1. Two series of simple nitrogen manuring trials, one on level of sulphate of ammonia applied to the seedbed at twenty-two centres and the other on the time of top dressing with ‘Nitro-Chalk’ at nineteen centres, were conducted on commercial farms in south-east Scotland during 1954 to 1957.2. The optimum level of sulphate of ammonia varied with season and farm type. The optimum dressing was at least 0·9 cwt. N/acre in the dry season of 1955, and in the other years was estimated to be 0·9 cwt. N/acre on arable farms and about 0·-25–0·4 cwt. on ley rotation farms when the barley did not follow sheeped turnips. In the latter event no fertilizer was best.3. The nitrogen content of the grain increased little until after the 1 cwt. sulphate of ammonia level, although the optimum yield was not obtained in many experiments without some rise in the grain nitrogen content.

Fourteen trials on spring barley and eleven on winter wheat, grown in the east of Scotland, compared the effects on yield of liquified anhydrous ammonia and solid ammonium nitrate at various levels of application.For grain yield, the optimum N level in these trials was about 100-113 kg N/ha. The object of including in the trials N input levels higher than optimum was attained. Yield response to the two forms of N was similar for both wheat and barley at the different N input levels.Winter injection of anhydrous ammonia was less efficient than spring application. Injection of anhydrous ammonia into young wheat resulted in frequent reduction of plant population and, on occasion, loss of yield.At equivalent rates, anhydrous ammonia caused less lodging than ammonium nitrate; it also appeared to be less readily leached from the soil.Ammonium nitrate gave more rapid early growth and this led to a greater proneness to leaf disease.Considering the complexity of storage and injection equipment required to handle anhydrous ammonia, it is questionable if these agronomic advantages justify its use on cereals where rates of use do not also confer the benefits of cheaper unit cost of nitrogen.nitrate. Whitear (1970) obtained similar responses from small rates of anhydrous ammonia and of Anhydrous ammonia has been used as a nitrogen ammonium sulphate applied in spring to winter source for cereals in the U.K. for a number of years, wheat in East Anglia, but with double these rates, Jameson (1959) found little difference in efficiency ammonium sulphate was the more efficient ferbetween anhydrous ammonia and'Nitro-Chalk'for tilizer. Sim (1970) showed that tine spacing on winter wheat but he noted the risk of mechanical anhydrous ammonia applicators could be greater damage to the crop by the injection equipment, than that commercially practised without loss of Jeater (1966) found ammonium nitrate to be yield, and that depth of ammonia placement, rate slightly more efficient than anhydrous ammonia for of application and soil type had small effects winter wheat, whilst yields of spring barley from on barley yield. Lodging was less with anhydrous both sources of N were similar. At Rothamsted ammonia than with solid fertilizer and also with (Experimented Station Report 1968; Widdowson widely spaced as opposed to closely spaced injector & Penny, 1970), anhydrous ammonia and 'Nitro-tines. Chalk' were compared on spring wheat. At low Between 1967 and 1970,14 trials on spring barley application rates yields from the solid fertilizer and 11 on winter wheat were carried out in the east consistently exceeded those from anhydrous am-of Scotland to compare anhydrous ammonia with monia, but this advantage diminished at higher solid ammonium nitrate, either prilled (34 % N) or rates of N. The conclusions were that anhydrous in mixture with calcium carbonate (21-26 % N) at ammonia was slightly less efficient than ammonium various levels of application.

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