The _eleventh_ season (1853-4,) gives us much more attractive-looking figures! We have over 21 bushels per acre on the plot which has grown eleven crops of wheat in eleven years without any manure. With barn-yard manure, over 41 bushels per acre. With ammonia-salts alone (17_a_), 45¾ bushels. With ammonia-salts and mixed minerals, (16_b_), over 50 bushels per acre, and 6,635 lbs. of straw. A total produce of nearly 5½ tons per acre. The _twelfth_ season (1854-5), gives us 17 bushels of wheat per acre on the continuously unmanured plot. Over 34½ bushels on the plot manured with barn-yard manure. And I think, for the first time since the commencement of the experiments, this plot produces the largest yield of any plot in the field. And well it may, for it has now had, in twelve years, 168 tons of barn-yard manure per acre! Several of the plots with ammonia-salts and mixed minerals, are nearly up to it in grain, and ahead of it in straw. The _thirteenth_ season (1855-6), gives 14½ bushels on the unmanured plot; over 36¼ bushels on the plot manured with barn-yard manure; and over 40 bushels on 8_a_, dressed with 600 lbs. ammonia-salts and mixed mineral manures. It will be noticed that 800 lbs. ammonia-salts does not give quite as large a yield this year as 600 lbs. I suppose 40 bushels per acre was all that the _season_ was capable of producing, and an extra quantity of ammonia did no good. 400 lbs. of ammonia-salts, on 7_a_, produced 37¼ bushels per acre, and 800 lbs. on 16_b_, only 37¾ bushels. That extra half bushel of wheat was produced at considerable cost. The _fourteenth_ season (1856-7), gives 20 bushels per acre on the unmanured plot, and 41 bushels on the plot with barn-yard manure. Mixed mineral manures alone on 5_a_ gives nearly 23 bushels per acre. Mixed mineral manures and 200 lbs. ammonia-salts, on 6_a_, give 35¼ bushels. In other words the ammonia gives us over 12 extra bushels of wheat, and 1,140 lbs. of straw. Mineral manures and 400 lbs. ammonia-salts, on 7_b_, give 46¼ bushels per acre. Mineral manures and 600 lbs. ammonia-salts, on 8_b_, give nearly 49 bushels per acre. Mineral manures and 800 lbs. of ammonia-salts, on 16_b_, give 50 bushels per acre, and 4,703 lbs. of straw. “This exceedingly heavy manuring,” said the Deacon, “does not pay. For instance, “200 lbs. ammonia-salts give an increase of 12¼ bushels per acre. 400 ” ” ” ” 23¼ ” ” 600 ” ” ” ” 26 ” ” 800 ” ” ” ” 27 ” ” The Deacon is right, and Mr. Lawes and Dr. Gilbert call especial attention to this point. The 200 lbs. of ammonia-salts contain about 50 lbs. of ammonia, and the 400 lbs., 100 lbs. of ammonia. And as I have said, 100 lbs. of ammonia per acre is an unusually heavy dressing. It is as much ammonia as is contained in 1,000 lbs. of average Peruvian guano. We will recur to this subject.