Ground Cover North : Ground Cover 054 February-March 2005 - North
n Is nitrogen sensing technology the latest aid in helping farmers increase crop yields, while at the same time cutting down on input costs? To find the answer to this question, South Australia-based consultant Dr Allan Mayfield is trialling a German-developed device that identifies the comparative nitrogen status in a crop through colour readings. Developed by Hydro Agri, the biggest fertiliser manufacturing company in the world, and called the Hydro-N Sensor, when fitted to a tractor or other vehicle it uses a series of sensors that pick up light reflections from the crop that equal a greenness rating. When linked to a computer it can be used to produce maps of ‘green versus yellow’ that indicate a crop’s nitrogen status. Dr Mayfield, who is trialling the N- Sensor for the Southern Precision Agriculture Association (SPAA) in conjunction with the Hart (SA) Field Days Group and others in projects supported by the GRDC, says the technology does not measure how much fertiliser (nitrogen) needs to be applied, it simply identifies areas where extra nitrogen would benefit growers’ yield and protein aims. “The computer-generated maps from the N-Sensor, when used in conjunction with variable rate technology (VRT) equipment, then allows nitrogen to be applied in application rates as and where required, rather than at a constant or paddock average rate,” he says. Dr Mayfield describes the N-Sensor as a diagnostic tool, not something that replaces good agronomic advice and decision making: “Growers still need to know the underlying reasons for variations in crop growth and yield through soil and/or tissue testing. “Those test results are entered into the N-Sensor and become the reference point from which the VRT-equipped machines vary the application rates according to need”. Dr Mayfield says the N-Sensor has to be calibrated or standardised for each crop paddock. The unit is fitted with a computer override mechanism that allows operators to change the application rate if, for example, crop yellowing is known to be due to some other factor such as shallow soil, root disease, salinity or waterlogging. In 2004, NSW farmer Richard Heath, a recent Nuffield Scholarship winner, trialled the N-Sensor on his Gunnedah property (in conjunction with Dr Mayfield). Mr Heath, who first learned about the N-Sensor during his scholarship prize trip to Europe, describes the N-Sensor as something that looks like an oversized spoiler mounted on a tractor or other vehicle, and fitted with optical sensors that establish normalised digitalised vegetation indices (NDVI). This information can be used to establish required (recommended) rates for fertiliser application using variable rate spreaders and/or boom sprays. “The N-Sensor uses optical sensors that scan a 50 square-metre area in front of the tractor (or other vehicle) at a frequency of one reading every second,” Mr Heath says. “With an average rate programmed into the applicator (spreader or sprayer), the VRT- equipped machine makes rate deviations up or down from that average based on the NDVI of each 50 square metres.” Mr Heath says different average rates could be programmed into the controller to account for factors other than nitrogen nutrition that may affect yield targets. Describing its working, he says the N-Sensor takes ambient light readings to ensure that differences in crop reflectance due to passing cloud or other shadows are taken into account. “Sun angle does have an influence and I found the sensors work best between 9.30am and 4.30pm under a consistent cloud cover,” he says. “The N-Sensor is Nitrogen ‘ready reckoner’ trialled Technology 17 FEBRUARY 2005 GROUND COVER LOOK. BE ALERT. CALL AN EXPERT. Grain growers are the key to protecting Australia’s crops from exotic insects and diseases like khapra beetle. It is important that you are aware of the risk, and if you spot anything unusual on your crop you should always check it out and call the Exotic Plant Pest Hotline on 1800 084 881. The call is free (except from mobiles) and early detection will help protect your industry. Visit www.planthealthaustralia.com.au for further information. This project has received funding from the Australian Government through the Department of Agriculture, Fisheries and Forestry. 1800 084 881 n With the increasing need to reduce spray drift and improve spray application efficiency, the GRDC is distributing the 2005 guidelines for drift reduction with this Ground Cover edition. The GRDC has also sent emails to growers, advisers and departmental staff in Central Queensland to improve awareness of the likelihood and potential cost of spray drift in unsuitable weather conditions. The GRDC says that the weather often experienced in Central Queensland in summer can increase the risk of spray drift and reduce spray efficiency. With some nozzles, up to 40 percent of herbicide may not reach the target. GRDC northern panel chairman Ian Buss, who farms at Springsure, says the targeted email was only a first step in a collaborative effort with other industry organisations to make growers aware of nozzle and application options that can reduce spray drift. “Spray drift has been an ongoing problem and such instances provide ammunition for other sectors of the community to criticise farm chemical practices,” he said. “Right now there is a push to limit the use of hormone herbicides.” The GRDC Spray Drift Alert email included information on techniques to minimise drift hazards, the effect of weather on spray applications, and on the use of Delta T as a measure of temperature and relative humidity. ∆For more information: Ian Buss 07 4984 6141, mobile 0419 707 67 not reliant on GPS technology to work, but where it can be connected to a receiver, maps can be generated for the scanned data as well as applied product.” He feels his crops in 2004 did ripen more evenly because of his use of the nitrogen sensor. “I believe this was because using the N-Sensor in conjunction with VRT-equipped applicators, meant every area of the crop I used it in was treated with the right amount of nitrogen.” Dr Mayfield says that it was during a Churchill Fellowship study tour of New Zealand and Europe that he picked up on the N-Sensor technology. “On that tour I found that management of nitrogen nutrition was a key factor for farmers who had doubled their crop yields from about six tonnes a hectare up to about 12t/ha in the past six years.” Dr Mayfield says he is using his trial work with the N-Sensor technology to assess the benefits of increased cereal production through better management of nitrogen in higher rainfall areas in southern Australia, where average cereal yields are around 4t/ha. ∆GRDC Research Code: SPA00003. For more information: Dr Allan Mayfield, 08 8842 3230, email@example.com SPRAY DRIFT ALERT David East reports on a potential new tool to help farmers increase crop yields New technology: the N-Sensor mounted on a tractor cabin.
Ground Cover 055 April-May 2005 - North
Ground Cover 053 December-January 2005 - North