Beccnt Publications on Manures. 77 



yards of the drill of potatoes ; nearly 1 ton to the acre. The 

 price at Glasgow, 261. for 3 tons, about 85. 8d. per cwt, or 

 rather above 8/. per acre ; not so much as would have been paid 

 for farm-yard manure. The rape dust yielded more than double 

 the produce of the ordinary manure, as 15 to 7; and the crop 

 of wheat after was very fine. At Dankeith the experiments I 

 saw were on a small scale, in the garden. Some rows of 

 potatoes manured with the above proportion of rape dust had 

 decidedly the largest and most vigorous-looking foliage. Other 

 rows, manured with half the usual quantity of manure and half 

 rape dust, and some others with nitrate of soda in the usual 

 proportion without manure, were all better to appearance than 

 that with the farm-yard manure, which was good dung, he said, 

 though rather new. How the result turned out at digging time 

 I have not yet heard, as the gardener left at Martinmas ; but 

 the rape dust he thought undoubtedly would carry through, 

 both from the great produce it had given at Barrochan last 

 year, and from the fact that those planted with the rape dust 

 were latest in coming through, more slow in growth at first, and 

 appeared to be still gaining vigour progressively. He found the 

 potato sets apt to decay when planted with the cut surface next 

 the rape dust, and found it necessary to have a stratum of earth 

 between it and the sets. The rape dust he found also to benefit 

 red beet greatly : it also benefited turnips. To peas it did no 

 good ; and cauliflowers and carrots it killed nearly entirely. It 

 seemed to encourage vermin, as he found insects in great abun- 

 dance about the roots of the cauliflowers, among the rape dust. 

 It appeared to hurt the cauliflowers even when mixed among the 

 soil. In the experiments on grass, the parts dressed with rape 

 dust and nitrate of soda in June made a great advance for about 

 a fortnight : after the first cut of the grass, the effects of the 

 nitrate of soda could hardly be perceived on the second growth, 

 and that of the rape dust only partially. Some nitrate of soda, 

 which he sprinkled on the foliage of plants, killed some and 

 hurt others : he approves of it most diluted with water. Many 

 complaints have this year been made of the nitrate's hurting fo- 

 liage : being presented to the foliage in a concentrated state, 

 without being so well diluted as that which goes to the roots 

 will be with the water of the soil, may be a cause ; as all food 

 in excess is found hurtful. As the upper side of the leaf does 

 not absorb so readily as the under side, nor as the spongioles of 

 the root, the nitrate will also lie longer in contact with the mem- 

 brane of the cuticle, and may act deleteriously. These salts are 

 not likely to be decomposed before reaching the roots. If the 

 nitrates were decomposed in the soil with the salts of iron, it 

 would render them of no use ; and as ammonia has a more 

 feeble affinity for acids than the other alkalies, it is not likely 



