264 ANNUAL OF SCIENTIFIC DISCOVERY. 



time. The best writers, both practical and theoretical, in England and 

 America, seem to incline to the first-mentioned practice, in reference par- 

 ticularly to grass and grain; and the best effects are shown to have resulted 

 from this method of the application of surface-manure. 



The practice of top-dressing, or of surface-manuring, has long been the 

 favorite method employed by all intelligent gardeners within the circle of 

 my acquaintance. "We have long ago learned that masses of rich, nitro- 

 genous manures are not what plants require about their roots; but that 

 manures are applied much more successfully (and less injuriously) by top- 

 dressing, either in solid or liquid form. Nature never manures her plants 

 with crude masses of concentrated fertilizing substances ; but imparts her 

 stimulating and mineral food in a state of the most minute division (almost 

 infinitesimal), chiefly from the surface of the earth. No wonder so many 

 fruit-trees have been killed, so many grape-vines destroyed or rendered bar- 

 ren by excess of wood, in consequence of the heavy manuring at the roots 

 so universally recommended by writers on gardening and horticulture. 



The great objection to surface-manuring is founded upon the probable 

 loss of ammonia, caused by the exposure of decaying manures upon the 

 surface of the earth. But this loss has been shown, by sound reasoning 

 and by facts deduced from practical experience, to be much less than is com- 

 monly apprehended; while the benefits arising from surface-manuring, in 

 other respects, inoVe than counterbalance any possible loss of ammonia 

 from this practice. 



In the first place, when manures are exposed upon the surface of the 

 earth, even in hot weather, decomposition no longer goes on so rapidly as 

 when the same manures are kept in a heap, and the ammonia that is pro- 

 duced is gradually carried into the soil by rains. The other soluble sub- 

 stances, as potash, lime, the phosphates, etc., are, of course, not lost, because 

 they arc not volatile. 



Nor are these soluble and valuable substances lost to plants by being 

 carried into the soil before they are needed by growing plants. It has 

 been conclusively shown by eminent scientific authorities, that any good 

 soil, containing a fair proportion of clay and carbon, is capable of taking 

 up and retaining effectually, ammonia, lime, potash, soda, etc., in a soluble 

 form, so that little, if any, passes off in the underdrainage water of such 

 soils. These substances, it is true, may Avash from the surface, but they 

 cannot pass through a good soil, and go off in the drainage water. 



By surface-manuring, we mulch the ground, and render it cooler in sum- 

 mer and warmer in winter. Mere shade is an important element in culture, 

 so important, that some writers have thought shade alone to be equivalent 

 to manure. A piece of soil heavily shaded by surface-manuring, actually 

 decomposes like a manure heap; that is, it undergoes a sort of putrefaction 

 or chemical change, which sets free its chemical constituents, unlocks, as 

 it were, its locked-up manurial treasures, and fits its natural elements to 

 become the food of plants. Darkness, moisture, and air, are the conditions 

 required for vegetable and mineral decomposition. These conditions are 

 produced in the soil by surface-manuring. 



Then, again, when the surface-manure decomposes, its elements are washed 

 into the soil, in a state of solution precisely fitted to meet the wants of 

 plants, and they become themselves active agents in promoting further 

 decomposition and chemical changes in the entire body of the soil. 



Manure then, I say, chiefly upon the surface. Do not waste your manures 



