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Sheep and beef types and N, P and GHG losses

Description

A spatial layer and a table of sheep and beef types and their associated loss rates for N, P and greenhouse gases.

 

Date: June 2024 Version: v2

Owner: AgResearch

Contact: Tony van der Weerden (AgResearch)

 

Link to report / paper

Layer of sheep and beef typologies

Sheep and beef types - table of mitigation effectiveness for N and P losses with GHG co-benefits

 

Preview Image

 

Dataset attributes

Spatial extent North Island and South Island of NZ
Spatial resolution Soil data is derived from S-map where available, otherwise the FSL. Slope is derived from a 15m DEM (20m contours). Climate data is supplied by Niwa and derived according to Wratt et al (2006).

Wratt, D.S., Tait, A., Griffiths, G., Espie, P., Jessen, M., Keys, J., Ladd, M., Lew, D., Lowther, W., Mitchell, N., Morton, J., Reid, J., Reid, S., Richardson, A., Sansom, J., Shankar, U., 2006. Climate for crops: integrating climate data with information about soils and crop requirements to reduce risks in agricultural decision-making. Meteorological Applications 13, 305-315

Temporal extent Farm system and environmental data represent the 2019/20 and 2020/21 production years
Temporal resolution Annual loss rates
Evaluation method (Validation) Expert assessment of independent dataset
Evaluation result (Numeric) N/A
N/A N/A
Uncertainty method N/A
Uncertainty data format (Numeric) N/A
Uncertainty data format (Categorical) N/A

 

Methodology

A database of 251 Overseer® farm nutrient budgets of real farms from across the sheep and beef sector was used to develop a statistical model to predict N and P losses and GHG emissions for farm type categories based on bio-geophysical attributes, namely rainfall, soil drainage class and slope.

Nitrogen losses (kg N/ha/yr) modelled by Overseer account for N run-off and leaching below the root zone from both livestock urine patches and from other non-urine sources such as fertiliser, or soil mineralisation.

Phosphorus losses (kg P/ha/yr) modelled by Overseer relate to both overland runoff (main loss process) and leaching below the root zone.
Greenhouse gas emissions are split into the short-lived GHG methane (CH4) and long-lived GHGs (nitrous oxide (N2O)), thereby aligning with the suggested methodology for domestic reporting of farm-scale GHG emissions (He Waka Eke Noa, 2022). Methane emissions are reported for methane gas (kg CH4/ha/yr), whereas N2O is reported as CO2 equivalents (kg CO2e/ha/yr), where N2O is converted to equivalent CO2 emissions using the 100-year time horizon global warming potential of 298 kg CO2-equivalent per kg N2O.

 

Fitness for purpose / limitations

This table indicates whether the dataset is suitable for different types of questions at different scales.

Note: Users should carefully consider their purpose as this dataset may not be suitable.

Operational Absolute Relative Screening/scoping
Block/farm No No NoNo
Multi-farms(5+) No No No No
Catchment No No No Maybe
National/regional Maybe Maybe YesYes
Caveat(s) A statistical model was used to estimate the environmental impact of each type. These types were designed to be a broad indication of potential environmental losses, typically to be used at a regional (preferable) or catchment scale. They do not replace in depth investigations for individual farms that are required for a more accurate assessment. Individual farm systems and farmer decisions, as well as local soil, climate and topography will mean that actual environmental losses will vary significantly from the average value indicated for each type.

Data and Resources