The significance of phosphorus fertilizers equate to soil nutrification and implies bountiful harvest. Howeover, the finiteness and uneven distribution of the recoverable reserves of phosphate rocks are a concern among farmers. The phosporus cycle involves absorption by crops, consumed and excreted by humans and animals. The Stevens Institute of Technology takes the global lead in mapping phosporus.
David Vaccari, director of the Department of Civil, Environmental, and Ocean Engineering of the Stevens Institute, and his team published their findings in the April 2019 issue of Earth's Future. His team conducted mapping the global flow of phosphorus. They were able to determine regional "hot spots" where fertilizers are in high demand and where there is a great potential to recycle phosphorus from animal and human waste.
"Ideally, the 45 million metric tons of phosphorus fertilizers each year would be completely reused, and we'd harvest their maximum potential to support food production," said Vaccari. "This work is a step towards understanding how to get to that point."
Researchers from Australia, Canada, China, Netherlands, and Sweden and the group led by Vaccari "combined recently developed datasets to map global crop production alongside human and livestock population levels. They then divided the planet into a grid of 10-kilometer wide blocks, allowing detailed local insights with an unprecedented overview of global phosphorus flows that bridges the global to the local, actionable level," as reported in Phys.
"In a field where a lack of well-integrated data has often impeded both local and regional planning, this global map is a key breakthrough," said Vaccari.
Places with unrecycled phosporus in regions in the world have been identified. Sixty-eight percent of farmlands with populous areas and 72 percent of farmlands with significant manure production nearby, are in locations that heavily rely on imported phosphorus. These areas include Brazil and India. There are also significant excess of waste rich in phosporus from the United States, Asia, and Europe. This implies that both developed and developing countries have the potential to recycle phosphorus.
"If we want to get serious about phosphorus recycling, these are the places where we're going to get the most bang for our buck," said Vaccari.
The findings show that animal manure has at least five times as much phosphorus contained compared to human waste. Thus, recycling efforts could be targeted in livestock operations. Around 50 percent of the croplands of the world are near manure-rich livestock operations. This shows that there could be direct application of manure in these regions.
Steve Powers, lead author from the Washington State University, is determining the amoutn of phosphorus that can be recaptured from animal and human waste. "If we can recycle more of this locally-available waste phosphorus back into agriculture, we might be able to keep it away from leak points while reducing our dependence on future fertilizer imports and mining," said Powers.
