462 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



GARDEN MANURES. 



By Feedeeick J. Bakee, F.R.H.S. 



[Read August 27, 1901.] 



Foe the purposes of this lecture it is felt that something difierent from 

 tables of analyses and accounts of experiments v/hich have been tried 

 and reported many hundreds of times is desirable. Yet we do not want 

 far-flown theories. We rather seek to give a few well-proved facts which 

 are either not so well understood as is desirable, or their importance not 

 sufficiently appreciated. Science has done much, very much, to help the 

 practical cultivator ; yet a misconception of its real teachings has led to 

 many errors, foremost among which, probably, are the fallacies respecting 

 plant ash. One has heard it stated that in the near future the cultivator 

 would only have to get his soil analysed and then turn to tables of the 

 composition of the crops he wished to grow to supply what is lacking, 

 and all would be well. Alas ! that such statements should ever have been 

 made. Our knowledge respecting the ashes of plants is useful if con- 

 sidered Avith several other factors, and the whole tested. We know that, 

 although the most abundant constituent of the much-used superphosphate 

 is a compound of lime, yet it is essential that another form of lime should 

 exist in the soil to render the whole harmless, i.e. to neutralise the 

 acidity. 



In dealing with manures our first consideration should be tJie soil. 

 This must supply, under ordinary conditions, both a home and food for 

 the plants. Manures should supply what is deficient. The fact does nut 

 seem to be sufficiently realised that every rod of ordinary soil to a depth 

 of 1 foot contains upwards of 20 lb. of each of all the important 

 ingredients of plant food {i.e. N, P, K), and most garden soils very much 

 more, or, in other words, sufficient for all the j)lants which vdll grow there 

 for many years. This large amount is of course chiefly in an inert con- 

 dition, although it may, by suitable means, be brought into an available 

 form. In order that plant food may be taken up by plants, it must be 

 soluble and diffusible. 



Water is necessary to carry it into the plant. This is most essential. 

 Hence for the well-being of plants we must have a suitable soil ; well 

 aerated, containing sufficient moisture, not too much, or it will prevent 

 the soil being aerated, and not too little, or the soil Avill hold it too 

 tenaciously and plants will wilt, although there be some water in the 

 soil. Given these and other necessary conditions, the plant mil take in 

 such food as is available, or can be made so by the plant. How, then> 

 may we Avork the soil, that it may be the best possible home for plants ? 

 It must be in a good physical condition, pervious to air and water, yet 

 retentive, holding water and plant food in such a manner that plants can 

 absorb them. The two chief means of getting it into this condition are farm- 

 yard or other organic manure and tillage. Here let us emphasise the 

 fact that the special merits of organic manures are the alterations which 



