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Watch: robot harvest investigates how autonomy can harness strip cropping benefits

Posted 12 September

An autonomous harvest has begun as part of an investigation into the benefits of strip intercropping tended by robots.

The three crops harvested – winter barley, harvested in late July, beans - to be harvested this month, and wheat - which was harvested in August – are the latest to be tended using technology developed in the Hands Free Farm and Hands Free Hectare projects.

The crop trials – now in their second year – aim to show how the use of the smaller and more precise machines previously utilised on the Hands Free Farm can also pay dividends when it comes to strip cropping.

Dr Ed Dickin, who is leading the work on the project alongside wider work on intercropping in the project, explained more about what has been happening at a recent research conference at 91Pro.

He said: “Intercropping is basically growing more than one crop in the same place at the same time. A classic example of it is grown by the native Americans – corn, beans and squash, known as ‘the three sisters’.

“Each crop benefits the other – the corn provides scaffolding for the beans, and shades the pumpkins, and then the beans produce nitrogen.

“That’s a classic type of intercropping – but what we find with intercropping, as mechanisation comes into agriculture, intercropping tends to disappear.”

Farmers can carry out different kinds of intercropping, including those using rows and strips – and, done successfully, it can increase crop yields from the same amount of land.

Ed added: “One of the key advantages of intercropping is, when you get the combinations right, you are getting more productivity from the same amount of land – and that’s really important with a lot of the demands on land use at the moment.”

“Strip intercropping allows a relay effect called ‘temporal complementarity’ where if neighbouring strips use resources - such as light, water and nutrients - at different times, the edge rows yield more than the centre rows. For example, winter barley builds its biomass in April and May, so edge rows next to spring beans, still small at this time, will get more light; and in turn the beans next to the barley, harvested in July, will get more light in the later summer to fill their pods.”

The challenge the team set themselves was to use the benefits of intercropping – specifically, strip cropping using narrow strips of each plant – to increase yield on the trial plot.

Ed added: “The problem is having narrow strips with conventional machinery is very labour intensive – when you are driving up and down the field, you have got to be very, very accurate – so this is where the robotics come in.

“The Hands Free Hectare started in 2017 and the idea was to grow a crop using these machines. We applied that to strip cropping.

“We tried this last year with some success, and what we did proved the concept. We proved the robotics have got enough precision to plant, spray, harvest these strips.

“And then we tried it again, and this year was going to be the big year when we got some really good data.

“Unfortunately, it rained, and it rained, and it rained and it rained. But we have got some results.”

Ed explained that – with the current two metre wide rows on the trial plots: “Each strip had 10 rows, and the edge rows of wheat and barley yielded around 150 per cent of the grain yield of the eight centre rows, so for each 10 rows in a strip we get 11 rows worth of yield.

“Narrower strips would give us a greater proportion of edge rows.

“In a second experiment, two-metre strips of wheat are alternated with a clover-rich legume fallow, with fertiliser and sprays only applied to the wheat strips. We are farming 50 per cent of the field area, so 50 per cent of the inputs, and we are getting 56 per cent of the yield from 50 per cent of the inputs.

“If we extrapolate to one metre rows, we get 64 per cent of the productivity from 50 per cent of the inputs.

“These yields are not bad, considering until May, we could not get on the field to apply fertiliser or plant protection products because it was too boggy.”

Further plans for the work, Ed added, include an InnovateUK project with a new startup working on agro-ecological farming robots, which will see a bespoke robot designed for the strip cropping work, and biodiversity surveys being carried out across the trial site.

Setting out what the researchers have called a ‘strip cropping manifesto’, he concluded: “A very, very simple idea – just growing crops in strips – could have a big impact on our landscapes.”