TALK FIRST BEFORE TACKLING EFFLUENT CHALLENGES

CHOOSING A NEW OR UPGRADED effluent system often involves a considerable capital spend, so being involved in the decisions about what will work best for you and your farm is crucial. This is particularly important if you’ve got someone doing your effluent storage calculation for you.

There is not a specific volume of storage your farm needs as it will vary depending on your farm’s location, soils, size, infrastructure and your management.

Take ownership of the decisions being made to ensure the final outcome is a good fit for you and your farm. It’s not all about getting the smallest storage volume, it’s about the ‘right’ storage volume that best fits your farm.

Regional Councils require storage volumes to be calculated using the Dairy Effluent Storage Calculator (DESC). The DESC has a library of more than 30 years of daily climate data (rainfall and evapotranspiration) for most dairying areas throughout the country, and uses this information to model a soil water balance.

The DESC calculates how much effluent is generated each day, and using the historical climate data determines how often soil moisture conditions were suitable for effluent irrigation. If irrigation could take place, it calculates how much effluent would be removed from storage. If effluent irrigation couldn’t take place it calculates how much effluent will be sent to storage. From these calculations it can determine how much storage you will need.

There are many inputs to the DESC that will determine how much storage your farm needs. These include soil risk, water use in the shed, effluent application depths, pump rates, milking season length, herd size, climate, catchment areas, and storm water diversions to name a few. Some of these will be “fixed” on your farm, such as climate, catchment areas, herd size and season length. Others can be variable and up for consideration as a mitigation in reducing storage requirements.

You must get involved with whoever is running the DESC for you. Ask them for a variety of scenarios showing the impact of options on storage and your farm’s management. Where do you want to spend your money; on mitigations or extra storage? Get them to run a number of scenarios that help you decide which options you want to pursue - make them earn their money! You can cost all the different options to get an idea of what you want to pay for. These are some useful questions to ask yourself as you work through the DESC:

• Do I have any low risk soil on my farm that is not currently in my effluent block?

• What would a low depth irrigation system look like on my farm? How easy or hard would it be to manage?

• What would a storm water diversion cost to install? What reduction in storage volume would it give me?

• How much water does my dairy shed currently use?

• Did they measure/calculate my water use or just use an “industry average”? Using industry average will not result in an accurate calculation for your farm

• What would water reduction look like on my farm?

• Green water recycling can have huge savings- did my consultant consider this option?

• How much storage would I need if I chose not to irrigate over calving? When you do the cost benefit of all the options - don’t forget to include the time it would take to manage your system as it’s pointless to choose options that give you the smallest possible storage requirement, but are a nightmare to manage. Choose a system that fits you and your farm- both from a labour/time point of view and cost.

• Logan Bowler is an independent advisor on dairy effluent systems. Call 021 225 9415

TECHNOLOGY AIDS REPORTING

IN 2020 VANTAGE NZ PICKED UP A range of proven tools and technologies to help ensure that effluent is managed as accurately and efficiently as possible.

To ensure that effluent is being applied effectively on-farm, soil moisture and environmental monitoring are vital. Incorporating soil moisture monitoring into your effluent management ensures farmers are keeping an accurate record of how they are affecting soil moisture levels, giving them the insight to adjust application rates based on soil moisture levels as required.

Another easy addition to an effluentbased soil moisture monitoring solution is a weather station to record rainfall and help automate record-keeping of rainfalls compared to when effluent was being applied on-farm.

Utilising an integrated solution through Vantage NZ, with the ability to also work off existing Halo Milk Vat Monitoring systems, provides the best value for money while ensuring that farm information is centrally stored for ease of reporting when it comes to compliance. While monitoring environmental factors to manage effluent is very important, so is proof-of-placement.

Vantage NZ brings to the NZ market the industry-leading suite of Trimble Agriculture precision hardware.

For farms that apply effluent through slurry spreaders, the Trimble GFX- 350 with Precision IQ and Trimble Ag Software allows proof-of-placement maps to be easily captured, the slurry applicator controlled, and the map automatically sent through to the Trimble Ag Software for easy recordkeeping.