Profiting from yield data

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Regular crop production reports generated via the Yield Prophet® sites scattered across southern Australia are helping local growers match nitrogen and fungicide inputs to yield potential

Photo of a crowd listening to a presentation

Soil characterisation underpins the accuracy of the crop production model Yield Prophet®.

PHOTO: BCG

Many growers rely wholly on their experience and intuition to make decisions about use of nitrogen.

In most cases this approach works well, but in seasons that could be considered unique or unusual, experience and intuition can start to break down.

The 2012 cropping season in Birchip, Victoria, was one such season.

Throughout the season there was little incentive to apply additional crop inputs because, with the exception of July, the monthly rainfall during the growing season was well below average and seasonal forecasts continued to predict below-average rainfall. 

Despite the poor season, Yield Prophet® recommended applying nitrogen to reach the predicted yield potential. The model was able to account objectively for the stored soil moisture generated by 137 millimetres of summer rainfall. Adding the required nitrogen meant the crops went on to yield close to their potential. 

In the absence of the decision-support tool it is unlikely that a grower would have applied extra inputs (nitrogen and fungicide) given that the growing-season rainfall reached only 185mm (Decile 3). 

This is a situation where using soil tests and Yield Prophet® helped correct grower experience and intuition.

What is Yield Prophet?

Yield Prophet® is an online crop-production model that uses soil test results, growing-season rainfall, stored soil water, crop management and historical climate data to provide objective, real-time assessments of seasonal yield potential.

The model estimates the probabilities of a specific paddock obtaining a range of yields (Figure 1). By matching crop inputs with the attainable yield in a given season, growers can avoid overinvesting or underinvesting in their crop. All major varieties of wheat and barley are supported, as well as (to a lesser extent) sorghum, canola and oats.

The model was developed by BCG and CSIRO, with GRDC support.

FIGURE 1 The Yield Prophet® simulation process

Illustration of the Yield Prophet simulation process.

SOURCE: BCG

Yield Prophet® helps with pre-sowing, and in-season and harvest management decisions such as:

  • whether to crop or fallow;
  • which crop or variety to grow;
  • the best time for sowing;
  • how much fertiliser to apply for yield and grain quality; 
  • whether to harvest for grain or hay; and
  • irrigation scheduling.

Yield Prophet® helps answer questions such as:

  • What is the potential yield range of a crop based on historic climate records?
  • Is there enough available nitrogen to meet the potential yield range?
  • How much moisture is present in the soil profile?
  • How long will a crop last without rain before yield potential is affected?
  • What is the financial risk of spending more money on crop inputs?
  • What is the minimum yield potential?
  • Is there an opportunity to forward-sell grain, especially once the risk of frost has passed?

Yield Prophet® combines six key components:

  • a pre-sowing soil test to determine soil water and nitrogen content;
  • a soil classification; 
  • historical and current climate data from the nearest Bureau of Meteorology weather station;
  • paddock-specific rainfall data (optional); 
  • crop details; and
  • a record of fertiliser and irrigation applications during the growing season.

Yield Prophet® produces a set of comprehensive reports based on input.

  • Crop report: this is the most commonly used report and contains various outputs about individual crops to help with decisions related to nitrogen management, irrigation management, hay cutting, frost risk assessment, marketing and insurance.
  • Nitrogen comparison report: outlines the impact of different nitrogen application decisions on yield.
  • Nitrogen profit report: calculates the profit arising from nitrogen management decisions.
  • Irrigation comparison and profit reports: outline the impact of water and nitrogen application decisions on yield and profit.
  • Sowing by variety report: evaluates the effect of different crop cultivars and sowing dates on yield.
  • Sowing opportunity report: outlines the impact of sowing date on yield, frost and heat-shock risk.
  • Fallow monitoring report: is used after harvest to monitor fallow soil moisture and nitrogen levels.
  • Stubble management report: assesses the impact of tillage and grazing decisions on soil nitrogen and moisture content.
  • Climate change report: outlines the potential impact of climate change on crop yields in 2030.
  • Climate adaptation report: predicts the yield under climate change using current and alternative cropping practices.

When a report is requested, the paddock-specific information is sent in an email from the Yield Prophet® database to a computer cluster where the simulation is processed. Using climate data for the current season, Yield Prophet® then simulates the soil water and nitrogen processes in the paddock together with the crop growth from the start of the season to the present.

Yield Prophet® calculates the amount of water and nitrogen available to the crop, and the crop’s water and nitrogen needs. This information is used to determine whether the crop is suffering stress from a lack of either of these resources and to assess any resulting reduction in growth and yield potential.

Using historic climate data, Yield Prophet® simulates crop growth and resource availability from the day on which the report was generated to the end of the season.

This process is repeated once for each year of climate record (approximately 120 years), providing 120 separate yield outcomes (Figure 1). These yields are plotted as a probability curve, providing growers with an estimate of the likelihood of obtaining a range of yields.

The output is then adapted to the requested report type and emailed to the website or the subscriber, where it can be viewed. Report generation takes from five to 15 minutes.

Yield Prophet reports

Yield Prophet® reports for a range of trial sites across western Victoria can be viewed online throughout the season at the Yield Prophet® website (www.yieldprophet.com.au).

Reports from Yield Prophet® are regularly published for four sites within Victorian grain-growing areas in The Break newsletter (www.dpi.vic.gov.au/agriculture/ about-agriculture/newsletters-and-updates/the-break -newsletters).

FarmLink New South Wales (www.farmlink.com.au) generates the free monthly newsletter Weather or Not, which provides growers with real-time information about nitrogen availability, plant-available water and predicted crop growth stages for designated crops in six locations across the FarmLink region.

The South Australian Hart Beat newsletter (www.hartfieldsite.org.au/pages/hart- beat-newsletters.php) provides growers and agronomists with regular updates of current and predicted crop and soil conditions as a season progresses at Yield Prophet® sites in Hart, Condowie, Spalding, Kybunga, Farrell Flat and Tarlee.

Yield Prophet® reports from a network of more than 20 Yield Prophet® sites across the central and southern wheatbelts of Western Australia and can be viewed online throughout the growing season at the Department of Agriculture and Food, WA, website (http://grains.agric.wa.gov.au/node/yield-prophet-central- and-southern-wheatbelt-wa).

More information:

Tim McClelland, BCG
03 5492 2787,
yieldprophet@bcg.org.au

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