The Chemistry of Garden Crops 



tained by burning. On the other hand, chalk, which is a more recent 

 form of carbonate of lime, is often highly productive, more especially 

 where, through long cultivation, it has been much broken up, and has 

 become loamy through accumulation of humus. Between the oldest 

 limestone and the latest chalk there are many intermediate kinds of 

 calcareous^ soils, and they are mostly good, owing to their richness in 

 phosphates, the products of the marine organisms of which these 

 rocks in great part, and in some cases wholly, consist. For the 

 growth of cereals these calcareous soils need a certain proportion of 

 silica, and where they have this we see some of the finest crops 

 of Wheat, Trifolium, Peas and Beans in these islands. If we could 

 mix some of our obdurate clays with our barren limestones, the two 

 comparatively worthless staples would probably prove remarkably 

 fertile. Although this is impossible, a consideration of the chemistry 

 of the imaginary mixture may be useful, more especially to the 

 gardener, who can in a small way accomplish many things that are 

 impracticable on a great scale. Sandy soils are characterised by 

 excess of silica, and Deficiency of alumina, phosphates and potash. 

 Here the mechanical texture is as serious a matter as it is in the case 

 of clay. The sand is too loose as the clay is too pasty, and it may 

 be that we have to prevent the estate from being blown away. It is 

 especially worthy of observation, however, that sandy soils are the 

 most readily amenable of any to the operation of tillage. If we 

 cannot take much out of them, we can put any amount into them, 

 and it is always necessary to calculate where the process of enrich- 

 ment is to stop. It is not less worthy of observation that sandy soils 

 can be rendered capable of producing almost every kind of crop, save 

 cereals and pulse, and even these can be secured where there is 

 some basis of peat or loam or clay with the sand. The parks and 

 gardens of Paris, Versailles, Haarlem, and Berlin are on deep sands 

 that drift before the wind when left exposed for any length of time 

 with no crop upon them; and not only do we see the finest of 

 Potatoes and the most nutritious of herbage produced on these 

 soils, but good Cauliflowers, Peas, Beans, Onions, fruits, and big 

 trees full of sound timber. It would be inaccurate to say that any 

 soil is beyond improvement, for the plough has found its way to 

 the foot of Stonehenge, where only a hundred years ago cultivation 

 was declared impossible, and on the granite of Dartmoor we may 

 now see a fine grass sward where not long since the only vegetation 

 comprised lichens and mosses. The farming and gardening at 

 Prince Town owe their success in great part to the judicious use of 



