Phosphorus is essential for agriculture, yet this important plant nutrient is rapidly being destroyed by soils around the world. The primary reason is soil erosion, which reports an international research team led by the University of Basel. Study in journal Nature communication Shows which continents and regions are most affected.
The world’s food production depends directly on phosphorus. However, this plant is not nutrient unlimited, originating from finite geological reserves. How quickly these reserves can be eliminated is a matter of scholarly debate. As is the controversial question, who owns the remaining reserves, and consequently political dependence.
Quantization using high-resolution data
An international research team led by Professor Christine Ellewell has investigated that the greatest loss of phosphorus is occurring in continents and regions around the world. Researchers combined high-resolution, spatially discrete global data on the phosphorus content of soils with locally local erosion rates. Based on this, they calculated how much phosphorus is lost through erosion in different countries.
An important conclusion of the study is that more than 50% of global phosphorus loss in agriculture is due to soil erosion. “The irony is that a role play was already known. The extent of that role has never been determined before with this level of spatial resolution,” Ellewell explains. Previously, experts reported losses mainly due to recycling, lack of food and feed waste and general mismanagement of phosphorus resources.
Too little in the field, too much in the water
Erosion releases mineral-phosphorus from agricultural lands into wetlands and water bodies, where excess of nutrients (called eutrophication) harms aquatic plant and animal communities. Researchers were able to validate their calculations using globally published measurement data on phosphorus content in rivers: elevated phosphorus content in water reflects phosphorus counts in soils in the respective region.
Mineral fertilizers can replace lost phosphorus in farms, but not all countries are able to use them equally. Although possible for countries such as Switzerland, and thanks to organic fertilizers, agriculture, Africa, Eastern Europe and South America register the largest phosphorus losses, with limited options to solve the potentially closed phosphorus cycle problem. “This is ironic, especially the largest geological phosphorus deposit in Africa.” “But mined phosphorus is exported and compared to this the cost is many times higher for most farmers in African countries, for example, European farmers.” Economic constraints are also the most important factor in phosphorus deficiency in Eastern Europe.
South America could potentially reduce the problem with better recycling of organic fertilizer and / or plant residues. On the other hand, farmers in Africa do not have this option, because Africa has little green fodder and very little animal husbandry to replace mineral fertilizers with manure and slurry, says Ellewell.
Who will control the reserves in future?
It is still unclear whether, in fact, phosphorus will exit for global agriculture. New, large deposits were discovered a few years ago in the Western Sahara and Morocco, although their reach is questionable. In addition, China, Russia and the United States are rapidly increasing their influence in these regions, suggesting that they may also control this important resource for future global food production. Europe has practically no phosphorus deposits of its own.
“Eighty-five percent of our food is produced directly or indirectly as a result of plants growing in the soil. Lack of phosphorus, the nutrient of the plant, should concern all people and societies,” Alevel says. If countries want to protect their independence from states that possess the remaining large deposits, they should reduce phosphorus losses in the soil.
The drastic reduction in soil erosion is an important step in the right direction. Land managers can reduce erosion by ensuring ground cover for as long as possible; For example, through mulching, green manure and intercropping, and through topography-adapted farming – shifting fields for sloping or terracing.
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Christine Ellewell et al. Soil erosion will increase global phosphorus deficiency, Nature communication (2020). DOI: 10.1038 / s41467-020-18326-7
Provided by the University of Basel
Quotes: Researchers first (2020, 11 September) quantified the worldwide loss of phosphorus due to soil erosion on 12 September 2020 from https://phys.org/news/2020-09-quantify-worldwide-loss-photorus-due Received. Html
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