Implementation of Plantain in OverseerFM

I am wondering what the origin of the equation for partitioning of N between urine and dung is?

ie. (11.9 NutrientDietConcentration 100 + 29.9)/100.0

Was this from studies using just grass clover pastures or was it from a wide range of diets? Given that the plantain adjustment is a maximum factor of 1-0.6/3 = 0.8 is there evidence that the N partitioning factor for a plantain diet is actually significantly different to the original relationship? Alternatively do the recent studies give good support for the original relationship for grass clover pastures and other supplementary feeds used in pasture based systems?

Sorry for the delay. As part of the FRNL programme, we did compare the estimates of measured urine N production and Overseer estimates. There was reasonable agreement when collated against all of the diet types, (plantain, fodder beet and standard pasture), especially given the challenge of measurement. This is reported in the 'integration' report on the FRNL website. I haven't checked that the scalar was significantly different. Of the two factors, this has the smallest effect on N leaching estimates.

As for a more general comment about the Ledgard et al. relationship based on %N in diet, as described above it gave a reasonable fit . However, by applying that scalar, we have introduced indirectly another aspect of feed composition - water soluble carbohydrate - but only for plantain. Longer-term, it may be that another look at that equation is needed and other dietary components included.

The Urine patch load equation of 750-(PP*500) is presumably for used for cattle urine patches.

Are there equivalent equations for sheep and deer?

Scalars are applied to N leaching for other species to reflect smaller UPN loads.

We recenttly updated the GHG inventory partitioning model.

Might be interested in this publication on plantain 'the role of lucerne and plantain on the East Coast of the north island

cheers Gerald

http://nzforagesystems.co.nz/wp-content/blogs.dir/57/uploads/library/Muir/198_East%20Coast%20Forage%20systems%20results%20booklet.pdf

Hi everyone,

Hoping someone can help out with my question?

We have a few landowners in our catchment that have plantain in their pasture and we are interested in gauging the % plantain value to enter into Overseer. Can you please indicate whom is coming up with the recommended sampling process for plantain data collection to enter into Overseer ie present/absence or % plantain in pasture by reference photos or any other method? Is the sampling method defined somewhere or is it still a work in progress?

Nga mihi

Penny

HI Penny,

I am involved in a bit of the work here. We have a couple of methods that we (AgR, DairyNZ and Massey) have evaluated for estimating plantain content in mixed pasture i.e. grass - based. At the moment we are working on a visual estimation approach which seems to do a good job at the block scale. That is, while there may be some variance in estimate for an individual paddock, at the block scale it's pretty solid. Which will be the number Overseer will likely need. Pip Hedley at DairyNZ will work on a booklet with guidance for the method and reference photos, a bit like Body Condition Scoring.

Thanks Mike - do you know when the above mentioned guidance booklet is likely to become available and is it planned to be available through a hyperlink in OverseerFM? Also is there any planned date for the plantain functionality in Overseer to be activated?

Nga mihi

Thanks Penny and Mike - once any guidance on this has been made we will look at how to link it to FM. With this discussion ending today, we will discuss on Monday the timeframe for releasing the functionality - we may have a couple of other changes to roll into a release and so will let you know timing as soon as we can. Just in case you had missed it - users can already enter their plantain pastures into FM and once the modelling is released their analysis results will be automatically updated.