158 TALKS ON MANURES. 



" This accumulation of nitrogenous plant-food, specially useful 

 to cereal crops, is, as shown in the preceding experiments, much 

 greater when clover is grown for seed, than when it is made into 

 hay. This affords an intelligible explanation of a fact long 

 observed by good practical men, although denied by other'; who 

 decline to accept their experience as resting upon trustworthy evi- 

 dence, because, as they say, land cannot become more fertile when 

 a crop is grown upon it for seed, which is carried off, than when 

 that crop is cut down and the produce consumed on the land. The 

 chemical points brought forward in the course of this inquiry, 

 show plainly that mere speculation as to what can take place in a 

 soil, and what not, do not much advance the true theory of cer- 

 tain agricultural practices. It is only by carefully investigating 

 subjects like the one under consideration, that positive proofs are 

 given, showing the correctness of intelligent observers in the fields. 

 Many years ago, I made a great many experiments relative to the 

 chemistry of farm-yard manure, and then showed, amongst other 

 particulars, that manure, spread at once on the land, need not 

 there and then be plowed in, inasmuch as neither a broiling sun, 

 nor a sweeping and drying wind will cause the slightest loss of 

 nmmonin; and that, therefore, the old-fashioned farmer who carts 

 his manure on the laud as soon as he can, and spreads it at once, 

 but who plows it in at his convenience, acts in perfect accordance 

 with correct chemical principles involved in the management of 

 farm-yard manure. On the present occasion, my main object has 

 been to show, not merely by reasoning on the subject, but by actual 

 experiments, that the larger the amounts of nitrogen, potash, soda, 

 lime, phosphoric acid, etc., which are removed from the laud in a 

 clover-crop, the better it is, nevertheless, made thereby for produc- 

 ing in the succeeding year an abundant crop of wheat, other cir- 

 cumstances being favorable to its growth. 



" Indeed, no kind of manure can be compared in point of efficacy 

 for wheat, to the manuring which the land gets in a really good 

 crop of clover. The farmer who wishes to derive the full benefit 

 from his clover-lay, should plow it up for wheat as soon as possi- 

 ble in the autumn, and leave it in a rough state as long as is admis- 

 sible, in order that the air may find free access into the land, and 

 the organic remains left in so much abundance in a good crop of 

 clover be changed into plant-food ; more especially, in other words, 

 in order that the crude nitrogenous organic matter in the clover- 

 roots and decaying leaves, may have time to become transformed 

 into ammoniacal compounds, and these, in the course of time, into 

 nitrates, which I am strongly inclined to think is the form in which 



