An OverseerFM add-on allows farmers to gauge the effects of plantain on N losses from pastures. Jackie Harrigan explains.

When Overseer pushes the go button on the plantain module in their nutrient management software in late August, farmers will be pleased to see at last the program taking into account the effects of plantain pastures helping to drive down nitrogen leaching on their farms.

The plug-in is the next step in the evolution of the nutrient management modelling software to account for the use of plantain on NZ farms and the positive effect the forage has been proven to have in decreasing levels of N leaching.

The changes are the outcome of four long years of scientific study into the effect of plantain under the Forages for Reduced Nitrate Leaching (FRNL) programme.

Research undertaken as part of the FRNL programme assessed the impact of Tonic plantain and, once the trial data was available, Overseer could use the evidence-based results in their model, said Overseer CEO Caroline Read.

“The last year has been spent with Agresearch scientists under the umbrella of the FRNL group looking at how we could implement what they found in the research into OverseerFM.”

The programme had added data entry functions ahead of the reporting season in June for their 5000 active farmer clients to add in the detail of how much plantain they have sown in their system, and at the end of August they will be able to see the impact on nitrate leaching based on the FRNL research.

Read says the company has worked hard to make the programme more useful and, with the recent addition of a knowledge base and more extensive in-app help, allow farmers access to more information to support farm planning and testing the impact of different scenarios such as using plantain.

“The programme is really user friendly now. There has been a historic reliance on consultants to generate results but it’s really encouraging to see farmers begin to get involved themselves and see what’s possible.”

“We are trying to make OverseerFM much more useful to farmers, rather than just using it to generate an N loss figure, by providing the information that the model generates in more meaningful ways so they can get value out of it. They can do much more detailed planning, see where changes need to be made, be part of a catchment group, and feed their information in there.”

OverseerFM costs $360+GST for a full year subscription, allowing each farm to make as many analyses of the farm as they like.

“You can have your year-end analysis and then do lots of predictive and scenario analyses that look at different ways of doing things,” Read said.

“The regional councils who use the system to generate a loss figure have independent auditors for assurance that the system is defendable.”

Once farmers start to use the plantain functionality, Read is looking forward to being able to see how many of their 11,000 signed-up farmers are using the herb varieties.

Environmentally functional plantain

At this stage the model has been amended to account for the effects of plantain on the cow and the diuretic effect that causes urine to be passed more often, be more dilute and therefore lower in nitrogen.

The effect works by a lower apportioning of the excreted nitrogen to urine and a lower nitrogen load per urine patch and therefore a decreased urine volume per animal per day.

“There are also soil biological processes at play in bringing down the N loss but research is ongoing on that aspect and, once the science is sorted, that will be added in as well,” Read said.

All of the research has been carried out on Ceres Tonic plantain (FRNL trials) known as an environmentally functional plantain and differentiated from other varieties that have not yet been researched.

The plantains are the Plantago lanceolata varieties – winter-active, prostrate, large but narrow-leaved types with a coarse root structure. The varieties tend to have lower dry matter content, higher structural carbohydrate/nitrogen ratio and lower proportions of total nitrogen that are soluble and degradable compared with ryegrass.

OverseerFM calculates the nitrogen in excreta and apportions this to urine and dung using an equation based on the concentration of nitrogen in the diet.

FRNL research identified that where animals are fed plantain the proportion of nitrogen allocated to urine is adjusted according to the proportion of plantain in the diet up to 60%, above which the proportion does not change.

The farmer simply estimates what proportion of the sward is plantain (Overseer is developing guidelines to do this) and enters it into the program, also accounting for the pasture proportion and any supplements fed to the animals.

Harvesting and direct feeding are assumed to be consistent with grazing but no proportion of plantain is calculated for supplements containing plantain that are ensiled or stored.

Overseer is encouraging the seed industry to work together on an agreed criteria to determine the environmentally functional plantains, with accompanying product labelling, so that the varieties are independently verified.

“We are not able to validate or verify the different plantains but it is up to the industry to come to a level of agreement so that farmers can distinguish which varieties to buy.”

Enabling an outputs-based regulatory system

New Zealand is fortunate to not have the blanket input controls enforced in Europe to mitigate N losses, says geologist turned water policy analyst Caroline Read, who has been the Overseer chief executive for the past four years.

Controlling inputs not only means a very expensive research and monitoring job, it kills innovation and flexibility, she says.

However the new Freshwater rules are moving in that direction with the limit of 190kg N/ha/year applied nitrogen.

“My goal is to try and encourage an outputs-based regime in New Zealand – it makes us so much more innovative and progressive. OverseerFM gives farmers the tools to engage with and to work with – and adding in more functionality helps farmers build trust in the product and the results they are getting – along with willingness with acceptance of the role of OverseerFM in regulation.”

“We are moving and people are starting to see the benefits – we keep bringing in other features that farmers can see value in. It’s a continual process of seeing the mitigation opportunities out there and getting the science and research to back an evidence-based approach to putting them into OverseerFM.”

Other mitigations included in the modelling programme are riparian strips and wetland areas, and Read said the fact there are so many different N mitigation innovations makes it an exciting space to work in.

New varietals

The next pasture forage on the list to include in the OverseerFM model is chicory, Read says.

“We have a number of varieties already – chicory will be the seventh and many farmers are using it so we need to get the research data into the model.”

Looking forward at the plethora of different varieties used in the likes of a regen mix, Read says what will likely happen is plants will be pooled together in similar groups.

Carbon stock tool

Farmers have been able to measure the greenhouse gases emitted from their farm for some time in OverseerFM, and new functionality added last year measures the other side – the carbon being sequestered in trees on the property.

“We added data from the MPI carbon look-up tables that provide the sequestration rates of different trees to our treeblocks to allow farmers to basically find out how much is being sequestered, or look at adding treeblocks to the farm,” Read said.

Since 2006 a Greenhouse Gas (GHG) report detailing methane, CO2 and nitrous oxide from all sources adds up the total GHGs emitted, so now both sides of the ledger are covered.