Four-Year Trial Confirms Plantain Cuts N Losses 33%
A four year trial has reaffirmed that mixing plantain into dairy pastures can help reduce nitrogen losses to freshwater while maintaining milk production and profitability, say researchers.
The update draws heavily on findings from the Catch Crops for Cleaner Freshwater project, led by the Bioeconomy Science Institute (BSI) and supported by the Ministry for Primary Industries' Sustainable Land Management and Climate Change (SLMACC) fund.
Additional SLMACC funding supported the translation of the research into the OverseerFM model.
What has changed
The changes update how the model represents nitrogen in harvested products, crop residues and roots, and how crop growth develops over time.
Overseer Ltd chief technology officer Mark-John Bruwer says it is important for farmers and advisers to understand both what has changed in the model and what that means for their results.
"This release updates the evidence used to represent crops and the way their nitrogen uptake responds to soil nitrogen availability," he says.
"As a result, some farmers and advisers may notice changes in modelled nitrogen losses. Where results change because of the update, that should not be mistaken for a change in what happened on the farm."
What the impact testing found
Impact testing showed that:
- farms growing cereals such as wheat, barley and oats generally had lower modelled nitrogen losses after the update
- farms growing kale generally had higher modelled losses
- the direction and size of changes depend on the individual farm system
- farms without crops showed no change in modelled nitrogen losses
The testing covered 195,590 analyses across the OverseerFM database. A separate assessment examined recent analyses from real farms to give a clear picture of practical impacts.
Farms significantly affected by the update have been contacted by the Overseer team.
All analyses in the OverseerFM database have been updated to model version 6.6.0. Bruwer encourages farmers and advisers to review the release notes and the impact assessment report on the Overseer website to understand how the changes relate to their farm.
Five new crop options
The release also adds five new crop options:
- annual/Italian ryegrass under a forage crop system
- pumpkin
- leek
- leafy lettuce
- spring onion
