Analyses of Ashes of Plants. 



137 



formed from the debris of the firsts follows almost as a natural 

 consequence. But though it is quite possible that from the uni- 

 versal prevalence of the most important mineral constituents of 

 cropsj sufficient working of the soil would enable us to dispense 

 with the addition of any artificial manures — it may be, and is^ far 

 more economical at the present time to supply the requisite dose 

 of mineral matter directly, than to seek to furnish it from the 

 natural resources of the soil by a costly expenditure of mechanical 

 force. It must be observed, however, that there are other ways 

 of bringing into play the dormant energies of the land, besides 

 deep and subsoil plouglnng and trenching. Some plants have an 

 extraordinary capacity and disposition to seek food at great depths 

 in the soil — not vegetable food, for there is none in such situa- 

 tions, generally speaking, to be had, but mineral food ; — for this 

 they will send down their roots, in many cases, to many times the 

 depth which the most enthusiastic advocate of subsoiling would 

 hope to attain — and in their subsequent growth at the expense of 

 so distant a source of nourishment they effect a far more important 

 chemical addition to the surface soil than the subsoil plough 

 could accomplish. 



The perfection of a fallow crop, either root or otherwise (other 

 circumstances of facility of cultivation, amount and feeding pro- 

 perties of the crop being equal), would be that which, whilst 

 requiring for the completion of its own structure a considerable 

 quantity of valuable mineral ingredients, should be possessed of 

 an energy and power of obtaining them quite independent of any 

 extraneous supply in the shape of artificial manures. In other 

 words, a scientific review of the conditions of vegetable growtli, 

 apart from circumstances of practical detail, would indicate as the 

 best fallow crop a plant with large spreading leaves, strong pene- 

 trating roots, and nutritive qualities in the feeding of stocky pro- 

 vided that at the same time its ash were in quantity and composi- 

 tion such as would benefit the cereals for which it is intended to 

 prepare the food. 



Of this latter point there would be little fear, supposing that the 

 plant was really superior in feeding properties ; for an examination 

 of the evidence at present existing in reference to the ash of plants, 

 amply demonstrates that those parts of plants (such as the seeds 

 of the cereals) which owe their high nutritive powers to the large 

 quantity of nitrogenized bodies (gluten, albumen, &c.) they con- 

 lain, are also proportionably rich — invariably so— in phosphates of 

 lime, magnesia, and potash. 



This question then might be resolved by either of two methods 

 of investigation. It might be decided practically — that is, it might 

 be ascertained by observation and experiment in the field what 



