[155] Schulze recommends one-third of a pound per day of sulphate of lime for each horse. [156] See Appendix, Note X., p. 284. [157] The food consisted of 30 lb. _potatoes_, 15 lb. _hay_, and 120 lb. _water_. [158] For further analyses of cow-manure, see Appendix, Note XI., p. 286. [159] This is for a pig of six to eight months old, and fed on potatoes. [160] It has been asserted that the use of pig-manure, when applied alone, is apt to give an unpleasant taste to the produce grown. [161] Taken from a very large number of analyses by a number of experimenters. See Heiden's 'Duengerlehre,' vol. i. p. 99. [162] See Storer, 'Agricultural Chemistry,' vol. ii. p. 96. A question of great importance is as to the amount of farmyard manure produced on a farm in a year, and its value. This is a question which is extremely difficult to satisfactorily deal with. Various methods of calculating this amount have been resorted to. It may be well to state these pretty fully. Some practical authorities estimate the amount by calculating that every ton of straw should produce 4 tons of manure. Another method consists in estimating the amount from the size of the farm. Sir John Lawes has calculated the composition of farmyard manure which should be produced in the case of a farm of 400 acres, farmed on the four-course system. He assumes that half of the roots and 100 tons of hay are consumed at the homestead; that the whole of the straw of the corn crops is retained at home as food and litter; that twelve horses have corn equal to 10 lb. of oats per head per day; and that about ten shillings per acre are expended in the purchase of cake for feeding stock. Under these conditions the amount of farmyard manure should be 855 tons (or an average of 8-1/2 tons for each of the 100 acres of root-crop) of _fresh undecomposed dung_. (For composition, see Appendix, Note XVII., p. 291.) Another method is by taking, as the data of calculation, the number of cattle, horses, sheep, &c., producing the manure. Lloyd considers that a fattening animal requires 3 tons of straw in the year, and makes about 12 tons of manure. A farmer, therefore, should make 8 tons of manure for every acre of that part of his land which, in the four-course rotation, is put down to turnips.