Ag nitrogen and tracking deforestation

Pesticides sprayed today pollutes water for decades.

Nitrogen from agriculture bigger problem than believed

Humans have long known that agriculture contributes to surface and groundwater pollution, particularly from nitrates that run off from nitrogen-based fertilizers. More troubling is new research that tells us even if farmers stop applying nitrogen fertilizers, elevated nitrate concentrations in rivers and lakes will remain high for decades, increasing the risk of a number of serious human health and environmental concerns.

The research was conducted by a team out of the University of Waterloo in Ontario, Canada, and published in a special issue of the journal Environmental Research Letters. In their paper, the Canadian team reveals that nitrogen builds up in soils, creating a long-term source of nitrate pollution in ground and surface waters.

“A large portion of the nitrogen applied as fertilizer has remained unaccounted for over the last decades,” said Nandita Basu, a professor in the Department of Earth and Environmental Sciences and Civil and Environmental Engineering, in a press release.

The team analyzed data from more than 2,000 soil samples from the Mississippi River Basin. In many areas, nitrate accumulation was not apparent in the upper soil layer, but instead was found from 25-100 centimeters (approximately 10-40 inches) beneath the soil surface.

“We hypothesize that this accumulation occurred not only because of the increased use of fertilizers, but also increases in soybean cultivation and changes in tillage practices over the past 80 years,” said team member Kim Van Meter in a press release.

Computer models from the research suggest nitrogen could still be leaching into waterways more than three decades after nitrogen is no longer being applied to fields.

Excess nitrogen robs waterways of oxygen, causing uninhabitable dead zones for aquatic life, damaging drinking water quality and increasing the risk of serious health problems.

New satellite alert system tracks deforestation

Satellite view of deforestation in the Amazon rainforest. The roads follow a 'fishbone' pattern.
Satellite view of deforestation in the Amazon rainforest. The roads follow a ‘fishbone’ pattern. Wikimedia Commons

Every year, deforestation removes forests equivalent to the size of Panama, according to National Geographic. To track and combat it more efficiently, the University of Maryland has partnered with Google to create a global satellite system for tracking deforestation, providing the fastest updates yet available on the pillaging of the world’s forests.

The Global Land Analysis and Discovery (GLAD) system allows users to track deforestation as quickly as one week after it happens. Previously, satellite coverage of deforestation could be updated monthly, at best, and it could look at areas in no greater detail than a 500-meter-by-500-meter grid. GLAD examines a 30-meter-by-30-meter grid, showing the area in much greater detail.

One way GLAD has been used is to look at widening roads in and out of densely forested areas — the widening of a road is one way to predict the transportation of deforested lumber. Once the satellites reveal deforestation, GLAD sends an alert to nearby government agencies. Anyone can sign up to receive GLAD alerts by location, be it a country, a national park or an area set aside for resource exploitation.

GLAD is already being used to monitor deforestation in Peru, the Congo and Indonesian Borneo. The Borneo monitoring, for example, has produced 58,000 alerts from the country’s palm oil plantations since the beginning of 2015. The Congo triggered 85,000 alerts in a single day in February, a massive output that suggests rapid mass deforestation for industrial mining.

— Tommy Wood