Grains Research and Development

Date: 24.07.2015

Improving northern farming systems performance

Author: Lindsay Bell (CSIRO), David Lawrence (DAFQ), Kaara Klepper (DAFQ), Jayne Gentry (DAFQ), Andrew Verrell (NSWDPI) and Guy McMullen (NSWDPI)

Take home message

  • GRDC is investing in research aimed at understanding how the performance of current farming systems can be improved.
  • Systems with different crop intensity (or frequency), crop sequences, system inputs and practices aimed at maintaining long-term soil resources are being compared experimentally.
  • System modifications and their interactions of these various modifications are being examined at a core experiment site on the Eastern Darling downs, and 6 regional sites across the northern region are examining locally relevant system modifications.
  • Experimental data and modelling are being used to assess changes and effects of the different farming systems on several attributes (e.g. water use efficiency, nutrient use efficiency, soil resource, pathogen and weed populations).


Recent analysis suggests that there is potential to increase the efficiency of current farming systems. An analysis of surveyed crop sequences found that only 29% were achieving 80% of their potential water use efficiency. Similarly farming systems are facing emerging challenges of increasing herbicide resistance, declining soil fertility and increasing soil-borne pathogens all which require responses in farming systems in order to maintain system productivity.

The northern farming systems initiative aims to address these emerging challenges by investigating the question: Can systems performance be improved by modifying our farming systems?

The research aims to deliver information on the following issues:

  • Key issues or areas where current systems are underperforming
  • Benchmarks for, and gaps between, current and potential system water use efficiency (not just crop water-use-efficiency)
  • What changes in farming systems enable further increases in system efficiency
  • Benefits and costs of crop choices on various aspects of farming systems (water, nutrients, weeds, pests)
  • Identify any possible future issues that are likely to arise in response to changes in farming systems

Experimental plans

The northern farming systems initiative will implement a co-ordinated experimental program to examine a range of modifications to farming systems and quantify their relative impact on a range of measures of system performance. These modifications have been chosen following consultations with growers, advisors and other researchers across the northern region and are targeted to address apparent current and emerging challenges to farming systems. The range of systems have been chosen to capture the range of possible cropping systems operating in the northern region.

The combined experimental program will consist of 1 core site located at Pampas on the Eastern Darling Downs and 6 regional sites located at Emerald Agricultural College (Central Queensland), Billa Billa (Western Downs/Border Rivers), Mungundi (Western NSW and Qld), Plant Breeding Institute, Narrabri (Northern NSW), Nowley Research Station, Spring Ridge (Liverpool Plains), and Trangie Research Station (Central West NSW).

The core site will compare 34 farming systems (see Table 1). These include 8 summer crop dominated systems, 8 winter crop dominated systems, 14 mixed summer-winter crop systems and 4 systems involving ley pastures. The cropping systems (not ley pasture systems) involve factorial combinations involving different crop intensity (i.e. the number of crops sown/yr), crop sequences (including the range of crops grown) and nutrient supply/balance. Each of these systems are based on differences in key decision points or rules which aim to bring about these distinct changes in the farming systems. The systems tested at the core site are common with systems being tested in the regional experimental sites.

At each regional site a ‘benchmark’ system, based on current decision rules used in the district, will be compared with a common set of 4 individual system modifications (i.e. higher crop intensity, higher crop diversity, high nutrient supply and high legume frequency) (see Table 2). Additional regionally relevant modifications to systems may also be included based on local demand for these treatments. Table 2 summarises the common set and different modifications to be tested at each region and the equivalent system in the core site.

Key metrics of systems performance

Over the life of the project each experimental farming system will be compared in terms of several attributes:

  • Total grain production and quality
  • Economics (inputs and returns)
  • Efficiency of use of water and nutrients,
  • Changes in soil nutrient stocks and soil health indicators
  • Dynamics and populations of soil pathogens and weed populations

Together this information will be used to assess the relative performance of the farming systems against several metrics. This will help us understand the strengths, weaknesses and identify any future risks associated with particular system modifications.

