Optimising effluent use on farms | Hill Laboratories - NZ

Optimising effluent-use on farm with Hill Labs

Optimising effluent-use on farm with Hill Labs

Date: 16 Oct 2020
Author: Hill Laboratories

With the changing landscape of New Zealand farming, it’s more important than ever that dairy farmers have all their processes in order, to meet the high standards that define our primary sector.

Nutrient management is a key area and it has now become a very precise process, so that pasture and animal response is optimised, soil health is maintained, and waste is minimised. Productive, sustainable farms with a light environmental footprint is the goal.

Part of the nutrient management process is making sure farm dairy effluent (FDE) is handled appropriately for the farm system and within approved rules.

Effluent has historically been viewed as a waste product to get rid of, but in fact it is a valuable source of nutrients. It is now commonplace to spread FDE on to land, using designated blocks for application. Those blocks are included in nutrient budgets that model potential losses to the environment, based on the area receiving the effluent.

Over recent years, researchers have also shown that FDE can be well-utilised on cropping paddocks that are part of the dairy platform. Paddocks which have a long history of effluent application may have a large bank of nutrients in the soil which have yet to be utilised.

Dairy effluent, depending on its treatment, can be particularly high in nitrogen and potassium which makes it an ideal fertiliser for maize crops for instance. Deep-rooting crops, such as maize, can mop-up the stored nutrients in effluent paddocks, thus recycling these valuable nutrients to other parts of the farm when fed-out and therefore reducing potential leaching losses.

It is important to understand that the nutrients in effluent applied to land tend to be in a slow-release form, with only ~50% of the nitrogen and phosphorous available in the first year of application (potassium is almost all available). For this reason, it is likely that in repeatedly-cropped paddocks, additional fertilizer nutrients will be needed for some crops.

Farmers may have limited insight on the nutrient composition of effluent being applied, which can change through the season, depending on the type of feed in the cow diet and also the time of year.

Testing your dairy effluent’s nutrient composition is a crucial step to optimise effluent use, and should be done a few times per year due to these seasonal variances.

Effluent testing should be seen as an important part of nutrient management along with soil and pasture testing. The more nutrients that can remain on-farm, the more value will be retained by the farmer and the better it will be for the environment.

Unless the effluent is measured for its nutrient content, the application rates of nitrogen can only be calculated using assumptions of the effluent composition. This may lead to over application of nutrients, resulting in non-compliance and potential environmental risk.

Hill Laboratories – New Zealand's largest privately owned analytical testing laboratory – have led the way in analytical testing for many years using the latest technology and methods.

Hill Laboratories makes it easy to do a regular testing programme, with their DIY Dairy Effluent Sampling Kit that can be ordered online. The system is a quick, easy-to-use and convenient way to order tests and sampling supplies. For registered users, the online system automatically remembers favourite tests - making life much simpler.

Effluent test results are reported for dry matter percentage and the total nutrients of nitrogen, potassium, phosphorus, calcium, magnesium and sodium. A worked example for two different application depths to give N, P and K as kg/ha are also provided in the test report.

For crop soils, an additional test request for the more readily plant-available forms of nitrogen (NH4-N and NO3-N) is recommended. This can be important, because as identified the nutrient-release rate from FDE can be variable.

Your effluent test results can be used in conjunction with soil tests to guide fertiliser decisions with the help of certified nutrient advisors. For instance, whether fertiliser can be withheld from the effluent block, or how much additional fertiliser may be needed for targeted crop yields.

Analysis of farm dairy effluent makes sense for multiple reasons: from a nutrient resource point of view and as a means of keeping nutrient-loading rates within regional regulatory frameworks.

Trust the New Zealand owned laboratory with methods developed specifically for our unique conditions, and proven systems for fast, accurate results.

Contact one of our customer service managers to find out more.