Ground Cover Supplement : GC Supplement - More profit from crop nutrition II
8 On-farm CASE STUDY NUTRITION MANAGES RISK By Rebecca Jennings VARIABLE-RATE (VR) TECHNOLOGY is now part of the risk-management strategy at 'Bullarto Downs' in the southern Victorian Mallee, in the face of low rainfall and increasingly dry springs. Manager Jim Christie is refocusing the no-till cropping program on the 6000-hectare farm at Hopetoun, which is owned by asset- management company Warakirri Cropping. Since taking on the role two years ago he has overseen the move towards controlled traffic on 12-metre machinery widths and the introduction of full VR for nitrogen and phosphorus application for a targeted, rather than blanket, approach to nutrient application. He is using yield maps, elevation maps and soil testing to map soil types and high/low production zones. In addition, satellite normalised difference vegetation index (NDVI) images are used to monitor crop growth and biomass during the growing season -- currently at 30m and 5m resolution but with plans to use 5m or less in the future. Jim draws on the expertise of his agronomist John Stuchbery, from AGRIvision, and Brendan Torpy, from Precision Agriculture, to manage the VR, yield and NDVI maps. "In our low-rainfall, high-risk area we need to minimise exposure to the business and maximise returns, regardless of what hand we are dealt -- whether it is high or low rainfall," Jim says. Soil variability drives crop performance at 'Bullarto Downs', where the sandy rises have higher potential to use water than the lower, heavier grey clay/loam areas, which take more water to convert to crops and have subsoil constraints including boron at depth. "Our canola yield maps last year showed production in a single paddock ranged from 300 kilograms/ha in the heavy clay/loam areas to 3 tonnes/ha on the sandy rises," Jim says. "That's a big difference, and an area we are targeting through VR nutrition to improve the overall return and profitability of the business." The Mallee is a low-rainfall area, but the past two years have been among the driest on record. The long-term annual average is 350 millimetres, but in 2015 'Bullarto Downs' received just 160mm. However, Jim says crop performance is hanging on despite seasonal conditions, thanks to his nutritional strategy. "Our cereals still yielded an average of 1.6t/ha and canola on long fallow reached 1.1t/ha in a dry year that followed a dry year, so there was no bank of moisture to draw on." With some local growers moving away from growing canola on the back of 0.5t/ha yields, Jim says this crop will continue to play an important role in his farming system as long as it maintains such results. "To produce more than 1t/ha in a tough season is a reflection that our nutrition strategies are working -- yield is the best indicator we are on the right track." MEASURE TO MANAGE Previously, Jim applied 40 to 50kg of urea at sowing. Now, using VR, he applies as much as 80kg/ha of urea in high production zones down to 10 to 20kg/ha in areas with lower potential. He believes in measuring to manage and has moved from paddock-based soil tests to zonal tests. In 2015, he took 50 diffusive gradients in thin films (DGT) tests to map variable phosphorus and provide a baseline for the farm, and plans to re-test every two to three years. "We previously applied a blanket rate of 40kg/ha of monoammonium phosphate (MAP), but last year soil tests showed that the low-yielding zones of canola had enough phosphorus to produce 3 to 4t, so we've cut those areas back to 10kg/ha and increased higher production zones to 60kg/ha. He has also moved from paddock to zonal basis for Yield Prophet®, and inputs data from high, low and average-yielding zones across paddocks to compare scenarios. Nitrogen-rich (100kg/ha urea) and nitrogen-low (10kg/ha) strips are other tools to assess the spectrum of crop nutrition requirements. Jim established phosphorus-rich strips for the first time this year, applying up to 100kg MAP/ha. Jim started his 2016 seeding campaign on 18 April and finished in the third week of May, capitalising on 15mm of rain received in early May. The cropping program is 20 per cent lentils, 23 per cent canola, 30 per cent wheat and 15 per cent barley with the balance fallowed. □ More information: Jim Christie, email@example.com PHOTO: JIM CHRISTIE ‘Bullarto Downs’ manager Jim Christie is optimising crop nutrition through variable-rate technology. COST SAVINGS Variable-rate application has delivered some cost savings (Jim Christie says he saved $15/ha on planting fertiliser in 2015) but the main beneft is optimising inputs for maximum production. "We are moving nutrients to the zones where they are going to be used to grow crops, rather than blanket application to areas that have subsoil constraints and lower yield potential." SAMPLE EARLY "One of the lessons we have learned is to take soil samples as early as possible, so we have time to get the results, analyse the data, develop a plan and prepare the VR maps."
GC Supplement - Spray application 2016
GC Supplement - Pulse breeding advances