Topcon Agriculture and Lincoln Agritech are assessing optical sensing technology or near infrared sensors for variable rate application of nitrogen fertilisers on pasture, especially on dairy farms.
Nitrogen fertiliser is usually applied uniformly over a pasture, irrespective of fertility, soil type or area of a paddock but the three-year study aims to enable farmers to apply the fertiliser at rates the soil needs.
Also known as optical sensing technology, it is commonly used for assessing biomass and the nitrogen status in arable crops.
Lincoln Agritech has shown when used on pasture, it can cut nitrogen use by 30% and a leaching by 13% while maintaining pasture yield.
Topcon sales and service representative James Storey says the system uses sensors attached to the cab of a tractor or truck. They take readings from either side of the vehicle to determine the level of chlorophyll in the pasture.
The readings are used to calculate average chlorophyll content of the area.
That determines the appropriate nitrogen fertiliser amount to be put on specific parts of the paddock.
Trampled area like gates don’t need any fertiliser and gullies do not need much if any nitrogen because nutrients wash to low-lying areas.
The three-year trial is halfway through and Storey says they are seeing a significant increase in grass growth but it is too early to accurately quantify.
They are looking for new farms to participate and to provide more data and have a contractor who will collate and provide information from three units he has attached to his tractors.
In the arable sector the technology ensures crop yields are uniform and a pasture paddock should achieve a similar result.
The technology includes a GPS system to provide proof of placement for fertiliser application, which will be essential for farm environment plans.
