24 Nov 2010

Sulphur nutrition and food security

Presented at the "Sulfur Metabolism in Plants" workshop

Rob Norton
1 International Plant Nutrition Institute, 54 Florence St Horsham, Victoria, 3400, Australia. rnorton@ipni.net

Food security is an issue that will continue to challenge agricultural production and distribution. While access to food has improved in the past couple of years the challenges of a changing climate, urbanisation, and resource security will require attention to improving productivity within the current land resource.
Fertilizers contribute half the world’s food. Sulphur is important as an essential plant nutrient as well as quality for a range of plant products. It is also critical for animal nutrition. In crops, N and S nutrition are closely tied and changes in N:S can result in changes in grain quality. This balance, along with the role of N and P, indicate that S is a key part of a balanced plant nutrition program to meet future food security.
Grains represent the major depletion of S in a national S audit, followed by livestock, and a national audit suggests an annual S removal of 0.4 kg S per ha, similar to an audit from 1995. This is balanced by the input of S containing fertilizer as well as the use of agricultural gypsum and manures.
Much of the sulphur in soils is present in organic matter, which must be mineralised before plants can access it. Sulphate ions remain in soil solution and are readily leached, and with changing farming systems, the number of S deficient soils is increasing. As a result, there has been a steady increase in the demand for sulphur for crop nutrition. There is a global supply of around 50 Mt of S, with nearly all recovered from S-rich oil and gas with a growth of around 5% per annum predicted. 85% of S is used for sulphuric acid production including the manufacture of a range of S containing fertilizers such as ammonium sulphate and single superphosphate, although newer S fortified products are entering the market.
2010 11 Sulphur and Food Security.pdf (size: 2.28 MB)

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