Optimising the yield and economic potential of high input cropping systems in the High Rainfall Zone

The High Rainfall Zone in southeastern Australia has high yield potentials for wheat and canola, but growers are faced with challenges about resource allocation in a relatively new and rapidly evolving cropping system. This project will develop tools that predict the production and economic response as well as the risks associated with applying the level of inputs needed for wheat and canola crops to achieve their potential in this region.


01 Mar 2014

Project Description

Outcomes, outputs and milestones.

Optimising the yield and economic potential of high input cropping systems in the HRZ

Grain production in the high rainfall zone (HRZ) of southern Australia has increased nearly two fold for wheat over the past 20 years from 1.7M t (average 1990 to 1995) to 3.2M t (2007-2011) and nearly tenfold for canola over the same period (81,000 t to 792,000 t). This trend is expected to continue as demand for food increases globally, production from the lower rainfall areas becomes more marginal under a varying climate, as yields increase in the HRZ to more closely reflect their predicted potential and as the area increases in response to greater yields and returns. However field experiments and modelling indicate that crop yields in this agro ecological zone could be doubled through the introduction of better adapted germplasm and improved management practices. An increase in wheat and canola yields of 50% above those currently achieved by growers has the potential to contribute an estimated $1.2 B to the grains industry. Progress towards attaining higher yields has been made through previous projects (DAV00061, DAV00083 and DAV00116) through the efforts of a multi-disciplinary team including crop physiologists, agronomists, modellers, grower groups, breeders and industry.

This project has three components that aim to realise the value of the investment to date and deliver more profitable farming systems to growers.
    · Outcome 1 aims to incorporate traits suited to the HRZ in new wheat germplasm.
    · Outcome 2 will provide breeders and researchers with an improved understanding of canola physiology and the identification of new cultivars and traits suited to the HRZ.
    · Outcome 3 will provide advisors and researchers with the tools and confidence to make informed decisions concerning input requirements for wheat and canola with high yield potential.

IPNI is particularly engaged with the third output concerning developing nutrient management plans for high yielding wheat and canola crops in this region.

Outputs and milestones to achieve Outcome 3
Outcome 3 will be achieved through the completion of three outputs and the rationale and milestones are indicated below.

Crops with high yield potential often require greater inputs for the potential to be realised. Management of these systems can be complex with high upfront costs for fertiliser, seed, fungicides, pesticides, herbicides and possibly plant growth regulators. For example, under experimental conditions at Hamilton where inputs have been unlimited, canola yields have exceeded 7t/ha. Such a crop requires approximately 490kgN, 70kg each of P and S and 100kg of K. Returns for these costs may not necessarily be realised due to unfavourable climatic conditions, inappropriate management decisions or other undetected limitations. Inputs therefore need to be matched not to the maximum yield potential but to the probability of achieving that potential and the likely returns (the economic potential).

Estimating yield potential and predicting likely returns can be complex and difficult. Many advisors are relatively new to cropping in the HRZ and have varying levels of knowledge and support in making recommendations. Often advisors do not feel adequately equipped to confidently assess crop demands and limitations, predict yield potential or the risks associated with high input systems in a variable climate. Consequently recommendations are often conservative and potential returns not realised due to lost opportunity. For example growers often apply 100 kg urea/ha in SW Vic regardless of starting soil N, consideration of other nutrients, time of sowing or cultivar. This component of the project will improve the ability of advisers and researchers to predict the yield and economic response of high yield potential wheat and canola under high input systems. This will be achieved by working with industry to

· Understand the basis for adviser recommendations (key business drivers)
· Collation of existing and new data to better understand and match supply with crop demand
· Quantify the risks of an over or under supply of inputs (main focus on nutrition but other input costs will be considered) using crop simulation and economic modelling
· Develop a Best Management Practice (BMP) guide for growers and advisers
· Conduct a workshop to promote the BMP guide

Output 1 - A benchmarking survey with industry (advisers) to better understand how recommendations are made and areas of uncertainty (June 2014)
    Output 2 - One workshop (East) including agronomists, soil scientists, crop nutritionists (IPNI), modellers, economists and industry to identify knowledge gaps and develop an experimental and modelling approach to more accurately predict demands and quantify the economic risks associated with applying costly inputs to crops with high yield potential (June 2014)
      Output 3 - A series of on-farm experiments (8 minimum located in Victoria; [DEPI and Southern Farming Systems]and South Australia; [MacKillop Farm Management Group, SARDI ,Yeruga Crop Research]), will be used to assess the production and economic consequences and risks of not optimising inputs for the yield potential of elite germplasm in HRZ environments. Results will be communicated through the development of a HRZ BMP guide for wheat and canola.

      Brendan Christy, Garry O’Leary, Penny Riffkin, Tina Acuna, Trent Potter and Angela Clough (2013). Long-season canola (Brassica napus L.) cultivars offer potential to substantially increase grain yield production in south-eastern Australia compared with current spring cultivars. Crop and Pasture Science 64, 901-913.
      Penny Riffkin, Trent Potter and Gavin Kearney (2012). Yield performance of late-maturing winter canola (Brassica napus L.) types in the High Rainfall Zone of southern Australia. Crop and Pasture Science, 63, 17-32.
      Roger Sylvester-Bradley, Penny Riffkin, Garry O’Leary (2012). Designing resource-efficient ideotypes for new cropping conditions: wheat (Triticum aestivum L.) in the High Rainfall Zone of southern Australia. Field Crops Research 125, 69-82.