A phosphate stockpile. Phosphorous, an important plant nutrient is difficult to be efficiently used by the plant. Silicon may mobilise its accessibility.
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Improving food security – silicon can increase phosphorus availability

Agricultural yields around the world can become more sustainable by using silicon to mobilise soil phosphorus, making it available for plants, according to a study by German and Danish researchers.

Phosphorus-based fertilisers, which are both environmentally damaging and a contain limited global resource, could conceivably become redundant for some years at a time. This is what researchers at the universities of Bayreuth in Germany and Copenhagen in Denmark have discovered investigating soils in the Arctic.

Agricultural yields depend very much on plants' access to sufficient quantities of essential nutrients. One of the most important nutrients is phosphorus. Although often present in large amounts in soils, a big share of phosphorus is strongly bound, especially to iron, which in turn is a component of various minerals. As a result, this phosphorus is immobile, rendering it un available to plants. Consequently, huge amounts of phosphorus-based fertilisers are utilised in agriculture today, to achieve the highest yields possible.

An interdisciplinary research team led by Dr Jörg Schaller (University of Bayreuth, Germany) and Professor Bo Elberling (University of Copenhagen, Denmark) have now found a way to make large amounts of the phosphorus yet strongly bound in soils available to plants. Silicon mobilises phosphorus from iron minerals, and enables it to be taken up by the roots of plants. The study has been published in the journal Scientific Reports.

Phosphorus a limited resource – silicon in endless supply

When farmers add precisely measured doses of silicon to their soils, they can do without phosphorus-based fertilisers for a certain period, stretching over several years in some cases, without any reduction in yield. “The environmental and agricultural advantages are obvious,” Schaller emphasised. “Phosphorus-based fertilisers are a limited resource, whereas silicon is in virtually endless supply. On the basis of our research results, the worldwide availability of phosphorus in the ground could be precisely controlled by targeted fertilising with silicon. This would represent an important contribution to global food security,” the Bayreuth environmental geochemist explains.

Especially in tropical and subtropical countries, several soils contain high amounts of strongly bound phosphorus, which could be mobilised bit by bit through the controlled application of silicon fertiliser.

This would mean making a significant contribution to environmental protection: A reduction in fertilisation with phosphorus and the precise control of phosphorus availability through silicon would lead to far less phosphorus leaching from fields to the aquatic ecosystems. Hence, the environmentally damaging eutrophication of waters (algal bloom) would be reduced.

150 soil samples taken in the Arctic

The scientists from Bayreuth and Copenhagen actually gained all of these insights through studies of Arctic soils. Soil samples were taken from over 150 sites on the Swedish mainland, Svalbard, the north coast of Russia and Greenland, and subsequently subjected to extensive analyses and experiments. For research into geochemical processes, permafrost soils have the advantage of not being influenced by agriculture or other human activity. “In selecting the soil samples, we made sure that the respective regions differed from one another as much as possible - for example with regard to soil types, landscape profile, and vegetation. In this way we wanted to ensure that our research results were not due to specific regional factors, but as far as possible, could be applicable globally,” Schaller explains.

(University of Bayreuth/wi)

Publication:

J. Schaller, S. Faucherre, H. Joss, M. Obst, M. Goeckede, B. Planer-Friedrich, S. Peiffer, B. Gilfedder, and B. Elberling: Silicon increases the phosphorus availability of Arctic soils, Scientific Reports (2019), DOI: 10.1038/s41598-018-37104-6