In 2004 the Grower Group Alliance (GGA) was successful in obtaining project funding through the National Landcare Program (NLP) Sustainable Industries Initiative. The funding has allowed 5 grower groups to focus on implementing sustainable agricultural production practices that protect the soil and optimise water and nutrient use in WA. The project has highlighted the key constraints to production in the Northern Agricultural Region as herbicide resistance, inefficient water use, changes in land capability due to salinity, sub-soil constraints to plant growth (ie. acidity) and seasonal variability and climate change. This project is aimed at increasing the awareness of these production constraints within the region and establishing communication networks for growers, with industry or other growers, to be able to access information on possible solutions.

The Liebe Group members rated seasonal risk as one of their major threats to production in our area. We therefore designed a project aimed to assess the benefits of yield prediction tools PYCAL and Yield Prophet to determine whether they can be beneficial to farmers in terms of realising yield potential/prediction and if so can they be used as a future tool to help with seeding and nutrition application decision making.

PYCAL – gives an indication of water limited POTENTIAL yield based on the French Schultz equation. Which is calculated as: Potential Yield (kg/ha) = Crop Water Use (mm) – Evaporation (110mm) x Water Use Efficiency (WUE). Crop water use is estimated as the sum of plant available water at the start of growing season (April 1) and the growing season rainfall. The model uses a standard WUE of 15 kg/mm/ha, although WUE in this case was calibrated for individual paddocks using five years of past yields and rainfall data.

Yield Prophet – is the commercialisation of the APSIM model. APSIM uses site specific soil characterisation data and the soil water and nitrogen content at time of sowing. This information coupled with historic rainfall data is used to calculate the probabilities of achieving certain yields given the range of decile year outcomes. Yield Prophet requires site specific soil characterisation in order to determine the Plant Available Water Capacity (PAWC) of the soil or essentially the bucket size of the soil. The characterisation should also detect other factors in play which may limit root growth (e.g. compaction, sub-soil acidity, shallow soils and salinity) and therefore a rooting depth is set for the model.

6 sites, with a variety of soil types and rainfall, were chosen on a yearly basis to trial these tools. The project finished in June 2008.

If you would like to know more information about this project please contact Chris O’Callaghan on (08) 9661 0570.

View results trial results from the 2006 season:

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