SECTIONAL TRANSACTIONS.— A[. 429 



2. Discussion on Cultivation Methods. 



Prof. J. A. S. Watson, Mr. W. J. Malden, Mr. J. R. Bond, 

 Dr. B. A. Keen, Mr. Newman. 



One of the most striking facts about tillage is that we of to-day know little more 

 of the essential principles than has been known for centuries. To a limited extent 

 science is able to explain, in terms of colloids, surface action and so on, facts that 

 have been a matter of common experience to countless generations of farmers — that 

 land which is ploughed too wet will dry into hard clods ; that these clods can be most 

 readily crumbled after frost, or after they have been dried and again moistened, or 

 that moisture will rise in a fine and firm tilth. Science, too, has shown that the 

 physical condition of the soil can be influenced by the addition of chemical flocculents, 

 but in the main we still rely, like our forefathers, on frost and drought and rain to 

 produce the results that we desire, and when these fail us we must resort, as they did, 

 to main force, exerted through crude and clumsj' implements. 



Such improvements as have been made in these implements have been arrived at 

 by purely empirical methods, without any fundamental knowledge of the problems 

 involved. A large amount of research in soil physics will have to be carried out 

 before we can state the problems of tillage in terms that our engineers can under- 

 stand. In the meantime we have the rather urgent practical problem before us of 

 cheapening and improving our processes. 



In this country, with its particular circumstances of soil and climate, the culti- 

 vator's immediate object may be to produce any one of four conditions of the soil : 

 these are distinguished as (a) winter furrow, (b) summer clod, (c) seed bed and 

 (d) summer tilth. 



In the case of the first the objects are chiefly two. The soil must be inverted so 

 as to expose a fresh layer to the action of weathering agents. Incidentally the surface 

 so exposed should be as great as possible. Secondly the surface layer or soil proper 

 should be left in an open condition so that rain may readily percolate through it. 

 This permits the aeration and weathering of the upper layers and ensures the storage 

 of the winter rain over against the needs of the next season's crop. For the production 

 of these conditions the plough, in particular the older long-breasted type, must be 

 regarded as a very satisfactory implement. 



(6) The object of the summer clod condition is to kill root weeds by a process of 

 desiccation. This is done by producing the negation of a tilth, a condition where 

 the upper soil is in large hard clods having as little contact as may be with the subsoil. 

 Here again the plough, properly used, is an efficient tool. 



(r) It is in the preparation of the seed bed that our existing farm implements so 

 often fail us. In the ordinary case what is desired is to commmute and aerate the soU, 

 and remove root-weeds while retaining the ' frost mould ' on the surface. In practice 

 the farmer is faced with the alternative of ploughing or of relying entirely on tined 

 implements. In the former case he buries the winter mould and brings raw clods to 

 the surface ; in the latter he may find that he has to cross and recross his land so 

 often that the bottom is trodden and pressed hard. What he needs is a machine that 

 will break down clods, aerate the lower layers and drag out root weeds without inverting 

 the soil. Above all he wants something which will do more in a single operation than 

 anything that is now available, in order that the disadvantages of drying out and 

 treading may be avoided. For two generations men's hopes have centred round 

 some form of power rotary tillage, and at the moment it seems that this is at the 

 point of practical success. 



(d) As regards summer tilth, the preservation of a loose mulch on top of a firm fine 

 soil has always been regarded as the essential principle. It is possible that the 

 importance of this mulch has been exaggerated in the past, but in practice a mulch 

 is often mamtaiued automatically in the process of weed control. The problem of 

 ' crusting ' at the time of germination of the seed has an undoubted importance, but 

 it seems almost impossible to devise any sure preventive. 



There is one more general aspect of the tillage problem that must receive con- 



ideration. Changes in the relative costs of man power and other forms of power 



have made it necessary to reorganise our labour units. Our normal working group, 



a ploughman with a pair of slow-moving horses, is no longer economical. If we are 



to keep our land under cultivation we must equip and train our labourer to earn his 



