Thursday, August 22, 2019

Precision agronomy helps grower optimise margins

May 1, 2019 by  
Filed under Crops

Essex grower Hew Willett is putting precision agronomy at the heart of efforts to improve efficiency on the family farm.

Keen to reduce production costs without compromising yields, Mr Willett has rolled out the Omnia precision farming system across 475ha of arable cropping after a successful trial season at Parklands Farm, near Chelmsford.

So far, the system has mainly been used for analysing yield maps and producing variable seed rate plans to improve yield consistency on the heavy clay soil, but Mr Willett and Farmacy agronomist Andrew Spackman are keen to expand its use to aid decision-making.

“I like the fact Omnia brings lots of data together in one place and is very intuitive to use,” says Mr Willett, who runs the farm with his mother Christy. “I aim to build the detail over coming seasons and use it to help increase efficiency.”

Last season’s variable seed rate work, combined with the farm’s Yield Enhancement Network (YEN) entry, revealed interesting results that will drive changes this year.

Variable seed rate plans were drawn up in Omnia, based on different layers of mapped data. These  included soil texture assessments, seedbed conditions, slug risk and weed pressure – most notably blackgrass.

“On the worst areas of heavy clay, germination has been as low as 40-50%, so we felt confident seed rates could be increased up to 480 seeds/m2 in these areas to give a more even plant population and get closer to our target of 700 heads/m2 by harvest,” Mr Willett says.

Yield map analysis combined with results from YEN showed that while plant stands were more even, the yield benefit was harder to define. “We’re on wide rows of almost 30cm with our Mzuri drill and it seems this might have been a factor limiting yields in our YEN trial last year.”

Mr Spackman says increasing seed rate on wide rows increases intra-row competition, resulting in smaller plants and ears, and leaves a band of under-utilised space between the rows.

Growth characteristics

“The jury’s still out on what the definitive row width is, especially as varieties differ in their growth characteristics. Skyfall, for example will spread more in autumn than an upright variety like Crusoe.

“Row width and varietal characteristics are just two of many aspects you must consider when planning how best to vary seed rates. It’s a multifactorial decision-making process. You can’t look at any one aspect in isolation or simply increase or decrease the amount of seed used.”

Moisture availability is a major limiting factor in the southeast, making it essential crop roots utilise as much water and nutrients below ground as possible, Mr Spackman adds.

“We can’t afford to have un-utilised areas in the field. Wide gaps between rows also let in more blackgrass and ryegrass. Equally, we need to consider the rooting demands [on nutrients and water] in very thick crops.”

Next steps

Mr Willett plans to change his drill this year and switch to more conventional 16-20cm row widths in the autumn. Building the bank of agronomic data held in Omnia is key to future agronomy at Parklands Farm, with the initial focus on soil health, he says.

A comprehensive soil sampling programme based on zonal field mapping was started this spring to set a baseline of soil health information and improve the existing data from previous grid-style surveys.

Mr Willett plans to overlay drainage maps in Omnia to highlight any correlations with poor yields or grassweed infestations and identify areas for remedial work, such as mole draining, subsoiling or ditch clearance.

This will encourage more targeted cultivations and the move towards a full direct drilling system with minimal soil disturbance. This should reduce establishment costs, and improve soil properties such as organic matter, structure, drainage, and water holding capacity.

“Soils in this region are naturally very good at retaining nutrients, so the key is creating the right conditions for crops to access them,” says Mr Spackman.

Mr Willett hopes to reduce artificial phosphate and potash applications while maintaining soil indices around Index 2. “To do this, we’ve got to have good structure that allows crops to root freely and extract nutrients throughout the profile.”

Grassweed benefits

The current rotation is split 50:50 between winter and spring cropping, largely because of high black-grass and ryegrass pressure. Crops include milling wheat, oilseed rape, spring barley, spring beans, borage and millet.

Mr Willett says Omnia’s gross margin mapping function, provides a good way of assessing the viability of alternative crops, and for identifying potentially loss-making areas of the field.

He has used the system’s ability to combine multiple yield maps (4-5 years) to highlight areas that consistently underperform. In total, 35ha has been taken out of production and put into environmental stewardship options such as wild bird cover and wild flower strips.

“Where we’ve taken land out of production, I’ve tried to plan it so the cropped and uncropped areas can be managed efficiently; for example by making the stewardship area wide enough to manage with existing machinery, and leave an even tramline width on remaining cropped areas.”