Innovation in Resourcing Geological Materials as Crop Nutrients

Abstract

Mineral resources are fundamental to the growth and development of human society. Extraction of metal ores has risen very slightly as a proportion of all resources, while construction and industrial mineral extraction has grown much more rapidly. This reflects growth in GDP, which is much faster than population growth, in turn reflecting improved standards of living, growth in urban housing/infrastructure and growth in the consumer society. Fertilizer minerals in particular are essential resources for production of the food needed by an increasing global population. Nitrogen fertilizer manufacture requires fossil fuels-especially natural gas (methane) as a source of the hydrogen needed for the HaberBosch process. Phosphate fertilizers are predominantly manufactured using phosphate rock as a source of phosphoric acid, and there is scope to recover phosphorus from contaminated waters. Potassium fertilizers are produced from evaporite deposits, mainly in the global north. It is difficult for poorer countries with deeply leached soils to access and make efficient use of existing conventional products. Globally, while N and P fertilizer application replaces the nutrient removed by crops and so is in balance, twice as much K is being removed from soils as is being replaced. This leads to the need for innovation in developing novel sources of K, especially to support agricultural production in the global south. Rocks containing K silicate minerals (such as feldspar and nepheline) occur widely as potential sources of K for use in soils where these minerals weather rapidly. Observations of surface corrosion in feldspars taken from soils after 10 years exposure to soil microbial systems demonstrates rates of dissolution 4 orders of magnitude greater than determined in the laboratory. Innovation in use of these minerals depends on an understanding of the role of microbial processes in silicate mineral decomposition.

Communicating Source Separation of Urine

“…the use of fossil fuels in the production of nitrogen in the Haber-Bosch process and the extraction of phosphate and potassium from mines. Potassium and phosphorus are mined in only a few countries in the world, which leads to geopolitical tensions and may be exacerbated in the future on the basis of the in part already insufficient nutrient supply of the soil (Ciceri et al, 2015;Cordell et al, 2009;Manning, 2015;Manning, 2018). Studies show that a high rate of soils both in developing regions like India as well as developed countries like the UK are deficient in at least one micronutrient (Jones et al, 2013).…”

Use of Mineral Weathering Bacteria to Enhance Nutrient Availability in Crops: A Review

“…Soluble K-fertilizers based on potash ("potassium-rich salt") are produced mainly from mined salts (i.e., sylvite and carnallite). Comparing to N and P fertilizers, these sources demand less industrial and chemical processing to result in a fertilizer product (Manning, 2018). The main resources of K salts are in the northern hemisphere.…”

“…Historically, access to conventional potash fertilizer could be difficult due to high prices, transport, and even geopolitical reasons. This situation leads to the innovative use of different materials and geological resources as K fertilizers, being the use of silicate rocks a clear example of this (Manning, 2018). Despite the low solubility of silicate rocks, a group of weathering bacteria known as K-solubilizing bacteria (KSB) display an efficient ability to release K and others plant nutrients from these sources (Etesami et al, 2017).…”

Inputs: Potassium Sources for Agricultural Systems

“…For example, potassium feldspar may contain almost 17% K 2 O, but the dissolution is 20 million times slower than nepheline, a less abundant K-bearing mineral with 15% K 2 O (Palandri and Kharaka 2004). The rate of K dissolution is key to its value as a source of plant nutrition (Manning 2018).…”