Dairy effluent management: how storage and application practices affect farms
Farm dairy effluent systems handle waste generated by dairy operations. Selecting or upgrading equipment requires professional advice, a clear assessment of operating requirements and consideration of future farm plans. The system needs to remain suitable across successive milking seasons. Terrain, climate and soil characteristics all influence the choice, alongside the selection of an appropriate person to undertake the work. Gathering information and establishing requirements are part of the planning process before installation or an upgrade.
Storage requires its own planning and design. Available options include lined ponds and tanks built above ground, with the choice depending on costs, site conditions for installation and local regulatory requirements. Pond liners can use compacted clay or synthetic materials, including polyethylene. The Dairy Effluent Storage Calculator helps assess the capacity a farm needs, while instructional videos and technical publications support planning and construction. Each storage option has advantages and disadvantages that need to be considered when choosing a facility.
Properly designed and built storage can save time and money, give farmers greater flexibility over irrigation and support efficient use of both nutrients and water. Other benefits include environmental protection and a lower risk of breaching effluent requirements. Storage levels need active monitoring, with contents reduced during favourable weather so that facilities do not enter higher-risk periods already full. Planning and working with suitable people are identified as central to constructing an effective storage facility.
For pasture application, a management plan gives the farm team a framework for operating the system. Soil moisture deficit determines when land can receive effluent without becoming saturated. Spreading when that deficit is sufficient allows plants to absorb nutrients and helps avoid surface run-off. The DairyNZ Farm Dairy Effluent Spreading Calculator is available to guide nutrient application. Understanding how much additional water the soil can accommodate is therefore part of deciding when to irrigate.
Application intensity and total depth also need to match the soil’s capacity to absorb liquid. Effluent should infiltrate without collecting on the surface, flowing away or draining below the root zone. Routine servicing of irrigation equipment supports its performance, and repeated bucket tests check whether the system is delivering effluent as intended. Maintenance, performance testing, application timing and storage monitoring are all components of the proposed team management plan.
Odour is becoming a greater concern as dairy herds expand and urban development moves closer to working farms. Potential sources include storage ponds and tanks, equipment that separates solids, accumulated sludge, feed pads and silage stacks. Spreading effluent or manure and removing sludge from ponds can also generate smells. Odour management features in effluent consents and can become a matter of compliance with regional council requirements.
A regional council receiving an odour complaint will visit the farm to assess conditions; possible consequences include infringement or abatement notices. Farmers receiving a neighbour’s complaint about an objectionable smell must investigate its origin. Such episodes generally subside quickly. Although an effluent pond is often responsible, the investigation should also check whether effluent held in the main lines is causing a problem.
