landscape risk to prevent loss of effluent into the surrounding environment.

New Zealand soils are classified in high and low soil risk categories for farm dairy effluent application.

New technology allows for the development of tools and programs to help with effluent, water, and nutrient management decisions on farm. 

Many expensive regional council fines can be avoided if a fail-safe device is installed on an irrigator.