“What he means,” said the Doctor, “is this: If you put a quantity of soluble and available manure on land, and do not sow any crop, the manure will not be wasted. The soil will retain it. It will change it from a soluble into a comparatively insoluble form. Had a crop been sown the first year, the manure would do far more good than it will the next year, and yet it may be that none of the manure is lost. It is merely locked up in the soil in such a form as will prevent it from running to waste. If it was not for this principle, our lands would have been long ago exhausted of all their available plant-food.” “I think I understand,” said the Deacon; “but if what you say is true, it upsets many of our old notions. We have thought it desirable to plow under manure, in order to prevent the ammonia from escaping. You claim, I believe, that there is little danger of any loss from spreading manure on the surface, and I suppose you would have us conclude that we make a mistake in plowing it under, as the soil renders it insoluble.” “It depends a good deal,” said I, “on the character of the soil. A light, sandy soil will not preserve manure like a clay soil. But it is undoubtedly true that our aim in all cases should be to apply manure in such a form and to such a crop as will give us the greatest _immediate_ benefit. Plowing under fresh manure every year for wheat is evidently not the best way to get the greatest benefit from it. But this is not the place to discuss this matter. Let us look at the result of Mr. Lawes’ experiments on wheat the third year:” Experiments at Rothamsted on the Growth of Wheat, Year After Year, on the Same Land. Table III.--Manures and Produce; 3rd Season, 1845-6. Manures and Seed (Old Red Lammas), Sown Autumn, 1845. Manures FM Farmyard Manure. A3W Ash from 3 loads (3,888 lbs.) Wheat-straw. LWM Liebig’s Wheat-manure. PG Peruvian Guano. SPL Superphosphate of Lime. SiP Silicate of Potass.[1] P-A Pearl-ash. S-A Soda-ash. MLS Magnesian Lime-stone. B-A Bone-ash. SAc Sulphuric Acid (Sp. gr. 1-7.) MAc Muriatic Acid. SAm Sulphate of Ammonia. MAm Muriate of Ammonia. RC Rape-Cake.