PA: it's here, ready or not by Guy Cotsell

GROWERS SHOULD be keeping careful yield data records now - they'll come in handy for future precision agriculture (PA) systems.

So says John Heap, Field Crops Pathology researcher with the South Australian Research and Development Institute in Adelaide. "It is vital that farmers connect their yield monitors to a GPS unit to capture yield map data as soon as possible," said Dr Heap. "The data, collected over successive years, will be invaluable when they are ready to start using PA."

Dr Heap believes PA will be common practice within the next 10 to 15 years. He told a recent GRDC Crop Update that PA equipment is within the reach of most growers and the challenge now is to interpret and act on the paddock data collected.

"Most paddocks in Australia are managed as a single uniform unit. This ignores the variability present in almost every paddock. There are high- and low-yielding patches within paddocks, which are often correlated to a range of yield constraints such as shallow soil, disease, boron etc. If one rate of input (e.g. fertiliser) is applied uniformly to the whole paddock, some patches will be under-fertilised, while others will be over-fertilised. There are enormous potential gains in profitability if we can apply the optimum level of inputs to each different patch within the paddock," Dr Heap said.

PA revisited

Precision agriculture uses a GPS system to map paddock data (e.g. yield, electromagnetic survey) and matches input levels and agronomic practices to the variation in soil attributes and crop requirements. The various data sets for a paddock are analysed to define different "management zones". Targeted soil sampling (using GPS positions) is used to measure the properties (e.g. nutrition, disease inoculum level, pH etc) of each management zone.

Tailored management strategies are then designed for each management zone, and machinery using variable rate technology (VRT) (e.g. seeder, fertiliser spreader) delivers the optimum level of input to each position in the paddock, driven by a computerised map linked to GPS. This system is called site-specific crop management (SSCM).

Yield monitors are available in many new headers, and variable-rate seeders and fertiliser spreaders are becoming more common. Protein sensors are now in an advanced state of development.

"The challenge for us now is to learn how to interpret paddock data in a reliable and efficient way, so that sensible and economic management decisions can be made and applied to each patch within a paddock," Dr Heap said.

Contact: Dr John Heap 08 8303 9444