66 



With tops returned to the soil a crop of 200 bushels per acre re- 

 moves 36 Ib. nitrogen, 13 Ib. phosphoric acid, and 60 Ib. potash. If th& 

 new German potatoes are, however, planted, and such crops as 300 

 cwt. and more are grown, the proportion of plant food removed is,. 

 of course, so much more, although the larger growth on the surface 

 returns also more into the soil if turned under. Professor Maercker 

 demands for these varieties, to obtain a fairly full crop, 58 J Ib. ct 

 nitrogen, 24 Ib. of phosphoric acid, and 79| Ib. of potash per acre, 

 but he says also that you cannot use only commercial manures. 

 The potatoes would only be able to take up about two-thirds of the 

 nitrate of soda or sulphate of ammonia, one-third of the phosphoric 

 acid, and about 60 per cent, of the potash contained in the respective 

 manures applied, and, if larger quantities to make up for the defi- 

 ciency were used, it would at least with nitrate of soda and kainit 

 (unless the new kainit is used) be injurious, and 6 cwt. of nitrate per 

 acre also too expensive. From 100 to 150 cwt. of the very best, 

 farmyard dung, supplemented by commercial manures, are, there- 

 fore, wanted. When green manuring is possible after a suffi- 

 cient rainfall in February or March, and the potatoes are planted 

 in August or later, you might obtain from 80 to 100 Ib. of ntro- 

 gen per acre. The Long Island Farmers Club use instead of 

 dung 440 Ib. of high-grade dried blood, and only 127 Ib. of nitrate 

 of soda per acre. 



The Permanent Nitrate Committee offered in 1896 prizes for 

 growing potatoes on not less than an acre with dung and fertilisers 

 used in the discretion of the competitors, but in conjunction with 

 nitrate of soda of 95 per cent, purity. The best return obtained, 

 the Cupar and North of Fifeshire Agricultural Society, on sandy, 

 clayey loam, with 30 tons of dung at time of planting, 4 cwt. of 

 superphosphate, | cwt. of sulphate of potash, 1 cwt. of steamed bone- 

 flour in drills, and 1 cwt. of nitrate of soda sown broadcast before 

 earthing up last time. The land had been two years in pasture, 

 and only in 1895 had a crop of oats. Result, 23 tons 12 cwt. 1 

 qr. and 25 Ib., against 15 tons 19 cwt. and 8 Ib. not manured. The 

 soil was, therefore, in very good heart before. The Blandford 

 Farmers' Club applied to strong loam, on clay 15 loads of dung in 

 winter, J cwt. of nitrate of soda at planting, and f cwt. nitrate of 

 soda in three dressings of 28 Ib. The crop resulted in 13 tons 1 

 cwt. 1 qr. 20 Ib., against 8 tons unmanured. The land had borne 

 wheat in 1893 and 1895 and mangolds in 1894. Skelton-in-Clove- 

 land Agricultural Society used merely 20 loads of dung and 1 cwt. 

 of nitrate of soda on strong soil, and the result was 17 tons 9 cwt. 3 

 qr. 15 Ib.. against 11 tons 11 cwt. 1 qr. 26 Ib. Previous crops in 

 1894 seeds, in 1895 oats. The Easingwold Agricultural Club- 

 manured sand on sand, which had turnips, oats, and clover in 1893. 

 1894, and 1895, with 15 tons of duns:. 5 cwt. kainit when planted, 

 and 1 cwt. nitrate of soda when earthed up, and the result was 12 

 tons 4 cwt. 18 Ib., against only 7 tpns 9 cwt. 10 Ib. without manure, 

 or an increase of 64 per cent. (The kainit should have been 

 applied much earlier, and the result might have been still better.)* 

 Dr. Aitken reports in the Highland Society Transactions. 1887. that. 



