The 2022 Sunline Education Trust Scholarship was awarded to Hannah Airey, supporting her to participate in research to improve the accuracy around potential nitrogen leaching and nutrient loss on Equine properties.
On Thursday morning Dr Chris Rogers Massey University, Windsor Park principal Rodney Schick and NZTBA CEO Justine Sclater met Hannah at Windsor Park, the main Waikato research farm, to discuss Hannah’s initial research project on a commercial thoroughbred breeding farm.
This looks at Overseer, as used by government organisations, as a model. Overseer makes a number of assumptions that results in over-estimation of the potential nitrogen leaching from equine properties. Because central and regional government are unlikely to change from using Overseer to model nutrient loss or fund substantial reworking’s to improve the accuracy of estimation for equine properties there is a need to identify where the major sources of errors are in the overseer modelling of equine properties. The generation of simple pragmatic corrections for these errors can then be applied to equine properties.
At an animal level, early work has identified how we can correct for errors in nitrogen digestion within the Overseer model. To understand the interaction of different grazing systems and Nitrogen leaching Massey established a small model equine property(~10acrees) to test Overseer estimation and actual Nitrogen and phosphorous loss.
Translating these findings to the commercial thoroughbred breeding industry requires some modelling of livestock management (stock density and rotation length), and farm profile (soil types, riparian planting etc) from initially a “model” or typical commercial thoroughbred farm. Snapshots of livestock management would be captured in each season (to be able to model the impact of additional mares on farm during the breeding season. The aim is to use this real data (Windsor Park), in association with the data from Massey University’s model farm, and test if a simple correction of output from Overseer is possible.
Intensive equine management (stabling and management of dung piles)
Nutrient leaching is at present the primary focus of the local regulatory authorities, however there is increasing attention on the role different livestock enterprises play in climate change (greenhouse gases) and the issue of sustainable farming enterprises (the concept of being carbon neutral).
Intensive management of horses results in the requirement to suitably dispose of bedding and manure. While incorrect management of dung and used bedding represents a highly visible and quantifiable risk for nutrient leaching, the application mitigation strategies could be applied easily at relatively low cost (such as increasing the carbon component of the composting dung pile, covering, ensuring not located near a waterway).
Strategically the thoroughbred industry could generate significant goodwill with regulatory authorities, with limited change in management or cost, with the adoption of good management practices with dung piles. To develop a pragmatic strategy for good management practices for dung and bedding management associated with intensive management of horses we initially need conduct an audit of industry current practice.
Proposed workflow and data collection
Model commercial farm
Collect data on the following parameters:
Single data collection (spatial data)
- Farm size
- Effective farm size and paddock layout (much of this can be obtained of measures from google earth)
- Plantings and riparian plantings (area can be calculated from google earth) but require detail of plant / tree species).
- Soil map of farm (can be obtained from online database once GPS coordinates are known)
Seasonal snapshot of stock management (autumn, winter, spring summer)
Livestock numbers
Paddocks grazed, stock class (broodmares, empties, yearlings etc), stocking density, rotation length, pasture mass on offer, farm pasture cover
Possibility of soil samples to quantify N content in grazed paddocks, and subsampling of water run-off.
(requires generation of sampling check sheet and data entry form)
Dung Pile Audit
Using a pro forma check sheet a survey of dung and used bedding management systems and quantities generated will be performed.
Sampling frame: commercial thoroughbred stud farms with the Waikato / South Auckland region
Primary points of interest to document:- Estimate of biomass generated (relative quantities and proportions of dung and bedding) and any seasonality to this
- Methods of management (composting, burn pile, collected by mushroom farm etc)
- Location and construction of the dung pile (base substrate, location, potential for leaching)
- Sustainability (utilisation of compostable material)
(requires generation of sampling check sheet and data entry form)
References:
1. Chin, Y.Y.; Back, P.J.; Gee, E.K.; Rogers, C.W. Deterministic modelling of nitrogen utilisation by horses managed under pasture-based, intensive and semi-intensive systems with different levels of pasture intake. New Zealand Journal of Animal Science and Production 2019, 79, 1-7.
2. Chin, Y.Y.; Back, P.J.; Gee, E.K.; Rogers, C.W. Livestock and pasture management on commercial Thoroughbred breeding farms: implications for estimating nitrogen loss. New Zealand Journal of Animal Science and Production 2019, 79, 65-70.
3. Rogers, C.W.; Back, P.J.; Gee, E.K.; Chin, Y.Y.; Linton, S.; Wark, A. Prediciting nutrient loss - what to do with equine properties? In Proceedings of the Proceedings of the Farmed Landscapes Research Centre Annual Workshop, 2020; p. 7.
4. Martin, N.P.; Adams, B.R.; Horne, D.L.; Linton, S.; Back, P.J.; Rogers, C.W. Horses, grazing and nitrogen in soils. In Proceedings of the Adaptive Strategies for Future Farming. , Palmerston North, 2022.
