The Chemistry of Garden Crops 



is of importance, and not seldom this produces an almost magical 

 effect on an old garden soil that has been heavily cropped and 

 liberally manured. Calcareous soils are greatly benefited by a free 

 application to them of manure from the stable and cow-byre ; but as 

 a rule it would be like carrying coals to Newcastle to dress these 

 soils with lime. Clay may be put on with advantage ; and nothing 

 benefits a hot chalky soil more than a good dose of mud from ponds 

 and ditches, which supplies at once humus, alumina, and silicates, 

 and gives ' staple ' to the soil, while preventing it also from ' burn- 

 ing.' In the manuring of sandy soils great care is requisite, because 

 of their absorbing power. In the bulb-growing districts of Holland, 

 manure from cowsheds is worth the enormous price of one shilling 

 per barrow-load, for digging into loose sand for a crop of Potatoes, 

 to be followed by bulbs. This is an exceptional case, but it illustrates 

 the subject usefully. Sandy soils are generally deficient in phos- 

 phates and alkalies ; hence it will on such soils be frequently found 

 that kainit (a crude form of potash) and superphosphate of lime will 

 conjointly produce the best results, more especially in raising 

 Potatoes, Onions, and Carrots, which are particularly well adapted 

 for sandy soils. Probably one of the best fertilisers is genuine 

 farmyard manure from stall-fed cattle, for it contains phosphates, 

 alkalies, and silicates in available forms and suitable proportions. 

 For similar reasons Peruvian Guano is often useful on such soils. 

 Artificial manure should be selected with a view to correct the 

 deficiencies of the soil, and to satisfy the requirements of the crops 

 to be grown on it. 



While we have thus dealt principally with the Inorganic or 

 mineral constituents of plants, and the way in which the deficiencies 

 of the soil in respect of any of them may be supplied by artificial 

 applications, we must not ignore the other class of constituents, the 

 Organic. These are supplied almost entirely from the atmosphere 

 itself, though, to a limited extent, the presence in the soil of humus 

 or vegetable matter contributes also. Yet this latter, as seen in the 

 case of land heavily dressed with farmyard or stable manure, vegetable 

 refuse, c., exercises important functions in other directions. Not 

 only are mineral constituents, in forms available for assimilation, 

 supplied, but soils so treated derive peculiar advantages as regards 

 their mechanical state and improved physical conditions, chiefly in 

 respect of retention of moisture, warmth, &c. Thus, sandy soils, 

 which are very apt, through poverty in humus, to lose their moisture 

 readily and to ' burn,' are rendered more retentive of moisture and 



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