CHEMISTRY IN RELATION TO HORTICULTURE. 



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gradually. Where, on the other hand, clover is not desired, but grass 

 only, then the potash should be omitted ; and if rapid growth of grass 

 be required, then" the more active forms of nitrogenous manures may be 

 applied. 



A material that came under my notice, and which was sold as 

 " lawn sand," was found to be nothing more than sand with sulphate of 

 ammonia added. Basic slag is a manure that has lately come much into 

 use for grass land, and answers particularly well on poor heavy clays, the 

 effect produced by it on the herbage being in many cases very remarkable. 

 It is impossible, however, to tell with any certainty beforehand whether 

 basic slag is likely to succeed or not, and this should always be a matter 

 for experimental trial on a small scale first. For garden crops I am 

 inclined to question its value, as also for the corn crops of the farm, it 

 being slow in its action, and I consider that it is most usefully employed 

 on grass land of the kind above stated. 



Of the value of lime I have already spoken, and either alone or in a 

 compost heap with earth it forms a most valuable material for improving 

 the mechanical condition of the soil, rendering heavy soil lighter and 

 imparting needed "substance" to light and sandy soils. Pond mud, 

 sewage sludge, nightsoil, and the like, have the objection of being, as a 

 rule, difficult to handle, and their best destination is generally the com- 

 post heap, which will receive, together with them, vegetable refuse of 

 every kind, and by mixing with lime and occasional turning over form 

 a useful mixture for top-dressing purposes. For destruction of weeds on 

 land, or on compost heaps, gas lime is a useful substance, but care must 

 be taken when it is spread on land that it be thoroughly exposed for some 

 weeks and not come in contact with any growing crop, or the injurious 

 ingredients it contains will be sure to kill the crop. The value of soot 

 consists, from a manurial point of view, in the sulphate of ammonia which 

 it contains, added to which it undoubtedly possesses other qualities which 

 make it destructive of insect life. Salt is frequently employed for plants 

 such as cabbage and mangel, and exercises a useful function in attracting 

 moisture. 



Were I to enter into a description of the different fertilisers which 

 are in common use or have been put forward for horticultural purposes, 

 I should have to write a separate paper on this subject alone. Suffice it, 

 for the present, to say that some of them are undoubtedly good, some of 

 doubtful value, and others not worth anything like what is charged for 

 them. Of all the materials which most nearly represent a general manure 

 like farmyard manure, but supplying the ingredients in concentrated form, 

 Peruvian guano is the best, and this is perhaps the most common con- 

 stituent in special horticultural manures. It has often been urged, and 

 with some reason, that horticultural manures are sold at extravagantly 

 high prices in no way approximating to their actual cost. This is, no 

 doubt, true in many cases, but, strong opponent as I am of " specialities " 

 in fertilisers, and doubtful as I am in general of their particular virtues> 

 it is yet right to point out that the conditions of preparation, sale, and 

 distribution of these is very different from what obtains in the sale of 

 fertilisers for farm crops and for use on a large scale. One must not 

 expect to get a tin or a packet of some fertiliser at anything like the rate 



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