378 TRANSACTIONS OP SECTION M. 



that on this particular class of land fertility has been well maintained by 

 moderate dressings of slag or superphosphate at three-year intervals. 



As regards the larger dressing of slag (lower section of table) it wUl be 

 seen that here also absolute productivity is not maintained at the high level of 

 the earlier years, though as between the ninth and fifteenth years the reduction is 

 very slignt. But comparing the production on the manured and unmanured 

 land it will be seen that in these three tests the proportionate increase of meat 

 as a result of repeated doses of phosphates is actually greater at the end of 

 21 years than it was in the beginning, the ratio rising from 2-3:1 to 4-1 -1 

 In other words, for every pound of meat produced on the unmanured land 5 ib 

 are being produced on the manured ground, and not only so, but the enhanced 

 production is being secured at a cost which leaves a very laro-e profit on the 

 improvement. ° 



The power of repeated moderate dressings of slag to maintain the improve- 

 ment produced by a large initial dressing of this substance is well illustrated 

 in another series of experiments commenced at Cockle Park in 1903. A field 

 (Hanging Leaves) of poor pasture on clay was equally treated in 1898 with about 

 6 cwt. of slag per acre. No further treatment was given till 1903 when 4 plots 

 each 10-1 acres in extent, were fenced off, and to all of them 10 cwt. per acre 

 of slag was given. Since that time a supplementary dressing of 5 cwt per acre 

 01 slag has been given to Plot 1 every 3 years, with the result that at the end 

 ot 15 years of this treatment the production of live-weight increase (in this 

 case both cattle and sheep) is nearly as high (200 lb. per acre, average 3 years 

 1915-17) as at the stage of maximum production (206 lb. per acre, 1906-8). Here, 

 as on Tree Field, under the influence of slag the meat produced is nearly five 

 times as great as on the untreated ground. ^^^ 



Another plot, No. 2, is concerned with the question as to whether cake can be 

 profitably, fed to cattle and sheep on land which has first been graded up with 

 a liberal dressing of basic slag. Both Plots 1 and 2 have had the same amount 

 of basic slag since 1898 (36 cwt. per acre) applied at the same time, the only 

 difference in the treatment being that the stock on Plot 2 have since 1904 

 consumed 3 cwt. of rough cotton cake per acre, except in 1917 when a mixture 

 of palm-kernel and earth-nut cakes was substituted. The quantity consumed 

 up to the end of 1917 is thus practically 2 tons per acre. The cake has in the 

 aggregate in 14 years added about 470 lb. to the live-weight increase per acre 

 produced by slag alone. This increase at present-day rates is valued at les.s 

 than dl, to secure which the expenditure on cake is estimated at about 26/., 

 so that the direct and indirect effects of the cake have been extremely unproht- 

 able. As a matter of fact, whereas slag alone give.«; an annual profit of more 

 than 21. per acre, the use of cake on slagged land reduces the profit to less than 

 1?. Clearly, therefore, cake-feeding on this class of land, which is receiving 

 basic slag, is not a commercial success. 



Another aspect of the same problem is dealt with on Plot 3. Both this plot 

 and No. 1 received the same initial dressing of slag — namely, ^ ton per acre for 

 1903— the differential treatment since that year consisting" in No. 1 receiving 

 every 3 years 5 cwt. of slag, whereas No. 3 has had 3 cwt. per acre per annum 

 of rough cotton cake fed upon it. The comparison, in fact, is between tlie 

 feeding value (indirect) of 5 cwt. of slag and the feeding value (direct and 

 indirect) of 9 cwt. of cotton cake. The results, with those on the other plot?, 

 are shown in the table on page 16. 



For the first two years, when no supplementary slag had been applied, the 

 cake appeared to give a good account of itself, but the first supplementary 

 dressing of slag distinctly reduced the difference in the two sets of live-weight 

 figures, after which the output of Plot 1 (slag) steadily improved, while that of 

 Plot 3 (cake) as steadily, and more markedly, declined, until in the period 

 1915 17 the slag was producing 55 lb. per acre per annum more animal incrense 

 than the cake. It would appear therefore that the accumulated cake residues 

 have had a positively injurious effect on the pasture, and that this effect is 

 being accentuated as time goes on. 



The fourth plot is concerned with the question as to the value of organic 

 nitrogen in fish meal as compared with the nitrogen in cake residues. Plots 2 



" Gilchrist, ' Cockle Park Guide,' 1919, p. 17. 



