INTRODUCTION. xxxix 



of the plants, and is lost to the farm. If, on the other hand, we grow clover, beans, peas, tares, or turnips, 

 the whole of this fifty pounds is organized in the crop, provided there is sufficient available mineral mat 

 ter in the soil; and if the crop is ploughed u ruler, or consumed by animals on the farm, the whole fifty 

 pounds of ammonia, or nearly so, will be retained for the use of the subsequent cereal crops. 



We have not space to dwell on this important difference in the two classes of plants here desig 

 nated, one of which (clover, &c.,) retains all the ammonia received from the soil and the atmosphere, 

 while the other class (the cereals) dissipate it into the atmosphere during their growth. A correct appli 

 cation of this fact forms the key to good farming. 



We must grow more green crops and a less breadth of cereals. 



M. Lconce de Lavergne, an eminent French writer, in his work on the Rural Economy of England, 

 Scotland, and Ireland, deduces the same law from his observations of the astonishing results of the English 

 system of rotation, though without offering any satisfactory explanation of its rationale. Speaking of 

 England, he says: &quot;That small country, which is no larger than a fourth of France, alone produces one 

 hundred and four millions of bushels of wheat, forty-eighty millions of barley, and ninety millions of 

 oats. If France produced in the same ratio, her yield would be four hundred millions of bushels of 

 wheat, five hundred and sixty millions of bushels of barley, oats, and other grain, equal to at least double 

 her present productions; and we ought to obtain more, considering the nature of our soil and climate, 

 both much more favorable to cereals than the soil and climate of England. These facts verify this 

 agricultural law, that, to reap largely of cereals, it is better to reduce than to extend the breadth of land 

 sown, and that by giving the greatest space to the forage crops, not only is a greater quantity of butcher s 

 meat, milk, and wool obtained, but a larger production of grain. France will achieve similar results 

 when she has covered her immense fallows with root and forage crops, and reduced the breadth of her 

 cereals by several millions of hectares.&quot; 



This is true. English farmers, guided by close observ.ation and experience, have slowly worked out 

 an admirable system of rotation, and now scientific investigations have elucidated the principles upon which 

 it is founded. We may not be able at present to pursue generally the same system of rotation in this 

 country, but the principles are as applicable here as there, and, if adopted, will produce the same 

 beneficial results. 



The application of plaster, ashes, superphosphate of lime, and other mineral manures, has rarely any- 

 great effect on the growth of the cereals ; but superphosphate of lime has an almost magical effect on 

 turnips, and plaster usually increases the growth of clover, so that these mineral manures, when applied 

 to these crops, may be rendered, indirectly, of great benefit to the cereals. 



An English farmer once said to the writer, &quot; Insure me a good crop of turnips, and I will insure 

 you a good crop of barley, and of every other crop in the rotation.&quot; Of so much value do British farmers 

 consider the turnip crop as a means of enriching the soil for the growth of the cereal grains, that they 

 spend more money in preparing the soil for turnips than for any other crop, frequently fifty dollars per 

 acre. The turnip crop has justly been termed the &quot; sheet anchor &quot; of British agriculture. It enables 

 the farmer to keep an immense stock of sheep and cattle, and thus enrich the soil ; the ammonia which 

 turnips obtain from the soil, the rain, and the atmosphere being retained and left on the farm for the 

 use of the following cereal crops. In the Norfolk or four-course system of rotation, one-fourth of the 

 arable land is sown to turnips, followed by barley, seeded with clover. It then lies one or two years 

 in clover, followed by wheat at one furrow. After the wheat, turnips again follow, and so on as before. 

 Latterly, by the use of superphosphate and guano for turnips, and by feeding large quantities of oil-cake 

 and other purchased cattle food, the land has become so rich that many farmers have thought it necessary 

 to introduce an extra grain crop into the rotation, in order to reduce the soil. But hitherto the rule 

 has been never to take two grain crops in succession. 



How different from this is the practice of some of our American farmers ! Corn, barley, and wheat 

 often follow each other in succession ; then seed down with timothy, red-top, or some other exhausting 



