HORTICULTURAL JOURNAL. 275 





the decomposition of organic matter in the soil, rendering them both avail- 

 able as food for plants. Again, the rain, as it falls and filters through a 

 well-drained, loamy soil, carries. to the plants one of the most needed and 

 expensive of all the constitaents of cereal crops. Our readers need not be 

 told that we mean ammonia. In our article on the Plowing in of Green 

 Crops, in the June number of 1852, will be found some of our reasons for 

 thinking ammonia the most valuable and necessary ingredient in all wheat 

 soils. The rain water which falls on an acre of land in a year, is estimated 

 to contain over 100 lbs. of ammonia, or sufficient for the growth of 17 

 bushels of wheat. The recent experiments of Way and Thompson have 

 shown that when ammonia is filtered through a soil containing a good pro- 

 portion of clay, the ammonia is retained in the soil, and the water passes 

 through free from it. Does this throw no light on the cause of the increased 

 crops following thorough underdraining? The other causes we have mention- 

 ed are merely concomitants. It is well known that mechanical texture of 

 soil, moisture, heat, electricity, and sunshine, indispensable as they are, will 

 not grow crops unless the required constituents of plants are present in the 

 soil in proper quantity an I quality. Does it throw no light on the benefi- 

 cial effects of summer-fallow on heavy clays. To our mind it gives a satis- 

 factory explanation to these questions that is consistent with experience and 

 well established scientific principles. It is simply, that the ammonia con- 

 tained in rain water is retained by the soil as the water .slowly percolates 

 through it to the drains beneath. In the case of a summer-fallow, the con- 

 stant plowing, dragging, &c., divides the particles of the soil, for the first 

 few inches in depth, so fine that they are capable of retaining all the am- 

 monia brought to the soil during the year on which it is summer-fallowed. 

 This ammonia it retains for the succeeding wheat crop. But even in this 

 case, if the land needs drainage, (and what land that should be summer-fal- 

 lowed does not ?j the full benefit i3 not obtained ; all the rain which falls in 

 the spring, autumn, and winter, when the soil is fully saturated, passes off in 

 surface water, the ammonia it contains along with it, together with a consid^ 

 erable quantity of matter taken from the soil in mechanical solution. 



The cost of underdraining is the most potent argument against its adop- 

 tion. Thirty dollars is considerable money to invest on an acre of laud; 

 but it must be remembered that it is -a, permanent investment — when once 

 well done it will last a century or more. It is not like laying out $7 per 

 acre in guano or other manure, which lasts but for one year, or two at 

 most. It is a perpetual means of obtaining increased crops. The 100 lbs., 

 of ammonia contained in the rain which falls on an acre per annum, cannot 

 be purchased in guano, its cheapest artificial source, for less than $15. 



