Ground Cover North : Ground Cover 095 November-December 2011 - North
Grain storage / Weed management NOVEMBER – DECEMBER 2011 GROUND COVER 7 using them to store grain for longer than three months increases the chance of damage to the polymer membrane. For those who plan to use silo bags this harvest, Mr Botta also encourages weekly monitoring to ensure the membrane is free of holes that would allow water to infiltrate and cause spoilage. Queensland grain storage specialist Philip Burrill of the Queensland Department of Employment, Economic Development and Innovation (DEEDI) agrees, adding that holes are usually caused by rodents and birds trying to get at the grain, and by foxes and other animals walking on top of the bags. “Birds in the local area where silo bags are used can quickly learn to puncture the bags to gain access to grain,” Mr Burrill says. “In some areas in central Queensland growers have stopped using silo bags because the bird damage has become too serious. Of course, cleaning up grain spills promptly and sealing damaged bags reduces the time birds spend around bags and developing a habit for feeding on the grain.” Mr Burrill and Mr Botta also encourage the use of secure fencing and synthetic bird netting to help minimise damage. If the membrane is pierced, silicone- based sealants can be used for repairs. Another important consideration for growers planning to use silo bags is where they will be positioned. Mr Botta says they are best placed on a hard, smooth, elevated and graded site with a gentle slope that allows water drainage. He says the heavy rain that fell during late 2010 and early 2011 created a headache for many eastern Australian growers who could not get to their silo bags because of boggy conditions. “Putting silo bags, for example, on a stubble paddock without grading the site can be a recipe for disaster. Sharp By Nicole Baxter n An authority on grain storage is encouraging growers to recognise the limitations of silo bags and only use them as a short- term option for stockpiling grain. Victorian grain storage specialist Peter Botta, of PCB Consulting, says storing grain in silo bags for more than three months after harvest will increase the risk of losing grain quality and value. He says although silo bags offer a useful means of managing harvest pressure, KEY POINTS n Use silo bags for three months only n Weekly inspection needed n Site bags on a hard, smooth, elevated and well-drained surface n Use fencing and bird netting to prevent pest damage to the membrane Experts say silo bags should be for short-term storage only, sited on a graded surface and kept well maintained. PHOTO:BRADCOLLISPHOTO:NICOLEBAXTER Trials across 12 locations in WA during 2010 showed the Harrington Seed Destructor was as effective as chaff carts and narrow windrow burning in reducing the ryegrass seed population. Silo bags handy, but limit to short-term use stubble, sticks and rocks can perforate the bag and allow water ingress,” he says. Another recommendation is to locate silo bags well away from trees (to reduce the risk posed by falling branches) and surrounding bush or grass verges that might harbour rodents and other wildlife. One of the weak points of the membrane- based storage system is the ability to achieve an effective seal at the end of the bag. Mr Burrill suggests folding the plastic back onto itself and then burying the folded section with soil. A GRDC-supported CSIRO report on silo bags notes another reason for limiting the use of silo bags to a three-month period only. Researchers James Darby and Len Caddick say condensation on the inside of the membrane can cause localised moulding and spoilage, especially during cooler times of the year and in cool locations. The researchers suggest orienting the silo bags in a north-south direction. Mr Botta cautions against using silo bags for handling over-moisture grain because self-heating will quickly occur, increasing the development of mould and the likelihood of quality losses. After grain out-turn, Mr Botta and Mr Burrill encourage the immediate removal of any grain spills and correct disposal of the used membrane to prevent the site from becoming a future breeding ground for stored grain insect pests. □ GRDC Research Code DAQ00158 More information: Peter Botta, 03 5762 4649, 0417 501 890, email@example.com; Philip Burrill, 07 4660 3620, 0427 696 500, firstname.lastname@example.org. gov.au; www.grdc.com.au/DAQ00158 Researchers in Western Australia have put the latest weapon in the war against weeds to the test with promising results n Trial results from research conducted at 12 locations across Western Australia in 2010 show that the Harrington Seed Destructor (HSD) is as effective as chaff carts and windrow burning in reducing ryegrass emergence. But the GRDC-supported HSD has the advantage of conserving all crop residues and does not require any post-harvest management. Dr Michael Walsh of the Australian Herbicide Resistance Initiative says ryegrass emergence was reduced by 40 to 60 per cent at each of the 12 sites across WA for the three different systems. “This equated to reductions in autumn plant counts from about 150 to 70 plants per square metre,” he says. Factors including the very dry finish to the 2010 cropping season and pre-harvest seed shed reduced the overall impact of all harvest weed-seed management systems, Dr Walsh says. “The result demonstrated that a long- term view must be taken in assessing the impact of harvest weed-seed management systems on weed populations. “But with most ryegrass seed remaining upright on intact seed heads, there was still the opportunity to compare the three weed- management systems; and the critical result is that at all 12 sites they were equally effective in reducing ryegrass emergence.” Dr Walsh says that while the trials focused on ryegrass, the HSD was also effective in controlling wild radish, wild oat and brome grass. “Trials to date have shown the HSD usually destroys at least 95 per cent of the weed seeds that exit the header in the chaff fraction during harvest,” Dr Walsh says. “These very high levels of weed seed destruction have repeatedly been achieved under commercial harvest conditions in wheat, barley and lupin crops.” Similar trials, supported by the Rural Industries Research and Development Corporation (RIRDC), will be held in south- east Australia during the 2011 harvest. □ GRDC Research Code UWA00124 More information: Michael Walsh, 08 6488 7872, email@example.com; www.grdc.com.au/UWA00124 WEEDS WEAPON SHOWS ITS POWER Silo bags provide a low-cost way of managing harvest logistics, but grain storage specialists say their use is best limited to about three months Looking to expand your cropping program, concerned about the risk? 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