Satellite ‘surveillance’ reveals which sustainable farming methods work—and which don’t

Until now, it has been difficult to measure how effective greener farming methods are across large swaths of land.

High-resolution satellite data can be used to monitor crops and help farmers double the gains from sustainable intensification, finds a new Nature Sustainability study.

It’s the first to show how satellite technology could be used to help farmers quantify the environmental and commercial benefits of sustainable farming – identifying which interventions work, and which don’t.

Sustainable intensification has become a buzzword in agriculture, covering a fleet of new farming methods, interventions, and technologies that are designed to scale up farming at the lowest-possible environmental cost. But one catch is that it’s difficult to measure how effective these methods really are across large areas of farmland.

The new study, however, provides some convincing evidence that some interventions really are worth their salt.

Using microsatellite data – which goes down to a less-than five-metre ground resolution, and can cheaply gather visual data over huge stretches of land – the researchers evaluated the effects of a new sustainable intensification method: a hand-held machine designed to spread fertilizer more evenly across farm fields. The visual data revealed that not only did this more efficient spreading approach have a lower environmental footprint, it also improved wheat yields by 5% across 127 smallscale farms in India.

The improved fertilizer distribution meant there was no increase in the amount showered across the fields, and that it was also reaching crops more uniformly. For farmers, the yield gain was substantial, accounting for about a third of management-related crop losses on the farms, the researchers calculated.

Environmentally, it also meant that less fertilizer was being wasted: the researchers estimated that with the reduced fertilizer use, nitrogen levels went down in the soil by almost 5% across farms. That would ultimately translate to less polluting nitrogen entering water and soil.

As well as this, the researchers were able to analyse the reams of satellite data they’d gathered to show that fields which previously had low wheat yields before the intervention were those that benefited the most from the more efficient fertilizer application. In these previously lower-yielding field, the more even fertilizer application actually doubled their output.

This underscored the value of microsatellite technology: by identifying where the greatest losses are occurring, it could also potentially reveal where the greatest gains can be made with sustainable intensification.

The satellites detected these overall yield changes visually by calculating how much green plant chlorophyll was present in each of the images they snapped. At high resolutions, this made it possible to estimate the density of a crop in the field over large areas, and thus its yield. Using this technique is also a far more efficient way to gather data about crop yields, compared to the standard – which typically relies on cumbersome, manual crop-cuts on the ground.

By testing out their satellite technology on smallholder farms in India, the researchers could also show its potential value under climate change. India is the world’s second-largest producer of wheat, much of which comes from smallholder farms like the ones in the study. Yet, wheat farmers are expected to suffer losses as temperatures rise. Using microsatellite data to identify areas vulnerable to yield losses through climate change, could help target areas that would most benefit from sustainable intensification.

That would boost food security and help farmers’ bottom lines – without unnecessarily harming the environment.

What’s more, the researchers think their discoveries could be applied to other countries and their crops, to evaluate the virtues of sustainable intensification in its many different forms. “Using satellite data to both evaluate and target interventions should be an important component of global efforts to enhance sustainable food production over the coming decades,” the researchers write.

 

By: GEOFFREY YORK
Image credit: Simon Allen from Pixabay

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