On Liquid Manure. 547 



available fertilising substances, how is it that upon them ordinary 

 larinyard manure is employed witli advantage? To this objection 

 1 would reply : I'armyard manure, in the first place, is a more 

 perfect manure than liquid manure, inasmuch as it contains a 

 considerable proportion of soluble and insoluble phosphates which 

 are very deficient in liquid manure, and, being a bulky manure, 

 performs important mechanical functions that cannot be realised 

 by the use of a liquid. In the second place, I would observe 

 that the retentive physical characters of clay soils preclude the 

 young plant from availing itself of the total amount of fertilising 

 matters dispersed througli the whole mass of the soil. In fact, 

 plants growing on stiliish soils feed only upon a very small 

 proportion of the bulk of soil ; whilst tliose grown on a porous 

 sandy soil penetrate it to a greater depth and in every direction, 

 and avail themselves of the manuring constituents uniformly 

 distributed amongst a large bulk of soil by the agency of liquid 

 manure. In short, a porous sandy soil is a more appropriate 

 vehicle for holding liquid manure. I indeed believe that little 

 benefit would arise from the application of solid manure to clay 

 soils, if it were possible to incorporate it with the soil as uniformly 

 as liquid manure, and to the same depth to which the latter 

 penetrates them. But decided benefit results from a good dress- 

 ing with ordinary yard-manure, because, in fact, only a small 

 proportion of the soil is actually manured, and because by the 

 very bulk of the manure the physical and chemical characters of 

 a portion only of the soil are so altered that in reality the plant 

 feeds upon a new and artificially-formed soil. 



However, it is not every clay soil that encloses in its substance 

 abundant stores of plant-food; there are poor clays as well as 

 poor sandy soils, and it may be asked, Might not liquid manure 

 produce a good effect upon sterile clay land ? I do not think it 

 would produce a very marked effect, for I conceive that the 

 close texture, coldness, and want of porosity which characterize 

 sterile clays, are opposed to the successful application of liquid 

 manure. As just observed, only a small portion of such soils can 

 be penetrated by the tender roots of plants, whilst by iar the 

 larger part of the soil enriched by the liquid manure is out oi 

 their reach. Consequently most of the liquid manure would be 

 lost under these circumstances, and the small quantity left in 

 the portion of soil penetrated by the roots cannot of course 

 produce any very striking result. 



Moreover, all clay-soils are generally more than sufficiently v.et 

 during the early part of ttie^'ear ; the additional quantity of water 

 supplied in liquid manure renders them wetter still ; and as much 

 heat is absorbed during the evaporation of water, the injury 

 done to the land by the resulting cold would not, 1 imagine, be 



