Ground Cover North : Ground Cover 094 September-October 2011 - North
SEPTEMBER -- OCTOBER 2011 GROUND COVER Nutrient management 17 Scaddan, WA, grain grower Kym Curnow (left) has saved $117,000 over three years on phosphorus alone by using geophysical surveys to vary phosphorus application on his property. Precision Agronomics Australia consultant Quenten Knight has been assisting Mr Curnow in his adoption of VRT gypsum, lime, potash and phosphorus. be produced, depending on the soil type and its responsiveness to gypsum. "When you look at the data, there's not a lot of difference in response between applying 2.5t/ha and 10t/ha of gypsum," he says. "But monitoring the trial over time will allow Mr Curnow to decide if the extra expense of applying 5 to 10t/ha of gypsum is more cost- effective than regular applications of 2.5t/ha." Mr Knight says the yield in the 2.5t/ha test strip will eventually start to decrease, while the yields in the 5 and 10t/ha test strips should remain high for longer. "This (declining yield) will indicate when it is time to reapply gypsum to areas that have had a lower rate applied," he says. Although Mr Curnow's test strips have shown little difference in yield response to the different rates of gypsum, Mr Knight says others have shown a significant response. He points to grain grower Lloyd Burrell's tests at Ravensthorpe as an example and says there are other cases where higher rates are required to give production an immediate "kick". In Mr Burrell's trial, testing crop responses to 0, 2.5, 5 and 10t/ha showed there was no significant difference between the treatments one year after applying gypsum. However, in year two (2009), field peas in the 10t treatment yielded 35 per cent more than the control. Three years after applying gypsum, Mr Burrell's trials showed the nil treatment yielded 1.4t/ha, the 2.5t treatment yielded 1.8t/ha, the 5t treatment yielded 2.1t/ha and the 10t treatment yielded 2.3t/ha. The water use efficiency improvements had taken the crop from achieving only 55 per cent of its yield potential to 85 per cent of its potential. To estimate the return on investment, PAA totalled the gross income from each treatment from 2008 to 2010 (barley 2008, field peas 2009 and wheat 2010) and then subtracted the initial gypsum treatment costs. While the 10t/ha treatment produced the most grain after three years on Mr Burrell's farm, the highest return on gypsum investment was achieved with the 5t/ha treatment. According to Quenten Knight, these results show that "you have to view every trial in isolation and that's why all growers need to implement their own on-farm test strips to assist decision-making". When it comes to the economics, Mr Curnow's 2009 yield data showed that applying gypsum on responsive soils could add an extra $100 a hectare to his returns (Figure 4, page 16). At a cost of about $35/ha for gypsum application, Mr Knight estimates the net return at $65/ha. Phosphorus tests Buoyed by these results, Mr Curnow was subsequently keen to trial VR phosphorus. In 2008, he engaged PAA again to produce an EM38 map and establish production zones. Mr Knight established a trial in one paddock to determine which soil types would respond to increased phosphorus rates. After harvest 2008, the trial results showed none of his soils were responsive, which allowed Mr Curnow to adopt a phosphorus-replacement strategy and a more focused soil-testing program. To estimate the phosphorus rates required for 2009, Mr Knight placed the 2008 yield map over the initial EM38 map of the paddock. Some parts of the paddock yielded 3.6t/ha. For these areas Mr Knight calculated the phosphorus rate based on a removal rate of phosphorus by crop type. For this particular paddock, the phosphorus rate applied went from a low rate of 10 units to a high rate of 15 units. In 2009, Mr Curnow used prescription application maps produced by PAA to apply VR phosphorus across 1900ha of his cereal program. Before moving to VRT, his standard approach was to apply a blanket application of 14kg/ha of phosphorus across his entire farm. With VRT, some areas were given 5kg/ha while others received up to 17kg/ha (10kg/ha of phosphorus on average). This meant that instead of using 154t of fertiliser, Mr Curnow's phosphate spend (at $5.60/kg) was reduced to 112t using VRT. Across 1900 hectares, VRT saved $42,000, or $21/ha, due to the high cost of phosphate in 2009. In 2010, cereals were sown across 2100ha. Had Mr Curnow used a blanket application of 14kg/ha of phosphorus, he would have used 215t of fertiliser. At 10kg/ha of phosphorus (on average) ranging from 5kg/ha up to 16kg/ha, only 158t of fertiliser (at a cost of $4.11/kg of phosphorus) was used. The fertiliser saving for 2010 was $33,000 or $15/ha. In 2011, Mr Curnow applied 173t of fertiliser (10.5kg/ha of phosphorus) compared with 230t if he was still applying a blanket rate of 14kg/ha of phosphorus -- a saving of 57t of fertiliser. Mr Knight says this saved Mr Curnow another $42,180 or $18.30/ha. Adding the 2009, 2010 and 2011 savings together across Mr Curnow's cereal program alone produced a $117,180 saving in phosphorus after three years. In addition to phosphorus, Mr Curnow is using VRT to vary nitrogen application. A base rate of nitrogen is applied at sowing and VRT is then used four to six weeks afterwards to apply liquid urea (Flexi-N), at varying rates, based on soil test results, previous paddock history and the seasonal outlook. Some areas are given no extra nitrogen while other sites receive 50 to 70 litres a hectare. Mr Curnow estimates the cost of adding a VR liquid nitrogen system to his Hardi tow-behind boomspray at $9000. □ GRDC Research Code DAW00193 More information: Kym Curnow, 08 9075 6048, 0427 756 048, email@example.com; Quenten Knight, 0427 720 004, firstname.lastname@example.org; www.grdc.com.au/DAW00193 PHOTO: NICOLE BAXTER Infratec™ Soﬁa On-farm grain analyser Wheat and barley -- protein and moisture Canola -- oil and moisture Results aligned with ALL bulk handler receival sites Why Infratec Soﬁa? Infratec Soﬁa calibratons are based on those used in the Infratec™ 1241 grain analyser, the analyser used exclusively by ALL Australian bulk handlers. So the results you get on-farm with Infratec Soﬁa are what you will see at receival. Results in less than 3 minutes Stable calibratons – no adjustments required Upgradeable with new crop calibratons Compact and mobile (240VAC/12VDC), weighs 9kg Comprehensive support and back up Australia-wide Questons? More informaton? Email: email@example.com Phone: 1300 360 848 For more informaton, and product & customer feedback videos, visit www.foss.com.au/soﬁa . . . . .
Ground Cover 095 November-December 2011 - North
Ground Cover 093 July-August 2011 - North