Article taken from Crop Production Magazine, June 2017.
The historical role of the agronomist is to provide technical crop protection advice to their farmer clients, but this role may be changing.
Numerous legislative challenges are currently regarded by many as putting the continued use of several important and well used agrochemicals under threat. What's more, chemical resistance, evident from the proliferation of blackgrass across many parts of the UK, has led to massive changes in farming practices.
This is leading to a changing role for on farm agronomy, according to Agrovista. As well as giving advice on chemical applications, today's agronomist needs to be able to use all the precision tools that are available to sample, analyse, map and advise on the best and most economical use of arable land.
Plantsystems is Agrovista's integrated precision technology and agronomy brand and the company is currently undertaking a long-term trial on wheat grown at Manor Farm, Ramsey, Cambs to evaluate the latest technology.
Lewis McKerrow, head of precision farming at Agrovista, explains that they are looking at two strategies. ""Improvement"" is where higher inputs on areas of fields known to perform well will hopefully lead to higher outputs. Secondly ""Optimisation"" indicates where there is a possibility that too many inputs are being used on poorer ground that may not be able to utilise them, so that lowering those inputs could actually maintain output and cut costs.
A trailed Veris MSP3 has been used to test soil organic matter, soil conductivity and pH. Fields have been mapped using the lsaria sensor and drone technology, with field slope, curve and soil type assessed and curve maps produced.
All this information has been combined with historic yield maps to produce variable rate sowing prescriptions, which have been applied to the land together with targeted variable rate nitrogen applications.
""It's about reducing the cost per tonne of growing the crop," explains Lewis McKerrow. ""When we overlaid the historical yield map with the curve maps it was apparent plants growing on ridges across the field had lower yields than those at the bottom of the ridge, due to the movement of nutrients down the slope.
""It's in these low yield areas that we may need to reduce nitrogen rates to improve margins by reducing inputs. The maps also indicated areas of the field with potential for water runoff - another reason to reduce nitrogen in that area.""
Conversely, in areas where the historic yield maps showed high yields, applying more nitrogen may increase yields further, he continues. In this way, the Optimise approach should reduce input costs, whereas the Improve strategy, although increasing input costs, should improve yields in the high-yielding areas.
Another tool that's being used during the trial is an Isaria crop sensor to enable real time variable rate nitrogen spreading. Developed by the Fritzmeier Group in Germany, the lsaria can be fitted on to the front hydraulics of a tractor in a matter of minutes. An in-cab terminal connects to most spreader/sprayer controllers and the sensor communicates with the terminal via Bluetooth.
The sensor is about 1m above the crop, completes up to 2000 measurements per second and will operate in daylight or at night. It measures crop biomass reflectivity to determine nitrogen requirement in real time, irrespective of any previous field performance history.
This year, the sensor's being used in 'absolute' wheat mode - an automatic mode that feeds the crop to a pre-set yield target. Additional crop sensing and scouting is also carried out using a drone together with the use of soil moisture probes.
There's also a requirement for software to analyse the data produced, and Agrovista has worked with Muddy Boots to develop its software's advanced field mapping and data-capture capabilities.
This more holistic approach to agronomy doesn't come without a cost. Lewis McKerrow says that annually, based on a 200ha farm it would cost about £31.20/ha to purchase the technology. Or to put it another way, an additional yield of 0.24t/ha using the Improve strategy would be needed or a 10% reduction in N, P and K on the poorer ground in the Optimise strategy.