HORTICULTURAL SOILS. 



71 



The analysis of the soil shows that it contains the vast 

 quantity of 640,000 lbs. per acre of organic matter when cut to 

 9 inches deep, and gives 11,650 lbs. of nitrogen per acre. Such 

 fibrous-rooted soils as the Ghent heath mould are of a light 

 texture, and peculiarly suited to the growth of most greenhouse 

 and conservatory plants. Their peculiar property is that they 

 facilitate drainage and aeration, causing a quick and active 

 growth with a free development of feeding roots ; and thus are 

 especially fitted for composting with other and stiffer descriptions 

 of soils. 



The soil, then, as it results by the processes thus briefly 

 indicated is a compound of coarse and fine materials, mixed with 

 clay, silica, and chalk ; together with a greater or smaller 

 amount of organic matter, holding a variable but usually large 

 quantity of moisture. 



Further, a soil rich in organic humus matter is rich in 

 nitrogen ; while a soil poor in organic substance is poor also in 

 nitrogenous plant-food ; and the permanent fertility of a soil is 

 found to be very closely connected with its power of retaining 

 plant-food. 



Table IV. illustrates the percentage amount of five selected 

 constituents — organic matter, nitrogen, potash, lime, and phos- 

 phoric acid — in seven widely different descriptions of soil. The 

 quantities quoted are in water-free soils. 



TABLE IV — Selected Chemical Constituents in Different Descriptions 

 of Soil. Quantities in 100 pounds of each, dry. 





Ordinary 

 average 

 loam 



Garden 

 bedding 

 loam 



Rich 

 garden 

 loam, 



[Rich 



pasture 

 soil 



Leaf 

 mould 



Peat 

 mould 

 (France) 



Heath 

 mould 

 (Ghent) 



Organic matter 



% 

 3-84 



% 

 4-05 



% 

 8-46 



% 

 14-55 



% 

 17-00 



% 

 18-80 



% 

 64-00 



Nitrogen . 



0-13 



0-23 



0-45 



0-59 



0-47 



1-40 



117 



Potash . 



0-20 



0-33 



0-73 



0-75 



0-50 



0-31 



014 



Lime 



0-66 



0-67 



2-08 



1-20 



0-18 



0-53 



0-35 



Phosphoric acid 



0-12 



0-48 



o-io 



1-00 



0-13 



0-20 



0-16 



The analytical results show that the proportion of plant- food 

 present in soils is very small, even when the land is extremely 

 fertile, the bulk of the soil serving chiefly as a support to the 

 growing crops and as a sponge to hold water for their use. 



