Tractor manufacturers "need to get their act together" and produce "smaller, smarter, lighter machines" to meet the demands growers now face, according to a leading academic.
Professor Simon Blackmore, head of engineering at Harper Adams University and an expert on automation in field growing, told a sustainability conference in Oxford last month: "Machines up to now have been based on cheap energy and we don't have that any more."
Claiming that 90 per cent of energy used in cultivation "goes on repairing the damage done by compaction", he said that "horsepower doesn't help when weight is the problem", such as on wet soils.
Instead, new farm machines should be based on the main drivers facing the sector, including minimising energy and chemical inputs, reducing labour costs, and even encouraging biodiversity by leaving non-competitive plants, he urged.
"There are good reasons for machines to get bigger, and there will always be a need for large tractors," he said. But at the other extreme, each plant can be treated individually using what he termed "plant-level husbandry".
Controlled-traffic farming is the next stage on from auto-steer on tractors, he said: "But current machines are not compatible to allow it - right now the manufacturers are on a dead-end street."
Giving examples of alternative approaches under development around the world, he said that "crop scouts" or "phenotyping robots" are being developed to take multiple measurements of crops in the field.
Blackmore himself is working on a "third generation" Scamp Scout to map crops and weeds using machine vision, while also detecting crop stress from the presence of ethylene and insect infestation from volatile compounds, measuring crop growth, detecting nutrient status from spectral analysis and calculating optimum cropping time.
"Already we have weed recognition software that can recognise up to 26 different weeds," he said.
He said guided "microspraying" can dramatically reduce the volume of herbicide required - typically from 720g of Glyphosate per hectare to 1g - as "nothing goes off-target".
Alternatively, targeted laser weeding uses a minimal energy charge to strike the plant's growing point.
Aerial vehicles Potential use for cropping
Several unmanned aerial vehicles (UAVs) took to the skies above Harper Adams University earlier this month to show their potential for cropping. The devices were demonstrated by specialist supplier KOREC. The firm's mapping consultant Martyn Palmer said: "An agronomist can tell the health of a crop using data from the UAV, and recommend to the farmer where they need to fertilise."