A Presidential Address provides an opportunity for an account of the state of the subject and a reading of the signposts which seem to point to future progress. The broad philosophical aspects of soil science were discussed by E. M. Crowther (1953) a quarter of a century ago in ‘The Sceptical Soil Chemist’, a paper which is worth reading again. This year our Vice‐President, D. J. Greenland (1978) discussed ‘The Responsibilities of Soil Science’. I shall concentrate on discussing some ways in which soil scientists may contribute further to agricultural development.
Fertilizer placed in contact with the seed damaged the germination of sugar beet, mangolds, swedes and peas in 1947; damage was also caused by fertilizer placed directly below the seed. In 1947 and 1948 some damage to the germination of sugar beet was caused by fertilizer in bands 3 in. below the soil surface and 1 in. to the side of the seed; in both years bands of fertilizer 3 in. to the side of the seed were safe. Where placement of medium or full fertilizer dressings is adopted for row crops, the bands should be placed not less than 2 in. from the seed to avoid the risk of injury to germination.All methods of placing gave consistently higher yields of peas than broadcasting fertilizer, the average advantage of placing being over 2 cwt. of peas per acre. In all the experiments on peas in 1948 early applications broadcast and worked deeply into the seed-bed were somewhat superior to late applications made at sowing time.
The results of about ninety field experiments carried out over three years to test dicalcium phosphate, nitrophosphate, ammoniated fertilizer and Gafsa rock phosphate are summarized and discussed. Soils with pH values of 6·5 and below are listed as ‘acid’, those with higher pH values as ‘neutral’. All comparisons were made in terms of fertilizers supplying the same total amounts of phosphorus.Dicalcium phosphate dihydrate gave approximately the same yields as superphosphate for potatoes (both on acid and on neutral soils) and for grass, kale and barley. In one group of swede experiments mostly carried out in the north-east of the country dicalcium phosphate was inferior to superphosphate, but it was equal to superphosphate in another group of swede experiments, most of which were on acid soils in wetter areas.A nitrophosphate made in England on pilot-plant scale was consistently inferior to superphosphate for barley, potatoes and swedes.
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