DairyNZ Effluent Pond Campaign

DairyNZ has launched a campaign called “Keep it Low” to encourage dairy farmers to keep the water level of their effluent ponds as low as possible. It follows on last year’s programme to set standards for effluent pond design and construction. North South Farms near Lumsden in Southland, has a well-designed and operated effluent ponding and irrigation system, where the principles of the DairyNZ campaign are illustrated. The farm has both travelling irrigator and K-Line system.

An effluent storage system on a dairy farm (commonly called “ponds”) needs to be well constructed and of appropriate size, but even the best-designed systems won’t cope if the ponds are full and the farm receives sustained wet weather. Hence the DairyNZ campaign “Keep it Low”. Farmers can be caught with overflowing ponds, or by non-compliant effluent irrigating of saturated paddocks. While effluent management is a top priority with all farmers, emptying the pond can be put off because of the pressure of urgent tasks.

DairyNZ’s “Keep it Low” campaign wants to remind farmers to irrigate when conditions allow from mid-summer through autumn, when the wet weather starts, so there is as much free storage in the ponds to help them cope later on. “A full pond means there is really no storage at all,” said Theresa Wilson, DairyNZ development project manager for effluent.

To help spread the message, the campaign is using a magnetic pond level indicator, t-shirts and a “prize pond” photo competition, where the prize is a BBQ hosted by former All Black prop, broadcaster and farmer Richard Loe.  “Having farmers compare their ponds helps us promote good practice for managing effluent ponds,” says Theresa. “Some farmers have said to us that it can also be a psychological issue that full ponds look better than empty ones, so in a light-hearted way we wanted to show off and celebrate good-looking, empty storage ponds.”

Farmers have made good progress meeting effluent management requirements over the past few seasons. Nationally the rate of serious non-compliance fell to 11% last season on the back of clearer information to farmers and improved infrastructure on farms. Theresa says DairyNZ is supporting farmers to bring this rate down further.

North South Farms is a well-established Southland dairy farm (14 years since conversion) 10km north of Lumsden on SH 6, and consists of 480ha of free-draining silt soils, presently milking 1200 cows.

Production is 380-400,000kg MS, wintering half of the herd on the property and growing 35ha of winter feed, fodder beets and swedes.

This dairy is run with a 600 ha support land unit that does cow wintering, young stock and 800 bulls for service bulls of FarmRight herds.

The North South property is owned by an equity partnership and managed by Neil Mitchell and five staff members, plus casuals. The farm dairy is a 50-bale rotary with a 60m rectangular yard.

North South has a sump feed to two weeping wall-ponds, followed by a 60-day storage pond. The effluent system is pumped to a travelling irrigator with GPS or when wet to 60-day storage pond which is emptied by K-Line irrigation. The system is electronically monitored by Smart Farms Systems of Invercargill and Aghub and displayed on-line with auto alerts by text and email. The computer in the cowshed is available for all staff to monitor Ag-Hub (feed, effluent, cow counts, herds and weights, weather and fertiliser).

Smart Farms offers pond monitoring, irrigator monitoring and field moisture monitoring, electronically linked by telemetry to the farm computer and to text alerts. Smart Farm Effluent Monitoring system will automatically shut the effluent irrigator off, whether K-Line or travelling, in the event of a range of circumstances, such as end of travel, irregular pressure, irrigator travelling too slow and many other situations, with the reason for stopping being displayed on the smart hub receiver. Other dairy farm monitoring applications include automatic transfer from effluent receiving sump to holding ponds activated by the high and low level probes, monitoring water trough flow rates and pressure which would indicate leaking water trough lines, field moisture sensors, water tank levels and much more.

Ag Hub is computerised farm management within a decision making portal, containing automated on-farm data capture, virtual displays and GPS maps. The service is internet-based and centrally deployed, which guards against loss and provides for new applications and technologies.

Dairy farmers and their staff members must know their effluent system capacities and emptying rates, according to environmental extension specialist Donna Corbin. She calls this “working backwards”. For example a three million litre capacity pond when full may take up to 3 months to empty at 4 hours pumping every day including weekends (depending on the system capabilities). As well, the application rates and depths of each irrigator must be known and verified, along with the infiltration rates for different soil types (which can also be weather dependent). Knowing what is happening above the soil is easy – if there is pooled rain water, don’t irrigate. However knowing how much capacity is left in the soil when there is no pooling is harder to determine. Environment Southland has a great free soil moisture map on their web site which helps farmers with a broad view of what is happening in the region, but there is also farm specific technology that can let farmers know what is happening on their farm and soil types and even text them how much they can apply. Each farm’s maximum application rate will vary depending upon what is in their individual consent. However, this is a maximum rate and there are times that you may be able to apply sustainably less (or nothing at all) than what is in your consent.

Donna says planning to have sufficient storage available in spring comes down to correct pond size AND planning ahead – preferably starting in February and March. Two thirds of Southland’s “problem rainfall” (which comes when soils are already saturated) typically occurs in August to October, and one third in April-May. So at these times the opportunities to empty storage ponds are limited.

Donna also points out that plans for dairy conversion must include due diligence of soils, terrain, weather conditions and site layout as well as the environmental requirements of effluent storage and irrigation. The process of planning, designing and installing the effluent system is short compared to the ongoing management over the life of the asset that you install. If the management required to run the system is long, hard or difficult, then you and your staff are stuck with it for the life of the storage or until you upgrade it again.

Launched in 2000, FarmRight is a farm investment and management consultancy, which started with three managed farms and has grown to 48, presently running over 30,000 cows and producing over 12 million kg MS.

Tony Cleland is a founding partner of FarmRight and he is currently chairman and farm investment manager. He has supervised a number of conversions over the past 11 years, gaining considerable experience in all facets of dairy conversion. Experience has proven that initial planning, management of contractors and timing is crucial to the overall success of a dairy conversion project. FarmRight employs over 20 people as farm consultants and administrators, and the farms it manages collectively employ over 300 people.