On Liquid Manure. 27 



centage of potash and soda in both is far from what it ought 

 to be in order to meet the wants of growing plants. Taking 

 potash, soda, and magnesia together, there is not quite a half per 

 cent, in these soils, and probably the major part of this fractional 

 percentage consists of magnesia. Sulphuric acid likewise is want- 

 ing in both soils. In short, both are poor soils that require to 

 be heavily manured before they can be made to yield a respect- 

 able crop, and that soon return to their natural sterile state when 

 the usual dressings of manure are withheld. 



Hungry soils of such and similar composition are grateful for 

 almost any kind of manure, for, as they are greatly deficient in 

 plant-food, manures that contain even small quantities of phos- 

 phoric acid or alkalies must produce a beneficial effect. The 

 poorer the soil the more striking will be the effect which the 

 manure produces, and the more diluted may the latter be before 

 it ceases to produce any visible effect. A liquid which is 

 very poor in these fertilizing constituents, when applied to land 

 which contains already potash, lime, phosphoric acid, and other 

 mineral substances required by plants, though possibly in deficient 

 quantities, may not make any perceptible impression, simply be- 

 cause it does not materially increase the original store of the 

 available fertilising substances in the soil ; whilst the same liquid, 

 when put upon land that contains no phosphoric acid whatever, 

 and a much smaller proportion of lime, potash, &c., than is con- 

 tained in the liquid manure, will produce a striking effect, in- 

 asmuch as the fertilizing constituents in the manure materially 

 increase the store of plant-food in the sail. 



Several of the liquid manures which I examined, compared 

 with other fertilisers, are poor manures. For the reasons just 

 mentioned liquid manure of this description cannot produce 

 any marked effect upon naturally fertile land, but on poor sandy 

 soils it unquestionably may be used with very great benefit. 



Nay, I think it can be shown (and experience confirms me in 

 this) that liquid manure in a concentrated state would act in- 

 juriously upon the vegetation on most soils which are benefited 

 by liquid manure, and that the more sterile and sandy the soil 

 naturally is, the greater the necessity for diluting the manure. 



Under ordinary circumstances it is the soil that furnishes to 

 plants a considerable proportion of the mineral matters which are 

 left behind on reducing them to ashes. As a rule the manure, in 

 addition to nitrogenised substances and other organic constituents, 

 is required to supply in preference those mineral matters which, 

 like phosphoric acid or potash, are generally sparingly distri- 

 buted through the soil. The natural resources of mineral plant- 

 food vary greatly in quantity and in quality in different soils. 

 In most, the more common fertilizing materials, such as lime and 



