In recent years, it is no longer exotic to see drones flying over the field. Thanks to the work they do, they are becoming an increasingly significant part of a farm's arsenal.

Today we're going to look at how drone data is being used to make nitrogen fertilizer more intelligent. Professor Barton explains that healthy vegetation reflects more near-infrared light than unhealthy vegetation.

The ratio of red to near-infrared bands on multispectral images can be used to estimate chlorophyll concentration and therefore to map biomass. This way you can see exactly where certain measures are needed, such as fertilizing after a change in weather or as a result of pest damage.

When the French agricultural technology company Airinov (which offers this kind of drone survey) partnered with a French agricultural cooperative, they found that over a 3-year period, in 627 fields with oilseed rape (Brassica napus), farmers used an average of 34 kilograms less nitrogen fertilizers per hectare than if they had used the conventional method. At current fertilizer prices, this saves a significant amount.

Bonirob – a car-sized robot originally developed by a team of scientists at the University of Applied Sciences in Osnabruck, Germany – can measure other indicators of soil quality using a variety of sensors and modules, including a moisture sensor and a penetrometer, which is used to estimate soil compaction.

According to Arno Ruckelshausen, an agricultural technologist in Osnabrück, Bonirob can take a soil sample, analyze it to precisely map real-time characteristics such as pH and phosphorus levels. The University of Sydney's smaller RIPPA robot can also determine soil characteristics that affect the crop production by measuring soil conductivity.

Soil mapping opens the door to planting different crops in a field to better match changing soil properties, such as water availability. "You can sow a differentiated field, for example, like deep-rooted varieties of barley or wheat in sandier parts," says Maurice Moloney, CEO of the Global Food Security Institute in Saskatoon, Canada.

Growing several crops together can also lead to more optimized pesticide use. "Nature is strongly against monocultures, which is one of the reasons we use huge amounts of herbicides and pesticides," says van Henten. "It's about making the best use of resources."

Some of the heaviest harvesters weigh 60 tons, are very expensive and leave behind a trail of soil compaction that can damage the soil for years, the expert said.

Mixed cropping would challenge an accepted pillar of agricultural wisdom: that economies of scale and the bulkiness of farm machinery mean that vast fields of a single crop are the most efficient way to farm, and the bigger the machine, the more efficient the process.