PRESIDENTIAL ADDRESS. 543 



nitrate, and partly also apparently because the growing croip seeing to interfere 

 witli bacterial activity. But in autumn, "when the crop is off, there is a great 

 rise in nitrate production, which becomes particularly marked if the land is 

 broken up immediately and given a late fallow. Finally, in early winter the 

 soil is left with a large amount of nitrate. If the soil lies bare through the 

 winter the nitrate is lost ; last winter the December and February rains were 

 specially disastrous, so that when spring came in we were left on' some of 

 our plots with only 40 lb. of nitrogen as nitrate out of an autumn stock of 

 70 to 100 lb. — having lost no less than 30 lb., and on some of the plots con- 

 siderably more, during the winter. 



Unfortunately the heaviest loss falls on the best manured land, and tlie 

 crops tliat suffer most are those like wheat or oats, that are grown on the 

 residues of the previous year's dressings. Some years ago Sir Napier Shaw 

 startled agriculturists by stating that every inch of rain falling during the 

 months of September, October, and November caused a falling-off of two bu.«hels 

 of wheat per acre from an ideal standard of 46 bushels per acre over the whole 

 of the Eastern Counties. There can be no doubt that the washing out of 

 nitrates is an important factor in this fall, and it is no exaggeration to say 

 tliat our losses from this cause are enormous. All this, of course, emphasises 

 the need of spring dressings of quick-acting nitrogenous manures, and accounts 

 for the marked improvements that set in on many soils when spring dressings 

 are given. 



A good way of getting round this difficulty is to sow a catch-crop in 

 autumn, and either to plough it in before the main crop is eown or to feed 

 it to stock, whichever is the more convenient. The practice is an old one, 

 hut, apart from the usual case of sowing clover in the growing corn, it is not 

 very common ; there are several practical difficulties, chiefly arising from the 

 dryness of the ground at harvest time. This can be met by sha,llow cultiva- 

 tions immediately the corn is cut, and without waiting for it to be carried. 

 The problem is under investigation. At Rothamsted we find mustard answers 

 very well ; it grows more easily than most other things do in September, and 

 it has a great capacity for taking up nitrates. Trifolium is also valuable 

 where it will stand the winter. It likes a firm seed bed, so that it only 

 wants harrowing in to the stubbles, and it not only takes up nitrate, but it 

 can fix nitrogen as well, though we do not know how far it actually does so 

 under these conditions. In Belgium carrots and turnips are both grown as 

 catch-crops. Carrot seed is broadcasted in winter wheat just before the ears 

 begin to form, and, although it can neither be rolled nor harrowed in, it has 

 no difficulty in germinating ; by the time the wheat is cut the plant is already 

 established, and it is about 2^ to 3 inches high. It is stiU weak^ but after 

 a harrowing to tear out weeds, and, if necessary, a dressing of liquid manure, 

 it begins to grow more vigorously, and finally yields a valuable crop. 

 Turnips are sown after harvest. The corn stocks are set in rows so as to 

 leave fairly wide strips of the field, which are at once lightly ploughed ; the 

 seed is then sown, and the land harrowed down and rolled. The strips on 

 which the stocks were placed are similarly sown at the earliest opportunity. 

 It is essential, however, that the ploughing and harrowing should be done 

 immediately after cutting, as otherwise soil moisture is lost, and germination 

 may not take place. A dressing of phosphate is usually given. 



It thus appears that the wastage of nitrates in winter can be greatly reduced, 

 but the process requires suitable crops and rapid cultivation methods. Neither 

 oi these ought to be beyond the power of the agriculturist to provide. TW 

 possibilities are many. Wibberley has discussed several schemes of continuous 

 cropping that satisfy these requirements, giving a succession of crops which 

 cover the land at the critical time when losses would occur. And our implement 

 makers are steadily increasing the number and effectiveness of the implements, 

 while motor traction promises also to increase the speed of working. 



Our experiments indicate two difficulties, which, however, ought not to be 

 beyond control : — 



1. This close succession of crops reduces the opportunities of fallowing and 

 cleaning the land. A fallow seems to have an effect on the soil nothing else can 

 quite produce. Thus in the season of 1913 the yields on the Hoosfield barley 



