Dry weather classification expands to North Island
The dry weather in some parts of the North Island has received medium-scale adverse event classification from the Government.
Sustainable management practices play a key role; particularly maximising the return from effluent. Three key components are:
- reducing fresh water use in the dairy shed
- keeping appropriate amounts of nutrients within the root zone of pasture
- keeping nutrients away from waterways and water tables.
But there’s a bunch of considerations when it comes to the performance of your effluent management system. Making sure it’s designed for the best outcome for your farm now and in future is one of the most important.
For example, not all dairy farmers separate effluent solids and liquids. This can have a significant impact on how you then store, distribute and apply effluent on your farm.
Separating has the potential to reduce fresh water use by recycling liquid for yard or pad wash down. It can also provide another source of organic matter and nutrients, beyond the designated effluent application area, that has already been paid for, and is highly valuable to your farm.
Getting back to basics
Let’s get back to basics and briefly overview the effluent management system.
Catchment
Catchment is the where and how much part of your effluent equation - in the cow shed, on the dairy yard, feed pad and silage stacks. The quantity of effluent from each catchment will depend on factors such as rainfall, water diversion, stock numbers and time spent in the area.
Processing
This is where the separation of liquids and solids occurs before the effluent enters your pond. Waste is made up of water, manure and grass fibre (organic matter) and inorganic matter such as light and heavy contaminants, including animal hair, silage, palm kernel, sand, stones and rubbish etc.
Storage and distribution
All the contaminants of effluent should be removed before large volume storage. Your pond sizing and type, and pump size, type and performance fall into this category. These are basically determined by:
- the size of your farm
- herd size and farm management
- the region and its environment
- whether solids and liquids have been separated
- the area to which effluent is applied
- effluent application method.
Application
This is the method of applying effluent to the farm such as travelling irrigators, pump and carry methods or low application methods.
Written in a list like this, it’s easy to assume effluent management is a linear process – and that catchment, first on the list, must also be the most important factor. But that’s not the case at all.
How you apply effluent determines many of the other decisions about the design of your effluent system, and each part of the system impacts on the performance of the others.
Effluent system design
Effluent management is increasingly under the compliance spotlight. Regulations from regional councils vary and in some areas district councils also have rules that need to be checked.
Irrigation NZ, NZ Milking and Pumping Trade Association and DairyNZ recently launched an Effluent System Design Accreditation programme to make sure service companies are working to a code of practices and standards.
The goal is to ensure all New Zealand dairy farmers have systems that can achieve dairy industry and wider community expectations for the land application of dairy effluent.
It is concerned with keeping all untreated effluent out of surface and groundwater; keeping land applied effluent nutrients in the root zone to capture their nutrient and economic value; and ensuring all systems are compliant 365 days a year.
Only a group of companies in New Zealand have achieved accreditation, including GEA Farm Technologies.
This programme signals the direction in which the industry is moving and the importance of viewing your effluent management system as one rather than separate processes. It is increasingly important to ensure you get the best advice from an accredited company that understands the industry’s standards and how to meet them when developing or changing your effluent system.
Accredited companies have been put through their paces, and will consider a broad range of factors when assessing and designing effluent management requirements including land typography, soil types, nutrient status, farming systems and water use.
Separation
There are valuable benefits from separating solids from liquids in effluent, such as improving effluent application and storage in a number of ways.
The liquid component contains only miniscule particles which can improve the efficiency of your pumps. This means you can pump the liquid further to extend your coverage area and there’s less risk of pumps, pipes and irrigators becoming blocked.
You can extend nutrients beyond the existing pump area by carrying solid organic matter to other parts of the farm that your pump doesn’t reach.
You can create cost efficiencies by using the solid matter on areas where you would otherwise apply a purchased fertiliser.
Pond management is improved with less solid settling and surface crusting.
Reducing fresh water use
Separation creates a source of recycled water, reducing dairy shed fresh water use by at least 50%. In some regions this can keep fresh water usage below levels where consents might otherwise be required.
For example, the liquid from some separators can be recycled and used to wash down the yard, particularly if your separator has been tested for the small particulate size left in the resulting liquid (the amount and size of solids left after the separation process).
The Houle slope screen separator has been used and tested for more than 30 years. It is proven to leave only miniscule particles in the liquid effluent – making it a great substitute for fresh water when washing yards.
Results achieved from some farms using this practice have been impressive – with one large farm we know of reducing its fresh water use from 70 litres per cow per day to <30 litres per cow per day.
What makes a good separator?
There are two types of separators: mechanical and passive.
Farmers need to be aware of all the pitfalls and benefits of any separation system. Some are expensive to maintain in dollars and time. Some are complicated, require power and need servicing by tradespeople. Some don’t actually perform as they were sold.
Passive separators don’t require a power supply, have a relatively low maintenance cost and are easy to maintain considering the high rates of effluent they process. No ‘moving parts’ also means minimal wear and tear.
It is recommended to get advice from a company accredited in effluent system design and backed by extensive local industry experience and comprehensive support.
Today, simply selling a pump and burying a pipeline is no longer servicing the farmer or industry to an acceptable level - let alone into the future. There is no such thing as an acceptable short cut.
Most importantly, consider any compliance the minimum standard and exceed it. Future proofing the design of your effluent management system will deliver a range of benefits to your farming business now and in future – economically, environmentally and in practical, everyday efficiencies.
• Murray McEwan is the Houle Solutions and field services technician for GEA Farm Technologies
• This article first appeared in Getting the Basics Right 2014 issue.