Systems modelling and analysis

A combination of several modelling approaches will be used in the project to examine the performance of current farming systems across the northern region. These models will provide predictions of the likely effects of the various systems modifications over the time and extrapolate experimental information to compare system performance under a range of climatic conditions and predict the implications at other locations and/or other combinations of systems (e.g. different sequences of crops) across the northern region. In particular, the simulation modelling will enable climate and price risk factors to be analysed for each of the systems.

Table 1.List of key modification foci for changes to farming systems, their associated rationale and impacts and how the characteristics or decisions would be altered to achieve the desired outcome. System treatments in italics are those that make up the current ‘benchmark’ system; System treatments denoted with a ^ are included in a full factorial at the core site and denoted with a # are only singular treatments or partial factorials at the core site.


System modifications


Anticipated impacts

Key characteristics & decision point change



Moderate crop intensity ^

Sowing on a conservative PAW threshold

Higher PAW requirement to trigger a crop sowing event (e.g. 150 mm)


High crop intensity ^

Increase the frequency of crops sown in order to maximise proportion of rainfall transpired by crops

Reduced fallow herbicide use

Increased C inputs & soil OC

Increased soil biological activity & nutrient cycling

Reduce losses of water during fallows

Lower PAW requirement to trigger a crop sowing event (e.g. 75 mm)


Low crop # intensity

Reduce the risk for a particular crop by maximising soil water at sowing by proceeding with a long fallow period.

Greatly reduced number of crops

Higher profitability per crop

Long fallow periods requiring large herbicide program and low ground cover risks

Crops only sown when very high PAW or full profile

Higher value/profitability crops are sown



Limited crop options ^

Only crops with higher direct profitability are grown

Soil-borne pathogens increase

Limited weed control & herbicide choices/em>

Crop options limited to: wheat, barley, chickpeas, sorghum


Diverse crop options ^

Utilise a wider range of crops to manage the build-up and damage from soil-borne pathogens and weeds in cropping systems

Increased soil biological activity & diversity

Alternate herbicide chemistry & hence slow HR onset

Crop choice altered to ensure 50% of crops are resistant to nematodes and no more than 2 non-resistant crops in a row.

Two crops with same in-crop mode of action can’t follow each other



Conservative nutrient supply^

Manage synthetic fertiliser input costs

Soil fertility declining and likely crop yield penalties in good seasons

Crop fertiliser budget to achieve 50th percentile yield


High nutrient supply ^

Background soil fertility is boosted and crops provided with adequate nutrients to maximise yield potential.

Soil chemical & biological fertility is maintained or increased

Crops able to maximise their seasonal yield potential

Initial organic amendments and subsoil P application

Fertiliser budget to achieve 90th percentile yield


High legume ^

Increase inputs of biological N from legumes in system to reduce fertiliser N inputs

Reduced N fertiliser requirements

Altered weed & pathogen populations

Legumes make up 50% crops sown

High biomass legumes chosen in preference



>No soil restoration

Non-grain crops are not included in crop sequences

- Soil quality declines and hence water capture and nutrient supply may limit system productivity

Grain crops only grown in crop sequences


Cover crops #

Cover crops used to restore soil cover, increase organic inputs and manage weeds and diseases

Reduced herbicide use

Reduce N inputs for crops in rotation

Altered weed and disease populations

Cover crops after crops leaving low ground cover

Brown manure (i.e. spray out) crops with yield < 50% of potential


Ley pasture #

Perennial ley pastures phases to rebuild soil organic matter, nutrient levels and build disease suppressive soil biology.

Reduced herbicide use

Reduce N inputs for crops in rotation

Altered weed and disease populations

A phase of grass and/or legume based pastures are sown in rotation with grain crops

Table 2. System modifications for experimental program at regional locations and the reference benchmark at the core site.Note the core site will also represent the Eastern Downs region farming systems.

Trt #


Regional sites


Billa Billa


Spring Ridge












High nutrient supply








High legume








Diverse crop options








High crop intensity








Low crop intensity








Ley pasture (grass only)








Ley pasture grass + N








Integrated weed mgnt







No. of systems








The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

We would like to thank those growers and advisors who have given their time to be involved in focus group meetings, who shared their perspectives and provided their input into the design of this project.

Contact details

Lindsay Bell (Complex systems team leader)

PO Box 102, Toowoomba 4350, Qld
Ph: 07 4688 1221 or 0409 881 988