306 AGRICULTURAL TEXT-BOOK. 



of animals, also, changes take place, by -which the food consumed ia 

 decomposed, and now compounds of much importance are, in conse 

 quence, introduced into the urine and dung. All these changes ave, in 

 some degree, connected with the richness and fertilizing quality of ani 

 mal manures, or with the special action of the variety which may be 

 used. To know on what the general efficacy or peculiar effect of such 

 manures depends, their changes and the substances produced by them, 

 should be understood. How different samples of the same kind of ma 

 nures differ in virtue ; how this virtue is modified, lost, preserved, or 

 augmented these questions are of much consequence in ordinary farm 

 ing, if the best, or most profitable results are to be obtained by the 

 practical man. 



G75. Mineral, or saline manures are combinations, or mixtures of diff 

 erent combinations of one or more of those mineral substances which 

 exist and are found in living plants. Thes-e saline substances are fixed 

 and definite in their composition. But to use them right to apply 

 them iu the proper place, at the proper time, and in the proper quantity 

 to understand their action, how they ought to be mixed, and why 

 their effects vary in different circumstances and localities all this re 

 quires that they should be thoroughly known, and their mode of action, 

 as single substances and as mixtures understood. (See Johnston s Ex- 

 pcrim. 



676. In order to show the very complex action of plants and manures on the soil, 

 we extract the following curious and instructive account of an experiment by a prac 

 tical English farmer, from the Journal of the Royal Agricul. Socy. of England, v I. 

 xiii p- 417. 1852. It is worthy of careful study, and shows more clearly than any 

 other document we are acquainted wilh, the difficulties which beset the farmer in the 

 management of his cropland manures : 



&quot; In the autumn of 1816, a field of three acres was manured at the rate of 20 tons 

 of farm yard manure per acre, and sown with rye for soiling in the following spring. 

 It produced a very heavy crop, hut on account of the stalks becoming too hard for 

 the horses, half the rye was allowed to remain for seed. The part of the field which 

 had been cut for soiling was immediately plowed and sown with glole turnips, with 

 a dressing of three cwt of Peruvian guano per acre. The turnips were very fine. 

 After the seed rye was harvested and the turnips cleared, the whole three acres were 

 plowed and set with beans the following February ; and now comes the curious part 

 of the affair. The beans came up well all over the field ; but a difference was soon 

 perceived between those on the seed-rye and turnip ground, the former looking much 

 more luxuriant than the latter, hut we were not prepared for what afterwards took 

 place. The beans that followed the turnips actually stopped all growth when six 

 inches high, and, of course, did not seed, whereas, after the seed-rye they grew BO 

 luxuriantly as to injure the produce, and this difference extended to the line where 

 we had discontinued cutting the green-rje the more conspicuous as we had atopped 

 in the middle of a land. 



