Nutrient performance indicators for the Australian grains industry

This project aims to develop and test a process to measure and report the nutrient use benchmarks partial nutrient balance (PNB) and partial factor productivity (PFP) for N, P, K and S for grain production systems against which growers can assess their nutrient management practices. These metrics will be derived at national, agroecological zone, regional and farm levels using published and surveyed information.


01 Mar 2015

Project Description

Fertilizers are a critical input to productive and sustainable farming and their effective use supports economic, social and environmental outcomes. While there are guidelines on nutrient best management practices using the principles of 4R nutrient stewardship (the Right source, applied at the Right rate, at the Right time and in the Right place), there are few metrics that can be used at a field, farm or regional scale to assess the effectiveness of those practices.

Project Aims
This project aims to develop and test a process to measure and report the nutrient use benchmarks partial nutrient balance (PNB) and partial/total factor productivity (PFP) for N, P and K for grain production against which growers can assess their nutrient management practices.These metrics will be derived at national, agroecological zone, regional and at farm level using published and collected information.
Nutrient Use Efficiency (NUE) indicators PNB or PFP can be configured in different ways to show the current starting point (benchmark) from which future improvements can be assessed (progress indicator). As such it indicates current system performance and if collected over time can demonstrate if and when interventions are needed to modify the indicator. The use of these indicators is consistent with the developing international dataset on NUE, particularly for nitrogen.

Neither PNB nor PFP are perfect indicators of nutrient management performance, nor is there a "magic" number for each. By definition, PFP will be highest where little or no fertilizer is used, and will decline as additional fertilizer is used. Similarly at no or low fertilizer input PNB will be high but this suggests that nutrients are being "mined" from the soil, while a low PNB suggests that nutrients in excess of removal are being applied, which has a risk of loss to the environment.

Using field experimental data, agronomic efficiency (AE, kg grain increase per kg fertilizer increase) can also be defined, but these values cannot be described at farm, region or national levels as there are no appropriate nil fertilizer values that can be used the estimate the increase. However, there are values in the literature that can be summarized for reference, but will provide little value as benchmarks for farmers as they cannot estimate their on-farm values to compare against experimental values.

The estimation of these nutrient performance metrics requires collection of farm level (i.e. disaggregated) data on nutrient use by crop at regional levels that can then be interpreted as PFP and PNB. While such information is "generally" known, there are no published data on the rates and types of fertilizers used in grain production by crop and region. In addition to providing regional and national values, it will provide growers with a useful indicator of the return (PFP) and efficiency (PNB) of their investment in nutrient management. This survey will only be undertaken within the growing regions in the GRDC Southern region on data from the past 5 years. The survey protocols will be transferable to the northern and western regions.

The outcome from this work will be a series of fertilizer nutrient efficiency benchmarks and processes to estimate them, that can be taken to growers and advisers for regional refinement, in the same way that the French and Schultz water use efficiency benchmarks have been developedand applied to assist growers with improved resource allocation.

A scoping study to benchmark all grains regions (at National level, and at agroecological zone and farm level in the GRDC souther region) for partial factor productivity, partial nutrient balance and agronomic efficiency. The review will identify how much variability exists between farms, statistical local areas, and regions for all major crops.

Data concerning on-farm fertilizer use by crops from industry sources, will be tested against industry figures on state fertilizer sales and farm surveys. Fixed N will be estimated using the protocols described by Herridge et al. Grain nutrient concentrations will be collated and presented as means, medians and frequency distributions. This component will be achieved through literature reviews, a desktop study and survey.