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The Country Gcntkiiuxiis Magazine 



on the contrary, do harm by stimulating tlie plant, 

 drawing the plant, and resulting in mildewed straw 

 and shrivelled grain. Nitrate of soda is valuable on 

 all those soils which are rich in mineral foorl ; hence 

 its action on clays. The best time to apply it is to- 

 wards the middle or end of March. In order to de- 

 termine the effect, it is well to miss a land ; the differ- 

 ence will be perceptible till harvest. Nitrate of .soda is 

 principally obtained from Chili and Peru ; it is a white 

 crystalline salt, very soluble in water, and readily at- 

 tracting moisture from the atmosphere. It is so soluble 

 that its effects have been seen without rain, the dew 

 being sufficient to dissolve it. It loses nothing by ex- 

 posure ; but the first shower carries it to the roots. 

 Commercial nitre is considered good wlien it does not 

 contain more than five per cent, of impurities. It is 

 a cheap form of nitrogen when it can be obtained at 

 ^15 a ton. 



C;ommon salt is useful in many ways. We can trace 

 its action under at least four different heads. It acts as 

 a direct manure, supplying soda and chlorine ; but, as 

 most soils contain abundance of both, it is not thus 

 that salt is chiefly valuable. Indirectly, salt increases 

 the solubility of certain silicates, hence its value in 

 conjunction with nitrate of soda ; and it is well known 

 that in many cases the addition of salt strengthens and 

 lightens the straw, clearly owing to an increased secre- 

 tion of silica. This may be effected in two ways. 

 When the soil contains carbonate of lime a double de- 

 composition ensues, carbonate of soda and chloride of 

 calcium being formed. Silica is soluble in carbonate 

 of soda. .Secondly, silicate of ammonia is more 

 soluble in a solution of salt than in water. A third 

 action of salt, which is of great importance on sandy 

 soils, consists in its property of retarding growth, and 

 thus prolonging vegetation and preventing premature 

 ripening, a frequent source of loss on hot forcing soils. 

 Lastly, salt absorbs moisture. In addition to the 

 above, a dressing of salt on clover ley, or on corn 

 stubbles, checks and destroys insect life. For this 

 purpose a dressing of 4 cwt. to 5 cwt. per acre may be 

 applied. 



PHOSPHATIC MANURES. 



The most important groups of artificial manures are 

 those in which soluble phosphate of lime forms the 

 presiding element. The influence of phosphates on 

 the growth of our green crops is remarkable. Bones 

 have been used as a dressing from an early period. It 

 was I^iebig who first pointed out that by the addition of 

 sulphuric acid the insoluble or only slowly soluble 

 would be changed into a more efficient substance. 

 The action of the acid will ])e readily understood. 

 There are several forms of phosphate of lime, the 

 solubility depending upon the proportion of acid to 

 base. In bones it exists as tricalcic phosphate. Sul- 

 phuric acid, by uniting with a portion of the lime, 



and taking it away from the phosphoric acid, converts 

 tricalcic into monocalcic phosphate. If an excess of 

 acid be used, nearly, but not the whole, of the phos- 

 phate is rendered soluble. The superiority of fresh or 

 boiled bones for the manufacture of superphosphate 

 over mineral phosphate, coprolites, and even burnt 

 ])ones, depends upon two points ; first, that the in- 

 soluble portion, which generally exists to the extent of 

 7 to 8 per cent., is capable of being gradually utilised 

 in the soil, whereas, as far as we know, the insoluble 

 from mineral sources is useless, because not capable of 

 solution in the soil ; secondly, because fresh bones 

 contain an appreciable quantity of nitrogen, which 

 adds considerably to value. Soluble phosphate, from 

 whatever source, is equally valuable ; hence, if we can 

 render all soluble, we shall have a valualjle manure, 

 whether from bones or coprolite. In order to dissohe 

 all or nearly all the phosphate, we must use a quantity 

 of acid that will make tlie mass semi-fluid, and manu- 

 facturers frequently use fresh bones finely ground as 

 driers ; such a plan ensures a high-quality manure. In 

 this way, and by the judicious mixture and due me- 

 chanical preparation of various materials, the manufac- 

 turer can produce a better manure, at less cost than can 

 be made by the farmer. And by the aid of chemical 

 analysis the purchaser can protect himself and ensure 

 money's value. It should always be remembered that 

 by analysis alone can wo. judge of a manure. We 

 cannot distinguish the good from the bad by colour, 

 feel, taste, or smell. The most eyeable manures are 

 often the least valuable. Varying with local condi- 

 tions, we ought to have a good bone phosphate made 

 from a mixture of fresh and burnt bones, containing 

 23 to 25 soluble, and 7 to 10 per cent, of insoluble, 

 with I ^ to 2 of nitrogen, at £(:>, 5s. to £6, los. a ton. 

 A mineral phosphate should yield 28 to 30 per cent, 

 of soluble, and 3 to 4 of insoluljle phosphate, and 

 should be bought at _;^5, los. to_;^6. Our advice is to 

 purchase only of men of known character, liuy by a 

 guaranteed analysis, and under an agreement that a 

 deduction pro rata shall be made if the manure is not 

 equal to representation, and send a fair sample from 

 bulk for analysis. The Royal Agricultural Society 

 offers great advantages to its members ; not the least, 

 the analysis of their manures, &c., at half the ordinary 

 commercial charge. 



Phospho-guano, which has been extensively used, is 

 an example of a highly soluble phosphate combined 

 with ammonia. Its base is a mineral phosphate, 

 found as a crust on certain trap rock islands within the 

 tropics. The following analysis has been recently 

 made, and proves the high value of Pho.spho-guano. 

 The present price is, we believe, about £i\ a ton. 

 How far the mixture of a good superphosphate with a 

 portion of Peruvian guano will compare as to price 

 and effects, is a question which farmers should deter- 

 mine for tliemselves h\ experiment. Phospho-guano 



