VRI key points


▶Water rates prescribed by computer generated maps


▶ Amounts varied to soil, slope and crop under every sprinkler


▶Variable rates achieved with fuel injector-like solenoids pulsing on/off


▶ Sprinklers locate by GPS and radio-link to central controller


According to Adrian Colwill of Briggs Irrigation, there are about 40 linear or pivot irrigators in the UK, but he doesn’t believe any have fitted variable rate irrigation yet.


on-farm monitoring stations. Subtle differences in crop growth stage, for example where rain caused a two-week drilling delay mid-way across a field, are also taken into account. In the US land under a pivot is typically planted in only one or two crops but the more varied cropping in Europe and the UK makes the case for the adoption of VRI there even stronger. “I can see this technology taking off more and


more rapidly in the US and elsewhere, driven by customers seeing the return on investment as well as increasing regulatory pressures and wa- ter constraints,” says Mr Magnusson. However, Stuart Styles, director of California Polytechnic’s Irrigation Research and Training Centre, says that in California and western US, low soil infil- tration rates mean surface and drip irrigation systems dominate: long sprinkler-type


UK farmer and manufacturer views


Adrian Colwill of Briggs Irrigation says there are about 40 linear or pivot irrigators in the UK, mostly owned by three large farming companies on very light soils, but while the firms are aware of VRI developments, he doesn’t believe any have fitted it yet. Booms and guns are much more common due to cli- mate, soils and crop rotation. “In any one field there may be an irrigated crop only one year in every three or four.” In theory VRI could go on Briggs’ booms which use sprinklers like those on the VRI equipped pivots, but many questions need answering first, he says. “What section width per controller? what fac- tors drive application maps? how to provide power? how durable VRI equipment would be on a machine that’s folded in and out and towed around daily? solenoid valve life?


Would it be viable with UK irrigators typically only working 500 to 600 hours/year? In the meantime, new hardware such as the Ger- man-made Raindancer takes GPS located, re- al-time pressure readings to provide proof of placement and/or, with appropriate software, automatically vary the speed of boom travel, hence the rate across the designated zones of the field,” Mr Colwill says. “We do not feel there is currently enough market demand for variable rate irrigation across the width of the boom but this may change.” Tim Jolly, one of the few British farmers with centre pivots and a member of the UK Irrigation Association’s executive committee, says irregular shaped fields bordered by hedges and trees are an- other reason why hose-reel supplied guns are still the norm. Removal of such features


requires local government consent which can be costly and time consuming, often provok- ing strong public opposition with no guaran- tee of success. There are also support pay- ments for their retention within wider environmental stewardship schemes. To date, VRI is not something he’s considered for their five pivots, which with four guns cov- er 320 ha of their 380 ha farm near Thetford, Norfolk. Mr Jolly: “Our soils are consistent so the advantage of VRI in crop would probably be limited but it could be useful to avoid areas where there’s no crop, such as roadways. It might also be useful under the first span of a pivot where accurate application is difficult, and on corners and low lying and/or wet spots… As with all things, VRI uptake will be a balance between cost and return.”


▶ FUTURE FARMING | 25 May 2018 25


▶ Full automation and remote control


machines can’t supply the right amount of water at the right location consistently, he explains. But a few VRI systems have been fitted where sprinklers are used, with some growers opting to do just the ends of pivots to get extra flexibil- ity where it’s most needed for a lower outlay, he adds. “Overall in the US, there might be closer to 5-10% of the systems that have been set up with the variable rate systems.”


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52