niESIDENTIAL ADDRESS. 545 



by rain, &c., and loet from the soil. On land laid down to grass no balance 

 is obtained : there is an excess of soil nitrogen, which at first could not be 

 explained, but was finally attributed to the activities of nitrogen-fixing 

 organisms living either in the free state, or in association with the various 

 leguminous crops. Nor is a balance obtained on arable soils heavily dressed 

 with farmyard manure, but here there is a deficit, the nitrogen in the crop being 

 consid'crably less than that given up by the manure and the soil. (Some of the 

 deficit undoubtedly arises from the loss of nitrates already discussed ; but there 

 is evidence of a further loss, which is attributed to the evolution of gaseous 

 nitrogen. It is impossible at present to draw a sharp line of demarcation 

 between these two processes in the field, and the investigation is therefore 

 being made in the laboratory. In the meantime the trouble may, however, be 

 met in two ways : 



1. The land may be left in grass for a few years so that the gain in nitrogen 

 during this period may bahmce the loss during the arable period. This is 

 already done in several rotations, but it suffers from the disadvantage that the 

 land during its recuperative grass period is producing less than during the 

 arable period. 



2. The land may be kept in arable cultivation, but the loss diminished by 

 ina-easing the efficiency of the manurial scheme, a problem that has already 

 been discussed. 



It is obvious that a knowledge of the times and ways of leakage of nitrogen 

 from the soil puts us in possession of means of reducing the wastage. Field 

 data of the kind required take a long time to accumulate because the normal 

 season that the agricultural investigator desires never seems to arrive. Only 

 when observations have gone on for a number of years can safe conclusions 

 be drawn. 



A further direction in which improvement is possible is in cultivation. 

 Reference has already been made to the necessity for increasing the speed of 

 ploughing so as to get the work forward, and enable the farmer to plough just 

 as much as he likes in autumn, or, if he wishes, to get in a bastard fallow or a 

 catch-crop. The motor plough seems the only solution, and as soon as the 

 difficulties of engine construction are got over and the price comes sufficiently 

 low, I think it must displace the horse-plough as inevitably as the railway 

 displaced the stage-coach. Both the soil and the human factors tend this way. 

 So long as a man and two horses, and in some parts of the country a man and 

 a boy and three horses, can only manage to plough an acre a day, it is obvious 

 that the farmer cannot afford to pay more than a small wage for the work ; but 

 when a man on a motor plough can do several acres a day a considerably higher 

 wage becomes possible. 



The work of ploughing can in many cases be lightened by dressings of chalk, 

 and its effectiveness increased by making a more economical use of tilths left 

 after certain crops. Experiments of this sort have been started at Eothamsted, 

 and might with advantage be made elsewhere. Cultivation is at present the 

 most empirical branch of soil management : the underlying principles are hardly 

 yet known, and the current explanations are for the most part mere guesses, 

 and sometimes not very happy guesses. We want more definitely ascertained 

 facts than we have got before we can begin to straighten out this difficult 

 subject. Further, we want better means of spreading the knowledge of good 

 implements and of testing new ones. 



The last economy to which I shall refer is the choice of crops. The farmer 

 grows his crops for profit, and clearly ought to select the most profitable for the 

 purpose. This can only be done by keeping accounts. No crop ought to be 

 grown that does not pay its way ; it should be displaced by one that does. On 

 our own farm we find that wheat, oats, and barley are about equally profitable ; 

 but the crops in the root- or fallow-break vary enormously — potatoes bringing in 

 most profit, while swedes, on the other hand, are invariably grown at a loss on 

 our land. I believe this would be found not uncom-mon in the southern part of 

 England. Amos and Oldershaw have recently gone into the cost of silage crops 

 in these conditions. More experiments and inquiries are greatly needed to 

 widen the range of this class of crops, and give us sorhething that will be as 

 useful as swedes but more profitable. 



1916 N N 



