Sulphur crop yields

Agricultural fertilization with sulphur is not a new concept - at the research level at least, sulphur has long been recognised as an essential plant nutrient. However because the complex role of sulphur - in soils, in plant material and in interaction with other essential element cycles - has never been fully understood, sulphur fertilizers have been used mainly on an empirical basis. As a result, sulphur fertilization has shown somewhat erratic performance Measured sulphur deficiency in soils has not always been correlated with poor crop yield and, as a corollary, sulphur fertilization of sulphur deficient soils has not always improved poor crop yields. Thus it has been difficult to routinely demonstrate an economic benefit to the farmer. 

Crop Yield Tonnes ha" Sulphur Nitrogen Phosphorus kg,ha l Potassium... 

Sodium anthraquinone-p-sulphonate ( silver salt ). Place 60 g. of fuming sulphuric acid (40-50 per cent. SO3) in a 250 or 500 ml. round-bottomed flask and add 50 g. of dry, finely-powdered anthra-quinone (Section IV,145). Fit an air condenser to the flask and heat the mixture slowly in an oil bath, with occasional shaking, so that at the end of 1 hour the temperature has reached 160°. Allow to cool and pour the warm mixture carefully into a 2 litre beaker containing 500 g. of crushed ice. Boil for about 15 minutes and filter off the unchanged anthraquinone at the pump. Neutralise the hot filtrate with sodium hydroxide and allow to cool, when the greater part of the sodium anthra-quinone-p-sulphonate separates as silvery glistening plates ( silver salt ). Filter these with suction and dry upon filter paper or upon a porous plate. A second crop of crystals may be isolated by concentration of the trate to half the original volume. The yield is 40-45 g. 

Another method 2 consists in passing the vapour of trimethylamine into a retort at red heat. The resulting products are passed into sulphuric acid, whereby ammonium cyanide is converted into hydrogen cyanide, which is now absorbed in potash to yield the corresponding cyanide. Ferrous hydroxide, prepared by addition of milk of lime to a solution of ferrous chloride, is added to the cyanide solution, and the liquid, after filtering, deposits a relatively pure crop of potassium ferrocyanide. 

Saalbach E (1973) The effect of sulphur, magnesium, and sodium on yield and quality of agricultural crops. Pontif Acad Sci Scr Varia 38 541-589. Sasaki N (1980) Epidemiolog.cal studies on hypertension in northeast Japan. In Kesteloot H and Joossens JV, eds. Epidemiology of Arterial Blood Pressure, pp. 367-377. Martinus Nijhoff Publishers The Hague, Boston, London. 

Dhankar, J. S., Kumar, V., Sangwan, P. S., and Karwasra, S. P. S. (1993). Effect of sulphur and molybdenum application on dry matter yield, uptake and utilization of soil and fertilizer-sulphur in raya crop (Brassica juncea Ojss). Agrochimica 37 4-5, 316-29. 

Excessive use of phosphate and artificial nitrogen fertilizer, again part of the quest to increase yields, is another cause of water-quality decline. It may result in cultural eutrophication, notably a substantial increase in the nutrient content of fresh and salt water, which encourages algal growth and an eventual overall decline in biodiversity (see Section 6.3.1). The problem is widespread in coimtries where intensive industrialized crop production is prevalent and is a major problem in enclosed seas such as the Mediterranean. Industry and domestic uses of water also exact a toll. For example, in parts of the USA, Canada and Europe acid rain , caused by the burning of sulphur-rich fossil fuels, has acidified catchments and reduced water pH below the levels tolerated by most fish species algal and microbial populations have also altered. Acidification is likely to spread substantially as industrialization continues in China, India etc. The issue is discussed in Sections 5.5 and 7.7. 

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